Add healthcheck API

[Quanzheng Long]

return format:

{
  "condition": "OK", # use constant value
  "hostname": "xxxxxx", # just return the hostname or IP
  "duration": 0  # return zero here is fine. 
}

Note 1

The format is required, because already defined in here and being used broadly at Indeed.

For duration, it means the time to calculate the health of the service in seconds.

For the first iteration(PR), we can just return zero.

For the second iteration, we can use Temporal/Cadence service client to perform the healthcheck like this:

_, err := serviceClient.CheckHealth(ctx, &client.CheckHealthRequest{})

and calculate the timeeslapsed of the API call. Because Temporal/Cadence is the only dependency of iWF.

Note 2:

We need to define a new API endpoint in the swagger: https://github.com/indeedeng/iwf-idl/blob/main/iwf.yaml#L13

The endpoint URL should be GET /info/healthcheck based on the Indeed standard.

[Krishna Dutt Panchagnula]

/assign

[Rajan Sharma]

@krishnaduttPanchagnula Are you working on this?

[Quanzheng Long]

Thanks @krishnaduttPanchagnula @Rajan-226 for your interests.

To help you get started, I just added more details to help. LMK if you have any questions.

[Rajan Sharma]

Thanks @longquanzheng, Will pick this up.

[Rajan Sharma]

@longquanzheng Will complete this tomorrow, Can you check the draft once though: #327