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podman-farm-build(1) General Commands Manual podman-farm-build(1)

NAME
podman-farm-build - Build images on farm nodes, then bundle them into a
manifest list

SYNOPSIS
podman farm build [options] [context]

DESCRIPTION
podman farm build Builds an image on all nodes in a farm and bundles
them up into a manifest list. It executes the podman build command on
the nodes in the farm with the given Containerfile. Once the images are
built on all the farm nodes, the images will be pushed to the registry
given via the --tag flag. Once all the images have been pushed, a mani-
fest list will be created locally and pushed to the registry as well.

The manifest list will contain an image per native architecture type
that is present in the farm.

The primary function of this command is to create multi-architecture
builds that will be faster than doing it via emulation using podman
build --arch --platform.

If no farm is specified, the build will be sent out to all the nodes
that podman system connection knows of.

Note: Since the images built are directly pushed to a registry, the
user must pass in a full image name using the --tag option in the for-
mat registry/repository/imageName[:tag]`.

OPTIONS
--add-host=hostname[;hostname[;...]]:ip
Add a custom host-to-IP mapping to the container's /etc/hosts file.

The option takes one or multiple semicolon-separated hostnames to be
mapped to a single IPv4 or IPv6 address, separated by a colon. It can
also be used to overwrite the IP addresses of hostnames Podman adds to
/etc/hosts by default (also see the --name and --hostname options).
This option can be specified multiple times to add additional mappings
to /etc/hosts. It conflicts with the --no-hosts option and conflicts
with no_hosts=true in containers.conf.

Instead of an IP address, the special flag host-gateway can be given.
This resolves to an IP address the container can use to connect to the
host. The IP address chosen depends on your network setup, thus there's
no guarantee that Podman can determine the host-gateway address auto-
matically, which will then cause Podman to fail with an error message.
You can overwrite this IP address using the host_containers_internal_ip
option in containers.conf.

The host-gateway address is also used by Podman to automatically add
the host.containers.internal and host.docker.internal hostnames to
/etc/hosts. You can prevent that by either giving the --no-hosts op-
tion, or by setting host_containers_internal_ip="none" in contain-
ers.conf. If no host-gateway address was configured manually and Podman
fails to determine the IP address automatically, Podman will silently
skip adding these internal hostnames to /etc/hosts. If Podman is run-
ning in a virtual machine using podman machine (this includes Mac and
Windows hosts), Podman will silently skip adding the internal hostnames
to /etc/hosts, unless an IP address was configured manually; the inter-
nal hostnames are resolved by the gvproxy DNS resolver instead.

Podman will use the /etc/hosts file of the host as a basis by default,
i.e. any hostname present in this file will also be present in the
/etc/hosts file of the container. A different base file can be config-
ured using the base_hosts_file config in containers.conf.

--annotation=annotation=value
Add an image annotation (e.g. annotation=value) to the image metadata.
Can be used multiple times.

Note: this information is not present in Docker image formats, so it is
discarded when writing images in Docker formats.

--authfile=path
Path of the authentication file. Default is ${XDG_RUNTIME_DIR}/contain-
ers/auth.json on Linux, and $HOME/.config/containers/auth.json on Win-
dows/macOS. The file is created by podman login. If the authorization
state is not found there, $HOME/.docker/config.json is checked, which
is set using docker login.

Note: There is also the option to override the default path of the au-
thentication file by setting the REGISTRY_AUTH_FILE environment vari-
able. This can be done with export REGISTRY_AUTH_FILE=path.

--build-arg=arg=value
Specifies a build argument and its value, which is interpolated in in-
structions read from the Containerfiles in the same way that environ-
ment variables are, but which are not added to environment variable
list in the resulting image's configuration.

--build-arg-file=path
Specifies a file containing lines of build arguments of the form
arg=value. The suggested file name is argfile.conf.

Comment lines beginning with # are ignored, along with blank lines.
All others must be of the arg=value format passed to --build-arg.

If several arguments are provided via the --build-arg-file and --build-
arg options, the build arguments are merged across all of the provided
files and command line arguments.

Any file provided in a --build-arg-file option is read before the argu-
ments supplied via the --build-arg option.

When a given argument name is specified several times, the last in-
stance is the one that is passed to the resulting builds. This means
--build-arg values always override those in a --build-arg-file.

--build-context=name=value
Specify an additional build context using its short name and its loca-
tion. Additional build contexts can be referenced in the same manner
as we access different stages in COPY instruction.

Valid values are:

• Local directory e.g. --build-context
project2=../path/to/project2/src (This option is not available with
the remote Podman client. On Podman machine setup (i.e macOS and Win-
dows) path must exists on the machine VM)

• HTTP URL to a tarball e.g. --build-context src=https://exam-
ple.org/releases/src.tar

• Container image specified with a container-image:// prefix, e.g.
--build-context alpine=container-image://alpine:3.15, (also accepts
docker://, docker-image://)

On the Containerfile side, reference the build context on all commands
that accept the from parameter. Heres how that might look:

FROM [name]
COPY --from=[name] ...
RUN --mount=from=[name]

The value of [name] is matched with the following priority order:

• Named build context defined with --build-context [name]=..

• Stage defined with AS [name] inside Containerfile

• Image [name], either local or in a remote registry

--cache-from=image
Repository to utilize as a potential cache source. When specified,
Buildah tries to look for cache images in the specified repository and
attempts to pull cache images instead of actually executing the build
steps locally. Buildah only attempts to pull previously cached images
if they are considered as valid cache hits.

Use the --cache-to option to populate a remote repository with cache
content.

Example

# populate a cache and also consult it
buildah build -t test --layers --cache-to registry/myrepo/cache --cache-from registry/myrepo/cache .

Note: --cache-from option is ignored unless --layers is specified.

--cache-to=image
Set this flag to specify a remote repository that is used to store
cache images. Buildah attempts to push newly built cache image to the
remote repository.

Note: Use the --cache-from option in order to use cache content in a
remote repository.

Example

# populate a cache and also consult it
buildah build -t test --layers --cache-to registry/myrepo/cache --cache-from registry/myrepo/cache .

Note: --cache-to option is ignored unless --layers is specified.

--cache-ttl
Limit the use of cached images to only consider images with created
timestamps less than duration ago. For example if --cache-ttl=1h is
specified, Buildah considers intermediate cache images which are cre-
ated under the duration of one hour, and intermediate cache images out-
side this duration is ignored.

Note: Setting --cache-ttl=0 manually is equivalent to using --no-cache
in the implementation since this means that the user does not want to
use cache at all.

--cap-add=CAP_xxx
When executing RUN instructions, run the command specified in the in-
struction with the specified capability added to its capability set.
Certain capabilities are granted by default; this option can be used to
add more.

--cap-drop=CAP_xxx
When executing RUN instructions, run the command specified in the in-
struction with the specified capability removed from its capability
set. The CAP_CHOWN, CAP_DAC_OVERRIDE, CAP_FOWNER, CAP_FSETID,
CAP_KILL, CAP_NET_BIND_SERVICE, CAP_SETFCAP, CAP_SETGID, CAP_SETPCAP,
and CAP_SETUID capabilities are granted by default; this option can be
used to remove them.

If a capability is specified to both the --cap-add and --cap-drop op-
tions, it is dropped, regardless of the order in which the options were
given.

--cert-dir=path
Use certificates at path (*.crt, *.cert, *.key) to connect to the reg-
istry. (Default: /etc/containers/certs.d) For details, see containers-
certs.d(5). (This option is not available with the remote Podman
client, including Mac and Windows (excluding WSL2) machines)

--cgroup-parent=path
Path to cgroups under which the cgroup for the container is created. If
the path is not absolute, the path is considered to be relative to the
cgroups path of the init process. Cgroups are created if they do not
already exist.

--cgroupns=how
Sets the configuration for cgroup namespaces when handling RUN instruc-
tions. The configured value can be "" (the empty string) or "private"
to indicate that a new cgroup namespace is created, or it can be "host"
to indicate that the cgroup namespace in which buildah itself is being
run is reused.

--cleanup
Remove built images from farm nodes on success (Default: false).

--compat-volumes
Handle directories marked using the VOLUME instruction (both in this
build, and those inherited from base images) such that their contents
can only be modified by ADD and COPY instructions. Any changes made in
those locations by RUN instructions will be reverted. Before the intro-
duction of this option, this behavior was the default, but it is now
disabled by default.

--cpp-flag=flags
Set additional flags to pass to the C Preprocessor cpp(1). Container-
files ending with a ".in" suffix is preprocessed via cpp(1). This op-
tion can be used to pass additional flags to cpp.Note: You can also set
default CPPFLAGS by setting the BUILDAH_CPPFLAGS environment variable
(e.g., export BUILDAH_CPPFLAGS="-DDEBUG").

--cpu-period=limit
Set the CPU period for the Completely Fair Scheduler (CFS), which is a
duration in microseconds. Once the container's CPU quota is used up, it
will not be scheduled to run until the current period ends. Defaults to
100000 microseconds.

On some systems, changing the resource limits may not be allowed for
non-root users. For more details, see https://github.com/contain-
ers/podman/blob/main/troubleshooting.md#26-running-containers-with-re-
source-limits-fails-with-a-permissions-error

This option is not supported on cgroups V1 rootless systems.

--cpu-quota=limit
Limit the CPU Completely Fair Scheduler (CFS) quota.

Limit the container's CPU usage. By default, containers run with the
full CPU resource. The limit is a number in microseconds. If a number
is provided, the container is allowed to use that much CPU time until
the CPU period ends (controllable via --cpu-period).

This option is not supported on cgroups V1 rootless systems.

--cpu-shares, -c=shares
CPU shares (relative weight).

By default, all containers get the same proportion of CPU cycles. This
proportion can be modified by changing the container's CPU share
weighting relative to the combined weight of all the running contain-
ers. Default weight is 1024.

The proportion only applies when CPU-intensive processes are running.
When tasks in one container are idle, other containers can use the
left-over CPU time. The actual amount of CPU time varies depending on
the number of containers running on the system.

For example, consider three containers, one has a cpu-share of 1024 and
two others have a cpu-share setting of 512. When processes in all three
containers attempt to use 100% of CPU, the first container receives 50%
of the total CPU time. If a fourth container is added with a cpu-share
of 1024, the first container only gets 33% of the CPU. The remaining
containers receive 16.5%, 16.5% and 33% of the CPU.

On a multi-core system, the shares of CPU time are distributed over all
CPU cores. Even if a container is limited to less than 100% of CPU
time, it can use 100% of each individual CPU core.

For example, consider a system with more than three cores. If the con-
tainer C0 is started with --cpu-shares=512 running one process, and an-
other container C1 with --cpu-shares=1024 running two processes, this
can result in the following division of CPU shares:

+-----+-----------+-----+--------------+
| PID | container | CPU | CPU share |
+-----+-----------+-----+--------------+
| 100 | C0 | 0 | 100% of CPU0 |
+-----+-----------+-----+--------------+
| 101 | C1 | 1 | 100% of CPU1 |
+-----+-----------+-----+--------------+
| 102 | C1 | 2 | 100% of CPU2 |
+-----+-----------+-----+--------------+

This option is not supported on cgroups V1 rootless systems.

--cpuset-cpus=number
CPUs in which to allow execution. Can be specified as a comma-separated
list (e.g. 0,1), as a range (e.g. 0-3), or any combination thereof
(e.g. 0-3,7,11-15).

This option is not supported on cgroups V1 rootless systems.

--cpuset-mems=nodes
Memory nodes (MEMs) in which to allow execution (0-3, 0,1). Only effec-
tive on NUMA systems.

If there are four memory nodes on the system (0-3), use --cpuset-
mems=0,1 then processes in the container only uses memory from the
first two memory nodes.

This option is not supported on cgroups V1 rootless systems.

--creds=[username[:password]]
The [username[:password]] to use to authenticate with the registry, if
required. If one or both values are not supplied, a command line
prompt appears and the value can be entered. The password is entered
without echo.

Note that the specified credentials are only used to authenticate
against target registries. They are not used for mirrors or when the
registry gets rewritten (see containers-registries.conf(5)); to authen-
ticate against those consider using a containers-auth.json(5) file.

--decryption-key=key[:passphrase]
The [key[:passphrase]] to be used for decryption of images. Key can
point to keys and/or certificates. Decryption is tried with all keys.
If the key is protected by a passphrase, it is required to be passed in
the argument and omitted otherwise.

--device=host-device[:container-device][:permissions]
Add a host device to the container. Optional permissions parameter can
be used to specify device permissions by combining r for read, w for
write, and m for mknod(2).

Example: --device=/dev/sdc:/dev/xvdc:rwm.

Note: if host-device is a symbolic link then it is resolved first. The
container only stores the major and minor numbers of the host device.

Podman may load kernel modules required for using the specified device.
The devices that Podman loads modules for when necessary are:
/dev/fuse.

In rootless mode, the new device is bind mounted in the container from
the host rather than Podman creating it within the container space. Be-
cause the bind mount retains its SELinux label on SELinux systems, the
container can get permission denied when accessing the mounted device.
Modify SELinux settings to allow containers to use all device labels
via the following command:

$ sudo setsebool -P container_use_devices=true

Note: if the user only has access rights via a group, accessing the de-
vice from inside a rootless container fails. The crun(1) runtime offers
a workaround for this by adding the option --annotation
run.oci.keep_original_groups=1.

--disable-compression, -D
Don't compress filesystem layers when building the image unless it is
required by the location where the image is being written. This is the
default setting, because image layers are compressed automatically when
they are pushed to registries, and images being written to local stor-
age only need to be decompressed again to be stored. Compression can
be forced in all cases by specifying --disable-compression=false.

--dns=ipaddr
Set custom DNS servers.

This option can be used to override the DNS configuration passed to the
container. Typically this is necessary when the host DNS configuration
is invalid for the container (e.g., 127.0.0.1). When this is the case
the --dns flag is necessary for every run.

The special value none can be specified to disable creation of /etc/re-
solv.conf in the container by Podman. The /etc/resolv.conf file in the
image is used without changes.

This option cannot be combined with --network that is set to none.

Note: this option takes effect only during RUN instructions in the
build. It does not affect /etc/resolv.conf in the final image.

--dns-option=option
Set custom DNS options to be used during the build.

--dns-search=domain
Set custom DNS search domains to be used during the build.

--env=env[=value]
Add a value (e.g. env=value) to the built image. Can be used multiple
times. If neither = nor a value are specified, but env is set in the
current environment, the value from the current environment is added to
the image. To remove an environment variable from the built image, use
the --unsetenv option.

--farm
This option specifies the name of the farm to be used in the build
process.

This option specifies the name of the farm to be used in the build
process.

--file, -f=Containerfile
Specifies a Containerfile which contains instructions for building the
image, either a local file or an http or https URL. If more than one
Containerfile is specified, FROM instructions are only be accepted from
the last specified file.

If a build context is not specified, and at least one Containerfile is
a local file, the directory in which it resides is used as the build
context.

Specifying the option -f - causes the Containerfile contents to be read
from stdin.

--force-rm
Always remove intermediate containers after a build, even if the build
fails (default true).

--format
Control the format for the built image's manifest and configuration
data. Recognized formats include oci (OCI image-spec v1.0, the de-
fault) and docker (version 2, using schema format 2 for the manifest).

Note: You can also override the default format by setting the BUIL-
DAH_FORMAT environment variable. export BUILDAH_FORMAT=docker

--from
Overrides the first FROM instruction within the Containerfile. If
there are multiple FROM instructions in a Containerfile, only the first
is changed.

With the remote podman client, not all container transports work as ex-
pected. For example, oci-archive:/x.tar references /x.tar on the remote
machine instead of on the client. When using podman remote clients it
is best to restrict use to containers-storage, and docker:// trans-
ports.

--group-add=group | keep-groups
Assign additional groups to the primary user running within the con-
tainer process.

• keep-groups is a special flag that tells Podman to keep the supple-
mentary group access.

Allows container to use the user's supplementary group access. If file
systems or devices are only accessible by the rootless user's group,
this flag tells the OCI runtime to pass the group access into the con-
tainer. Currently only available with the crun OCI runtime. Note: keep-
groups is exclusive, other groups cannot be specified with this flag.
(Not available for remote commands, including Mac and Windows (exclud-
ing WSL2) machines)

--help, -h
Print usage statement

--hooks-dir=path
Each *.json file in the path configures a hook for buildah build con-
tainers. For more details on the syntax of the JSON files and the se-
mantics of hook injection. Buildah currently support both the 1.0.0 and
0.1.0 hook schemas, although the 0.1.0 schema is deprecated.

This option may be set multiple times; paths from later options have
higher precedence.

For the annotation conditions, buildah uses any annotations set in the
generated OCI configuration.

For the bind-mount conditions, only mounts explicitly requested by the
caller via --volume are considered. Bind mounts that buildah inserts by
default (e.g. /dev/shm) are not considered.

If --hooks-dir is unset for root callers, Buildah currently defaults to
/usr/share/containers/oci/hooks.d and /etc/containers/oci/hooks.d in
order of increasing precedence. Using these defaults is deprecated. Mi-
grate to explicitly setting --hooks-dir.

--http-proxy
By default proxy environment variables are passed into the container if
set for the Podman process. This can be disabled by setting the value
to false. The environment variables passed in include http_proxy,
https_proxy, ftp_proxy, no_proxy, and also the upper case versions of
those. This option is only needed when the host system must use a proxy
but the container does not use any proxy. Proxy environment variables
specified for the container in any other way overrides the values that
have been passed through from the host. (Other ways to specify the
proxy for the container include passing the values with the --env flag,
or hard coding the proxy environment at container build time.) When
used with the remote client it uses the proxy environment variables
that are set on the server process.

Defaults to true.

--identity-label
Adds default identity label io.buildah.version if set. (default true).

--ignorefile
Path to an alternative .containerignore file.

--iidfile=ImageIDfile
Write the built image's ID to the file. When --platform is specified
more than once, attempting to use this option triggers an error.

--ipc=how
Sets the configuration for IPC namespaces when handling RUN instruc-
tions. The configured value can be "" (the empty string) or "con-
tainer" to indicate that a new IPC namespace is created, or it can be
"host" to indicate that the IPC namespace in which podman itself is be-
ing run is reused, or it can be the path to an IPC namespace which is
already in use by another process.

--isolation=type
Controls what type of isolation is used for running processes as part
of RUN instructions. Recognized types include oci (OCI-compatible run-
time, the default), rootless (OCI-compatible runtime invoked using a
modified configuration and its --rootless option enabled, with --no-
new-keyring --no-pivot added to its create invocation, with network and
UTS namespaces disabled, and IPC, PID, and user namespaces enabled; the
default for unprivileged users), and chroot (an internal wrapper that
leans more toward chroot(1) than container technology).

Note: You can also override the default isolation type by setting the
BUILDAH_ISOLATION environment variable. export BUILDAH_ISOLATION=oci

--jobs=number
Run up to N concurrent stages in parallel. If the number of jobs is
greater than 1, stdin is read from /dev/null. If 0 is specified, then
there is no limit in the number of jobs that run in parallel.

--label=label
Add an image label (e.g. label=value) to the image metadata. Can be
used multiple times.

Users can set a special LABEL io.containers.capabilities=CAP1,CAP2,CAP3
in a Containerfile that specifies the list of Linux capabilities re-
quired for the container to run properly. This label specified in a
container image tells Podman to run the container with just these capa-
bilities. Podman launches the container with just the specified capa-
bilities, as long as this list of capabilities is a subset of the de-
fault list.

If the specified capabilities are not in the default set, Podman prints
an error message and runs the container with the default capabilities.

--layer-label=label[=value]
Add an intermediate image label (e.g. label=value) to the intermediate
image metadata. It can be used multiple times.

If label is named, but neither = nor a value is provided, then the la-
bel is set to an empty value.

--layers
Cache intermediate images during the build process (Default is true).

Note: You can also override the default value of layers by setting the
BUILDAH_LAYERS environment variable. export BUILDAH_LAYERS=true

--local, -l
Build image on local machine as well as on farm nodes.

--logfile=filename
Log output which is sent to standard output and standard error to the
specified file instead of to standard output and standard error. This
option is not supported on the remote client, including Mac and Windows
(excluding WSL2) machines.

--memory, -m=number[unit]
Memory limit. A unit can be b (bytes), k (kibibytes), m (mebibytes), or
g (gibibytes).

Allows the memory available to a container to be constrained. If the
host supports swap memory, then the -m memory setting can be larger
than physical RAM. If a limit of 0 is specified (not using -m), the
container's memory is not limited. The actual limit may be rounded up
to a multiple of the operating system's page size (the value is very
large, that's millions of trillions).

This option is not supported on cgroups V1 rootless systems.

--memory-swap=number[unit]
A limit value equal to memory plus swap. A unit can be b (bytes), k
(kibibytes), m (mebibytes), or g (gibibytes).

Must be used with the -m (--memory) flag. The argument value must be
larger than that of
-m (--memory) By default, it is set to double the value of --memory.

Set number to -1 to enable unlimited swap.

This option is not supported on cgroups V1 rootless systems.

--network=mode, --net
Sets the configuration for network namespaces when handling RUN in-
structions.

Valid mode values are:

• none: no networking.

• host: use the Podman host network stack. Note: the host mode gives
the container full access to local system services such as D-bus and
is therefore considered insecure.

• ns:path: path to a network namespace to join.

• private: create a new namespace for the container (default)

• <network name|ID>: Join the network with the given name or ID, e.g.
use --network mynet to join the network with the name mynet. Only
supported for rootful users.

• slirp4netns[:OPTIONS,...]: use slirp4netns(1) to create a user net-
work stack. It is possible to specify these additional options, they
can also be set with network_cmd_options in containers.conf:

• allow_host_loopback=true|false: Allow slirp4netns to reach the host
loopback IP (default is 10.0.2.2 or the second IP from slirp4netns
cidr subnet when changed, see the cidr option below). The default
is false.

• mtu=MTU: Specify the MTU to use for this network. (Default is
65520).

• cidr=CIDR: Specify ip range to use for this network. (Default is
10.0.2.0/24).

• enable_ipv6=true|false: Enable IPv6. Default is true. (Required for
outbound_addr6).

• outbound_addr=INTERFACE: Specify the outbound interface slirp binds
to (ipv4 traffic only).

• outbound_addr=IPv4: Specify the outbound ipv4 address slirp binds
to.

• outbound_addr6=INTERFACE: Specify the outbound interface slirp
binds to (ipv6 traffic only).

• outbound_addr6=IPv6: Specify the outbound ipv6 address slirp binds
to.

• pasta[:OPTIONS,...]: use pasta(1) to create a user-mode networking
stack.
This is the default for rootless containers and only supported in
rootless mode.
By default, IPv4 and IPv6 addresses and routes, as well as the pod
interface name, are copied from the host. If port forwarding isn't
configured, ports are forwarded dynamically as services are bound on
either side (init namespace or container namespace). Port forwarding
preserves the original source IP address. Options described in
pasta(1) can be specified as comma-separated arguments.
In terms of pasta(1) options, --config-net is given by default, in
order to configure networking when the container is started, and
--no-map-gw is also assumed by default, to avoid direct access from
container to host using the gateway address. The latter can be over-
ridden by passing --map-gw in the pasta-specific options (despite not
being an actual pasta(1) option).
Also, -t none and -u none are passed to disable automatic port for-
warding based on bound ports. Similarly, -T none and -U none are
given to disable the same functionality from container to host.
Some examples:

• pasta:--map-gw: Allow the container to directly reach the host us-
ing the gateway address.

• pasta:--mtu,1500: Specify a 1500 bytes MTU for the tap interface in
the container.

• pasta:--ipv4-only,-a,10.0.2.0,-n,24,-g,10.0.2.2,--dns-for-
ward,10.0.2.3,-m,1500,--no-ndp,--no-dhcpv6,--no-dhcp, equivalent to
default slirp4netns(1) options: disable IPv6, assign 10.0.2.0/24 to
the tap0 interface in the container, with gateway 10.0.2.3, enable
DNS forwarder reachable at 10.0.2.3, set MTU to 1500 bytes, disable
NDP, DHCPv6 and DHCP support.

• pasta:-I,tap0,--ipv4-only,-a,10.0.2.0,-n,24,-g,10.0.2.2,--dns-for-
ward,10.0.2.3,--no-ndp,--no-dhcpv6,--no-dhcp, equivalent to default
slirp4netns(1) options with Podman overrides: same as above, but
leave the MTU to 65520 bytes

• pasta:-t,auto,-u,auto,-T,auto,-U,auto: enable automatic port for-
warding based on observed bound ports from both host and container
sides

• pasta:-T,5201: enable forwarding of TCP port 5201 from container to
host, using the loopback interface instead of the tap interface for
improved performance

--no-cache
Do not use existing cached images for the container build. Build from
the start with a new set of cached layers.

--no-hostname
Do not create the /etc/hostname file in the container for RUN instruc-
tions.

By default, Buildah manages the /etc/hostname file, adding the con-
tainer's own hostname. When the --no-hostname option is set, the im-
age's /etc/hostname will be preserved unmodified if it exists.

--no-hosts
Do not modify the /etc/hosts file in the container.

Podman assumes control over the container's /etc/hosts file by default
and adds entries for the container's name (see --name option) and host-
name (see --hostname option), the internal host.containers.internal and
host.docker.internal hosts, as well as any hostname added using the
--add-host option. Refer to the --add-host option for details. Passing
--no-hosts disables this, so that the image's /etc/hosts file is kept
unmodified. The same can be achieved globally by setting no_hosts=true
in containers.conf.

This option conflicts with --add-host.

--omit-history
Omit build history information in the built image. (default false).

This option is useful for the cases where end users explicitly want to
set --omit-history to omit the optional History from built images or
when working with images built using build tools that do not include
History information in their images.

--os-feature=feature
Set the name of a required operating system feature for the image which
is built. By default, if the image is not based on scratch, the base
image's required OS feature list is kept, if the base image specified
any. This option is typically only meaningful when the image's OS is
Windows.

If feature has a trailing -, then the feature is removed from the set
of required features which is listed in the image.

--os-version=version
Set the exact required operating system version for the image which is
built. By default, if the image is not based on scratch, the base im-
age's required OS version is kept, if the base image specified one.
This option is typically only meaningful when the image's OS is Win-
dows, and is typically set in Windows base images, so using this option
is usually unnecessary.

--pid=pid
Sets the configuration for PID namespaces when handling RUN instruc-
tions. The configured value can be "" (the empty string) or "con-
tainer" to indicate that a new PID namespace is created, or it can be
"host" to indicate that the PID namespace in which podman itself is be-
ing run is reused, or it can be the path to a PID namespace which is
already in use by another process.

--platforms=p1,p2,p3...
Build only on farm nodes that match the given platforms.

--pull=policy
Pull image policy. The default is missing.

• always: Always pull the image and throw an error if the pull fails.

• missing: Only pull the image when it does not exist in the local con-
tainers storage. Throw an error if no image is found and the pull
fails.

• never: Never pull the image but use the one from the local containers
storage. Throw an error when no image is found.

• newer: Pull if the image on the registry is newer than the one in the
local containers storage. An image is considered to be newer when
the digests are different. Comparing the time stamps is prone to er-
rors. Pull errors are suppressed if a local image was found.

--quiet, -q
Suppress output messages which indicate which instruction is being
processed, and of progress when pulling images from a registry, and
when writing the output image.

--retry=attempts
Number of times to retry pulling or pushing images between the registry
and local storage in case of failure. Default is 3.

--retry-delay=duration
Duration of delay between retry attempts when pulling or pushing images
between the registry and local storage in case of failure. The default
is to start at two seconds and then exponentially back off. The delay
is used when this value is set, and no exponential back off occurs.

--rm
Remove intermediate containers after a successful build (default true).

--runtime=path
The path to an alternate OCI-compatible runtime, which is used to run
commands specified by the RUN instruction.

Note: You can also override the default runtime by setting the BUIL-
DAH_RUNTIME environment variable. export BUILDAH_RUNTIME=/usr/lo-
cal/bin/runc

--runtime-flag=flag
Adds global flags for the container runtime. To list the supported
flags, please consult the manpages of the selected container runtime.

Note: Do not pass the leading -- to the flag. To pass the runc flag
--log-format json to buildah build, the option given is --runtime-flag
log-format=json.

--sbom=preset
Generate SBOMs (Software Bills Of Materials) for the output image by
scanning the working container and build contexts using the named com-
bination of scanner image, scanner commands, and merge strategy. Must
be specified with one or more of --sbom-image-output, --sbom-image-
purl-output, --sbom-output, and --sbom-purl-output. Recognized pre-
sets, and the set of options which they equate to:

• "syft", "syft-cyclonedx":
--sbom-scanner-image=ghcr.io/anchore/syft
--sbom-scanner-command="/syft scan -q dir:{ROOTFS} --output cy-
clonedx-json={OUTPUT}"
--sbom-scanner-command="/syft scan -q dir:{CONTEXT} --output cy-
clonedx-json={OUTPUT}"
--sbom-merge-strategy=merge-cyclonedx-by-component-name-and-version

• "syft-spdx":
--sbom-scanner-image=ghcr.io/anchore/syft
--sbom-scanner-command="/syft scan -q dir:{ROOTFS} --output spdx-
json={OUTPUT}"
--sbom-scanner-command="/syft scan -q dir:{CONTEXT} --output spdx-
json={OUTPUT}"
--sbom-merge-strategy=merge-spdx-by-package-name-and-versioninfo

• "trivy", "trivy-cyclonedx":
--sbom-scanner-image=ghcr.io/aquasecurity/trivy
--sbom-scanner-command="trivy filesystem -q {ROOTFS} --format cy-
clonedx --output {OUTPUT}"
--sbom-scanner-command="trivy filesystem -q {CONTEXT} --format cy-
clonedx --output {OUTPUT}"
--sbom-merge-strategy=merge-cyclonedx-by-component-name-and-version

• "trivy-spdx":
--sbom-scanner-image=ghcr.io/aquasecurity/trivy
--sbom-scanner-command="trivy filesystem -q {ROOTFS} --format spdx-
json --output {OUTPUT}"
--sbom-scanner-command="trivy filesystem -q {CONTEXT} --format spdx-
json --output {OUTPUT}"
--sbom-merge-strategy=merge-spdx-by-package-name-and-versioninfo

--sbom-image-output=path
When generating SBOMs, store the generated SBOM in the specified path
in the output image. There is no default.

--sbom-image-purl-output=path
When generating SBOMs, scan them for PURL (package URL
<https://github.com/package-url/purl-spec/blob/master/PURL-SPECIFICA-
TION.rst>) information, and save a list of found PURLs to the specified
path in the output image. There is no default.

--sbom-merge-strategy=method
If more than one --sbom-scanner-command value is being used, use the
specified method to merge the output from later commands with output
from earlier commands. Recognized values include:

• cat
Concatenate the files.

• merge-cyclonedx-by-component-name-and-version
Merge the "component" fields of JSON documents, ignoring values from
documents when the combination of their "name" and "version" values
is
already present. Documents are processed in the order in which they
are
generated, which is the order in which the commands that generate
them
were specified.

• merge-spdx-by-package-name-and-versioninfo
Merge the "package" fields of JSON documents, ignoring values from
documents when the combination of their "name" and "versionInfo"
values is
already present. Documents are processed in the order in which they
are
generated, which is the order in which the commands that generate
them
were specified.

--sbom-output=file
When generating SBOMs, store the generated SBOM in the named file on
the local filesystem. There is no default.

--sbom-purl-output=file
When generating SBOMs, scan them for PURL (package URL
<https://github.com/package-url/purl-spec/blob/master/PURL-SPECIFICA-
TION.rst>) information, and save a list of found PURLs to the named
file in the local filesystem. There is no default.

--sbom-scanner-command=image
Generate SBOMs by running the specified command from the scanner image.
If multiple commands are specified, they are run in the order in which
they are specified. These text substitutions are performed:
- {ROOTFS}
The root of the built image's filesystem, bind mounted.
- {CONTEXT}
The build context and additional build contexts, bind mounted.
- {OUTPUT}
The name of a temporary output file, to be read and merged with
others or copied elsewhere.

--sbom-scanner-image=image
Generate SBOMs using the specified scanner image.

--secret=id=id,src=path
Pass secret information used in the Containerfile for building images
in a safe way that are not stored in the final image, or be seen in
other stages. The secret is mounted in the container at the default
location of /run/secrets/id.

To later use the secret, use the --mount option in a RUN instruction
within a Containerfile:

RUN --mount=type=secret,id=mysecret cat /run/secrets/mysecret

--security-opt=option
Security Options

• apparmor=unconfined : Turn off apparmor confinement for the container

• apparmor=alternate-profile : Set the apparmor confinement profile for
the container

• label=user:USER : Set the label user for the container processes

• label=role:ROLE : Set the label role for the container processes

• label=type:TYPE : Set the label process type for the container
processes

• label=level:LEVEL : Set the label level for the container processes

• label=filetype:TYPE : Set the label file type for the container files

• label=disable : Turn off label separation for the container

• no-new-privileges : Not supported

• seccomp=unconfined : Turn off seccomp confinement for the container

• seccomp=profile.json : JSON file to be used as the seccomp filter
for the container.

--shm-size=number[unit]
Size of /dev/shm. A unit can be b (bytes), k (kibibytes), m
(mebibytes), or g (gibibytes). If the unit is omitted, the system uses
bytes. If the size is omitted, the default is 64m. When size is 0,
there is no limit on the amount of memory used for IPC by the con-
tainer. This option conflicts with --ipc=host.

--skip-unused-stages
Skip stages in multi-stage builds which don't affect the target stage.
(Default: true).

--squash
Squash all of the image's new layers into a single new layer; any pre-
existing layers are not squashed.

--squash-all
Squash all of the new image's layers (including those inherited from a
base image) into a single new layer.

--ssh=default | id[=socket>
SSH agent socket or keys to expose to the build. The socket path can
be left empty to use the value of default=$SSH_AUTH_SOCK

To later use the ssh agent, use the --mount option in a RUN instruction
within a Containerfile:

RUN --mount=type=ssh,id=id mycmd

--tag, -t=imageName
Specifies the name which is assigned to the resulting image if the
build process completes successfully. If imageName does not include a
registry name, the registry name localhost is prepended to the image
name.

--target=stageName
Set the target build stage to build. When building a Containerfile
with multiple build stages, --target can be used to specify an interme-
diate build stage by name as the final stage for the resulting image.
Commands after the target stage is skipped.

--timestamp=seconds
Set the create timestamp to seconds since epoch to allow for determin-
istic builds (defaults to current time). By default, the created time-
stamp is changed and written into the image manifest with every commit,
causing the image's sha256 hash to be different even if the sources are
exactly the same otherwise. When --timestamp is set, the created time-
stamp is always set to the time specified and therefore not changed,
allowing the image's sha256 hash to remain the same. All files commit-
ted to the layers of the image is created with the timestamp.

If the only instruction in a Containerfile is FROM, this flag has no
effect.

--tls-verify
Require HTTPS and verify certificates when contacting registries (de-
fault: true). If explicitly set to true, TLS verification is used. If
set to false, TLS verification is not used. If not specified, TLS ver-
ification is used unless the target registry is listed as an insecure
registry in containers-registries.conf(5)

--ulimit=type=soft-limit[:hard-limit]
Specifies resource limits to apply to processes launched when process-
ing RUN instructions. This option can be specified multiple times.
Recognized resource types include:
"core": maximum core dump size (ulimit -c)
"cpu": maximum CPU time (ulimit -t)
"data": maximum size of a process's data segment (ulimit -d)
"fsize": maximum size of new files (ulimit -f)
"locks": maximum number of file locks (ulimit -x)
"memlock": maximum amount of locked memory (ulimit -l)
"msgqueue": maximum amount of data in message queues (ulimit -q)
"nice": niceness adjustment (nice -n, ulimit -e)
"nofile": maximum number of open files (ulimit -n)
"nproc": maximum number of processes (ulimit -u)
"rss": maximum size of a process's (ulimit -m)
"rtprio": maximum real-time scheduling priority (ulimit -r)
"rttime": maximum amount of real-time execution between blocking
syscalls
"sigpending": maximum number of pending signals (ulimit -i)
"stack": maximum stack size (ulimit -s)

--unsetenv=env
Unset environment variables from the final image.

--unsetlabel=label
Unset the image label, causing the label not to be inherited from the
base image.

--userns=how
Sets the configuration for user namespaces when handling RUN instruc-
tions. The configured value can be "" (the empty string) or "con-
tainer" to indicate that a new user namespace is created, it can be
"host" to indicate that the user namespace in which podman itself is
being run is reused, or it can be the path to a user namespace which is
already in use by another process.

--userns-gid-map=mapping
Directly specifies a GID mapping to be used to set ownership, at the
filesystem level, on the working container's contents. Commands run
when handling RUN instructions defaults to being run in their own user
namespaces, configured using the UID and GID maps.

Entries in this map take the form of one or more triples of a starting
in-container GID, a corresponding starting host-level GID, and the num-
ber of consecutive IDs which the map entry represents.

This option overrides the remap-gids setting in the options section of
/etc/containers/storage.conf.

If this option is not specified, but a global --userns-gid-map setting
is supplied, settings from the global option is used.

If none of --userns-uid-map-user, --userns-gid-map-group, or --userns-
gid-map are specified, but --userns-uid-map is specified, the GID map
is set to use the same numeric values as the UID map.

--userns-gid-map-group=group
Specifies that a GID mapping to be used to set ownership, at the
filesystem level, on the working container's contents, can be found in
entries in the /etc/subgid file which correspond to the specified
group. Commands run when handling RUN instructions defaults to being
run in their own user namespaces, configured using the UID and GID
maps. If --userns-uid-map-user is specified, but --userns-gid-map-
group is not specified, podman assumes that the specified user name is
also a suitable group name to use as the default setting for this op-
tion.

NOTE: When this option is specified by a rootless user, the specified
mappings are relative to the rootless user namespace in the container,
rather than being relative to the host as it is when run rootful.

--userns-uid-map=mapping
Directly specifies a UID mapping to be used to set ownership, at the
filesystem level, on the working container's contents. Commands run
when handling RUN instructions default to being run in their own user
namespaces, configured using the UID and GID maps.

Entries in this map take the form of one or more triples of a starting
in-container UID, a corresponding starting host-level UID, and the num-
ber of consecutive IDs which the map entry represents.

This option overrides the remap-uids setting in the options section of
/etc/containers/storage.conf.

If this option is not specified, but a global --userns-uid-map setting
is supplied, settings from the global option is used.

If none of --userns-uid-map-user, --userns-gid-map-group, or --userns-
uid-map are specified, but --userns-gid-map is specified, the UID map
is set to use the same numeric values as the GID map.

--userns-uid-map-user=user
Specifies that a UID mapping to be used to set ownership, at the
filesystem level, on the working container's contents, can be found in
entries in the /etc/subuid file which correspond to the specified user.
Commands run when handling RUN instructions defaults to being run in
their own user namespaces, configured using the UID and GID maps. If
--userns-gid-map-group is specified, but --userns-uid-map-user is not
specified, podman assumes that the specified group name is also a suit-
able user name to use as the default setting for this option.

--uts=how
Sets the configuration for UTS namespaces when handling RUN instruc-
tions. The configured value can be "" (the empty string) or "con-
tainer" to indicate that a new UTS namespace to be created, or it can
be "host" to indicate that the UTS namespace in which podman itself is
being run is reused, or it can be the path to a UTS namespace which is
already in use by another process.

--volume, -v=[HOST-DIR:CONTAINER-DIR[:OPTIONS]]
Mount a host directory into containers when executing RUN instructions
during the build.

The OPTIONS are a comma-separated list and can be one or more of:

• [rw|ro]

• [z|Z|O]

• [U]

• [[r]shared|[r]slave|[r]private][1] <#Footnote1>

The CONTAINER-DIR must be an absolute path such as /src/docs. The HOST-
DIR must be an absolute path as well. Podman bind-mounts the HOST-DIR
to the specified path when processing RUN instructions.

You can specify multiple -v options to mount one or more mounts.

You can add the :ro or :rw suffix to a volume to mount it read-only or
read-write mode, respectively. By default, the volumes are mounted
read-write. See examples.

Chowning Volume Mounts

By default, Podman does not change the owner and group of source volume
directories mounted. When running using user namespaces, the UID and
GID inside the namespace may correspond to another UID and GID on the
host.

The :U suffix tells Podman to use the correct host UID and GID based on
the UID and GID within the namespace, to change recursively the owner
and group of the source volume.

Warning use with caution since this modifies the host filesystem.

Labeling Volume Mounts

Labeling systems like SELinux require that proper labels are placed on
volume content mounted into a container. Without a label, the security
system might prevent the processes running inside the container from
using the content. By default, Podman does not change the labels set by
the OS.

To change a label in the container context, add one of these two suf-
fixes :z or :Z to the volume mount. These suffixes tell Podman to rela-
bel file objects on the shared volumes. The z option tells Podman that
two containers share the volume content. As a result, Podman labels the
content with a shared content label. Shared volume labels allow all
containers to read/write content. The Z option tells Podman to label
the content with a private unshared label. Only the current container
can use a private volume.

Note: Do not relabel system files and directories. Relabeling system
content might cause other confined services on the host machine to
fail. For these types of containers, disabling SELinux separation is
recommended. The option --security-opt label=disable disables SELinux
separation for the container. For example, if a user wanted to volume
mount their entire home directory into the build containers, they need
to disable SELinux separation.

$ podman build --security-opt label=disable -v $HOME:/home/user .

Overlay Volume Mounts

The :O flag tells Podman to mount the directory from the host as a tem-
porary storage using the Overlay file system. The RUN command contain-
ers are allowed to modify contents within the mountpoint and are stored
in the container storage in a separate directory. In Overlay FS terms
the source directory is the lower, and the container storage directory
is the upper. Modifications to the mount point are destroyed when the
RUN command finishes executing, similar to a tmpfs mount point.

Any subsequent execution of RUN commands sees the original source di-
rectory content, any changes from previous RUN commands no longer ex-
ists.

One use case of the overlay mount is sharing the package cache from the
host into the container to allow speeding up builds.

Note:

• Overlay mounts are not currently supported in rootless mode.

• The O flag is not allowed to be specified with the Z or z flags.
Content mounted into the container is labeled with the private label.
On SELinux systems, labels in the source directory needs to be read-
able by the container label. If not, SELinux container separation
must be disabled for the container to work.

• Modification of the directory volume mounted into the container with
an overlay mount can cause unexpected failures. Do not modify the di-
rectory until the container finishes running.

By default bind mounted volumes are private. That means any mounts done
inside containers are not be visible on the host and vice versa. This
behavior can be changed by specifying a volume mount propagation prop-
erty.

When the mount propagation policy is set to shared, any mounts com-
pleted inside the container on that volume is visible to both the host
and container. When the mount propagation policy is set to slave, one
way mount propagation is enabled and any mounts completed on the host
for that volume is visible only inside of the container. To control the
mount propagation property of volume use the :[r]shared, :[r]slave or
:[r]private propagation flag. For mount propagation to work on the
source mount point (mount point where source dir is mounted on) has to
have the right propagation properties. For shared volumes, the source
mount point has to be shared. And for slave volumes, the source mount
has to be either shared or slave. [1] <#Footnote1>

Use df <source-dir> to determine the source mount and then use findmnt
-o TARGET,PROPAGATION <source-mount-dir> to determine propagation prop-
erties of source mount, if findmnt utility is not available, the source
mount point can be determined by looking at the mount entry in
/proc/self/mountinfo. Look at optional fields and see if any propaga-
tion properties are specified. shared:X means the mount is shared,
master:X means the mount is slave and if nothing is there that means
the mount is private. [1] <#Footnote1>

To change propagation properties of a mount point use the mount com-
mand. For example, to bind mount the source directory /foo do mount
--bind /foo /foo and mount --make-private --make-shared /foo. This con-
verts /foo into a shared mount point. The propagation properties of
the source mount can be changed directly. For instance if / is the
source mount for /foo, then use mount --make-shared / to convert / into
a shared mount.

EXAMPLES
Build named image and manifest list using specified Containerfile with
default farm:

$ podman farm build --local -t name -f /path/to/containerfile .

Build named image and manifest list using the specified farm:

$ podman farm build --farm myfarm -t name .

Build named image and manifest list using the specified farm, removing
all images from farm nodes, after they are pushed to registry:

$ podman farm build --farm myfarm --cleanup -t name .

Build named images and manifest list for specified platforms using de-
fault farm:

$ podman farm build --platforms arm64,amd64 -t name .

SEE ALSO
podman(1), podman-farm(1), buildah(1), containers-certs.d(5), contain-
ers-registries.conf(5), crun(1), runc(8), useradd(8), Containerfile(5),
containerignore(5)

HISTORY
September 2023, Originally compiled by Urvashi Mohnani <umohnani@red-
hat.com>

FOOTNOTES
1: The Podman project is committed to inclusivity, a core value of open
source. The master and slave mount propagation terminology used here is
problematic and divisive, and needs to be changed. However, these
terms are currently used within the Linux kernel and must be used as-is
at this time. When the kernel maintainers rectify this usage, Podman
will follow suit immediately.

podman-farm-build(1)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=podman-farm-build&sektion=1&manpath=FreeBSD+Ports+14.3.quarterly>

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