path: root/docs/source/markdown/podman-run.1.md.in

% podman-run 1

## NAME
podman\-run - Run a command in a new container

## SYNOPSIS
**podman run** [*options*] *image* [*command* [*arg* ...]]

**podman container run** [*options*] *image* [*command* [*arg* ...]]

## DESCRIPTION

Run a process in a new container. **podman run** starts a process with its own
file system, its own networking, and its own isolated process tree. The _image_
which starts the process may define defaults related to the process that will be
run in the container, the networking to expose, and more, but **podman run**
gives final control to the operator or administrator who starts the container
from the image. For that reason **podman run** has more options than any other
Podman command.

If the _image_ is not already loaded then **podman run** will pull the _image_, and
all image dependencies, from the repository in the same way running **podman
pull** _image_ , before it starts the container from that image.

Several files will be automatically created within the container. These include
_/etc/hosts_, _/etc/hostname_, and _/etc/resolv.conf_ to manage networking.
These will be based on the host's version of the files, though they can be
customized with options (for example, **--dns** will override the host's DNS
servers in the created _resolv.conf_). Additionally, a container environment
file is created in each container to indicate to programs they are running in a
container. This file is located at _/run/.containerenv_. When using the
--privileged flag the .containerenv contains name/value pairs indicating the
container engine version, whether the engine is running in rootless mode, the
container name and id, as well as the image name and id that the container is based on.

When running from a user defined network namespace, the _/etc/netns/NSNAME/resolv.conf_
will be used if it exists, otherwise _/etc/resolv.conf_ will be used.

Default settings are defined in `containers.conf`. Most settings for remote
connections use the servers containers.conf, except when documented in man
pages.

## IMAGE

  The image is specified using transport:path format. If no transport is specified, the `docker` (container registry)
transport will be used by default. For remote Podman, including Mac and Windows (excluding WSL2) machines, `docker` is the only allowed transport.

  **dir:**_path_
  An existing local directory _path_ storing the manifest, layer tarballs and signatures as individual files. This
is a non-standardized format, primarily useful for debugging or noninvasive container inspection.

    $ podman save --format docker-dir fedora -o /tmp/fedora
    $ podman run dir:/tmp/fedora echo hello

  **docker://**_docker-reference_ (Default)
  An image reference stored in a remote container image registry. Example: "quay.io/podman/stable:latest".
The reference can include a path to a specific registry; if it does not, the
registries listed in registries.conf will be queried to find a matching image.
By default, credentials from `podman login` (stored at
$XDG_RUNTIME_DIR/containers/auth.json by default) will be used to authenticate;
otherwise it falls back to using credentials in $HOME/.docker/config.json.

    $ podman run registry.fedoraproject.org/fedora:latest echo hello

  **docker-archive:**_path_[**:**_docker-reference_]
An image stored in the `docker save` formatted file. _docker-reference_ is only used when creating such a
file, and it must not contain a digest.

    $ podman save --format docker-archive fedora -o /tmp/fedora
    $ podman run docker-archive:/tmp/fedora echo hello

  **docker-daemon:**_docker-reference_
  An image in _docker-reference_ format stored in the docker daemon internal storage. The _docker-reference_ can also be an image ID (docker-daemon:algo:digest).

    $ sudo docker pull fedora
    $ sudo podman run docker-daemon:docker.io/library/fedora echo hello

  **oci-archive:**_path_**:**_tag_
  An image in a directory compliant with the "Open Container Image Layout Specification" at the specified _path_
and specified with a _tag_.

    $ podman save --format oci-archive fedora -o /tmp/fedora
    $ podman run oci-archive:/tmp/fedora echo hello

## OPTIONS
@@option add-host

@@option annotation.container

@@option arch

#### **--attach**, **-a**=*stdin* | *stdout* | *stderr*

Attach to STDIN, STDOUT or STDERR.

In foreground mode (the default when **-d**
is not specified), **podman run** can start the process in the container
and attach the console to the process's standard input, output, and
error. It can even pretend to be a TTY (this is what most commandline
executables expect) and pass along signals. The **-a** option can be set for
each of **stdin**, **stdout**, and **stderr**.

@@option authfile

@@option blkio-weight

@@option blkio-weight-device

@@option cap-add

@@option cap-drop

@@option cgroup-conf

@@option cgroup-parent

@@option cgroupns

@@option cgroups

@@option chrootdirs

@@option cidfile.write

@@option conmon-pidfile

@@option cpu-period

@@option cpu-quota

@@option cpu-rt-period

@@option cpu-rt-runtime

@@option cpu-shares

@@option cpus.container

@@option cpuset-cpus

@@option cpuset-mems

#### **--detach**, **-d**

Detached mode: run the container in the background and print the new container ID. The default is *false*.

At any time you can run **podman ps** in
the other shell to view a list of the running containers. You can reattach to a
detached container with **podman attach**.

When attached in the tty mode, you can detach from the container (and leave it
running) using a configurable key sequence. The default sequence is `ctrl-p,ctrl-q`.
Specify the key sequence using the **--detach-keys** option, or configure
it in the **containers.conf** file: see **containers.conf(5)** for more information.

#### **--detach-keys**=*sequence*

Specify the key sequence for detaching a container. Format is a single character `[a-Z]` or one or more `ctrl-<value>` characters where `<value>` is one of: `a-z`, `@`, `^`, `[`, `,` or `_`. Specifying "" will set the sequence to the default value of *ctrl-p,ctrl-q*.

This option can also be set in **containers.conf**(5) file.

@@option device

Note: if the user only has access rights via a group, accessing the device
from inside a rootless container will fail. Use the `--group-add keep-groups`
flag to pass the user's supplementary group access into the container.

@@option device-cgroup-rule

@@option device-read-bps

@@option device-read-iops

@@option device-write-bps

@@option device-write-iops

@@option disable-content-trust

#### **--dns**=*ipaddr*

Set custom DNS servers. Invalid if using **--dns** with **--network** that is set to **none** or **container:**_id_.

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 will be used without changes.

@@option dns-opt.container

@@option dns-search.container

@@option entrypoint

#### **--env**, **-e**=*env*

Set environment variables.

This option allows arbitrary environment variables that are available for the process to be launched inside of the container. If an environment variable is specified without a value, Podman will check the host environment for a value and set the variable only if it is set on the host. As a special case, if an environment variable ending in __*__ is specified without a value, Podman will search the host environment for variables starting with the prefix and will add those variables to the container.

See [**Environment**](#environment) note below for precedence and examples.

#### **--env-file**=*file*

Read in a line delimited file of environment variables. See **Environment** note below for precedence.

@@option env-host

@@option env-merge

@@option expose

@@option gidmap.container

@@option group-add

@@option health-cmd

@@option health-interval

@@option health-on-failure

@@option health-retries

@@option health-start-period

@@option health-timeout

#### **--help**

Print usage statement

@@option hostname.container

@@option hostuser

@@option http-proxy

@@option image-volume

@@option init

@@option init-path

@@option interactive

@@option ip

@@option ip6

@@option ipc

@@option label

@@option label-file

@@option link-local-ip

@@option log-driver

#### **--log-opt**=*name=value*

Logging driver specific options.

Set custom logging configuration. The following *name*s are supported:

**path**: specify a path to the log file
    (e.g. **--log-opt path=/var/log/container/mycontainer.json**);

**max-size**: specify a max size of the log file
    (e.g. **--log-opt max-size=10mb**);

**tag**: specify a custom log tag for the container
   (e.g. **--log-opt tag="{{.ImageName}}"**.

This option is currently supported only by the **journald** log driver.

@@option mac-address

@@option memory

@@option memory-reservation

@@option memory-swap

@@option memory-swappiness

@@option mount

@@option name.container

#### **--network**=*mode*, **--net**

Set the network mode for the container. Invalid if using **--dns**, **--dns-opt**, or **--dns-search** with **--network** set to **none** or **container:**_id_. If used together with **--pod**, the container will not join the pod's network namespace.

Valid _mode_ values are:

- **bridge[:OPTIONS,...]**: Create a network stack on the default bridge. This is the default for rootful containers. It is possible to specify these additional options:
  - **alias=name**: Add network-scoped alias for the container.
  - **ip=IPv4**: Specify a static ipv4 address for this container.
  - **ip=IPv6**: Specify a static ipv6 address for this container.
  - **mac=MAC**: Specify a static mac address for this container.
  - **interface_name**: Specify a name for the created network interface inside the container.

  For example to set a static ipv4 address and a static mac address, use `--network bridge:ip=10.88.0.10,mac=44:33:22:11:00:99`.
- \<network name or ID\>[:OPTIONS,...]: Connect to a user-defined network; this is the network name or ID from a network created by **[podman network create](podman-network-create.1.md)**. Using the network name implies the bridge network mode. It is possible to specify the same options described under the bridge mode above. You can use the **--network** option multiple times to specify additional networks.
- **none**: Create a network namespace for the container but do not configure network interfaces for it, thus the container has no network connectivity.
- **container:**_id_: Reuse another container's network stack.
- **host**: Do not create a network namespace, the container will use the host's network. 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. This will use the **bridge** mode for rootful containers and **slirp4netns** for rootless ones.
- **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 should bind to (ipv4 traffic only).
  - **outbound_addr=IPv4**: Specify the outbound ipv4 address slirp should bind to.
  - **outbound_addr6=INTERFACE**: Specify the outbound interface slirp should bind to (ipv6 traffic only).
  - **outbound_addr6=IPv6**: Specify the outbound ipv6 address slirp should bind to.
  - **port_handler=rootlesskit**: Use rootlesskit for port forwarding. Default.
  Note: Rootlesskit changes the source IP address of incoming packets to an IP address in the container network namespace, usually `10.0.2.100`. If your application requires the real source IP address, e.g. web server logs, use the slirp4netns port handler. The rootlesskit port handler is also used for rootless containers when connected to user-defined networks.
  - **port_handler=slirp4netns**: Use the slirp4netns port forwarding, it is slower than rootlesskit but preserves the correct source IP address. This port handler cannot be used for user-defined networks.

@@option network-alias

@@option no-healthcheck

@@option no-hosts

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

@@option oom-kill-disable

@@option oom-score-adj

@@option os.pull

#### **--passwd**

Allow Podman to add entries to /etc/passwd and /etc/group when used in conjunction with the --user option.
This is used to override the Podman provided user setup in favor of entrypoint configurations such as libnss-extrausers.

@@option passwd-entry

@@option personality

@@option pid

@@option pidfile

@@option pids-limit

@@option platform

#### **--pod**=*name*

Run container in an existing pod. If you want Podman to make the pod for you, prefix the pod name with **new:**.
To make a pod with more granular options, use the **podman pod create** command before creating a container.
If a container is run with a pod, and the pod has an infra-container, the infra-container will be started before the container is.

@@option pod-id-file.container

@@option preserve-fds

@@option privileged

@@option publish

**Note:** If a container will be run within a pod, it is not necessary to publish the port for
the containers in the pod. The port must only be published by the pod itself. Pod network
stacks act like the network stack on the host - you have a variety of containers in the pod,
and programs in the container, all sharing a single interface and IP address, and
associated ports. If one container binds to a port, no other container can use that port
within the pod while it is in use. Containers in the pod can also communicate over localhost
by having one container bind to localhost in the pod, and another connect to that port.

@@option publish-all

@@option pull

#### **--quiet**, **-q**

Suppress output information when pulling images

@@option read-only

@@option read-only-tmpfs

@@option replace

@@option requires

@@option restart

#### **--rm**

Automatically remove the container when it exits. The default is **false**.

#### **--rmi**

After exit of the container, remove the image unless another
container is using it. The default is *false*.

@@option rootfs

@@option sdnotify

@@option seccomp-policy

@@option secret

#### **--security-opt**=*option*

Security Options

- **apparmor=unconfined** : Turn off apparmor confinement for the container
- **apparmor**=_your-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

Note: Labeling can be disabled for all containers by setting label=false in the **containers.conf** (`/etc/containers/containers.conf` or `$HOME/.config/containers/containers.conf`) file.

- **mask**=_/path/1:/path/2_: The paths to mask separated by a colon. A masked path
  cannot be accessed inside the container.

- **no-new-privileges**: Disable container processes from gaining additional privileges

- **seccomp=unconfined**: Turn off seccomp confinement for the container.
- **seccomp=profile.json**: JSON file to be used as a seccomp filter. Note that the `io.podman.annotations.seccomp` annotation is set with the specified value as shown in `podman inspect`.

- **proc-opts**=_OPTIONS_ : Comma-separated list of options to use for the /proc mount. More details
  for the possible mount options are specified in the **proc(5)** man page.

- **unmask**=_ALL_ or _/path/1:/path/2_, or shell expanded paths (/proc/*): Paths to unmask separated by a colon. If set to **ALL**, it will unmask all the paths that are masked or made read-only by default.
  The default masked paths are **/proc/acpi, /proc/kcore, /proc/keys, /proc/latency_stats, /proc/sched_debug, /proc/scsi, /proc/timer_list, /proc/timer_stats, /sys/firmware, and /sys/fs/selinux.**.  The default paths that are read-only are **/proc/asound**, **/proc/bus**, **/proc/fs**, **/proc/irq**, **/proc/sys**, **/proc/sysrq-trigger**, **/sys/fs/cgroup**.

Note: Labeling can be disabled for all containers by setting **label=false** in the **containers.conf**(5) file.

#### **--shm-size**=*number[unit]*

Size of _/dev/shm_. A _unit_ can be **b** (bytes), **k** (kibibytes), **m** (mebibytes), or **g** (gibibytes).
If you omit the unit, the system uses bytes. If you omit the size entirely, the default is **64m**.
When _size_ is **0**, there is no limit on the amount of memory used for IPC by the container.

#### **--sig-proxy**

Sets whether the signals sent to the **podman run** command are proxied to the container process. SIGCHLD, SIGSTOP, and SIGKILL are not proxied. The default is **true**.

@@option stop-signal

@@option stop-timeout

@@option subgidname

@@option subuidname

@@option sysctl

@@option systemd

@@option timeout

@@option tls-verify

@@option tmpfs

@@option tty

```
echo "asdf" | podman run --rm -i someimage /bin/cat
```

@@option tz

@@option uidmap.container

@@option ulimit

@@option umask

@@option unsetenv

@@option unsetenv-all

#### **--user**, **-u**=*user[:group]*

Sets the username or UID used and, optionally, the groupname or GID for the specified command. Both *user* and *group* may be symbolic or numeric.

Without this argument, the command will run as the user specified in the container image. Unless overridden by a `USER` command in the Containerfile or by a value passed to this option, this user generally defaults to root.

When a user namespace is not in use, the UID and GID used within the container and on the host will match. When user namespaces are in use, however, the UID and GID in the container may correspond to another UID and GID on the host. In rootless containers, for example, a user namespace is always used, and root in the container will by default correspond to the UID and GID of the user invoking Podman.

@@option userns.container

@@option uts.container

#### **--variant**=*VARIANT*
Use _VARIANT_ instead of the default architecture variant of the container image. Some images can use multiple variants of the arm architectures, such as arm/v5 and arm/v7.

@@option volume

Use the **--group-add keep-groups** option to pass the user's supplementary group access into the container.

@@option volumes-from

@@option workdir

## Exit Status

The exit code from **podman run** gives information about why the container
failed to run or why it exited. When **podman run** exits with a non-zero code,
the exit codes follow the **chroot**(1) standard, see below:

  **125** The error is with Podman itself

    $ podman run --foo busybox; echo $?
    Error: unknown flag: --foo
    125

  **126** The _contained command_ cannot be invoked

    $ podman run busybox /etc; echo $?
    Error: container_linux.go:346: starting container process caused "exec: \"/etc\": permission denied": OCI runtime error
    126

  **127** The _contained command_ cannot be found

    $ podman run busybox foo; echo $?
    Error: container_linux.go:346: starting container process caused "exec: \"foo\": executable file not found in $PATH": OCI runtime error
    127

  **Exit code** _contained command_ exit code

    $ podman run busybox /bin/sh -c 'exit 3'; echo $?
    3

## EXAMPLES

### Running container in read-only mode

During container image development, containers often need to write to the image
content. Installing packages into _/usr_, for example. In production,
applications seldom need to write to the image.  Container applications write
to volumes if they need to write to file systems at all. Applications can be
made more secure by running them in read-only mode using the **--read-only** switch.
This protects the container's image from modification. Read-only containers may
still need to write temporary data. The best way to handle this is to mount
tmpfs directories on _/run_ and _/tmp_.

```
$ podman run --read-only -i -t fedora /bin/bash

$ podman run --read-only --read-only-tmpfs=false --tmpfs /run -i -t fedora /bin/bash
```

### Exposing log messages from the container to the host's log

If you want messages that are logged in your container to show up in the host's
syslog/journal then you should bind mount the _/dev/log_ directory as follows.

```
$ podman run -v /dev/log:/dev/log -i -t fedora /bin/bash
```

From inside the container you can test this by sending a message to the log.

```
(bash)# logger "Hello from my container"
```

Then exit and check the journal.

```
(bash)# exit

$ journalctl -b | grep Hello
```

This should list the message sent to logger.

### Attaching to one or more from STDIN, STDOUT, STDERR

If you do not specify **-a**, Podman will attach everything (stdin, stdout, stderr).
You can specify to which of the three standard streams (stdin, stdout, stderr)
you'd like to connect instead, as in:

```
$ podman run -a stdin -a stdout -i -t fedora /bin/bash
```

### Sharing IPC between containers

Using **shm_server.c** available here: https://www.cs.cf.ac.uk/Dave/C/node27.html

Testing **--ipc=host** mode:

Host shows a shared memory segment with 7 pids attached, happens to be from httpd:

```
$ sudo ipcs -m

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status
0x01128e25 0          root       600        1000       7
```

Now run a regular container, and it correctly does NOT see the shared memory segment from the host:

```
$ podman run -it shm ipcs -m

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status
```

Run a container with the new **--ipc=host** option, and it now sees the shared memory segment from the host httpd:

```
$ podman run -it --ipc=host shm ipcs -m

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status
0x01128e25 0          root       600        1000       7
```
Testing **--ipc=container:**_id_ mode:

Start a container with a program to create a shared memory segment:
```
$ podman run -it shm bash
$ sudo shm/shm_server &
$ sudo ipcs -m

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status
0x0000162e 0          root       666        27         1
```
Create a 2nd container correctly shows no shared memory segment from 1st container:
```
$ podman run shm ipcs -m

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status
```

Create a 3rd container using the **--ipc=container:**_id_ option, now it shows the shared memory segment from the first:

```
$ podman run -it --ipc=container:ed735b2264ac shm ipcs -m
$ sudo ipcs -m

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status
0x0000162e 0          root       666        27         1
```

### Mapping Ports for External Usage

The exposed port of an application can be mapped to a host port using the **-p**
flag. For example, an httpd port 80 can be mapped to the host port 8080 using the
following:

```
$ podman run -p 8080:80 -d -i -t fedora/httpd
```

### Mounting External Volumes

To mount a host directory as a container volume, specify the absolute path to
the directory and the absolute path for the container directory separated by a
colon. If the source is a named volume maintained by Podman, it is recommended to
use its name rather than the path to the volume. Otherwise the volume will be
considered as an orphan and wiped if you execute **podman volume prune**:

```
$ podman run -v /var/db:/data1 -i -t fedora bash

$ podman run -v data:/data2 -i -t fedora bash

$ podman run -v /var/cache/dnf:/var/cache/dnf:O -ti fedora dnf -y update

$ podman run -d -e MYSQL_ROOT_PASSWORD=root --user mysql --userns=keep-id -v ~/data:/var/lib/mysql:z,U mariadb
```

Using **--mount** flags to mount a host directory as a container folder, specify
the absolute path to the directory or the volume name, and the absolute path
within the container directory:

````
$ podman run --mount type=bind,src=/var/db,target=/data1 busybox sh

$ podman run --mount type=bind,src=volume-name,target=/data1 busybox sh
````

When using SELinux, be aware that the host has no knowledge of container SELinux
policy. Therefore, in the above example, if SELinux policy is enforced, the
_/var/db_ directory is not writable to the container. A "Permission Denied"
message will occur and an **avc:** message in the host's syslog.

To work around this, at time of writing this man page, the following command
needs to be run in order for the proper SELinux policy type label to be attached
to the host directory:

```
$ chcon -Rt svirt_sandbox_file_t /var/db
```

Now, writing to the _/data1_ volume in the container will be allowed and the
changes will also be reflected on the host in _/var/db_.

### Using alternative security labeling

You can override the default labeling scheme for each container by specifying
the **--security-opt** flag. For example, you can specify the MCS/MLS level, a
requirement for MLS systems. Specifying the level in the following command
allows you to share the same content between containers.

```
podman run --security-opt label=level:s0:c100,c200 -i -t fedora bash
```

An MLS example might be:

```
$ podman run --security-opt label=level:TopSecret -i -t rhel7 bash
```

To disable the security labeling for this container versus running with the
#### **--permissive** flag, use the following command:

```
$ podman run --security-opt label=disable -i -t fedora bash
```

If you want a tighter security policy on the processes within a container,
you can specify an alternate type for the container. You could run a container
that is only allowed to listen on Apache ports by executing the following
command:

```
$ podman run --security-opt label=type:svirt_apache_t -i -t centos bash
```

Note you would have to write policy defining a **svirt_apache_t** type.

To mask additional specific paths in the container, specify the paths
separated by a colon using the **mask** option with the **--security-opt**
flag.

```
$ podman run --security-opt mask=/foo/bar:/second/path fedora bash
```

To unmask all the paths that are masked by default, set the **unmask** option to
**ALL**. Or to only unmask specific paths, specify the paths as shown above with
the **mask** option.

```
$ podman run --security-opt unmask=ALL fedora bash
```

To unmask all the paths that start with /proc, set the **unmask** option to
**/proc/***.

```
$ podman run --security-opt unmask=/proc/* fedora bash
```

```
$ podman run --security-opt unmask=/foo/bar:/sys/firmware fedora bash
```

### Setting device weight

If you want to set _/dev/sda_ device weight to **200**, you can specify the device
weight by **--blkio-weight-device** flag. Use the following command:

```
$ podman run -it --blkio-weight-device "/dev/sda:200" ubuntu
```

### Using a podman container with input from a pipe

```
$ echo "asdf" | podman run --rm -i --entrypoint /bin/cat someimage
asdf
```

### Setting automatic user namespace separated containers

```
# podman run --userns=auto:size=65536 ubi8-micro cat /proc/self/uid_map
0 2147483647      65536
# podman run --userns=auto:size=65536 ubi8-micro cat /proc/self/uid_map
0 2147549183      65536
```

### Setting Namespaced Kernel Parameters (Sysctls)

The **--sysctl** sets namespaced kernel parameters (sysctls) in the
container. For example, to turn on IP forwarding in the containers
network namespace, run this command:

```
$ podman run --sysctl net.ipv4.ip_forward=1 someimage
```

Note that not all sysctls are namespaced. Podman does not support changing sysctls
inside of a container that also modify the host system. As the kernel
evolves we expect to see more sysctls become namespaced.

See the definition of the **--sysctl** option above for the current list of
supported sysctls.

### Set UID/GID mapping in a new user namespace

Running a container in a new user namespace requires a mapping of
the uids and gids from the host.

```
$ podman run --uidmap 0:30000:7000 --gidmap 0:30000:7000 fedora echo hello
```

### Configuring Storage Options from the command line

Podman allows for the configuration of storage by changing the values
in the _/etc/container/storage.conf_ or by using global options. This
shows how to set up and use fuse-overlayfs for a one-time run of busybox
using global options.

```
podman --log-level=debug --storage-driver overlay --storage-opt "overlay.mount_program=/usr/bin/fuse-overlayfs" run busybox /bin/sh
```

### Configure timezone in a container

```
$ podman run --tz=local alpine date
$ podman run --tz=Asia/Shanghai alpine date
$ podman run --tz=US/Eastern alpine date
```

### Adding dependency containers

The first container, container1, is not started initially, but must be running before container2 will start.
The `podman run` command will start the container automatically before starting container2.

```
$ podman create --name container1 -t -i fedora bash
$ podman run --name container2 --requires container1 -t -i fedora bash
```

Multiple containers can be required.

```
$ podman create --name container1 -t -i fedora bash
$ podman create --name container2 -t -i fedora bash
$ podman run --name container3 --requires container1,container2 -t -i fedora bash
```

### Configure keep supplemental groups for access to volume

```
$ podman run -v /var/lib/design:/var/lib/design --group-add keep-groups ubi8
```

### Configure execution domain for containers using personality flag

```
$ podman run --name container1 --personality=LINUX32 fedora bash
```

### Run a container with external rootfs mounted as an overlay

```
$ podman run --name container1 --rootfs /path/to/rootfs:O bash
```

### Handling Timezones in java applications in a container.

In order to use a timezone other than UTC when running a
Java application within a container, the `TZ` environment variable must be
set within the container. Java applications will ignore the value set with the
`--tz` option.

```
# Example run
podman run -ti --rm  -e TZ=EST mytzimage
lrwxrwxrwx. 1 root root 29 Nov  3 08:51 /etc/localtime -> ../usr/share/zoneinfo/Etc/UTC
Now with default timezone:
Fri Nov 19 18:10:55 EST 2021
Java default sees the following timezone:
2021-11-19T18:10:55.651130-05:00
Forcing UTC:
Fri Nov 19 23:10:55 UTC 2021
```

### Run a container connected to two networks (called net1 and net2) with a static ip

```
$ podman run --network net1:ip=10.89.1.5 --network net2:ip=10.89.10.10 alpine ip addr
```

### Rootless Containers

Podman runs as a non-root user on most systems. This feature requires that a new enough version of **shadow-utils**
be installed. The **shadow-utils** package must include the **newuidmap**(1) and **newgidmap**(1) executables.

In order for users to run rootless, there must be an entry for their username in _/etc/subuid_ and _/etc/subgid_ which lists the UIDs for their user namespace.

Rootless Podman works better if the fuse-overlayfs and slirp4netns packages are installed.
The **fuse-overlayfs** package provides a userspace overlay storage driver, otherwise users need to use
the **vfs** storage driver, which is diskspace expensive and does not perform well. slirp4netns is
required for VPN, without it containers need to be run with the **--network=host** flag.

## ENVIRONMENT

Environment variables within containers can be set using multiple different options,
in the following order of precedence (later entries override earlier entries):

- Container image: Any environment variables specified in the container image.
- **--http-proxy**: By default, several environment variables will be passed in from the host, such as **http_proxy** and **no_proxy**. See **--http-proxy** for details.
- **--env-host**: Host environment of the process executing Podman is added.
- **--env-file**: Any environment variables specified via env-files. If multiple files are specified, then they override each other in order of entry.
- **--env**: Any environment variables specified will override previous settings.

Run containers and set the environment ending with a __*__.
The trailing __*__ glob functionality is only active when no value is specified:

```
$ export ENV1=a
$ podman run --env 'ENV*' alpine env | grep ENV
ENV1=a
$ podman run --env 'ENV*=b' alpine env | grep ENV
ENV*=b
```

## CONMON

When Podman starts a container it actually executes the conmon program, which
then executes the OCI Runtime.  Conmon is the container monitor.  It is a small
program whose job is to watch the primary process of the container, and if the
container dies, save the exit code.  It also holds open the tty of the
container, so that it can be attached to later. This is what allows Podman to
run in detached mode (backgrounded), so Podman can exit but conmon continues to
run.  Each container has their own instance of conmon. Conmon waits for the
container to exit, gathers and saves the exit code, and then launches a Podman
process to complete the container cleanup, by shutting down the network and
storage.   For more information on conmon, please reference the conmon(8) man
page.

## FILES

**/etc/subuid**

**/etc/subgid**

NOTE: Use the environment variable `TMPDIR` to change the temporary storage location of downloaded container images. Podman defaults to use `/var/tmp`.

## SEE ALSO
**[podman(1)](podman.1.md)**, **[podman-save(1)](podman-save.1.md)**, **[podman-ps(1)](podman-ps.1.md)**, **[podman-attach(1)](podman-attach.1.md)**, **[podman-pod-create(1)](podman-pod-create.1.md)**, **[podman-port(1)](podman-port.1.md)**, **[podman-start(1)](podman-start.1.md)**, **[podman-kill(1)](podman-kill.1.md)**, **[podman-stop(1)](podman-stop.1.md)**, **[podman-generate-systemd(1)](podman-generate-systemd.1.md)**, **[podman-rm(1)](podman-rm.1.md)**, **[subgid(5)](https://www.unix.com/man-page/linux/5/subgid)**, **[subuid(5)](https://www.unix.com/man-page/linux/5/subuid)**, **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)**, **[systemd.unit(5)](https://www.freedesktop.org/software/systemd/man/systemd.unit.html)**, **[setsebool(8)](https://man7.org/linux/man-pages/man8/setsebool.8.html)**, **[slirp4netns(1)](https://github.com/rootless-containers/slirp4netns/blob/master/slirp4netns.1.md)**, **[fuse-overlayfs(1)](https://github.com/containers/fuse-overlayfs/blob/main/fuse-overlayfs.1.md)**, **proc(5)**, **[conmon(8)](https://github.com/containers/conmon/blob/main/docs/conmon.8.md)**, **personality(2)**

## HISTORY
September 2018, updated by Kunal Kushwaha `<kushwaha_kunal_v7@lab.ntt.co.jp>`

October 2017, converted from Docker documentation to Podman by Dan Walsh for Podman `<dwalsh@redhat.com>`

November 2015, updated by Sally O'Malley `<somalley@redhat.com>`

June 2014, updated by Sven Dowideit `<SvenDowideit@home.org.au>`

April 2014, Originally compiled by William Henry `<whenry@redhat.com>` based on docker.com source material and internal work.

## 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 should 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.