Container storage migration

A computer program product for migrating a container from a source host to a target host, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a device to cause the device to:

• provision a copy-on-write union filesystem on the target host with (i) one or more network filesystem-mounted directories from the source host set to read-only and (ii) at least one directory set to read-write;
• identify one or more files that have been (i) updated by a given container and (ii) copied over by the copy-on-write union filesystem;
• remove the one or more identified files from a directory path on the target host;
• copy, from the source host into the directory path on the target host, each of one or more files that have not been updated by the given container;
• merge the copy-on-write union filesystem and the directory path on the target host;
• and
• initiate the given container on the target host based on said merging.

A system for migrating a container from a source host to a target host comprising:

• a memory;
• and
• at least one processor coupled to the memory and configured for:
• provisioning a copy-on-write union filesystem on the target host with (i) one or more network filesystem-mounted directories from the source host set to read-only and (ii) at least one directory set to read-write;
• identifying one or more files that have been (i) updated by a given container and (ii) copied over by the copy-on-write union filesystem;
• removing the one or more identified files from a directory path on the target host;
• copying, from the source host into the directory path on the target host, each of one or more files that have not been updated by the given container;
• merging the copy-on-write union filesystem and the directory path on the target host;
• and
• initiating the given container on the target host based on said merging.

A computer-implemented method, comprising:

• creating a write-able directory on a local filesystem;
• mounting the write-able directory with a network filesystem directory exported from a host source, wherein the network filesystem directory is mounted as read-only;
• creating a layered filesystem on a container, wherein the layered filesystem comprises (i) a single layer that is write-able and (ii) one or more additional layers that are each read-only;
• establishing a symbolic link on the single layer that is write-able in the layered filesystem to the mounted network filesystem directory;
• and
• instantiating the container based on said symbolic link;
• wherein said steps are carried out by at least one computing device.