Implement a health check for the tracker container

[josecelano]

We need to check the three services provided by the container:

• API
• HTTP Tracker (1 or more)
• UDP Tracker (1 or more)

And we also need to:

• Check them only when they are enabled in the configuration.

Implementation

• High-level health-checker API (in the future management API). It only checks enabled services. It makes a request to the service healthcheck endpoints.
• Healthcheck API endpoint
• Healthcheck HTTP Tracker endpoint
• Healthcheck UDP Tracker request (using the connect request endpoint).

With the default configuration, you can use the endpoint: http://localhost:1313/health_check

It will return an OK Json response:

{
  "status": "Ok", 
  "message": ""
}

or an Error response:

{ 
  "status": "Error",
  "message": "API is not healthy. Health check endpoint: http://127.0.0.1:1212/health_check"
}

NOTICE: health checks are not executed when services use port 0 in the configuration. Service launchers must be changed to return the bound port so the health checker handler can connect.

[codecov]

Codecov Report

Attention: 69 lines in your changes are missing coverage. Please review.

Comparison is base (50372d8) 84.28% compared to head (5e0a686) 84.20%.

Files	Patch %	Lines
src/servers/health_check_api/handlers.rs	38.33%	37 Missing ⚠️
src/bootstrap/jobs/health_check_api.rs	0.00%	17 Missing ⚠️
src/servers/health_check_api/resources.rs	58.33%	5 Missing ⚠️
src/servers/health_check_api/responses.rs	50.00%	3 Missing ⚠️
src/lib.rs	85.71%	2 Missing ⚠️
src/servers/health_check_api/server.rs	86.66%	2 Missing ⚠️
src/app.rs	0.00%	1 Missing ⚠️
.../servers/apis/v1/context/health_check/resources.rs	66.66%	1 Missing ⚠️
src/servers/http/v1/handlers/health_check.rs	83.33%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #512      +/-   ##
===========================================
- Coverage    84.28%   84.20%   -0.08%     
===========================================
  Files          100      110      +10     
  Lines         7141     7289     +148     
===========================================
+ Hits          6019     6138     +119     
- Misses        1122     1151      +29     

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[josecelano]

Hi @da2ce7 @mario-nt @WarmBeer this is ready for review.

For the time being, it only actually checks the internal services (API, UDP and HTTP tracker) if the port defined in the configuration is not 0. It's a big effort to get the real port back after launching those services. We have some pending issues for that. We can improve this PR after refactoring those services. I think this solution is enough at least to check that containers are "ready".

If you think it's a good solution I can add the missing tests at least for the part that it's easily testable.

[josecelano]

ACK 5e0a686