Add version information for in-VM agent, shim, firecracker-conta…

[kzys]

Investigating issues like #370 will be easier if the agent can report
the version.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[kzys]

Right now, firecracker-containerd and firecracker-ctr have "some" version information.

% ./firecracker-control/cmd/containerd/firecracker-containerd -v                                    
containerd github.com/containerd/containerd 1.3.1+unknown                                           
% ./firecracker-control/cmd/containerd/firecracker-ctr -v                                           
ctr github.com/containerd/containerd 1.3.1+unknown                                                  

The shim is not having any.

% ./runtime/containerd-shim-aws-firecracker -h
Usage of ./runtime/containerd-shim-aws-firecracker:
  -address string
        grpc address back to main containerd
  -bundle string
        path to the bundle if not workdir
  -debug
        enable debug output in logs
  -httptest.serve string
        if non-empty, httptest.NewServer serves on this address and blocks
  -id string
        id of the task
  -namespace string
        namespace that owns the shim
  -publish-binary string
        path to publish binary (used for publishing events) (default "containerd")
  -socket string
        abstract socket path to serve
  -test.bench regexp
        run only benchmarks matching regexp
...

[samuelkarp]

goimports is complaining, but other than the lint issue I think this code looks fine.

CI is failing

[kzys]

Realized that we must not write anything on "start", since the stdin is used for passing the address of the shim.

• https://github.com/containerd/containerd/blob/cbfff2fb789ae8b6f2233a13fe123a1a2cd53e21/runtime/v2/README.md#start
• https://github.com/containerd/containerd/blob/324a94790d7c4d5757b89d002f7b528082fc6496/runtime/v2/shim/shim.go#L215

Will fix!

[kzys]

After the change, the shim will log the line like below;

time="2020-01-10T20:49:24.643207368Z" level=info msg="successfully started shim (git commit: a731d81a6313ba8d78036e6bf976808554f442eb)." runtime=aws.firecracker task_id=container-TestStopVM_Isolated_ErrorExit vmID=TestStopVM_Isolated_ErrorExit

agent will have -version

% ./agent/agent -version
containerd Firecracker agent (git commit: a731d81a6313ba8d78036e6bf976808554f442eb)

firecracker-containerd follows what containerd does.

% ./firecracker-control/cmd/containerd/firecracker-containerd -v
containerd github.com/containerd/containerd 1.3.1+unknown a731d81a6313ba8d78036e6bf976808554f442eb
% containerd -v
containerd containerd.io 1.2.10 b34a5c8af56e510852c35414db4c1f4fa6172339