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

Provided by: podman_4.9.3+ds1-1build2_amd64

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
       manifest 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 format registry/repository/imageName[:tag]`.

OPTIONS

--add-host=host:ip
Add a custom host-to-IP mapping (host:ip)

Add a line to /etc/hosts. The format is hostname:ip. The --add-host option can be set
multiple times. Conflicts with the --no-hosts option.

--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}/containers/auth.json on
Linux, and $HOME/.config/containers/auth.json on Windows/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 authentication file by
setting the REGISTRY_AUTH_FILE environment variable. 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 instructions read from
the Containerfiles in the same way that environment 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 arguments supplied via
the --build-arg option.

When a given argument name is specified several times, the last instance 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 location. 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 Winows) path must exists on the machine VM)

• HTTP URL to a tarball – e.g. --build-context
src=https://example.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. Here’s 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 created under the duration of one hour, and intermediate cache
images outside 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 dones not want to use cache at all.

--cap-add=CAP_xxx
When executing RUN instructions, run the command specified in the instruction 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 instruction 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 options, 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 registry. (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 instructions. 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).

--cpp-flag=flags
Set additional flags to pass to the C Preprocessor cpp(1). Containerfiles ending with a
".in" suffix is preprocessed via cpp(1). This option 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/containers/podman/blob/main/troubleshooting.md#26-running-containers-
with-resource-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 containers. 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 container C0 is started
with --cpu-shares=512 running one process, and another 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 effective 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 authenticate 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. Because 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 device 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 storage 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/resolv.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 default) and docker (version 2, using schema
format 2 for the manifest).

Note: You can also override the default format by setting the BUILDAH_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 expected. 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:// transports.

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

• keep-groups is a special flag that tells Podman to keep the supplementary 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 container. 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 (excluding WSL2) machines)

--help, -h
Print usage statement

--hooks-dir=path
Each *.json file in the path configures a hook for buildah build containers. For more
details on the syntax of the JSON files and the semantics 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. Migrate 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 instructions. The configured
value can be "" (the empty string) or "container" 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
being 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 runtime, 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 required for the container to run properly.
This label specified in a container image tells Podman to run the container with just
these capabilities. Podman launches the container with just the specified capabilities, as
long as this list of capabilities is a subset of the default 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 label 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 instructions.

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 network stack.
This is the default for rootless containers. 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 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 overridden 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 forwarding 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 using 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-
forward,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-
forward,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 forwarding 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 instructions.

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

--no-hosts
Do not create /etc/hosts for the container. By default, Podman manages /etc/hosts, adding
the container's own IP address and any hosts from --add-host. --no-hosts disables this,
and the image's /etc/hosts is preserved unmodified.

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 image's required OS version is kept, if the
base image specified one. This option is typically only meaningful when the image's OS is
Windows, 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 instructions. The configured
value can be "" (the empty string) or "container" 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
being 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 always.

• always, true: 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 containers
storage. Throw an error if no image is found and the pull fails.

• never, false: 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 errors. 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 in case of failure when performing pull of images from registry.
Default is 3.

--retry-delay=duration
Duration of delay between retry attempts in case of failure when performing pull of images
from registry. Default is 2s.

--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 BUILDAH_RUNTIME environment
variable. export BUILDAH_RUNTIME=/usr/local/bin/runc

--runtime-flag=flag
Adds global flags for the container rutime. 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.

--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 : White listed syscalls seccomp Json file to be used as a
seccomp filter

--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 container.
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 preexisting 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 intermediate 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 deterministic builds
(defaults to current time). By default, the created timestamp 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
timestamp is always set to the time specified and therefore not changed, allowing the
image's sha256 hash to remain the same. All files committed 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 (default: true). If
explicitly set to true, TLS verification is used. If set to false, TLS verification is
not used. If not specified, TLS verification 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 processing 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 instructions. The configured
value can be "" (the empty string) or "container" 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 number 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 option.

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 number 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 suitable user name to use as the default
setting for this option.

--uts=how
Sets the configuration for UTS namespaces when handling RUN instructions. The configured
value can be "" (the empty string) or "container" 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: [1] ⟨#Footnote1⟩

• [rw|ro]

• [z|Z|O]

• [U]

• [[r]shared|[r]slave|[r]private]

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 suffixes :z or :Z to the
volume mount. These suffixes tell Podman to relabel 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 temporary storage using
the Overlay file system. The RUN command containers 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 directory content, any
changes from previous RUN commands no longer exists.

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 readable 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 directory 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 property.

When the mount propagation policy is set to shared, any mounts completed 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 properties 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
propagation 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 command. For example, to
bind mount the source directory /foo do mount --bind /foo /foo and mount --make-private
--make-shared /foo. This converts /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

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

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

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

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

HISTORY

       September 2023, Originally compiled by Urvashi Mohnani <umohnani@redhat.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)

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

EXAMPLES

SEE ALSO

HISTORY

FOOTNOTES