What started out as a simple PR to remove the "Readonly" column became an
adventure to add a proper type for a "View" snapshot. The short story here is
that we now get the following output:
```
$ sudo ctr snapshot ls
ID PARENT KIND
sha256:08c2295a7fa5c220b0f60c994362d290429ad92f6e0235509db91582809442f3 Committed
testing4 sha256:08c2295a7fa5c220b0f60c994362d290429ad92f6e0235509db91582809442f3 Active
```
In pursuing this output, it was found that the idea of having "readonly" as an
attribute on all snapshots was redundant. For committed, they are always
readonly, as they are not accessible without an active snapshot. For active
snapshots that were views, we'd have to check the type before interpreting
"readonly". With this PR, this is baked fully into the kind of snapshot. When
`Snapshotter.View` is called, the kind of snapshot is `KindView`, and the
storage system reflects this end to end.
Unfortunately, this will break existing users. There is no migration, so they
will have to wipe `/var/lib/containerd` and recreate everything. However, this
is deemed worthwhile at this point, as we won't have to judge validity of the
"Readonly" field when new snapshot types are added.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
e.g. dist pull --snapshotter btrfs ...; ctr run --snapshotter btrfs ...
(empty string defaults for overlayfs)
Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Now that we have most of the services required for use with containerd,
it was found that common patterns were used throughout services. By
defining a central `errdefs` package, we ensure that services will map
errors to and from grpc consistently and cleanly. One can decorate an
error with as much context as necessary, using `pkg/errors` and still
have the error mapped correctly via grpc.
We make a few sacrifices. At this point, the common errors we use across
the repository all map directly to grpc error codes. While this seems
positively crazy, it actually works out quite well. The error conditions
that were specific weren't super necessary and the ones that were
necessary now simply have better context information. We lose the
ability to add new codes, but this constraint may not be a bad thing.
Effectively, as long as one uses the errors defined in `errdefs`, the
error class will be mapped correctly across the grpc boundary and
everything will be good. If you don't use those definitions, the error
maps to "unknown" and the error message is preserved.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
To simplify use of types, we have consolidate the packages for the mount
and descriptor protobuf types into a single Go package. We also drop the
versioning from the type packages, as these types will remain the same
between versions.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
This moves both the Mount type and mountinfo into a single mount
package.
This also opens up the root of the repo to hold the containerd client
implementation.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Remove rootfs service in place of snapshot service. Adds
diff service for extracting and creating diffs. Diff
creation is not yet implemented. This service allows
pulling or creating images without needing root access to
mount. Additionally in the future this will allow containerd
to ensure extractions happen safely in a chroot if needed.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
