hectcastro/riak repository overview

⁠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.

Many (but not all) Docker environments set the DOCKER_HOST environment variable to help the client find the Docker host. Some environments use a Unix domain socket by default.

If your Docker client connects to the Docker host via TCP, ensure that your DOCKER_HOST environmental variable is set correctly:

$ export DOCKER_HOST="tcp://127.0.0.1:2375"

Note: If you're using boot2docker⁠ ensure that you forward the virtual machine port range (49000-49900). If you want to set DOCKER_RIAK_BASE_HTTP_PORT, ensure that you forward that port range instead:

$ 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

⁠sysctl

In order to tune the Docker host housing Riak containers, consider applying the following sysctl settings:

vm.swappiness = 0
net.ipv4.tcp_max_syn_backlog = 40000
net.core.somaxconn = 40000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_fin_timeout = 15
net.ipv4.tcp_keepalive_intvl = 30
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_moderate_rcvbuf = 1

⁠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)
• DOCKER_RIAK_BASE_HTTP_PORT - A flag to use fixed port assignment. If set, manually forward port DOCKER_RIAK_BASE_HTTP_PORT + $index to 8098 (Riak's HTTP port) and forward DOCKER_RIAK_BASE_HTTP_PORT + $index + DOCKER_RIAK_PROTO_BUF_PORT_OFFSET to 8087 (Riak's Protocol Buffers port).
• DOCKER_RIAK_PROTO_BUF_PORT_OFFSET - Optional port offset (default: 100)
• DOCKER_RIAK_BACKEND - Optional Riak backend to use (default: bitcask)
• DOCKER_RIAK_STRONG_CONSISTENCY - Enables strong consistency subsystem (values: on or off, default: off)

⁠Launch cluster

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

Bringing up cluster nodes:

Starting riak01..... Completed
Starting riak02..... Completed
Starting riak03..... Completed
Starting riak04..... Completed
Starting riak05..... Completed

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/services/sshd/keys/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.

⁠Stopping

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

⁠Destroying

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