diff options
Diffstat (limited to 'docs/source/markdown/podman-create.1.md')
| -rw-r--r-- | docs/source/markdown/podman-create.1.md | 66 |
1 files changed, 63 insertions, 3 deletions
diff --git a/docs/source/markdown/podman-create.1.md b/docs/source/markdown/podman-create.1.md index db9ff937b..11a2410a8 100644 --- a/docs/source/markdown/podman-create.1.md +++ b/docs/source/markdown/podman-create.1.md @@ -975,11 +975,71 @@ Remote connections use local containers.conf for defaults Set the umask inside the container. Defaults to `0022`. Remote connections use local containers.conf for defaults -#### **\-\-uidmap**=*container_uid:host_uid:amount* +#### **\-\-uidmap**=*container_uid*:*from_uid*:*amount* -UID map for the user namespace. Using this flag will run the container with user namespace enabled. It conflicts with the `--userns` and `--subuidname` flags. +Run the container in a new user namespace using the supplied mapping. This +option conflicts with the **\-\-userns** and **\-\-subuidname** options. This +option provides a way to map host UIDs to container UIDs. It can be passed +several times to map different ranges. -The following example maps uids 0-2000 in the container to the uids 30000-31999 on the host and gids 0-2000 in the container to the gids 30000-31999 on the host. `--uidmap=0:30000:2000` +The _from_uid_ value is based upon the user running the command, either rootful or rootless users. +* rootful user: *container_uid*:*host_uid*:*amount* +* rootless user: *container_uid*:*intermediate_uid*:*amount* + +When **podman create** is called by a privileged user, the option **\-\-uidmap** +works as a direct mapping between host UIDs and container UIDs. + +host UID -> container UID + +The _amount_ specifies the number of consecutive UIDs that will be mapped. +If for example _amount_ is **4** the mapping would look like: + +| host UID | container UID | +| - | - | +| _from_uid_ | _container_uid_ | +| _from_uid_ + 1 | _container_uid_ + 1 | +| _from_uid_ + 2 | _container_uid_ + 2 | +| _from_uid_ + 3 | _container_uid_ + 3 | + +When **podman create** is called by an unprivileged user (i.e. running rootless), +the value _from_uid_ is interpreted as an "intermediate UID". In the rootless +case, host UIDs are not mapped directly to container UIDs. Instead the mapping +happens over two mapping steps: + +host UID -> intermediate UID -> container UID + +The **\-\-uidmap** option only influences the second mapping step. + +The first mapping step is derived by Podman from the contents of the file +_/etc/subuid_ and the UID of the user calling Podman. + +First mapping step: +| host UID | intermediate UID | +| - | - | +| UID for the user starting Podman | 0 | +| 1st subordinate UID for the user starting Podman | 1 | +| 2nd subordinate UID for the user starting Podman | 2 | +| 3rd subordinate UID for the user starting Podman | 3 | +| nth subordinate UID for the user starting Podman | n | + +To be able to use intermediate UIDs greater than zero, the user needs to have +subordinate UIDs configured in _/etc/subuid_. See **subuid**(5). + +The second mapping step is configured with **\-\-uidmap**. + +If for example _amount_ is **5** the second mapping step would look like: + +| intermediate UID | container UID | +| - | - | +| _from_uid_ | _container_uid_ | +| _from_uid_ + 1 | _container_uid_ + 1 | +| _from_uid_ + 2 | _container_uid_ + 2 | +| _from_uid_ + 3 | _container_uid_ + 3 | +| _from_uid_ + 4 | _container_uid_ + 4 | + +Even if a user does not have any subordinate UIDs in _/etc/subuid_, +**\-\-uidmap** could still be used to map the normal UID of the user to a +container UID by running `podman create --uidmap $container_uid:0:1 --user $container_uid ...`. #### **\-\-ulimit**=*option* |