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GHC with Docker

Docker is the fastest/recommended way to get GHC up and running. GHC Docker images are hosted at Docker Hub In the best case an install/run of GHC is a matter of minutes!

If you are reading this from Docker Hub, local links will not work. In that case use the Docker Readme at GHC GitHub.

Since GHC release 0.4.0 GHC can run completely with two Docker containers from the same GHC Docker image:

  • GHC Webapp the web/Flask app
  • GHC Runner : the daemon runner app that schedules and executes GHC's Probes

Requirements

Docker installed and Docker daemon running. Docker Compose is separate install.

For installing Docker on Ubuntu there is a bash helper script.

NB: The docker commands below may need to be prepended with sudo, dependent on your login rights.

Build

This step is not necessary as GHC Docker images are available from Docker Hub. Only in cases where you have local changes, this step is required.

Go to the GHC source root dir, where the Dockerfile resides, and issue:

docker build -t geopython/geohealthcheck .

At this point you may override several files that are copied into the Docker image. For example run.sh which launches GHC using the robust gunicorn WSGI server.

Run

docker run -d --name ghc_web -p 8083:80 -v ghc_sqlitedb:/GeoHealthCheck/DB geopython/geohealthcheck:latest

go to http://localhost:8083 (port 80 in GHC Container is mapped to 8083 on host).

NB this runs GHC standalone with a SQLite DB and with the GHC Runner that performs the healthchecks. But this may in cases not be optimal as the GHC Webapp may get overloaded from processing by the GHC Runner. Tip: to see detailed logging add -e GHC_LOG_LEVEL=10 .

This mode can be disabled by passing GHC_RUNNER_IN_WEBAPP to as an ENV var to the Docker container:

docker run  --name ghc_web -e GHC_RUNNER_IN_WEBAPP=False -p 8083:80 -v ghc_sqlitedb:/GeoHealthCheck/DB geopython/geohealthcheck:latest

This allows both the GHC Webapp (Dashboard)and GHC Runner within a separate Docker containers.

You can then run GHC Runner as a separate container by overriding the default ENTRYPOINT with /run-runner.sh:

docker run -d --name ghc_runner --entrypoint "/run-runner.sh" -v ghc_sqlitedb:/GeoHealthCheck/DB geopython/geohealthcheck:latest

But the most optimal way to run GHC with scheduled jobs and optionally Postgres as backend DB, is to use Docker Compose, see below.

Using docker-compose

This allows a complete Docker setup, including scheduling and optionally using Postgres/PostGIS as database (recommended).
See the Docker Compose Documentation for more info. GHC Webapp and Runner are in this case deployed as separate processes (Docker containers).

Note that the docker-compose YAML files below are meant as examples to be adapted to your local deployment situation.

Using sqlite DB (default)

Using the default docker-compose.yml will run GHC with a SQLite DB.

To run (-d allows running in background):

cd docker/compose
docker-compose -f docker-compose.yml up  [-d]

# go to http://localhost:8083 (port 80 in GHC Container is mapped to 8083 on host)

Using PostGIS DB

The file docker-compose.postgis.yml is similar but uses Postgres as the database.

To run:

cd docker/compose
docker-compose -f docker-compose.postgis.yml up [-d]

# go to http://localhost:8083 (port 80 in GHC Container is mapped to 8083 on host)

On the first run, the PG container will create an empty DB. The GHC container will wait until PG is ready and if DB is empty populate the DB with GHC tables. NB you may see errors on first run from the cron-jobs. These are always immediately run at startup while the GHC container is still waiting for the DB to be ready.

To access your Postgres DB while running:


# Bash into running GHC Container
docker exec -it ghc_web bash

# In GHC Container access DB with psql using DB parms
psql -h postgis_ghc -U ghc ghc

The PG DB data is kept in a Docker volume usually located at
/var/lib/docker/volumes/docker_ghc_pgdb/_data.

NB you may want to remove the port mapping 5432:5432 for the postgis container (it is not required for GHC and may expose a security issue). It is then still possible to access your database, like via psql, by figuring out the Docker host IP address on your Docker host as follows:

  export PGHOST=`sudo docker inspect --format '{{ .NetworkSettings.IPAddress }}' postgis`
  psql -U ghc ghc

Cron jobs

DEPRECATED: Cronjobs via docker-compose are since v0.4.0 no longer scheduled via Jobber (cron) but within GHC itself. The GHC Docker Image can run as a Container in a daemon runner role that executes all GHC scheduled runs from the DB directly. But with the per-Resource scheduling introduced in v0.4.0, cron-jobs cannot support the detailed scheduling required.

Configuration

The default GHC configuration is specified within the Dockerfile. This allows overriding these ENV vars during deployment (as opposed to having to build your own GHC Docker Image). Docker (-e options) and Docker Compose (environment and/or env_file sections) allow setting Environment variables.

Here we use .env files.

  ghc_runner:
    image: geopython/geohealthcheck:latest

    container_name: ghc_runner

    env_file:
      - ghc.env

    entrypoint:
      - /run-runner.sh

    volumes:
      - ghc_sqlitedb:/GeoHealthCheck/DB

This applies variables specified in ghc.env to the Docker container.

One may override these with another file as is done in the Postgres version:

  ghc_runner:
    image: geopython/geohealthcheck:latest

    container_name: ghc_runner

    env_file:
      - ghc.env
      - ghc-postgis.env

    links:
      - postgis_ghc

    depends_on:
      - postgis_ghc

    entrypoint:
      - /run-runner.sh

  postgis_ghc:
    image: mdillon/postgis:9.6-alpine

    container_name: postgis_ghc

    env_file:
      - ghc-postgis.env

    volumes:
      - ghc_pgdb:/var/lib/postgresql/data

Here ghc-postgis.env adds extra Postgres-related config settings.

Other tasks

You can always bash into the GHC Container to run maintenance tasks. The GHC installation is at /GeoHealthCheck within the Docker Container.


# Bash into running GHC Container
docker exec -it docker_geohealthcheck_1 bash

# setup Python venv
source /venv/bin/activate .
cd /GeoHealthCheck/
 
# next can use Paver commands e.g. DB upgrade
paver upgrade

etc

NB: database upgrades (paver upgrade) are always performed automatically when running GHC via Docker.