Copying files to or from an OKD container

You can use the CLI to copy local files to or from a remote directory in a container using the rsync command.

Understanding how to copy files

The oc rsync command, or remote sync, is a useful tool for copying database archives to and from your pods for backup and restore purposes. You can also use oc rsync to copy source code changes into a running pod for development debugging, when the running pod supports hot reload of source files.

  1. $ oc rsync <source> <destination> [-c <container>]

Requirements

Specifying the Copy Source

The source argument of the oc rsync command must point to either a local directory or a pod directory. Individual files are not supported.

When specifying a pod directory the directory name must be prefixed with the pod name:

  1. <pod name>:<dir>

If the directory name ends in a path separator (/), only the contents of the directory are copied to the destination. Otherwise, the directory and its contents are copied to the destination.

Specifying the Copy Destination

The destination argument of the oc rsync command must point to a directory. If the directory does not exist, but rsync is used for copy, the directory is created for you.

Deleting Files at the Destination

The --delete flag may be used to delete any files in the remote directory that are not in the local directory.

Continuous Syncing on File Change

Using the --watch option causes the command to monitor the source path for any file system changes, and synchronizes changes when they occur. With this argument, the command runs forever.

Synchronization occurs after short quiet periods to ensure a rapidly changing file system does not result in continuous synchronization calls.

When using the --watch option, the behavior is effectively the same as manually invoking oc rsync repeatedly, including any arguments normally passed to oc rsync. Therefore, you can control the behavior via the same flags used with manual invocations of oc rsync, such as --delete.

Copying files to and from containers

Support for copying local files to or from a container is built into the CLI.

Prerequisites

When working with oc rsync, note the following:

  • rsync must be installed. The oc rsync command uses the local rsync tool, if present on the client machine and the remote container.

    If rsync is not found locally or in the remote container, a tar archive is created locally and sent to the container where the tar utility is used to extract the files. If tar is not available in the remote container, the copy will fail.

    The tar copy method does not provide the same functionality as oc rsync. For example, oc rsync creates the destination directory if it does not exist and only sends files that are different between the source and the destination.

    In Windows, the cwRsync client should be installed and added to the PATH for use with the oc rsync command.

Procedure

  • To copy a local directory to a pod directory:

    1. $ oc rsync <local-dir> <pod-name>:/<remote-dir> -c <container-name>

    For example:

    1. $ oc rsync /home/user/source devpod1234:/src -c user-container

  • To copy a pod directory to a local directory:

    1. $ oc rsync devpod1234:/src /home/user/source

    Example output

    1. $ oc rsync devpod1234:/src/status.txt /home/user/

Using advanced Rsync features

The oc rsync command exposes fewer command line options than standard rsync. In the case that you want to use a standard rsync command line option that is not available in oc rsync, for example the --exclude-from=FILE option, it might be possible to use standard rsync ‘s --rsh (-e) option or RSYNC_RSH environment variable as a workaround, as follows:

  1. $ rsync --rsh='oc rsh' --exclude-from=<file_name> <local-dir> <pod-name>:/<remote-dir>

or:

Export the RSYNC_RSH variable:

  1. $ export RSYNC_RSH='oc rsh'

Then, run the rsync command:

  1. $ rsync --exclude-from=<file_name> <local-dir> <pod-name>:/<remote-dir>

Both of the above examples configure standard rsync to use oc rsh as its remote shell program to enable it to connect to the remote pod, and are an alternative to running oc rsync.