Overview

In this exercise, you will write a golang application that continually queries an http endpoint, parses the objects in the json response, and outputs informational text about them after a timeout.

HTTP Server

The included source code (server.go) will run a local http server on your machine. It has a "/containers" endpoint that will return a json response. The response contains a list of container objects. The statuses of the containers will change over time. An example response from this http server:

[
  {
    "id": "068d9117685312461f4c3d7eb038b57665ecad966b4e7e5de66e23bbcbe156e2",
    "names": [
      "/conductor_cgls"
    ],
    "image": "gcr.io/conductor/hlm:20220808134517",
    "imageID": "sha256:dd692ed0e3000806102989bb261e02b3724f2e15b09cb8c5976e289460a60aa7",
    "state": "running",
    "status": "Up 7m29s (healthy)"
  },
  {
    "id": "bb4746c2124e75b9891c451e40bb3da37f94e32090edb95a256a2e73bf4306dc",
    "names": [
      "/conductor_hlm"
    ],
    "image": "gcr.io/conductor/hlm:20220808134517",
    "imageID": "sha256:b2d8853ef92f0916dd1be0c1aab8dcfafc979471d56d1fd8aa5a663e18a23f87",
    "state": "running",
    "status": "Up 7m29s (healthy)"
  },
  {
    "id": "32d6abc33c399cd1cfcabe07f4922bc3ac1858725d44be2cbb405184ccf6d095",
    "names": [
      "/conductor_plm"
    ],
    "image": "gcr.io/conductor/plm:20220808134517",
    "imageID": "sha256:62ac29fa0629270f13de19a419de8561f84e6a32d16c4f025eef708ef58ec490",
    "state": "running",
    "status": "Up 7m29s (healthy)"
  },
  {
    "id": "917948e476dad84e1f465f1f0b18ba4ebaf347b6b07c9dcf8aa257098cb943c2",
    "names": [
      "/conductor_rvl"
    ],
    "image": "gcr.io/conductor/rvl:20220808134517",
    "imageID": "sha256:4d52848b3ba75052bee0089a8b0f40d0db7f3c0f31ecfa78e11559e50d90f181",
    "state": "running",
    "status": "Up 7m29s (healthy)"
  }
]

The status field values look like this: Up {time} ({health_status}) where {health_status} is one of starting, healthy, or unhealthy.

Exercise

Write a golang application that outputs the names of any containers that don't pass our quality check. The quality check consists of querying the endpoint every 5 seconds until all the containers are running, ready, and healthy or the timeout (20 seconds) is reached, whichever comes first. We expect to see four healthy containers: conductor_cgls, conductor_hlm, conductor_plm, and conductor_rvl.

If all containers pass, the program should output

All containers pass!

If all containers do not pass, the program should output the names of the failing containers like so:

Failing Containers:
  Not Healthy: [/conductor_rvl]
  Not Ready: [/conductor_hlm]
  Not Running: [/conductor_cgls]

Quality Check

running means the container is in the list of containers returned by the server.

not running means the container is not in the list of containers returned by the server.

ready means the container is running and it has a status of either "healthy" or "unhealthy".

not ready means the container is running and it has a status that is not "healthy" or "unhealthy". For example, while the container is starting up, the status will be "starting".

healthy means the container is running, ready, and has a status of "healthy".

not healthy means the container is running, ready, and has a status of "unhealthy".