Development Installation

These are development setup and standards that are adhered to by the core development team while developing Read the Docs and related services. If you are a contributor to Read the Docs, it might a be a good idea to follow these guidelines as well.

Note

We do not recommend to follow this guide to deploy an instance of Read the Docs for production usage. Take into account that this setup is only useful for developing purposes.

Set up your environment

1. install Docker following their installation guide.

2. clone the readthedocs.org repository:

   git clone --recurse-submodules https://github.com/readthedocs/readthedocs.org/
   

3. install the requirements from common submodule:

   pip install -r common/dockerfiles/requirements.txt
   

4. build the Docker image for the servers:

   Warning

   This command could take a while to finish since it will download several Docker images.

   inv docker.build
   

   Tip

   If you pass GITHUB_TOKEN environment variable to this command, it will add support for readthedocs-ext.

5. pull down Docker images for the builders:

   inv docker.pull --only-latest
   

6. start all the containers:

   inv docker.up  --init  # --init is only needed the first time
   

7. add read permissions to the storage backend:

   • go to http://localhost:9000/ (MinIO S3 storage backend)

   • login as admin / password

   • click “…” next to the static bucket name and then “Edit Policy”

   • leave “prefix” empty and click “Add” to give “Read Only” access on the static bucket

   • click on the “+” icon on the bottom-right corner, then “Create bucket” with the name media, hit Enter on the keyboard, and repeat the operation above to give “Read Only” access to it

8. go to http://community.dev.readthedocs.io to access your local instance of Read the Docs.

Check that everything works

1. go to http://community.dev.readthedocs.io and check that the appearance and style looks correct (otherwise the MinIO buckets might be misconfigured, see above)

2. login as admin / admin and verify that the project list appears

3. go to the “Read the Docs” project, click on the “Build version” button to build latest, and wait until it finishes

4. click on the “View docs” button to browse the documentation, and verify that it works

Working with Docker Compose

We wrote a wrapper with invoke around docker-compose to have some shortcuts and save some work while typing docker compose commands. This section explains these invoke commands:

inv docker.build

Builds the generic Docker image used by our servers (web, celery, build and proxito).

inv docker.up

Starts all the containers needed to run Read the Docs completely.

• --no-search can be passed to disable search

• --init is used the first time this command is ran to run initial migrations, create an admin user, etc

• --no-reload makes all celery processes and django runserver to use no reload and do not watch for files changes

inv docker.shell

Opens a shell in a container (web by default).

• --no-running spins up a new container and open a shell

• --container specifies in which container the shell is open

inv docker.manage {command}

Executes a Django management command in a container.

Tip

Useful when modifying models to run makemigrations.

inv docker.down

Stops and removes all containers running.

• --volumes will remove the volumes as well (database data will be lost)

inv docker.restart {containers}

Restarts the containers specified (automatically restarts NGINX when needed).

inv docker.attach {container}

Grab STDIN/STDOUT control of a running container.

Tip

Useful to debug with pdb. Once the program has stopped in your pdb line, you can run inv docker.attach web and jump into a pdb session (it also works with ipdb and pdb++)

Tip

You can hit CTRL-p CTRL-p to detach it without stopping the running process.

inv docker.test

Runs all the test suites inside the container.

• --arguments will pass arguments to Tox command (e.g. --arguments "-e py36 -- -k test_api")

inv docker.pull

Downloads and tags all the Docker images required for builders.

• --only-latest does not pull stable and testing images.

inv docker.buildassets

Build all the assets and “deploy” them to the storage.

Adding a new Python dependency

The Docker image for the servers is built with the requirements defined in the current checked out branch. In case you need to add a new Python dependency while developing, you can use the common/dockerfiles/entrypoints/common.sh script as shortcut.

This script is run at startup on all the servers (web, celery, builder, proxito) which allows you to test your dependency without re-building the whole image. To do this, add the pip command required for your dependency in common.sh file:

# common.sh
pip install my-dependency==1.2.3

Once the PR that adds this dependency was merged, you can rebuild the image so the dependency is added to the Docker image itself and it’s not needed to be installed each time the container spins up.

Debugging Celery

In order to step into the worker process, you can’t use pdb or ipdb, but you can use celery.contrib.rdb:

from celery.contrib import rdb; rdb.set_trace()

When the breakpoint is hit, the Celery worker will pause on the breakpoint and will alert you on STDOUT of a port to connect to. You can open a shell into the container with inv docker.shell celery (or build) and then use telnet or netcat to connect to the debug process port:

nc 127.0.0.1 6900

The rdb debugger is similar to pdb, there is no ipdb for remote debugging currently.

Configuring connected accounts

These are optional steps to setup the connected accounts (GitHub, GitLab, and BitBucket) in your development environment. This will allow you to login to your local development instance using your GitHub, Bitbucket, or GitLab credentials and this makes the process of importing repositories easier.

However, because these services will not be able to connect back to your local development instance, webhooks will not function correctly. For some services, the webhooks will fail to be added when the repository is imported. For others, the webhook will simply fail to connect when there are new commits to the repository.

Fig. 11 Configuring an OAuth consumer for local development on Bitbucket

• Configure the applications on GitHub, Bitbucket, and GitLab. For each of these, the callback URI is http://community.dev.readthedocs.io/accounts/<provider>/login/callback/ where <provider> is one of github, gitlab, or bitbucket_oauth2. When setup, you will be given a “Client ID” (also called an “Application ID” or just “Key”) and a “Secret”.

• Take the “Client ID” and “Secret” for each service and enter it in your local Django admin at: http://community.dev.readthedocs.io/admin/socialaccount/socialapp/. Make sure to apply it to the “Site”.

Core team standards

Core team members expect to have a development environment that closely approximates our production environment, in order to spot bugs and logical inconsistencies before they make their way to production.

This solution gives us many features that allows us to have an environment closer to production:

Celery runs as a separate process

Avoids masking bugs that could be introduced by Celery tasks in a race conditions.

Celery runs multiple processes

We run celery with multiple worker processes to discover race conditions between tasks.

Docker for builds

Docker is used for a build backend instead of the local host build backend. There are a number of differences between the two execution methods in how processes are executed, what is installed, and what can potentially leak through and mask bugs – for example, local SSH agent allowing code check not normally possible.

Serve documentation under a subdomain

There are a number of resolution bugs and cross-domain behavior that can only be caught by using USE_SUBDOMAIN setting.

PostgreSQL as a database

It is recommended that Postgres be used as the default database whenever possible, as SQLite has issues with our Django version and we use Postgres in production. Differences between Postgres and SQLite should be masked for the most part however, as Django does abstract database procedures, and we don’t do any Postgres-specific operations yet.

Celery is isolated from database

Celery workers on our build servers do not have database access and need to be written to use API access instead.

Use NGINX as web server

All the site is served via NGINX with the ability to change some configuration locally.

MinIO as Django storage backend

All static and media files are served using Minio –an emulator of S3, which is the one used in production.

Serve documentation via El Proxito

Documentation is proxied by NGINX to El Proxito and proxied back to NGINX to be served finally. El Proxito is a small application put in front of the documentation to serve files from the Django Storage Backend.

Search enabled by default

Elasticsearch is properly configured and enabled by default. All the documentation indexes are updated after a build is finished.