containerd/server
Stephen J Day 0e72ce5c5b
services/introspection: implement plugin reporting
With this change, we integrate all the plugin changes into the
introspection service.

All plugins can be listed with the following command:

```console
$ ctr plugins
TYPE                            ID             PLATFORM       STATUS
io.containerd.content.v1        content        -              ok
io.containerd.metadata.v1       bolt           -              ok
io.containerd.differ.v1         walking        linux/amd64    ok
io.containerd.grpc.v1           containers     -              ok
io.containerd.grpc.v1           content        -              ok
io.containerd.grpc.v1           diff           -              ok
io.containerd.grpc.v1           events         -              ok
io.containerd.grpc.v1           healthcheck    -              ok
io.containerd.grpc.v1           images         -              ok
io.containerd.grpc.v1           namespaces     -              ok
io.containerd.snapshotter.v1    btrfs          linux/amd64    error
io.containerd.snapshotter.v1    overlayfs      linux/amd64    ok
io.containerd.grpc.v1           snapshots      -              ok
io.containerd.monitor.v1        cgroups        linux/amd64    ok
io.containerd.runtime.v1        linux          linux/amd64    ok
io.containerd.grpc.v1           tasks          -              ok
io.containerd.grpc.v1           version        -              ok
```

There are few things to note about this output. The first is that it is
printed in the order in which plugins are initialized. This useful for
debugging plugin initialization problems. Also note that even though the
introspection GPRC api is a itself a plugin, it is not listed. This is
because the plugin takes a snapshot of the initialization state at the
end of the plugin init process. This allows us to see errors from each
plugin, as they happen. If it is required to introspect the existence of
the introspection service, we can make modifications to include it in
the future.

The last thing to note is that the btrfs plugin is in an error state.
This is a common state for containerd because even though we load the
plugin, most installations aren't on top of btrfs and the plugin cannot
be used. We can actually view this error using the detailed view with a
filter:

```console
$ ctr plugins --detailed id==btrfs
Type:          io.containerd.snapshotter.v1
ID:            btrfs
Platforms:     linux/amd64
Exports:
               root      /var/lib/containerd/io.containerd.snapshotter.v1.btrfs
Error:
               Code:        Unknown
               Message:     path /var/lib/containerd/io.containerd.snapshotter.v1.btrfs must be a btrfs filesystem to be used with the btrfs snapshotter
```

Along with several other values, this is a valuable tool for evaluating the
state of components in containerd.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2017-10-10 17:29:24 -07:00
..
config.go Handle signals first on boot 2017-09-15 10:00:19 -04:00
server_linux.go update docs and comments 2017-09-25 14:48:28 +08:00
server_solaris.go update docs and comments 2017-09-25 14:48:28 +08:00
server_unsupported.go update docs and comments 2017-09-25 14:48:28 +08:00
server_windows.go Resurrect State directory 2017-08-03 09:15:53 -07:00
server.go services/introspection: implement plugin reporting 2017-10-10 17:29:24 -07:00