podman/docs/source/markdown/podman-build.1.md.in

% podman-build 1

## NAME
podman\-build - Build a container image using a Containerfile

## SYNOPSIS
**podman build** [*options*] [*context*]

**podman image build** [*options*] [*context*]

## DESCRIPTION
**podman build** Builds an image using instructions from one or more
Containerfiles or Dockerfiles and a specified build context directory. A
Containerfile uses the same syntax as a Dockerfile internally. For this
document, a file referred to as a Containerfile can be a file named
either 'Containerfile' or 'Dockerfile'.

The build context directory can be specified as the http(s) URL of an archive,
git repository or Containerfile.

When invoked with `-f` and a path to a Containerfile, with no explicit CONTEXT
directory, Podman uses the Containerfile's parent directory as its build context.

Containerfiles ending with a ".in" suffix are preprocessed via CPP(1).  This
can be useful to decompose Containerfiles into several reusable parts that can
be used via CPP's **#include** directive. Containerfiles ending in .in are
restricted to no comment lines unless they are CPP commands.
Note, a Containerfile.in file can still be used by other tools when manually
preprocessing them via `cpp -E`.

When the URL is an archive, the contents of the URL is downloaded to a temporary
location and extracted before execution.

When the URL is a Containerfile, the Containerfile is downloaded to a temporary
location.

When a Git repository is set as the URL, the repository is cloned locally and
then set as the context.

NOTE: `podman build` uses code sourced from the `Buildah` project to build
container images.  This `Buildah` code creates `Buildah` containers for the
`RUN` options in container storage. In certain situations, when the
`podman build` crashes or users kill the `podman build` process, these external
containers can be left in container storage. Use the `podman ps --all --storage`
command to see these containers. External containers can be removed with the
`podman rm --storage` command.

`podman buildx build` command is an alias of `podman build`.  Not all `buildx build` features are available in Podman. The `buildx build` option is provided for scripting compatibility.

## OPTIONS

@@option add-host

#### **--all-platforms**

Instead of building for a set of platforms specified using the **--platform** option, inspect the build's base images, and build for all of the platforms for which they are all available.  Stages that use *scratch* as a starting point can not be inspected, so at least one non-*scratch* stage must be present for detection to work usefully.

@@option annotation.image

#### **--arch**=*arch*

Set the architecture of the image to be built, and that of the base image to be
pulled, if the build uses one, to the provided value instead of using the
architecture of the build host. Unless overridden, subsequent lookups of the
same image in the local storage matches this architecture, regardless of the
host. (Examples: arm, arm64, 386, amd64, ppc64le, s390x)

@@option authfile

@@option build-arg

@@option build-arg-file

@@option build-context

@@option cache-from

@@option cache-to

@@option cache-ttl

@@option cap-add.image

@@option cap-drop.image

@@option cert-dir

@@option cgroup-parent

@@option cgroupns.image

#### **--compress**

This option is added to be aligned with other containers CLIs.
Podman doesn't communicate with a daemon or a remote server.
Thus, compressing the data before sending it is irrelevant to Podman. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)

@@option cpp-flag

@@option cpu-period

@@option cpu-quota

@@option cpu-shares

@@option cpuset-cpus

@@option cpuset-mems

@@option creds

#### **--cw**=*options*

Produce an image suitable for use as a confidential workload running in a
trusted execution environment (TEE) using krun (i.e., *crun* built with the
libkrun feature enabled and invoked as *krun*).  Instead of the conventional
contents, the root filesystem of the image will contain an encrypted disk image
and configuration information for krun.

The value for *options* is a comma-separated list of key=value pairs, supplying
configuration information which is needed for producing the additional data
which will be included in the container image.

Recognized _keys_ are:

*attestation_url*: The location of a key broker / attestation server.
If a value is specified, the new image's workload ID, along with the passphrase
used to encrypt the disk image, will be registered with the server, and the
server's location will be stored in the container image.
At run-time, krun is expected to contact the server to retrieve the passphrase
using the workload ID, which is also stored in the container image.
If no value is specified, a *passphrase* value *must* be specified.

*cpus*: The number of virtual CPUs which the image expects to be run with at
run-time.  If not specified, a default value will be supplied.

*firmware_library*: The location of the libkrunfw-sev shared library.  If not
specified, `buildah` checks for its presence in a number of hard-coded
locations.

*memory*: The amount of memory which the image expects to be run with at
run-time, as a number of megabytes.  If not specified, a default value will be
supplied.

*passphrase*: The passphrase to use to encrypt the disk image which will be
included in the container image.
If no value is specified, but an *attestation_url* value is specified, a
randomly-generated passphrase will be used.
The authors recommend setting an *attestation_url* but not a *passphrase*.

*slop*: Extra space to allocate for the disk image compared to the size of the
container image's contents, expressed either as a percentage (..%) or a size
value (bytes, or larger units if suffixes like KB or MB are present), or a sum
of two or more such specifications.  If not specified, `buildah` guesses that
25% more space than the contents will be enough, but this option is provided in
case its guess is wrong.

*type*: The type of trusted execution environment (TEE) which the image should
be marked for use with.  Accepted values are "SEV" (AMD Secure Encrypted
Virtualization - Encrypted State) and "SNP" (AMD Secure Encrypted
Virtualization - Secure Nested Paging).  If not specified, defaults to "SNP".

*workload_id*: A workload identifier which will be recorded in the container
image, to be used at run-time for retrieving the passphrase which was used to
encrypt the disk image.  If not specified, a semi-random value will be derived
from the base image's image ID.

This option is not supported on the remote client, including Mac and Windows
(excluding WSL2) machines.


@@option decryption-key

@@option device

Note: if the user only has access rights via a group, accessing the device
from inside a rootless container fails. The **[crun(1)](https://github.com/containers/crun/tree/main/crun.1.md)** runtime offers a
workaround for this by adding the option
**--annotation run.oci.keep_original_groups=1**.

@@option disable-compression

@@option disable-content-trust

@@option dns

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.

@@option dns-option.image

@@option dns-search.image

@@option env.image

@@option file

@@option force-rm

@@option format

@@option from

@@option group-add

@@option help

@@option hooks-dir

@@option http-proxy

@@option identity-label

@@option ignorefile

@@option iidfile

@@option ipc.image

@@option isolation

@@option jobs

@@option label.image

@@option layer-label

@@option layers

@@option logfile

#### **--logsplit**=*bool-value*

If `--logfile` and `--platform` are specified, the `--logsplit` option allows
end-users to split the log file for each platform into different files in the
following format: `${logfile}_${platform-os}_${platform-arch}`.
This option is not supported on the remote client, including Mac and Windows
(excluding WSL2) machines.

@@option manifest

@@option memory

@@option memory-swap

@@option network.image

@@option no-cache

@@option no-hostname

@@option no-hosts

This option conflicts with **--add-host**.

@@option omit-history

@@option os

@@option os-feature

@@option os-version.image

#### **--output**, **-o**=*output-opts*

Output destination (format: type=local,dest=path)

The --output (or -o) option extends the default behavior of building a container image by allowing users to export the contents of the image as files on the local filesystem, which can be useful for generating local binaries, code generation, etc. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)

The value for --output is a comma-separated sequence of key=value pairs, defining the output type and options.

Supported _keys_ are:
- **dest**: Destination path for exported output. Valid value is absolute or relative path, `-` means the standard output.
- **type**: Defines the type of output to be used. Valid values is documented below.

Valid _type_ values are:
- **local**: write the resulting build files to a directory on the client-side.
- **tar**: write the resulting files as a single tarball (.tar).

If no type is specified, the value defaults to **local**.
Alternatively, instead of a comma-separated sequence, the value of **--output** can be just a destination (in the **dest** format) (e.g. `--output some-path`, `--output -`) where `--output some-path` is treated as if **type=local** and `--output -` is treated as if **type=tar**.

@@option pid.image

#### **--platform**=*os/arch[/variant][,...]*

Set the *os/arch* of the built image (and its base image, when using one)
to the provided value instead of using the current operating system and
architecture of the host (for example `linux/arm`).  Unless overridden,
subsequent lookups of the same image in the local storage matches this
platform, regardless of the host.

If `--platform` is set, then the values of the `--arch`, `--os`, and
`--variant` options is overridden.

The `--platform` option can be specified more than once, or given a
comma-separated list of values as its argument.  When more than one platform is
specified, the `--manifest` option is used instead of the `--tag`
option.

Os/arch pairs are those used by the Go Programming Language.  In several cases
the *arch* value for a platform differs from one produced by other tools such as
the `arch` command.  Valid OS and architecture name combinations are listed as
values for $GOOS and $GOARCH at https://golang.org/doc/install/source#environment,
and can also be found by running `go tool dist list`.

While `podman build` is happy to use base images and build images for any
platform that exists, `RUN` instructions are able to succeed without
the help of emulation provided by packages like `qemu-user-static`.

@@option pull.image

Pull image policy. The default is **missing**.

@@option quiet

@@option retry

@@option retry-delay

@@option rm

@@option runtime

@@option runtime-flag

@@option secret.image

@@option security-opt.image

@@option shm-size

#### **--sign-by**=*fingerprint*

Sign the image using a GPG key with the specified FINGERPRINT. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines,)

@@option skip-unused-stages

@@option squash

@@option squash-all

@@option ssh

#### **--stdin**

Pass stdin into the RUN containers. Sometime commands being RUN within a Containerfile
want to request information from the user. For example apt asking for a confirmation for install.
Use --stdin to be able to interact from the terminal during the build.

@@option tag

@@option target

@@option timestamp

@@option tls-verify

@@option ulimit.image

@@option unsetenv.image

@@option unsetlabel

@@option userns.image

@@option userns-gid-map

@@option userns-gid-map-group

@@option userns-uid-map

@@option userns-uid-map-user

@@option uts

#### **--variant**=*variant*

Set the architecture variant of the image to be built, and that of the base
image to be pulled, if the build uses one, to the provided value instead of
using the architecture variant of the build host.

@@option volume.image

## EXAMPLES

### Build an image using local Containerfiles

```
$ podman build .

$ podman build -f Containerfile.simple .

$ cat $HOME/Containerfile | podman build -f - .

$ podman build -f Containerfile.simple -f Containerfile.notsosimple .

$ podman build -f Containerfile.in $HOME

$ podman build -t imageName .

$ podman build --tls-verify=true -t imageName -f Containerfile.simple .

$ podman build --tls-verify=false -t imageName .

$ podman build --runtime-flag log-format=json .

$ podman build --runtime-flag debug .

$ podman build --authfile /tmp/auths/myauths.json --cert-dir $HOME/auth --tls-verify=true --creds=username:password -t imageName -f Containerfile.simple .

$ podman build --memory 40m --cpu-period 10000 --cpu-quota 50000 --ulimit nofile=1024:1028 -t imageName .

$ podman build --security-opt label=level:s0:c100,c200 --cgroup-parent /path/to/cgroup/parent -t imageName .

$ podman build --volume /home/test:/myvol:ro,Z -t imageName .

$ podman build -v /var/lib/yum:/var/lib/yum:O -t imageName .

$ podman build --layers -t imageName .

$ podman build --no-cache -t imageName .

$ podman build --layers --force-rm -t imageName .

$ podman build --no-cache --rm=false -t imageName .

$ podman build --network mynet .
```

### Building a multi-architecture image using the --manifest option (requires emulation software)

```
$ podman build --arch arm --manifest myimage /tmp/mysrc

$ podman build --arch amd64 --manifest myimage /tmp/mysrc

$ podman build --arch s390x --manifest myimage /tmp/mysrc

$ podman build --platform linux/s390x,linux/ppc64le,linux/amd64 --manifest myimage /tmp/mysrc

$ podman build --platform linux/arm64 --platform linux/amd64 --manifest myimage /tmp/mysrc
```

### Building an image using a URL, Git repo, or archive

  The build context directory can be specified as a URL to a Containerfile, a
Git repository, or URL to an archive. If the URL is a Containerfile, it is
downloaded to a temporary location and used as the context. When a Git
repository is set as the URL, the repository is cloned locally to a temporary
location and then used as the context. Lastly, if the URL is an archive, it is
downloaded to a temporary location and extracted before being used as the
context.

#### Building an image using a URL to a Containerfile

  Podman downloads the Containerfile to a temporary location and then use
it as the build context.

```
$ podman build https://10.10.10.1/podman/Containerfile
```

#### Building an image using a Git repository

  Podman clones the specified GitHub repository to a temporary location and
use it as the context. The Containerfile at the root of the repository is used
and it only works if the GitHub repository is a dedicated repository.

```
$ podman build -t hello  https://github.com/containers/PodmanHello.git
$ podman run hello
```

  Note: GitHub does not support using `git://` for performing `clone` operation due to recent changes in their security guidance (https://github.blog/2021-09-01-improving-git-protocol-security-github/). Use an `https://` URL if the source repository is hosted on GitHub.

#### Building an image using a URL to an archive

  Podman fetches the archive file, decompress it, and use its contents as the
build context. The Containerfile at the root of the archive and the rest of the
archive are used as the context of the build. Passing the
`-f PATH/Containerfile` option as well tells the system to look for that file
inside the contents of the archive.

```
$ podman build -f dev/Containerfile https://10.10.10.1/podman/context.tar.gz
```

  Note: supported compression formats are 'xz', 'bzip2', 'gzip' and 'identity'
(no compression).

## Files

### .containerignore/.dockerignore

If the file *.containerignore* or *.dockerignore* exists in the context directory,
`podman build` reads its contents. Use the `--ignorefile` option to override the
.containerignore path location.
Podman uses the content to exclude files and directories from the context
directory, when executing COPY and ADD directives in the
Containerfile/Dockerfile

The .containerignore and .dockerignore files use the same syntax; if both
are in the context directory, podman build only uses .containerignore.

Users can specify a series of Unix shell globs in a .containerignore file to
identify files/directories to exclude.

Podman supports a special wildcard string `**` which matches any number of
directories (including zero). For example, **/*.go excludes all files that
end with .go that are found in all directories.

Example .containerignore file:

```
# exclude this content for image
*/*.c
**/output*
src
```

`*/*.c`
Excludes files and directories whose names ends with .c in any top level
subdirectory. For example, the source file include/rootless.c.

`**/output*`
Excludes files and directories starting with `output` from any directory.

`src`
Excludes files named src and the directory src as well as any content in it.

Lines starting with ! (exclamation mark) can be used to make exceptions to
exclusions. The following is an example .containerignore file that uses this
mechanism:
```
*.doc
!Help.doc
```

Exclude all doc files except Help.doc from the image.

This functionality is compatible with the handling of .containerignore files
described here:

https://github.com/containers/common/blob/main/docs/containerignore.5.md

**registries.conf** (`/etc/containers/registries.conf`)

registries.conf is the configuration file which specifies which container
registries is consulted when completing image names which do not include
a registry or domain portion.

## Troubleshooting

### lastlog sparse file

Using a useradd command within a Containerfile with a large UID/GID creates
a large sparse file `/var/log/lastlog`.  This can cause the
build to hang forever.  Go language does not support sparse files correctly,
which can lead to some huge files being created in the container image.

When using the `useradd` command within the build script, pass the
`--no-log-init or -l` option to the `useradd` command.  This option tells
useradd to stop creating the lastlog file.

## SEE ALSO
**[podman(1)](podman.1.md)**, **[buildah(1)](https://github.com/containers/buildah/blob/main/docs/buildah.1.md)**, **[containers-certs.d(5)](https://github.com/containers/image/blob/main/docs/containers-certs.d.5.md)**, **[containers-registries.conf(5)](https://github.com/containers/image/blob/main/docs/containers-registries.conf.5.md)**, **[crun(1)](https://github.com/containers/crun/blob/main/crun.1.md)**, **[runc(8)](https://github.com/opencontainers/runc/blob/main/man/runc.8.md)**, **[useradd(8)](https://www.unix.com/man-page/redhat/8/useradd)**, **[podman-ps(1)](podman-ps.1.md)**, **[podman-rm(1)](podman-rm.1.md)**, **[Containerfile(5)](https://github.com/containers/common/blob/main/docs/Containerfile.5.md)**, **[containerignore(5)](https://github.com/containers/common/blob/main/docs/containerignore.5.md)**

## HISTORY
Aug 2020, Additional options and .containerignore added by Dan Walsh `<dwalsh@redhat.com>`

May 2018, Minor revisions added by Joe Doss `<joe@solidadmin.com>`

December 2017, Originally compiled by Tom Sweeney `<tsweeney@redhat.com>`

## FOOTNOTES
<a name="Footnote1">1</a>: 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.