Containers Module (Python)

Useful tools for building python-based applications in Docker.

Usage

Docker Health check wrapper

The docker health check wrapper can be used in conjunction with your entrypoint by extending the Docker class. Healthchecks can be written as subclasses of the main app class and your entrypoint can be injected via the "entrypoint" function.

Setting up health checks in your DockerFile

Since Docker requires an executable file or entry command to initiate healthchecks, you'll need accommodate this. See below for and example healthcheck executable and assocaited dockerfile snippet.

* Optional Environment setup

Additional environment variables can be set as follows

Parameter	Type	Description
HEALTHCHECK_PORT	int	Used to determine which port to serve healthchecks from. Defaults to 5050
BUILD_VERSION	str	build version

Healthcheck Executable (Docker)

  #!/usr/bin/env python3.11
  import sys
  from Containers.health import Docker
  ### This is a wrapper, entry point for DOCKER health checks
  ### It is assumed that your app is run using 
  ### Containers.health.Docker as a base class
  sys.exit(Docker.read_healthchecks())

Dockerfile (Docker)

  FROM ubuntu:20.04
  HEALTHCHECK --interval=30s --timeout=3s --retries=3 CMD [ "healthcheck" ]
#   HEALTHCHECK --interval=30s --timeout=3s --retries=3 CMD [ "python3.11","./healthcheck.py" ] Optional usage
  ENV HEALTHCHECK_PORT=5050
  COPY ./healthcheck /usr/local/bin ## If using alternate usage, this is not required
  RUN chmod +x /usr/local/bin/healthcheck ## ""
  ENTRYPOINT ['python3.11','./myapp.py']

Example app (myapp.py)

  import time
  from Containers.health import Docker

  class myapp(Docker):
      class MyCustomCheck(Docker.health_check):
          def check(self):
              return True
          pass
      class MyCustomCheck2(Docker.health_check):
          def check(self):
              return True
          pass
      class youreWrong(Docker.health_check):
          ### This check fails to load due to incorrect naming convention
          def acheck(self):
              return False
          pass
      def entrypoint(self):
          self.log.info('Starting application!')
          ### DO some stuff
          time.sleep(120)
          pass

      pass

  if __name__ == '__main__':
      myapp()

API Reference

Get Health_checks

  GET /health_check.json

  {
    "name": "myapp",
    "services": {
      "MyCustomCheck": {
        "name": "MyCustomCheck",
        "status": "green"
      },
      "MyCustomCheck2": {
        "name": "MyCustomCheck2",
        "status": "green"
      }
    },
    "metadata": {
      "build": "unknown"
    }
  }