guest OCI hooks are not working with Kata

[bpradipt]

Description of problem

OCI hooks are not working with Kata. Created a rootfs with hook scripts and enabled guest_hook_path = "/usr/share/oci/hooks" in the configuration.toml.
Running the container results in the following error:

Error response from daemon: OCI runtime create failed: rpc error: code = Unknown desc = open /run/kata-containers/shared/containers/7217217f69ef8af65581790aa06fe3b54499dd3b8f1a79e6116
94ec670a6182a/config.json: read-only file system: unknown.
time="2020-06-10T11:49:58Z" level=error msg="error waiting for container: context canceled"

The problem got introduced since the following commit a3dec26

Expected result

Container should start and hooks should run

Actual result

Container fails to start.

[devimc]

cc @bergwolf

[bpradipt]

The following call is failing - https://github.com/kata-containers/agent/blob/master/grpc.go#L679
since the root path is read-only and it's trying to write the config.json in that path
Relevant code - https://github.com/kata-containers/agent/blob/master/oci.go#L29-L39

One option is to write the config.json to a rw path - eg /run/. However I'm not sure what's the other side-effect of the same.

[dgibson]

To clarify, AFAICT this is specifically about hooks set with the guest_hook_path configuration option. Hooks set in the OCI config.json appear to work ok, and are executed on the host, rather than the sandbox VM.

[jodh-intel]

Updated title to make that point clearer.

[amshinde]

I think the fix has been merged.
@bpradipt Please feel free open if work still needs to be done in this area.