feat: Enable json logging format

[stewartshea]

Specifically for GKE environments that leverage Google Cloud Operations Logging, logs generated by the provider are all classified as ERROR rather than the proper type as outlined in stdout/stderr. It would be helpful to be able to set the log output in json format such that Operations Logging can properly classify the log type.

[tomhjp]

Thanks for raising! I'd like to add this. The equivalent Vault server log option are here for reference/consistency: https://www.vaultproject.io/docs/commands/server#log-format. Although we already diverged by using -debug instead of -log-level.

The logging library supports JSON output already, so it should be relatively straightforward if you're interested in tackling it: https://pkg.go.dev/github.com/hashicorp/go-hclog#LoggerOptions. Otherwise I'll get to this at some point.

[stewartshea]

Thanks @tomhjp for the details, I'll see if I can set aside a little time to tackle and PR it.

[krishnadas-m]

Is this request still open? It would be great if this capability is added to the csi.

[jbgcarnes]

@tomhjp Let me know if there are any issues with the MR.