containers.conf

containers.conf(5) configuration containers.conf(5)

NAME

   containers.conf - The container engine configuration file specifies default configuration options and command-line flags for container engines.

DESCRIPTION

   Container  engines  like Podman & Buildah read containers.conf file, if it exists and modify the defaults for running containers on the host. containers.conf
   uses a TOML format that can be easily modified and versioned.

   Container engines read the /usr/share/containers/containers.conf and /etc/containers/containers.conf, and  /etc/containers/containers.conf.d/.conf  files  if
   they  exist.  When  running  in  rootless  mode, they also read $HOME/.config/containers/containers.conf and $HOME/.config/containers/containers.conf.d/.conf
   files.

   Fields specified in containers conf override the default options, as well as options in previously read containers.conf files.

   Config files in the .d directories, are added in alpha numeric sorted order and must end in .conf.

   Not all options are supported in all container engines.

   Note container engines also use other configuration files for configuring the environment.

           storage.conf for configuration of container and images storage.

           registries.conf for definition of container registires to search while pulling.  container images.

           policy.conf for controlling which images can be pulled to the system.

FORMAT

   The TOML format https://github.com/toml-lang/toml is used as the encoding of the configuration file.  Every option is nested under its table. No  bare  op
   tions are used. The format of TOML can be simplified to:

          [table1]
          option = value

          [table2]
          option = value

          [table3]
          option = value

          [table3.subtable1]
          option = value

CONTAINERS TABLE

   The containers table contains settings to configure and manage the OCI runtime.

   annotations = [] List of annotations. Specified as "key=value" pairs to be added to all containers.

   Example: "run.oci.keep_original_groups=1"

   apparmor_profile="container-default"

   Used to change the name of the default AppArmor profile of container engines.  The default profile name is "container-default".

   base_hosts_file=""

   The  hosts  entries  from the base hosts file are added to the containers hosts file. This must be either an absolute path or as special values "image" which
   uses the hosts file from the container image or "none" which means no base hosts file is used. The default is "" which will use /etc/hosts.

   cgroups="enabled"

   Determines  whether  the  container will create CGroups.  Options are:
     enabled   Enable cgroup support within container
     disabled  Disable cgroup support, will inherit cgroups from parent
     no-conmon Do not create a cgroup dedicated to conmon.

   cgroupns="private"

   Default way to to create a cgroup namespace for the container.  Options are: private Create private Cgroup Namespace for the container.  host     Share  host
   Cgroup Namespace with the container.

   default_capabilities=[]

   List of default capabilities for containers.

   The default list is:

          default_capabilities = [
          "AUDIT_WRITE",
                "CHOWN",
                "DAC_OVERRIDE",
                "FOWNER",
                "FSETID",
                "KILL",
                "MKNOD",
                "NET_BIND_SERVICE",
                "NET_RAW",
                "SETGID",
                "SETPCAP",
                "SETUID",
                "SYS_CHROOT",
          ]

   default_sysctls=[]

   A list of sysctls to be set in containers by default, specified as "name=value".

   Example:"net.ipv4.ping_group_range=0 1000".

   default_ulimits=[]

   A list of ulimits to be set in containers by default, specified as "name=soft-limit:hard-limit".

   Example: "nofile=1024:2048".

   devices=[]

   List of devices.  Specified as 'device-on-host:device-on-container:permissions'.

   Example: "/dev/sdc:/dev/xvdc:rwm".

   dns_options=[]

   List of default DNS options to be added to /etc/resolv.conf inside of the container.

   dns_searches=[]

   List of default DNS search domains to be added to /etc/resolv.conf inside of the container.

   dns_servers=[]

   A  list  of  dns servers to override the DNS configuration passed to the container. The special value none can be specified to disable creation of /etc/re
   solv.conf in the container.

   env=["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin", "TERM=xterm"]

   Environment variable list for the container process, used for passing environment variables to the container.

   env_host=false

   Pass all host environment variables into the container.

   host_containers_internal_ip=""

   Set the ip for the host.containers.internal entry in the containers /etc/hosts file. This can be set to "none" to disable adding this entry.  By  default  it
   will automatically choose the host ip.

   NOTE:  When  using  podman  machine  this entry will never be added to the containers hosts file instead the gvproxy dns resolver will resolve this hostname.
   Therefore it is not possible to disable the entry in this case.

   http_proxy=true

   Default proxy environment variables will be passed into the container.  The environment variables passed  in  include:  http_proxy,  https_proxy,  ftp_proxy,
   no_proxy,  and  the upper case versions of these. The no_proxy option is needed when host system uses a proxy but container should not use proxy. Proxy envi
   ronment variables specified for the container in any other way will override the values passed from the host.

   init=false

   Run an init inside the container that forwards signals and reaps processes.

   init_path="/usr/libexec/podman/catatonit"

   Path to the container-init binary, which forwards signals and reaps processes within containers. Note that the container-init binary will only be  used  when
   the --init for podman-create and podman-run is set.

   ipcns="shareable"

   Default way to to create a IPC namespace for the container.  Options are:
     host     Share host IPC Namespace with the container.
     none     Create shareable IPC Namespace for the container without a private /dev/shm.
     private  Create private IPC Namespace for the container, other containers are not allowed to share it.
     shareable Create shareable IPC Namespace for the container.

   keyring=true

   Indicates whether the container engines create a kernel keyring for use within the container.

   label=true

   Indicates whether the container engine uses MAC(SELinux) container separation via labeling. This option is ignored on disabled systems.

   log_driver=""

   Logging  driver for the container. Currently available options are k8s-file, journald, none and passthrough, with json-file aliased to k8s-file for scripting
   compatibility.  The journald driver is used by default if the systemd journal is readable and writable.  Otherwise, the k8s-file driver is used.

   log_size_max=-1

   Maximum size allowed for the container's log file. Negative numbers indicate that no size limit is imposed. If  it  is  positive,  it  must  be  >=  8192  to
   match/exceed conmon's read buffer. The file is truncated and re-opened so the limit is never exceeded.

   log_tag=""

   Default format tag for container log messages. This is useful for creating a specific tag for container log messages. Container log messages default to using
   the truncated container ID as a tag.

   netns="private"

   Default way to to create a NET namespace for the container.  Options are:
     private Create private NET Namespace for the container.
     host    Share host NET Namespace with the container.
     none    Containers do not use the network.

   no_hosts=false

   Create /etc/hosts for the container. By default, container engines manage /etc/hosts, automatically adding  the container's  own  IP  address.

   pidns="private"

   Default way to to create a PID namespace for the container.  Options are:
     private Create private PID Namespace for the container.
     host    Share host PID Namespace with the container.

   pids_limit=1024

   Maximum number of processes allowed in a container. 0 indicates that no limit is imposed.

   prepare_volume_on_create=false

   Copy the content from the underlying image into the newly created volume when the container is created instead of when it is started. If false, the container
   engine will not copy the content until the container is started. Setting it to true may have negative performance implications.

   seccomp_profile="/usr/share/containers/seccomp.json"

   Path to the seccomp.json profile which is used as the default seccomp profile for the runtime.

   shm_size="65536k"

   Size  of  /dev/shm.  The  format is <number><unit>. number must be greater than 0.  Unit is optional and can be: b (bytes), k (kilobytes), m(megabytes), or g
   (gigabytes).  If you omit the unit, the system uses bytes. If you omit the size entirely, the system uses 65536k.

   tz=""

   Set timezone in container. Takes IANA timezones as well as local, which sets the timezone in the container to match the host machine.  If not set, then  con
   tainers will run with the time zone specified in the image.

   Examples:
     tz="local"
     tz="America/New_York"

   umask="0022"

   Sets umask inside the container.

   userns="host"

   Default way to to create a USER namespace for the container.  Options are:
     private Create private USER Namespace for the container.
     host    Share host USER Namespace with the container.

   userns_size=65536

   Number of UIDs to allocate for the automatic container creation. UIDs are allocated from the container UIDs listed in /etc/subuid & /etc/subgid.

   utsns="private"

   Default way to to create a UTS namespace for the container.  Options are:
     private Create private UTS Namespace for the container.
     host    Share host UTS Namespace with the container.

   volumes=[]

   List of volumes.  Specified as "directory-on-host:directory-in-container:options".

   Example:  "/db:/var/lib/db:ro".

NETWORK TABLE

   The network table contains settings pertaining to the management of CNI plugins.

   network_backend=""

   Network  backend determines what network driver will be used to set up and tear down container networks.  Valid values are "cni" and "netavark".  The default
   value is empty which means that it will automatically choose CNI or netavark. If there are already containers/images or CNI networks preset  it  will  choose
   CNI.

   Before  changing this value all containers must be stopped otherwise it is likely that iptables rules and network interfaces might leak on the host. A reboot
   will fix this.

   cni_plugin_dirs=[]

   List of paths to directories where CNI plugin binaries are located.

   The default list is:

          cni_plugin_dirs = [
            "/usr/local/libexec/cni",
            "/usr/libexec/cni",
            "/usr/local/lib/cni",
            "/usr/lib/cni",
            "/opt/cni/bin",
          ]

   default_network="podman"

   The network name of the default network to attach pods to.

   default_subnet="10.88.0.0/16"

   The subnet to use for the default network (named above in default_network).  If the default network does not exist, it  will  be  automatically  created  the
   first time a tool is run using this subnet.

   default_subnet_pools=[]

   DefaultSubnetPools  is  a  list  of subnets and size which are used to allocate subnets automatically for podman network create.  It will iterate through the
   list and will pick the first free subnet with the given size. This is only used for ipv4 subnets, ipv6 subnets are always assigned randomly.

   The default list is (10.89.0.0-10.255.255.0/24):

          default_subnet_pools = [
            {"base" = "10.89.0.0/16", "size" = 24},
            {"base" = "10.90.0.0/15", "size" = 24},
            {"base" = "10.92.0.0/14", "size" = 24},
            {"base" = "10.96.0.0/11", "size" = 24},
            {"base" = "10.128.0.0/9", "size" = 24},
          ]

   network_config_dir="/etc/cni/net.d/"

   Path to the directory where network configuration files are located.  For  the  CNI  backend  the  default  is  "/etc/cni/net.d"  as  root  and  "$HOME/.con‐
   fig/cni/net.d" as rootless.  For the netavark backend "/etc/containers/networks" is used as root and "$graphroot/networks" as rootless.

   dns_bind_port=53

   Port  to  use  for dns forwarding daemon with netavark in rootful bridge mode and dns enabled.  Using an alternate port might be useful if other dns services
   should run on the machine.

ENGINE TABLE

   The engine table contains configuration options used to set up container engines such as Podman and Buildah.

   active_service=""

   Name of destination for accessing the Podman service. See SERVICE DESTINATION TABLE below.

   cgroup_manager="systemd"

   The cgroup management implementation used for the runtime. Supports cgroupfs and systemd.

   conmon_env_vars=[]

   Environment variables to pass into Conmon.

   conmon_path=[]

   Paths to search for the conmon container manager binary. If the paths are empty or no valid path was found, then the $PATH environment variable will be  used
   as the fallback.

   The default list is:

          conmon_path=[
              "/usr/libexec/podman/conmon",
              "/usr/local/libexec/podman/conmon",
              "/usr/local/lib/podman/conmon",
              "/usr/bin/conmon",
              "/usr/sbin/conmon",
              "/usr/local/bin/conmon",
              "/usr/local/sbin/conmon",
              "/run/current-system/sw/bin/conmon",
          ]

   detach_keys="ctrl-p,ctrl-q"

   Keys sequence used for detaching a container.  Specify the keys sequence used to detach a container.  Format is a single character [a-Z] or a comma separated
   sequence of ctrl-<value>, where <value> is one of: a-z, @, ^, [, \, ], ^ or _

   enable_port_reservation=true

   Determines whether the engine will reserve ports on the host when they are forwarded to containers. When enabled, when ports  are  forwarded  to  containers,
   they  are held open by conmon as long as the container is running, ensuring that they cannot be reused by other programs on the host. However, this can cause
   significant memory usage if a container has many ports forwarded to it.  Disabling this can save memory.

   env=[]

   Environment variables to be used when running the container engine (e.g., Podman, Buildah). For example "http_proxy=internal.proxy.company.com".  Note  these
   environment  variables  will not be used within the container. Set the env section under [containers] table, if you want to set environment variables for the
   container.

   events_logfile_path=""

   Define where event logs will be stored, when events_logger is "file".

   events_logfile_max_size="1m"

   Sets the maximum size for events_logfile_path.  The unit can be b (bytes), k (kilobytes), m (megabytes) or g (gigabytes).  The format for the size  is  <num
   ber><unit>,  e.g., 1b or 3g.  If no unit is included then the size will be in bytes.  When the limit is exceeded, the logfile will be rotated and the old one
   will be deleted.  If the maximumn size is set to 0, then no limit will be applied, and the logfile will not be rotated.

   events_logger="journald"

   The default method to use when logging events.

   The default method is different based on the platform that Podman is being run upon.  To determine the current value, use this command:

   podman info --format {{.Host.EventLogger}

   Valid values are: file, journald, and none.

   helper_binaries_dir=["/usr/libexec/podman", ...]

   A is a list of directories which are used to search for helper binaries.

   The default paths on Linux are: - /usr/local/libexec/podman - /usr/local/lib/podman - /usr/libexec/podman - /usr/lib/podman

   The default paths on macOS are: - /usr/local/opt/podman/libexec -    /opt/homebrew/bin -    /opt/homebrew/opt/podman/libexec -  /usr/local/bin  -    /usr/lo
   cal/libexec/podman -    /usr/local/lib/podman -    /usr/libexec/podman -    /usr/lib/podman

   The default path on Windows is: - C:\Program Files\RedHat\Podman

   hooks_dir=["/etc/containers/oci/hooks.d", ...]

   Path to the OCI hooks directories for automatically executed hooks.

   image_default_format="oci"|"v2s2"|"v2s1"

   Manifest  Type  (oci,  v2s2,  or  v2s1)  to use when pulling, pushing, building container images. By default images pulled and pushed match the format of the
   source image. Building/committing defaults to OCI.  Note: image_build_format is deprecated.

   image_default_transport="docker://"

   Default transport method for pulling and pushing images.

   image_parallel_copies=0

   Maximum number of image layers to be copied (pulled/pushed) simultaneously.  Not setting this field will fall back to containers/image defaults. (6)

   image_volume_mode="bind"

   Tells container engines how to handle the builtin image volumes.

           bind: An anonymous named volume will be  created  and  mounted into the container.

           tmpfs: The volume is mounted onto the container as a tmpfs, which allows the users to create content that disappears when the container is stopped.

           ignore: All volumes are just ignored and no action is taken.

   infra_command="/pause"

   Infra (pause) container image command for pod infra containers. When running a pod, we start a /pause process in a container to hold open the namespaces  as
   sociated with the pod. This container does nothing other then sleep, reserving the pods resources for the lifetime of the pod.

   infra_image=""

   Infra  (pause)  container  image for pod infra containers. When running a pod, we start a pause process in a container to hold open the namespaces associated
   with the pod. This container does nothing other then sleep, reserving the pods resources for the lifetime of the pod. By  default  container  engines  run  a
   builtin container using the pause executable. If you want override specify an image to pull.

   lock_type="shm"

   Specify the locking mechanism to use; valid values are "shm" and "file".  Change the default only if you are sure of what you are doing, in general "file" is
   useful only on platforms where cgo is not available for using the faster "shm" lock type. You may need to run "podman system renumber" after you  change  the
   lock type.

   multi_image_archive=false

   Allows  for  creating  archives (e.g., tarballs) with more than one image. Some container engines, such as Podman, interpret additional arguments as tags for
   one image and hence do not store more than one image. The default behavior can be altered with this option.

   namespace=""

   Default engine namespace. If the engine is joined to a namespace, it will see only containers and pods that were created in the same namespace, and will cre
   ate  new  containers and pods in that namespace. The default namespace is "", which corresponds to no namespace. When no namespace is set, all containers and
   pods are visible.

   network_cmd_path=""

   Path to the slirp4netns binary.

   network_cmd_options=[]

   Default options to pass to the slirp4netns binary.

   Valid options values are:

           allow_host_loopback=true|false: Allow the slirp4netns to reach the host loopback IP (10.0.2.2). 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 a 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.

   no_pivot_root=false

   Whether to use chroot instead of pivot_root in the runtime.

   num_locks=2048

   Number of locks available for containers and pods. Each created container or pod consumes one lock. The default number available is 2048. If this is changed,
   a lock renumbering must be performed, using the podman system renumber command.

   pod_exit_policy="continue"

   Set the exit policy of the pod when the last container exits.  Supported policies are:

   
   Exit Policy  Description                                             
   
   continue     The pod continues running when the last  container  ex 
                its. Used by default.                                   
   
   stop         The  pod is stopped when the last container exits. Used 
                in play kube.                                           
   

   pull_policy="always"|"missing"|"never"

   Pull image before running or creating a container. The default is missing.

           missing: attempt to pull the latest image from the registries listed in registries.conf if a local image does not exist. Raise an error if the image
            is not in any listed registry and is not present locally.

           always:  pull  the image from the first registry it is found in as listed in registries.conf. Raise an error if not found in the registries, even if
            the image is present locally.

           never: do not pull the image from the registry, use only the local version. Raise an error if the image is not present locally.

   remote = false Indicates whether the application should be running in remote mode. This flag modifies the --remote option on container engines.  Setting  the
   flag to true will default podman --remote=true for access to the remote Podman service.

   runtime=""

   Default  OCI specific runtime in runtimes that will be used by default. Must refer to a member of the runtimes table. Default runtime will be searched for on
   the system using the priority: "crun", "runc", "kata".

   runtime_supports_json=["crun", "runc", "kata", "runsc", "krun"]

   The list of the OCI runtimes that support --format=json.

   runtime_supports_kvm=["kata", "krun"]

   The list of OCI runtimes that support running containers with KVM separation.

   runtime_supports_nocgroups=["crun", "krun"]

   The list of OCI runtimes that support running containers without CGroups.

   image_copy_tmp_dir="/var/tmp"

   Default location for storing temporary container image content. Can be overridden with the TMPDIR environment variable. If you specify  "storage",  then  the
   location  of  the  container/storage  tmp  directory  will be used. If set then it is the users responsibility to cleanup storage. Configure tmpfiles.d(5) to
   cleanup storage.

   service_timeout=5

   Number of seconds to wait without a connection  before the podman system service times out and exits

   static_dir="/var/lib/containers/storage/libpod"

   Directory for persistent libpod files (database, etc).  By default this will be configured relative to where containers/storage stores containers.

   stop_timeout=10

   Number of seconds to wait for container to exit before sending kill signal.

   exit_command_delay=300

   Number of seconds to wait for the API process for the exec call before sending exit command mimicking the Docker behavior of 5 minutes (in seconds).

   tmp_dir="/run/libpod"

   The path to a temporary directory to store per-boot container.  Must be a tmpfs (wiped after reboot).

   volume_path="/var/lib/containers/storage/volumes"

   Directory where named volumes will be created in using the default volume driver.  By default this will be configured relative  to  where  containers/storage
   store containers. This convention is followed by the default volume driver, but may not be by other drivers.

   chown_copied_files=true

   Determines whether file copied into a container will have changed ownership to the primary uid/gid of the container.

   compression_format=""

   Specifies the compression format to use when pushing an image. Supported values are: gzip, zstd and zstd:chunked.

SERVICE DESTINATION TABLE

   The service_destinations table contains configuration options used to set up remote connections to the podman service for the podman API.

   [service_destinations.{name}] URI to access the Podman service uri="ssh://user@production.example.com/run/user/1001/podman/podman.sock"

   Example URIs:

           rootless local  - unix://run/user/1000/podman/podman.sock

           rootless remote - ssh://user@engineering.lab.company.com/run/user/1000/podman/podman.sock

           rootful local  - unix://run/podman/podman.sock

           rootful remote - ssh://root@10.10.1.136:22/run/podman/podman.sock

   identity="~/.ssh/id_rsa

   Path to file containing ssh identity key

   [engine.volume_plugins]

   A table of all the enabled volume plugins on the system. Volume plugins can be used as the backend for Podman named volumes. Individual plugins are specified
   below, as a map of the plugin name (what the plugin will be called) to its path (filepath of the plugin's unix socket).

SECRET TABLE

   The secret table contains settings for the configuration of the secret subsystem.

   driver=file

   Name of the secret driver to be used.  Currently valid values are:
     * file
     * pass

   [secrets.opts]

   The driver specific options object.

MACHINE TABLE

   The machine table contains configurations for podman machine VMs

   cpus=1 Number of CPU's a machine is created with.

   disk_size=10

   The size of the disk in GB created when init-ing a podman-machine VM

   image=""

   Default image URI when creating a new VM using podman machine init.  Options: On Linux/Mac, testing, stable, next. On Windows, the major version  of  the  OS
   (e.g  36) for Fedora 36. For all platforms you can alternatively specify a custom download URL to an image. Container engines translate URIs $OS and $ARCH to
   the native OS and ARCH. URI "https://example.com/$OS/$ARCH/foobar.ami" would become "https://example.com/linux/amd64/foobar.ami" on a Linux AMD machine.  The
   default value is testing on Linux/Mac, and on Windows.

   memory=2048

   Memory in MB a machine is created with.

   user=""

   Username to use and create on the podman machine OS for rootless container access. The default value is user. On Linux/Mac the default iscore.

   volumes=["$HOME:$HOME"]

   Host  directories  to  be mounted as volumes into the VM by default.  Environment variables like $HOME as well as complete paths are supported for the source
   and destination. An optional third field :ro can be used to tell the container engines to mount the volume readonly.

FILES

   containers.conf

   Distributions often provide a /usr/share/containers/containers.conf file to define default container configuration. Administrators  can  override  fields  in
   this  file by creating /etc/containers/containers.conf to specify their own configuration. Rootless users can further override fields in the config by creat
   ing a config file stored in the $HOME/.config/containers/containers.conf file.

   If the CONTAINERS_CONF path environment variable is set, just this path will be used. This is primarily used for testing.

   Fields specified in the containers.conf file override the default options, as well as options in previously read containers.conf files.

   storage.conf

   The /etc/containers/storage.conf file is the default storage configuration file.  Rootless users can override  fields  in  the  storage  config  by  creating
   $HOME/.config/containers/storage.conf.

   If the CONTAINERS_STORAGE_CONF path environment variable is set, this path is used for the storage.conf file rather than the default.  This is primarily used
   for testing.

SEE ALSO

   containers-storage.conf(5), containers-policy.json(5), containers-registries.conf(5), tmpfiles.d(5)

engine Container containers.conf(5)