d2p-migrator

d2p-migrator

d2p-migrator is a system tool for ops to migrate containers from docker world to pouchcontainer world.

Scenaris

PouchContainer has a lot of advanced features towards Docker. Under some circumstance, when upgrading dockerd to pouchd, the legacy containers cannot be removed. These containers must be running in place. As a result, it is an essential functionality to migrate legacy containers to those which are managed by pouchcontainer.

Migrate Steps

We assume that dockerd is running with controlling containerd 0.2.3 in environment. Docker has not supported containerd 1.0.0+ yet, so image management is not in the scope of docker. While PouchContainer takes advantanges of containerd 1.0.0+ to manage containers and images. Migration containers from docker's management to pouchd must take both image and container into consideration. Here are the steps to accomplish a migration job.

Step 1 - Install containerd 1.0.3 independently, rename it to d2p-containerd

Step 2 - Pull Images via ctr

Step 3 - Prepare snapshotters with containerd's API

Step 4 - Setting QuotaID to UpperDir/MergedDir

Step 5 - Stop all containers and dockerd

Step 6 - Move legacy content from old_upperdir/* to new-upperdir/

Step 7 - Convert old container's metadata in dockerd to new's in pouchd

Step 8 - Stop running containerd 1.0.3

Step 9 - Install PouchContainer with rpm including containerd 1.0.3

Step 10 - Start all containers in pouchd

To be continued