Docker Compose setup for CKAN

Overview
Quick start
Development mode
- Create an extension
- Running the debugger (pdb / ipdb)
CKAN images
- Extending the base images
- Applying patches
Known Issues

Overview

This is a set of Docker images and configuration files to run a CKAN site.

It is largely based on two existing projects:

Keitaro's CKAN Docker images
Docker Compose setup currently included in CKAN core

It includes the following images, all based on Alpine Linux:

CKAN: modified from keitaro/ckan (see CKAN Images) for more details). File uploads are stored in a named volume.
DataPusher: modified from keitaro/datapusher
PostgreSQL: Official PostgreSQL image. Database files are stored in a named volume.
Solr: official Solr image with CKAN's schema. Index data is stored in a named volume.
Redis: standard Redis image

The site is configured via env vars (the base CKAN image loads ckanext-envvars), that you can set in the .env file.

Quick start

Copy the included .env.example and rename it to .env to modify it depending on your own needs.

Using the default values on the .env.example file will get you a working CKAN instance. There is a sysadmin user created by default with the values defined in CKAN_SYSADMIN_NAME and CKAN_SYSADMIN_PASSWORD(ckan_admin and test1234 by default). I shouldn't be telling you this but obviously don't run any public CKAN instance with the default settings.

To build the images:

docker-compose build

To start the containers:

docker-compose up

Development mode

To develop local extensions use the docker-compose.dev.yml file:

To build the images:

docker-compose -f docker-compose.dev.yml build

To start the containers:

docker-compose -f docker-compose.dev.yml up

See CKAN Images for more details of what happens when using development mode.

Create an extension

You can use the paster template in much the same way as a source install, only executing the command inside the CKAN container and setting the mounted src/ folder as output:

docker-compose -f docker-compose.dev.yml exec ckan-dev /bin/bash -c "paster --plugin=ckan create -t ckanext ckanext-myext -o /srv/app/src_extensions"

The new extension will be created in the src/ folder. You might need to change the owner of its folder to have the appropiate permissions.

Running the debugger (pdb / ipdb)

To run a container and be able to add a breakpoint with pdb or ipdb, run the ckan-dev container with the --service-ports option:

docker-compose -f docker-compose.dev.yml run --service-ports ckan-dev

This will start a new container, displaying the standard output in your terminal. If you add a breakpoint in a source file in the src folder (import pdb; pdb.set_trace()) you will be able to inspect it in this terminal next time the code is executed.

CKAN images

    +-------------------------+                +----------+
    |                         |                |          |
    | openknowledge/ckan-base +---------------->   ckan   | (production)
    |                         |                |          |
    +-----------+-------------+                +----------+
                |
                |
    +-----------v------------+                 +----------+
    |                        |                 |          |
    | openknowledge/ckan-dev +----------------->   ckan   | (development)
    |                        |                 |          |
    +------------------------+                 +----------+

The Docker images used to build your CKAN project are located in the ckan/ folder. There are two Docker files:

Dockerfile: this is based on openknowledge/ckan-base (with the Dockerfile on the /ckan-base/<version> folder), an image with CKAN with all its dependencies, properly configured and running on uWSGI (production setup)
Dockerfile.dev: this is based on openknowledge/ckan-dev (with the Dockerfile on the /ckan-dev/<version> folder), wich extends openknowledge/ckan-base to include:
- Any extension cloned on the src folder will be installed in the CKAN container when booting up Docker Compose (docker-compose up). This includes installing any requirements listed in a requirements.txt (or pip-requirements.txt) file and running python setup.py develop.
- The CKAN image used will development requirements needed to run the tests .
- CKAN will be started running on the paster development server, with the --reload option to watch changes in the extension files.
- Make sure to add the local plugins to the CKAN__PLUGINS env var in the .env file.

From these two base images you can build your own customized image tailored to your project, installing any extensions and extra requirements needed.

Extending the base images

To perform extra initialization steps you can add scripts to your custom images and copy them to the /docker-entrypoint.d folder (The folder should be created for you when you build the image). Any *.sh and *.py file in that folder will be executed just after the main initialization script (prerun.py) is executed and just before the web server and supervisor processes are started.

For instance, consider the following custom image:

ckan
├── docker-entrypoint.d
│   └── setup_validation.sh
├── Dockerfile
└── Dockerfile.dev

We want to install an extension like ckanext-validation that needs to create database tables on startup time. We create a setup_validation.sh script in a docker-entrypoint.d folder with the necessary commands:

#!/bin/bash

# Create DB tables if not there
paster --plugin=ckanext-validation validation init-db -c $CKAN_INI

And then in our Dockerfile we install the extension and copy the initialization scripts:

FROM openknowledge/ckan-dev:2.9

RUN pip install -e git+https://github.com/frictionlessdata/ckanext-validation.git#egg=ckanext-validation && \
    pip install -r https://raw.githubusercontent.com/frictionlessdata/ckanext-validation/master/requirements.txt

COPY docker-entrypoint.d/* /docker-entrypoint.d/

Applying patches

When building your project specific CKAN images (the ones defined in the ckan/ folder), you can apply patches to CKAN core or any of the built extensions. To do so create a folder inside ckan/patches with the name of the package to patch (ie ckan or ckanext-??). Inside you can place patch files that will be applied when building the images. The patches will be applied in alphabetical order, so you can prefix them sequentially if necessary.

For instance, check the following example image folder:

ckan
├── patches
│   ├── ckan
│   │   ├── 01_datasets_per_page.patch
│   │   ├── 02_groups_per_page.patch
│   │   ├── 03_or_filters.patch
│   └── ckanext-harvest
│       └── 01_resubmit_objects.patch
├── Dockerfile
└── Dockerfile.dev

Known Issues

Running the tests: Running the tests for CKAN or an extension inside the container will delete your current database. We need to patch CKAN core in our image to work around that.

nvnikolov/docker-ckan