hacking.rst

description:	How to hack on Deis including setup instructions

Hacking on Deis

We try to make it simple to hack on Deis. However, there are necessarily several moving pieces and some setup required. We welcome any suggestions for automating or simplifying this process.

If you're just getting into the Deis codebase, look for GitHub issues with the label easy-fix. These are more straightforward or low-risk issues and are a great way to become more familiar with Deis.

Prerequisites

You can develop on any supported platform including your laptop, cloud providers or on bare metal. We strongly recommend a minimum 3-node cluster.

Deis is written in both python and Go, so you will need to install both Python 2.7 and the latest version of Go.

If your local workstation does not support the linux/amd64 target environment, you will have to install Go from source with cross-compile support for that environment. This is because some of the components are built on your local machine and then injected into a docker container. To do that, run

$ sudo su
$ curl -sSL https://golang.org/dl/go1.4.src.tar.gz | tar -v -C /usr/local -xz
$ cd /usr/local/go/src
$ # compile Go for our default platform first, then add cross-compile support
$ ./make.bash --no-clean
$ GOOS=linux GOARCH=amd64 ./make.bash --no-clean

After that, you should be able to compile Deis' components as normal.

The development workflow requires a Docker Registry that is accessible to you (the developer) and to all of the hosts in your cluster.

You will also need a deisctl client to update images and restart components.

Fork the Repository

To get Deis running for development, first fork the Deis repository, then clone your fork of the repository:

$ git clone git@github.com:<username>/deis.git
$ cd deis

Install the Client

Your Deis client should match your server's version. For developers, one way to ensure this is to use Python 2.7 to install requirements and then run client/deis.py in the Deis code repository. Then make a symlink or shell alias for deis to ensure it is found in your $PATH:

$ make -C client/ install
$ sudo ln -fs $(pwd)/client/deis.py /usr/local/bin/deis
$ deis
Usage: deis <command> [<args>...]

Configure SSH Tunneling

To connect to the cluster using deisctl, you must add the private key to ssh-agent. For example, when using Vagrant:

$ ssh-add ~/.vagrant.d/insecure_private_key

Set DEISCTL_TUNNEL so the deisctl client on your workstation can connect to one of the hosts in your cluster:

$ export DEISCTL_TUNNEL=172.17.8.100

Test connectivity using deisctl list:

$ deisctl list

Start Up a Development Cluster

To start up and configure a local vagrant cluster for development, you can use the dev-cluster target. This requires that deisctl and vagrant are installed.

$ make dev-cluster

Configure a Docker Registry

The development workflow requires Docker Registry set at the DEV_REGISTRY environment variable. If you're developing locally you can use the dev-registry target to spin up a quick, disposable registry inside a Docker container. The target dev-registry prints the registry's address and port when using boot2docker; otherwise, use your host's IP address as returned by ifconfig with port 5000 for DEV_REGISTRY.

$ make dev-registry

To configure the registry for local Deis development:
    export DEV_REGISTRY=192.168.59.103:5000

Note

For Docker 1.3.1 and later, docker push to this development registry may fail without SSL certificate support. Restart docker with an --insecure-registry flag.

For boot2docker 1.3.1 for example, add EXTRA_ARGS="--insecure-registry 192.168.59.103:5000" to /var/lib/boot2docker/profile and restart docker with sudo /etc/init.d/docker restart.

If you are developing elsewhere, you must set up a registry yourself. Make sure it meets the following requirements:

1. You can push Docker images from your workstation
2. Hosts in the cluster can pull images with the same URL

Note

If the development registry is insecure and has an IP address in a range other than 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16, you'll have to modify contrib/coreos/user-data.example and whitelist your development registry so the daemons can pull your custom components.

Development Workflow

Deis includes Makefile targets designed to simplify the development workflow. This workflow is typically:

1. Update source code and commit your changes using git
2. Use make -C <component> build to build a new Docker image
3. Use make -C <component> dev-release to push a snapshot release
4. Use make -C <component> restart to restart the component

This can be shortened to a one-liner using the deploy target:

$ make -C controller deploy

You can also use the same tasks on the root Makefile to operate on all components at once. For example, make deploy will build, dev-release, and restart all components on the cluster.

Important

In order to cut a dev-release, you must commit changes using git to increment the SHA used when tagging Docker images

Test Your Changes

Deis ships with a comprehensive suite of automated tests, most written in Go. See :ref:`testing` for instructions on running the tests.

Useful Commands

Once your controller is running, here are some helpful commands.

Tail Logs

$ deisctl journal controller

Rebuild Services from Source

$ make -C controller build push restart

Restart Services

$ make -C controller restart

Django Shell

$ deisctl list             # determine which host runs the controller
$ ssh core@<host>          # SSH into the controller host
$ nse deis-controller      # inject yourself into the container
$ cd /app                  # change into the django project root
$ ./manage.py shell        # get a django shell

Have commands other Deis developers might find useful? Send us a PR!

Pull Requests

Please read :ref:`standards`. It contains a checklist of things you should do when proposing a change to Deis.