Added healthcheck endpoint

[sheldor1510]

@larsks For #160 , I discussed with @tzumainn and decided to do the healthcheck at the root endpoint (<host_url>/) similar to how the Ironic API does.

So, the API returns this at <host_url>/:

{
  "name": "ESI Leap API",
  "description": "ESI Leap is an OpenStack service for leasing baremetal nodes, designed to run on top of multi-tenant Ironic.",
  "versions": [
    {
      "id": "v1.0",
      "status": "CURRENT",
      "links": [
        {
          "href": "<host_url>/v1",
          "rel": "self"
        }
      ]
    }
  ]
}

The rest of the requests return this if accessed unauthenticated:

{
  "error": {
    "code": 401,
    "title": "Unauthorized",
    "message": "The request you have made requires authentication."
  }
}

[larsks]

@tzumainn I worry that we are conflating two things here:

1. Health check
2. Version discovery

If we're going to report a versions string, then either (a) there should be code to dynamically discover what API versions are supported by the code or (b) there should be a way to register version information.

What do you think?

[tzumainn]

@tzumainn I worry that we are conflating two things here:

1. Health check
2. Version discovery

If we're going to report a versions string, then either (a) there should be code to dynamically discover what API versions are supported by the code or (b) there should be a way to register version information.

What do you think?

To be honest I don't see a huge practical difference between the two (although I could be missing something)! I do agree with your comment about versions though.

[larsks]

To be honest I don't see a huge practical difference between the two

The difference is that the health check endpoint doesn't really require any additional logic, so it can be implemented immediately, while setting up version discovery seems like a bigger project.

I defer to your judgement on this; if you're happy with the current implementation, I'm not going to object.

@tzumainn

[sheldor1510]

@larsks I had discussed with @tzumainn and planned to implement the API versioning functionality (which will help us with version discovery for the returned object) in this PR. Should I go ahead with that on this PR or make a separate PR?

[larsks]

@sheldor1510 I would make that a separate PR.

[tzumainn]

may as well create a unit test for this, just for completeness!

[sheldor1510]

created and tested!

[tzumainn]

thanks!

[tzumainn]

Looks good! One last request - can you squash your commits into a single commit? That helps maintain a clean commit history.

[tzumainn]

looks good - thanks!