docker-riak

This is a Docker project to bring up a local Riak cluster.

Prerequisites

Install Docker

Follow the instructions on Docker's website to install Docker.

From there, ensure that your DOCKER_HOST environmental variable is set correctly:

$ export DOCKER_HOST="tcp://127.0.0.1:4243"

Note: If you're using boot2docker ensure that you forward the virtual machine port range (49000-49900). This will allow you to interact with the containers as if they were running locally:

$ for i in {49000..49900}; do
 VBoxManage modifyvm "boot2docker-vm" --natpf1 "tcp-port$i,tcp,,$i,,$i";
 VBoxManage modifyvm "boot2docker-vm" --natpf1 "udp-port$i,udp,,$i,,$i";
done

Running

Clone repository and build Riak image

$ git clone https://github.com/hectcastro/docker-riak.git
$ cd docker-riak
$ make build

Environmental variables

• DOCKER_RIAK_CLUSTER_SIZE – The number of nodes in your Riak cluster (default: 5)
• DOCKER_RIAK_AUTOMATIC_CLUSTERING – A flag to automatically cluster Riak (default: false)
• DOCKER_RIAK_DEBUG – A flag to set -x on the cluster management scripts (default: false)

Launch cluster

$ DOCKER_RIAK_AUTOMATIC_CLUSTERING=1 DOCKER_RIAK_CLUSTER_SIZE=5 make start-cluster
./bin/start-cluster.sh

Bringing up cluster nodes:

  Successfully brought up [riak01]
  Successfully brought up [riak02]
  Successfully brought up [riak03]
  Successfully brought up [riak04]
  Successfully brought up [riak05]

Please wait approximately 30 seconds for the cluster to stabilize.

Testing

From outside the container, we can interact with the HTTP or Protocol Buffers interfaces.

HTTP

The HTTP interface has an endpoint called /stats that emits Riak statistics. The test-cluster Makefile target hits a random container's /stats endpoint and pretty-prints its output to the console.

The most interesting attributes for testing cluster membership are ring_members:

$ make test-cluster | egrep -A6 "ring_members"
    "ring_members": [
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]"
    ],

And ring_ownership:

$ make test-cluster | egrep "ring_ownership"
    "ring_ownership": "[{'[email protected]',3},\n {'[email protected]',4},\n {'[email protected]',3},\n {'[email protected]',4},\n {'[email protected]',3},\n {'[email protected]',4},\n {'[email protected]',3},\n {'[email protected]',4},\n {'[email protected]',3},\n {'[email protected]',3},\n {'[email protected]',3},\n {'[email protected]',3},\n {'[email protected]',3},\n {'[email protected]',3},\n {'[email protected]',3},\n {'[email protected]',3},\n {'[email protected]',3},\n {'[email protected]',3},\n {'[email protected]',3},\n {'[email protected]',3}]",

Together, these attributes let us know that this particular Riak node knows about all of the other Riak instances.

SSH

The phusion/baseimage-docker image has the ability to enable an insecure key for conveniently logging into a container via SSH. It is enabled in the Dockerfile by default here:

RUN /usr/sbin/enable_insecure_key

In order to login to the container via SSH using the insecure key, follow the steps below.

Use docker inspect to determine the container IP address:

$ docker inspect $CONTAINER_ID | grep IPAddress
        "IPAddress": "172.17.0.2",

Download the insecure key, alter its permissions, and use it to SSH into the container via its IP address:

$ curl -o insecure_key -fSL https://github.com/phusion/baseimage-docker/raw/master/image/insecure_key
$ chmod 600 insecure_key
$ ssh -i insecure_key [email protected]

Note: If you're using boot2docker, ensure that you're issuing the SSH command from within the virtual machine running boot2docker.

Destroying

$ make stop-cluster
./bin/stop-cluster.sh
Stopped the cluster and cleared all of the running containers.