1podman-build(1)() podman-build(1)()
2
6 podman-build - Build a container image using a Containerfile
7
10 podman build [options] [context]
11 podman image build [options] [context]
14
17 podman build Builds an image using instructions from one or more Con‐
18 tainerfiles or Dockerfiles and a specified build context directory. A
19 Containerfile uses the same syntax as a Dockerfile internally. For this
20 document, a file referred to as a Containerfile can be a file named
21 either
22 The build context directory can be specified as the http(s) URL of an
25 archive, git repository or Containerfile.
26 If no context directory is specified, then Podman will assume the cur‐
29 rent working directory as the build context, which should contain the
30 Containerfile.
31 Containerfiles ending with a ".in" suffix will be preprocessed via
34 CPP(1). This can be useful to decompose Containerfiles into several
35 reusable parts that can be used via CPP's #include directive. Notice,
36 a Containerfile.in file can still be used by other tools when manually
37 preprocessing them via cpp -E.
38 When the URL is an archive, the contents of the URL is downloaded to a
41 temporary location and extracted before execution.
42 When the URL is an Containerfile, the Containerfile is downloaded to a
45 temporary location.
46 When a Git repository is set as the URL, the repository is cloned
49 locally and then set as the context.
50 NOTE: podman build uses code sourced from the buildah project to build
53 container images. This buildah code creates buildah containers for the
54 RUN options in container storage. In certain situations, when the pod‐
55 man build crashes or users kill the podman build process, these exter‐
56 nal containers can be left in container storage. Use the podman ps
57 --all --storage command to see these containers. External containers
58 can be removed with the podman rm --storage command.
59
62 --add-host=host
63 Add a custom host-to-IP mapping (host:ip)
64 Add a line to /etc/hosts. The format is hostname:ip. The --add-host
67 option can be set multiple times.
68 --annotation=annotation
71 Add an image annotation (e.g. annotation=value) to the image metadata.
72 Can be used multiple times.
73 Note: this information is not present in Docker image formats, so it is
76 discarded when writing images in Docker formats.
77 --arch=arch
80 Set the ARCH of the image to the provided value instead of the archi‐
81 tecture of the host.
82 --authfile=path
85 Path of the authentication file. Default is ${XDG_RUNTIME_DIR}/contain‐
86 ers/auth.json, which is set using podman login. If the authorization
87 state is not found there, $HOME/.docker/config.json is checked, which
88 is set using docker login.
89 Note: You can also override the default path of the authentication file
92 by setting the REGISTRY_AUTH_FILE environment variable. export REG‐
93 ISTRY_AUTH_FILE=path
94 --build-arg=arg=value
97 Specifies a build argument and its value, which will be interpolated in
98 instructions read from the Containerfiles in the same way that environ‐
99 ment variables are, but which will not be added to environment variable
100 list in the resulting image's configuration.
101 --cache-from
104 Images to utilize as potential cache sources. Podman does not currently
105 support caching so this is a NOOP.
106 --cap-add=CAP_xxx
109 When executing RUN instructions, run the command specified in the
110 instruction with the specified capability added to its capability set.
111 Certain capabilities are granted by default; this option can be used to
112 add more.
113 --cap-drop=CAP_xxx
116 When executing RUN instructions, run the command specified in the
117 instruction with the specified capability removed from its capability
118 set. The CAP_AUDIT_WRITE, CAP_CHOWN, CAP_DAC_OVERRIDE, CAP_FOWNER,
119 CAP_FSETID, CAP_KILL, CAP_MKNOD, CAP_NET_BIND_SERVICE, CAP_SETFCAP,
120 CAP_SETGID, CAP_SETPCAP, CAP_SETUID, and CAP_SYS_CHROOT capabilities
121 are granted by default; this option can be used to remove them.
122 If a capability is specified to both the --cap-add and --cap-drop
125 options, it will be dropped, regardless of the order in which the
126 options were given.
127 --cert-dir=path
130 Use certificates at path (*.crt, *.cert, *.key) to connect to the reg‐
131 istry. Default certificates directory is /etc/containers/certs.d. (Not
132 available for remote commands)
133 --cgroup-parent=path
136 Path to cgroups under which the cgroup for the container will be cre‐
137 ated. If the path is not absolute, the path is considered to be rela‐
138 tive to the cgroups path of the init process. Cgroups will be created
139 if they do not already exist.
140 --compress
143 This option is added to be aligned with other containers CLIs. Podman
144 doesn't communicate with a daemon or a remote server. Thus, compress‐
145 ing the data before sending it is irrelevant to Podman.
146 --cni-config-dir=directory
149 Location of CNI configuration files which will dictate which plugins
150 will be used to configure network interfaces and routing for containers
151 created for handling RUN instructions, if those containers will be run
152 in their own network namespaces, and networking is not disabled.
153 --cni-plugin-path=directory[:directory[:directory[...]]]
156 List of directories in which the CNI plugins which will be used for
157 configuring network namespaces can be found.
158 --cpu-period=limit
161 Set the CPU period for the Completely Fair Scheduler (CFS), which is a
162 duration in microseconds. Once the container's CPU quota is used up, it
163 will not be scheduled to run until the current period ends. Defaults to
164 100000 microseconds.
165 On some systems, changing the CPU limits may not be allowed for
168 non-root users. For more details, see https://github.com/contain‐
169 ers/podman/blob/master/troubleshooting.md#26-running-contain‐
170 ers-with-cpu-limits-fails-with-a-permissions-error
171 --cpu-quota=limit
174 Limit the CPU Completely Fair Scheduler (CFS) quota.
175 Limit the container's CPU usage. By default, containers run with the
178 full CPU resource. The limit is a number in microseconds. If you pro‐
179 vide a number, the container will be allowed to use that much CPU time
180 until the CPU period ends (controllable via --cpu-period).
181 On some systems, changing the CPU limits may not be allowed for
184 non-root users. For more details, see https://github.com/contain‐
185 ers/podman/blob/master/troubleshooting.md#26-running-contain‐
186 ers-with-cpu-limits-fails-with-a-permissions-error
187 --cpu-shares, -c=shares
190 CPU shares (relative weight)
191 By default, all containers get the same proportion of CPU cycles. This
194 proportion can be modified by changing the container's CPU share
195 weighting relative to the weighting of all other running containers.
196 To modify the proportion from the default of 1024, use the --cpu-shares
199 flag to set the weighting to 2 or higher.
200 The proportion will only apply when CPU-intensive processes are run‐
203 ning. When tasks in one container are idle, other containers can use
204 the left-over CPU time. The actual amount of CPU time will vary depend‐
205 ing on the number of containers running on the system.
206 For example, consider three containers, one has a cpu-share of 1024 and
209 two others have a cpu-share setting of 512. When processes in all three
210 containers attempt to use 100% of CPU, the first container would
211 receive 50% of the total CPU time. If you add a fourth container with a
212 cpu-share of 1024, the first container only gets 33% of the CPU. The
213 remaining containers receive 16.5%, 16.5% and 33% of the CPU.
214 On a multi-core system, the shares of CPU time are distributed over all
217 CPU cores. Even if a container is limited to less than 100% of CPU
218 time, it can use 100% of each individual CPU core.
219 For example, consider a system with more than three cores. If you start
222 one container {C0} with -c=512 running one process, and another con‐
223 tainer {C1} with -c=1024 running two processes, this can result in the
224 following division of CPU shares:
225 PID container CPU CPU share
228 100 {C0} 0 100% of CPU0
229 101 {C1} 1 100% of CPU1
230 102 {C1} 2 100% of CPU2
231 --cpuset-cpus=num
235 CPUs in which to allow execution (0-3, 0,1)
236 --cpuset-mems=nodes
239 Memory nodes (MEMs) in which to allow execution (0-3, 0,1). Only effec‐
240 tive on NUMA systems.
241 If you have four memory nodes on your system (0-3), use
244 --cpuset-mems=0,1 then processes in your container will only use memory
245 from the first two memory nodes.
246 --creds=creds
249 The [username[:password]] to use to authenticate with the registry if
250 required. If one or both values are not supplied, a command line
251 prompt will appear and the value can be entered. The password is
252 entered without echo.
253 --decryption-key=key[:passphrase]
256 The [key[:passphrase]] to be used for decryption of images. Key can
257 point to keys and/or certificates. Decryption will be tried with all
258 keys. If the key is protected by a passphrase, it is required to be
259 passed in the argument and omitted otherwise.
260 --device=host-device[:container-device][:permissions]
263 Add a host device to the container. Optional permissions parameter can
264 be used to specify device permissions, it is combination of r for read,
265 w for write, and m for mknod(2).
266 Example: --device=/dev/sdc:/dev/xvdc:rwm.
269 Note: if _hostdevice is a symbolic link then it will be resolved first.
272 The container will only store the major and minor numbers of the host
273 device.
274 Note: if the user only has access rights via a group, accessing the
277 device from inside a rootless container will fail. The crun(1) runtime
278 offers a workaround for this by adding the option
279 --annotation run.oci.keep_original_groups=1.
282 --disable-compression, -D
283 Don't compress filesystem layers when building the image unless it is
284 required by the location where the image is being written. This is the
285 default setting, because image layers are compressed automatically when
286 they are pushed to registries, and images being written to local stor‐
287 age would only need to be decompressed again to be stored. Compression
288 can be forced in all cases by specifying --disable-compression=false.
289 --disable-content-trust
292 This is a Docker specific option to disable image verification to a
293 Docker registry and is not supported by Podman. This flag is a NOOP
294 and provided solely for scripting compatibility.
295 --dns=dns
298 Set custom DNS servers
299 This option can be used to override the DNS configuration passed to the
302 container. Typically this is necessary when the host DNS configuration
303 is invalid for the container (e.g., 127.0.0.1). When this is the case
304 the --dns flag is necessary for every run.
305 The special value none can be specified to disable creation of
308 /etc/resolv.conf in the container by Podman. The /etc/resolv.conf file
309 in the image will be used without changes.
310 --dns-option=option
313 Set custom DNS options
314 --dns-search=domain
317 Set custom DNS search domains
318 --file, -f=Containerfile
321 Specifies a Containerfile which contains instructions for building the
322 image, either a local file or an http or https URL. If more than one
323 Containerfile is specified, FROM instructions will only be accepted
324 from the first specified file.
325 If a build context is not specified, and at least one Containerfile is
328 a local file, the directory in which it resides will be used as the
329 build context.
330 If you specify -f -, the Containerfile contents will be read from
333 stdin.
334 --force-rm=true|false
337 Always remove intermediate containers after a build, even if the build
338 fails (default true).
339 --format
342 Control the format for the built image's manifest and configuration
343 data. Recognized formats include oci (OCI image-spec v1.0, the
344 default) and docker (version 2, using schema format 2 for the mani‐
345 fest).
346 Note: You can also override the default format by setting the BUIL‐
349 DAH_FORMAT environment variable. export BUILDAH_FORMAT=docker
350 --from
353 Overrides the first FROM instruction within the Containerfile. If
354 there are multiple FROM instructions in a Containerfile, only the first
355 is changed.
356 -h, --help
359 Print usage statement
362 --http-proxy
365 Pass through HTTP Proxy environment variables.
366 --iidfile=ImageIDfile
369 Write the image ID to the file.
370 --ignorefile
373 Path to an alternative .dockerignore file.
374 --ipc=how
377 Sets the configuration for IPC namespaces when handling RUN instruc‐
378 tions. The configured value can be "" (the empty string) or "con‐
379 tainer" to indicate that a new IPC namespace should be created, or it
380 can be "host" to indicate that the IPC namespace in which podman itself
381 is being run should be reused, or it can be the path to an IPC names‐
382 pace which is already in use by another process.
383 --isolation=type
386 Controls what type of isolation is used for running processes as part
387 of RUN instructions. Recognized types include oci (OCI-compatible run‐
388 time, the default), rootless (OCI-compatible runtime invoked using a
389 modified configuration and its --rootless flag enabled, with
390 --no-new-keyring --no-pivot added to its create invocation, with net‐
391 work and UTS namespaces disabled, and IPC, PID, and user namespaces
392 enabled; the default for unprivileged users), and chroot (an internal
393 wrapper that leans more toward chroot(1) than container technology).
394 Note: You can also override the default isolation type by setting the
397 BUILDAH_ISOLATION environment variable. export BUILDAH_ISOLATION=oci
398 --jobs=number
401 Run up to N concurrent stages in parallel. If the number of jobs is
402 greater than 1, stdin will be read from /dev/null. If 0 is specified,
403 then there is no limit in the number of jobs that run in parallel.
404 --label=label
407 Add an image label (e.g. label=value) to the image metadata. Can be
408 used multiple times.
409 Users can set a special LABEL io.containers.capabilities=CAP1,CAP2,CAP3
412 in a Containerfile that specified the list of Linux capabilities
413 required for the container to run properly. This label specified in a
414 container image tells Podman to run the container with just these capa‐
415 bilities. Podman launches the container with just the specified capa‐
416 bilities, as long as this list of capabilities is a subset of the
417 default list.
418 If the specified capabilities are not in the default set, Podman will
421 print an error message and will run the container with the default
422 capabilities.
423 --layers
426 Cache intermediate images during the build process (Default is true).
427 Note: You can also override the default value of layers by setting the
430 BUILDAH_LAYERS environment variable. export BUILDAH_LAYERS=true
431 --logfile=filename
434 Log output which would be sent to standard output and standard error to
435 the specified file instead of to standard output and standard error.
436 --loglevel=number
439 Adjust the logging level up or down. Valid option values range from -2
440 to 3, with 3 being roughly equivalent to using the global --debug
441 option, and values below 0 omitting even error messages which accompany
442 fatal errors.
443 --manifest manifest
446 Name of the manifest list to which the image will be added. Creates the
447 manifest list if it does not exist. This option is useful for building
448 multi architecture images.
449 --memory, -m=LIMIT
452 Memory limit (format: [], where unit = b (bytes), k (kilobytes), m
453 (megabytes), or g (gigabytes))
454 Allows you to constrain the memory available to a container. If the
457 host supports swap memory, then the -m memory setting can be larger
458 than physical RAM. If a limit of 0 is specified (not using -m), the
459 container's memory is not limited. The actual limit may be rounded up
460 to a multiple of the operating system's page size (the value would be
461 very large, that's millions of trillions).
462 --memory-swap=LIMIT
465 A limit value equal to memory plus swap. Must be used with the -m
466 (--memory) flag. The swap LIMIT should always be larger than -m (--mem‐
467 ory) value. By default, the swap LIMIT will be set to double the value
468 of --memory.
469 The format of LIMIT is <number>[<unit>]. Unit can be b (bytes), k
472 (kilobytes), m (megabytes), or g (gigabytes). If you don't specify a
473 unit, b is used. Set LIMIT to -1 to enable unlimited swap.
474 --network=mode, --net
477 Sets the configuration for network namespaces when handling RUN
478 instructions.
479 Valid mode values are:
482 · none: no networking.
485 · host: use the Podman host network stack. Note: the host mode
487 gives the container full access to local system services such
488 as D-bus and is therefore considered insecure.
489 · ns:path: path to a network namespace to join.
491 · private: create a new namespace for the container (default).
493 --no-cache
497 Do not use existing cached images for the container build. Build from
498 the start with a new set of cached layers.
499 --os=string
502 Set the OS to the provided value instead of the current operating sys‐
503 tem of the host.
504 --pid=pid
507 Sets the configuration for PID namespaces when handling RUN instruc‐
508 tions. The configured value can be "" (the empty string) or "con‐
509 tainer" to indicate that a new PID namespace should be created, or it
510 can be "host" to indicate that the PID namespace in which podman itself
511 is being run should be reused, or it can be the path to a PID namespace
512 which is already in use by another process.
513 --platform="Linux"
516 This option has no effect on the build. Other container engines use
517 this option to control the execution platform for the build (e.g., Win‐
518 dows, Linux) which is not required for Buildah as it supports only
519 Linux.
520 --pull
523 When the option is specified or set to "true", pull the image. Raise
524 an error if the image could not be pulled, even if the image is present
525 locally.
526 If the option is disabled (with --pull=false) or not specified, pull
529 the image from the registry only if the image is not present locally.
530 Raise an error if the image is not found in the registries and is not
531 present locally.
532 --pull-always
535 Pull the image from the first registry it is found in as listed in reg‐
536 istries.conf. Raise an error if not found in the registries, even if
537 the image is present locally.
538 --pull-never
541 Do not pull the image from the registry, use only the local version.
542 Raise an error if the image is not present locally.
543 --quiet, -q
546 Suppress output messages which indicate which instruction is being pro‐
547 cessed, and of progress when pulling images from a registry, and when
548 writing the output image.
549 --rm=true|false
552 Remove intermediate containers after a successful build (default true).
553 --runtime=path
556 The path to an alternate OCI-compatible runtime, which will be used to
557 run commands specified by the RUN instruction.
558 Note: You can also override the default runtime by setting the BUIL‐
561 DAH_RUNTIME environment variable. export BUILDAH_RUN‐
562 TIME=/usr/local/bin/runc
563 --security-opt=option
566 Security Options
567 · apparmor=unconfined : Turn off apparmor confinement for the
570 container
571 · apparmor=your-profile : Set the apparmor confinement profile
573 for the container
574 · label=user:USER : Set the label user for the container
576 processes
577 · label=role:ROLE : Set the label role for the container
579 processes
580 · label=type:TYPE : Set the label process type for the con‐
582 tainer processes
583 · label=level:LEVEL : Set the label level for the container
585 processes
586 · label=filetype:TYPE : Set the label file type for the con‐
588 tainer files
589 · label=disable : Turn off label separation for the con‐
591 tainer
592 · no-new-privileges : Not supported
594 · seccomp=unconfined : Turn off seccomp confinement for the con‐
596 tainer
597 · seccomp=profile.json : White listed syscalls seccomp Json
599 file to be used as a seccomp filter
600 --shm-size=size
604 Size of /dev/shm. The format is <number><unit>. number must be greater
605 than 0. Unit is optional and can be b (bytes), k (kilobytes),
606 m(megabytes), or g (gigabytes). If you omit the unit, the system uses
607 bytes. If you omit the size entirely, the system uses 64m.
608 --sign-by=fingerprint
611 Sign the image using a GPG key with the specified FINGERPRINT.
612 --squash
615 Squash all of the image's new layers into a single new layer; any pre‐
616 existing layers are not squashed.
617 --squash-all
620 Squash all of the new image's layers (including those inherited from a
621 base image) into a single new layer.
622 --stdin
625 Pass stdin into the RUN containers. Sometime commands being RUN within
626 a Containerfile want to request information from the user. For example
627 apt asking for a confirmation for install. Use --stdin to be able to
628 interact from the terminal during the build.
629 --tag, -t=imageName
632 Specifies the name which will be assigned to the resulting image if the
633 build process completes successfully. If imageName does not include a
634 registry name, the registry name localhost will be prepended to the
635 image name.
636 --target=stageName
639 Set the target build stage to build. When building a Containerfile
640 with multiple build stages, --target can be used to specify an interme‐
641 diate build stage by name as the final stage for the resulting image.
642 Commands after the target stage will be skipped.
643 --timestamp seconds
646 Set the create timestamp to seconds since epoch to allow for determin‐
647 istic builds (defaults to current time). By default, the created time‐
648 stamp is changed and written into the image manifest with every commit,
649 causing the image's sha256 hash to be different even if the sources are
650 exactly the same otherwise. When --timestamp is set, the created time‐
651 stamp is always set to the time specified and therefore not changed,
652 allowing the image's sha256 hash to remain the same. All files commit‐
653 ted to the layers of the image will be created with the timestamp.
654 --tls-verify=true|false
657 Require HTTPS and verify certificates when talking to container reg‐
658 istries (defaults to true).
659 --ulimit=type=soft-limit[:hard-limit]
662 Specifies resource limits to apply to processes launched when process‐
663 ing RUN instructions. This option can be specified multiple times.
664 Recognized resource types include:
665 "core": maximum core dump size (ulimit -c)
666 "cpu": maximum CPU time (ulimit -t)
667 "data": maximum size of a process's data segment (ulimit -d)
668 "fsize": maximum size of new files (ulimit -f)
669 "locks": maximum number of file locks (ulimit -x)
670 "memlock": maximum amount of locked memory (ulimit -l)
671 "msgqueue": maximum amount of data in message queues (ulimit -q)
672 "nice": niceness adjustment (nice -n, ulimit -e)
673 "nofile": maximum number of open files (ulimit -n)
674 "nproc": maximum number of processes (ulimit -u)
675 "rss": maximum size of a process's (ulimit -m)
676 "rtprio": maximum real-time scheduling priority (ulimit -r)
677 "rttime": maximum amount of real-time execution between blocking
678 syscalls
679 "sigpending": maximum number of pending signals (ulimit -i)
680 "stack": maximum stack size (ulimit -s)
681 --userns=how
684 Sets the configuration for user namespaces when handling RUN instruc‐
685 tions. The configured value can be "" (the empty string) or "con‐
686 tainer" to indicate that a new user namespace should be created, it can
687 be "host" to indicate that the user namespace in which podman itself is
688 being run should be reused, or it can be the path to an user namespace
689 which is already in use by another process.
690 --userns-uid-map=mapping
693 Directly specifies a UID mapping which should be used to set ownership,
694 at the filesystem level, on the working container's contents. Commands
695 run when handling RUN instructions will default to being run in their
696 own user namespaces, configured using the UID and GID maps.
697 Entries in this map take the form of one or more triples of a starting
700 in-container UID, a corresponding starting host-level UID, and the num‐
701 ber of consecutive IDs which the map entry represents.
702 This option overrides the remap-uids setting in the options section of
705 /etc/containers/storage.conf.
706 If this option is not specified, but a global --userns-uid-map setting
709 is supplied, settings from the global option will be used.
710 If none of --userns-uid-map-user, --userns-gid-map-group, or
713 --userns-uid-map are specified, but --userns-gid-map is specified, the
714 UID map will be set to use the same numeric values as the GID map.
715 --userns-gid-map=mapping
718 Directly specifies a GID mapping which should be used to set ownership,
719 at the filesystem level, on the working container's contents. Commands
720 run when handling RUN instructions will default to being run in their
721 own user namespaces, configured using the UID and GID maps.
722 Entries in this map take the form of one or more triples of a starting
725 in-container GID, a corresponding starting host-level GID, and the num‐
726 ber of consecutive IDs which the map entry represents.
727 This option overrides the remap-gids setting in the options section of
730 /etc/containers/storage.conf.
731 If this option is not specified, but a global --userns-gid-map setting
734 is supplied, settings from the global option will be used.
735 If none of --userns-uid-map-user, --userns-gid-map-group, or
738 --userns-gid-map are specified, but --userns-uid-map is specified, the
739 GID map will be set to use the same numeric values as the UID map.
740 --userns-uid-map-user=user
743 Specifies that a UID mapping which should be used to set ownership, at
744 the filesystem level, on the working container's contents, can be found
745 in entries in the /etc/subuid file which correspond to the specified
746 user. Commands run when handling RUN instructions will default to
747 being run in their own user namespaces, configured using the UID and
748 GID maps. If --userns-gid-map-group is specified, but
749 --userns-uid-map-user is not specified, podman will assume that the
750 specified group name is also a suitable user name to use as the default
751 setting for this option.
752 --userns-gid-map-group=group
755 Specifies that a GID mapping which should be used to set ownership, at
756 the filesystem level, on the working container's contents, can be found
757 in entries in the /etc/subgid file which correspond to the specified
758 group. Commands run when handling RUN instructions will default to
759 being run in their own user namespaces, configured using the UID and
760 GID maps. If --userns-uid-map-user is specified, but
761 --userns-gid-map-group is not specified, podman will assume that the
762 specified user name is also a suitable group name to use as the default
763 setting for this option.
764 --uts=how
767 Sets the configuration for UTS namespaces when the handling RUN
768 instructions. The configured value can be "" (the empty string) or
769 "container" to indicate that a new UTS namespace should be created, or
770 it can be "host" to indicate that the UTS namespace in which podman
771 itself is being run should be reused, or it can be the path to a UTS
772 namespace which is already in use by another process.
773 --variant=""
776 Set the architecture variant of the image to be pulled.
777 --volume, -v[=[HOST-DIR:CONTAINER-DIR[:OPTIONS]]]
780 Create a bind mount. If you specify, -v /HOST-DIR:/CONTAINER-DIR, Pod‐
781 man
782 bind mounts /HOST-DIR in the host to /CONTAINER-DIR in the Podman
783 container. The OPTIONS are a comma delimited list and can be: [1]
784 ⟨#Footnote1⟩
785 · [rw|ro]
788 · [z|Z|O]
790 · [[r]shared|[r]slave|[r]private]
792 The CONTAINER-DIR must be an absolute path such as /src/docs. The
796 HOST-DIR must be an absolute path as well. Podman bind-mounts the
797 HOST-DIR to the path you specify. For example, if you supply /foo as
798 the host path, Podman copies the contents of /foo to the container
799 filesystem on the host and bind mounts that into the container.
800 You can specify multiple -v options to mount one or more mounts to a
803 container.
804 You can add the :ro or :rw suffix to a volume to mount it read-only or
807 read-write mode, respectively. By default, the volumes are mounted
808 read-write. See examples.
809 Labeling Volume Mounts
812 Labeling systems like SELinux require that proper labels are placed on
815 volume content mounted into a container. Without a label, the security
816 system might prevent the processes running inside the container from
817 using the content. By default, Podman does not change the labels set by
818 the OS.
819 To change a label in the container context, you can add either of two
822 suffixes :z or :Z to the volume mount. These suffixes tell Podman to
823 relabel file objects on the shared volumes. The z option tells Podman
824 that two containers share the volume content. As a result, Podman
825 labels the content with a shared content label. Shared volume labels
826 allow all containers to read/write content. The Z option tells Podman
827 to label the content with a private unshared label. Only the current
828 container can use a private volume.
829 Overlay Volume Mounts
832 The :O flag tells Podman to mount the directory from the host as a tem‐
835 porary storage using the Overlay file system. The RUN command contain‐
836 ers are allowed to modify contents within the mountpoint and are stored
837 in the container storage in a separate directory. In Overlay FS terms
838 the source directory will be the lower, and the container storage
839 directory will be the upper. Modifications to the mount point are
840 destroyed when the RUN command finishes executing, similar to a tmpfs
841 mount point.
842 Any subsequent execution of RUN commands sees the original source
845 directory content, any changes from previous RUN commands no longer
846 exists.
847 One use case of the overlay mount is sharing the package cache from the
850 host into the container to allow speeding up builds.
851 Note:
854 - Overlay mounts are not currently supported in rootless mode.
857 - The `O` flag is not allowed to be specified with the `Z` or `z` flags.
858 Content mounted into the container is labeled with the private label.
862 On SELinux systems, labels in the source directory needs to be
863 readable by the container label. If not, SELinux container separation
864 must be disabled for the container to work.
865 - Modification of the directory volume mounted into the container
866 with an overlay mount can cause unexpected failures. It is recommended
867 that you do not modify the directory until the container finishes run‐
868 ning.
869 By default bind mounted volumes are private. That means any mounts done
872 inside containers will not be visible on the host and vice versa. This
873 behavior can be changed by specifying a volume mount propagation prop‐
874 erty.
875 When the mount propagation policy is set to shared, any mounts com‐
878 pleted inside the container on that volume will be visible to both the
879 host and container. When the mount propagation policy is set to slave,
880 one way mount propagation is enabled and any mounts completed on the
881 host for that volume will be visible only inside of the container. To
882 control the mount propagation property of volume use the :[r]shared,
883 :[r]slave or :[r]private propagation flag. The propagation property can
884 be specified only for bind mounted volumes and not for internal volumes
885 or named volumes. For mount propagation to work on the source mount
886 point (mount point where source dir is mounted on) has to have the
887 right propagation properties. For shared volumes, the source mount
888 point has to be shared. And for slave volumes, the source mount has to
889 be either shared or slave. [1] ⟨#Footnote1⟩
890 Use df <source-dir> to determine the source mount and then use findmnt
893 -o TARGET,PROPAGATION <source-mount-dir> to determine propagation prop‐
894 erties of source mount, if findmnt utility is not available, the source
895 mount point can be determined by looking at the mount entry in
896 /proc/self/mountinfo. Look at optional fields and see if any propaga‐
897 tion properties are specified. shared:X means the mount is shared,
898 master:X means the mount is slave and if nothing is there that means
899 the mount is private. [1] ⟨#Footnote1⟩
900 To change propagation properties of a mount point use the mount com‐
903 mand. For example, to bind mount the source directory /foo do mount
904 --bind /foo /foo and mount --make-private --make-shared /foo. This will
905 convert /foo into a shared mount point. The propagation properties of
906 the source mount can be changed directly. For instance if / is the
907 source mount for /foo, then use mount --make-shared / to convert / into
908 a shared mount.
909
912 Build an image using local Containerfiles
913 $ podman build .
914 $ podman build -f Containerfile.simple .
916 $ cat $HOME/Dockerfile | podman build -f - .
918 $ podman build -f Dockerfile.simple -f Containerfile.notsosimple .
920 $ podman build -f Dockerfile.in $HOME
922 $ podman build -t imageName .
924 $ podman build --tls-verify=true -t imageName -f Dockerfile.simple .
926 $ podman build --tls-verify=false -t imageName .
928 $ podman build --runtime-flag log-format=json .
930 $ podman build --runtime-flag debug .
932 $ podman build --authfile /tmp/auths/myauths.json --cert-dir $HOME/auth --tls-verify=true --creds=username:password -t imageName -f Dockerfile.simple .
934 $ podman build --memory 40m --cpu-period 10000 --cpu-quota 50000 --ulimit nofile=1024:1028 -t imageName .
936 $ podman build --security-opt label=level:s0:c100,c200 --cgroup-parent /path/to/cgroup/parent -t imageName .
938 $ podman build --volume /home/test:/myvol:ro,Z -t imageName .
940 $ podman build -v /var/lib/yum:/var/lib/yum:O -t imageName .
942 $ podman build --layers -t imageName .
944 $ podman build --no-cache -t imageName .
946 $ podman build --layers --force-rm -t imageName .
948 $ podman build --no-cache --rm=false -t imageName .
950 Building an multi-architecture image using a --manifest option (Requires
954 emulation software)
955 podman build --arch arm --manifest myimage /tmp/mysrc podman build
956 --arch amd64 --manifest myimage /tmp/mysrc podman build --arch s390x
957 --manifest myimage /tmp/mysrc
958 Building an image using a URL, Git repo, or archive
961 The build context directory can be specified as a URL to a Container‐
962 file, a Git repository, or URL to an archive. If the URL is a Contain‐
963 erfile, it is downloaded to a temporary location and used as the con‐
964 text. When a Git repository is set as the URL, the repository is cloned
965 locally to a temporary location and then used as the context. Lastly,
966 if the URL is an archive, it is downloaded to a temporary location and
967 extracted before being used as the context.
968 Building an image using a URL to a Containerfile
971 Podman will download the Containerfile to a temporary location and then
972 use it as the build context.
973 $ podman build https://10.10.10.1/podman/Containerfile
976 Building an image using a Git repository
980 Podman will clone the specified GitHub repository to a temporary loca‐
981 tion and use it as the context. The Containerfile at the root of the
982 repository will be used and it only works if the GitHub repository is a
983 dedicated repository.
984 $ podman build git://github.com/scollier/purpletest
987 Building an image using a URL to an archive
991 Podman will fetch the archive file, decompress it, and use its contents
992 as the build context. The Containerfile at the root of the archive and
993 the rest of the archive will get used as the context of the build. If
994 you pass -f PATH/Containerfile option as well, the system will look for
995 that file inside the contents of the archive.
996 $ podman build -f dev/Containerfile https://10.10.10.1/podman/context.tar.gz
999 Note: supported compression formats are 'xz', 'bzip2', 'gzip' and
1003 'identity' (no compression).
1004
1007 .dockerignore
1008 If the file .dockerignore exists in the context directory, buildah copy
1009 reads its contents. Use the --ignorefile flag to override .dockerignore
1010 path location. Podman uses the content to exclude files and directo‐
1011 ries from the context directory, when executing COPY and ADD directives
1012 in the Containerfile/Dockerfile
1013 Users can specify a series of Unix shell globals in a .dockerignore
1016 file to identify files/directories to exclude.
1017 Podman supports a special wildcard string ** which matches any number
1020 of directories (including zero). For example, */.go will exclude all
1021 files that end with .go that are found in all directories.
1022 Example .dockerignore file:
1025 # exclude this content for image
1028 */*.c
1029 **/output*
1030 src
1031 */*.c Excludes files and directories whose names ends with .c in any
1035 top level subdirectory. For example, the source file include/root‐
1036 less.c.
1037 **/output* Excludes files and directories starting with output from any
1040 directory.
1041 src Excludes files named src and the directory src as well as any con‐
1044 tent in it.
1045 Lines starting with ! (exclamation mark) can be used to make exceptions
1048 to exclusions. The following is an example .dockerignore file that uses
1049 this mechanism:
1050 *.doc
1053 !Help.doc
1054 Exclude all doc files except Help.doc from the image.
1058 This functionality is compatible with the handling of .dockerignore
1061 files described here:
1062 https://docs.docker.com/engine/reference/builder/#dockerignore-file
1065 registries.conf (/etc/containers/registries.conf)
1068 registries.conf is the configuration file which specifies which con‐
1071 tainer registries should be consulted when completing image names which
1072 do not include a registry or domain portion.
1073
1076 lastlog sparse file
1077 If you are using a useradd command within a Containerfile with a large
1078 UID/GID, it will create a large sparse file /var/log/lastlog. This can
1079 cause the build to hang forever. Go language does not support sparse
1080 files correctly, which can lead to some huge files being created in
1081 your container image.
1082 If you are using useradd within your build script, you should pass the
1085 --no-log-init or -l option to the useradd command. This option tells
1086 useradd to stop creating the lastlog file.
1087
1090 podman(1), buildah(1), containers-registries.conf(5), crun(8), runc(8),
1091 useradd(8), podman-ps(1), podman-rm(1)
1092
1095 Aug 2020, Additional options and .dockerignore added by Dan Walsh
1096 dwalsh@redhat.com ⟨mailto:dwalsh@redhat.com⟩
1097 May 2018, Minor revisions added by Joe Doss joe@solidadmin.com
1100 ⟨mailto:joe@solidadmin.com⟩
1101 December 2017, Originally compiled by Tom Sweeney tsweeney@redhat.com
1104 ⟨mailto:tsweeney@redhat.com⟩
1105
1108 1: The Podman project is committed to inclusivity, a core value of open
1109 source. The master and slave mount propagation terminology used here is
1110 problematic and divisive, and should be changed. However, these terms
1111 are currently used within the Linux kernel and must be used as-is at
1112 this time. When the kernel maintainers rectify this usage, Podman will
1113 follow suit immediately.
1114 podman-build(1)()