This blog post will explain how to create and scale a Couchbase Cluster using full armor of Docker – Docker Machine, Docker Swarm and Docker Compose. Here is what we’ll do:

Create a 3-node Docker Swarm Cluster using Docker Machine

Run a Couchbase instance on two nodes

Create a cluster

Rebalance the cluster

Scale and rebalance the cluster again

Docker Swarm Cluster using Consul

Create a three-node Docker Swarm cluster using Docker Machine:

# Docker Machine for Consul docker-machine create -d virtualbox consul-machine # Start Consul docker $(docker-machine config consul-machine) run -d --restart=always -p "8500:8500" -h "consul" progrium/consul -server -bootstrap # Docker Swarm master docker-machine create -d virtualbox --swarm --swarm-master --swarm-discovery="consul://$(docker-machine ip consul-machine):8500" --engine-opt="cluster-store=consul://$(docker-machine ip consul-machine):8500" --engine-opt="cluster-advertise=eth1:2376" swarm-master # Docker Swarm node-01 docker-machine create -d virtualbox --swarm --swarm-discovery="consul://$(docker-machine ip consul-machine):8500" --engine-opt="cluster-store=consul://$(docker-machine ip consul-machine):8500" --engine-opt="cluster-advertise=eth1:2376" swarm-node-01 # Docker Swarm node-02 docker-machine create -d virtualbox --virtualbox-disk-size "5000" --swarm --swarm-discovery="consul://$(docker-machine ip consul-machine):8500" --engine-opt="cluster-store=consul://$(docker-machine ip consul-machine):8500" --engine-opt="cluster-advertise=eth1:2376" swarm-node-02 # Configure to use Docker Swarm cluster eval "$(docker-machine env --swarm swarm-master)" 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 # Docker Machine for Consul docker - machine create - d virtualbox consul - machine # Start Consul docker $ ( docker - machine config consul - machine ) run - d -- restart = always - p "8500:8500" - h "consul" progrium / consul - server - bootstrap # Docker Swarm master docker - machine create - d virtualbox -- swarm -- swarm - master -- swarm - discovery = "consul://$(docker-machine ip consul-machine):8500" -- engine - opt = "cluster-store=consul://$(docker-machine ip consul-machine):8500" -- engine - opt = "cluster-advertise=eth1:2376" swarm - master # Docker Swarm node-01 docker - machine create - d virtualbox -- swarm -- swarm - discovery = "consul://$(docker-machine ip consul-machine):8500" -- engine - opt = "cluster-store=consul://$(docker-machine ip consul-machine):8500" -- engine - opt = "cluster-advertise=eth1:2376" swarm - node - 01 # Docker Swarm node-02 docker - machine create - d virtualbox -- virtualbox - disk - size "5000" -- swarm -- swarm - discovery = "consul://$(docker-machine ip consul-machine):8500" -- engine - opt = "cluster-store=consul://$(docker-machine ip consul-machine):8500" -- engine - opt = "cluster-advertise=eth1:2376" swarm - node - 02 # Configure to use Docker Swarm cluster eval "$(docker-machine env --swarm swarm-master)"

Provision a Swarm cluster with Docker Machine provide more details about why and what’s done in this script. Here is a summary:

Create a Docker Machine and run Consul for service discovery

Create three Docker Machines – one for Master and two for Worker nodes.Each machine is configured to be part of a Swarm cluster using --swarm . It also uses the Consul service discovery specified using --swarm-discovery .

Couchbase Nodes on Docker Swarm

Create two instances of Couchbase using Docker Compose:

version: "2" services: db: image: arungupta/couchbase network_mode: "host" ports: - 8091:8091 - 8092:8092 - 8093:8093 - 11210:11210 1 2 3 4 5 6 7 8 9 10 version : "2" services : db : image : arungupta / couchbase network_mode : "host" ports : - 8091 : 8091 - 8092 : 8092 - 8093 : 8093 - 11210 : 11210

arungupta/couchbase image is used here. This image is defined at Couchbase Docker Image. It uses the Official Couchbase Docker Image add

configures it as explained:

Setups memory for Index and Data Configures the Couchbase server with Index, Data, and Query service Sets up username and password credentials Loads the travel-sample bucket

Compose file uses host network. This is equivalent to using --net=host on docker run CLI. It allows the container to use the host networking stack. It also limits only a single Couchbase container to run on

a single Docker Machine. So this means that our Couchbase cluster can scale based upon the number of Docker Machines – 3 in our case. The exact command to use this Compose file is:

docker-compose scale db=2 WARNING: The "db" service specifies a port on the host. If multiple containers for this service are created on a single host, the port will clash. Creating and starting couchbasedockerswarm_db_1 ... Creating and starting couchbasedockerswarm_db_2 ... Pulling db (arungupta/couchbase:latest)... swarm-node-02: Pulling arungupta/couchbase:latest... swarm-master: Pulling arungupta/couchbase:latest... swarm-node-01: Pulling arungupta/couchbase:latest... Pulling db (arungupta/couchbase:latest)... swarm-node-02: Pulling arungupta/couchbase:latest... : downloaded Creating and starting couchbasedockerswarm_db_1 ... done Creating and starting couchbasedockerswarm_db_2 ... done 1 2 3 4 5 6 7 8 9 10 11 12 docker - compose scale db = 2 WARNING : The "db" service specifies a port on the host . If multiple containers for this service are created on a single host , the port will clash . Creating and starting couchbasedockerswarm_db_1 . . . Creating and starting couchbasedockerswarm_db_2 . . . Pulling db ( arungupta / couchbase : latest ) . . . swarm - node - 02 : Pulling arungupta / couchbase : latest . . . swarm - master : Pulling arungupta / couchbase : latest . . . swarm - node - 01 : Pulling arungupta / couchbase : latest . . . Pulling db ( arungupta / couchbase : latest ) . . . swarm - node - 02 : Pulling arungupta / couchbase : latest . . . : downloaded Creating and starting couchbasedockerswarm_db_1 . . . done Creating and starting couchbasedockerswarm_db_2 . . . done

There are three nodes in the Docker Swarm cluster. The default scheduler strategy is spread and so the containers will be spread on different hosts. This is evident

by docker ps :

docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 4c8c149f4e34 arungupta/couchbase "/entrypoint.sh /opt/" 44 seconds ago Up 44 seconds swarm-node-02/couchbasedockerswarm_db_1 d3b6a1dbddb5 arungupta/couchbase "/entrypoint.sh /opt/" 44 seconds ago Up 44 seconds swarm-node-01/couchbasedockerswarm_db_2 1 2 3 4 docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 4c8c149f4e34 arungupta / couchbase "/entrypoint.sh /opt/" 44 seconds ago Up 44 seconds swarm - node - 02 / couchbasedockerswarm_db_1 d3b6a1dbddb5 arungupta / couchbase "/entrypoint.sh /opt/" 44 seconds ago Up 44 seconds swarm - node - 01 / couchbasedockerswarm_db_2

Note, one Couchbase server is running on swarm-node-01 and another on swarm-node-02 . Each server is configured with an administrator username Administrator and password password . Find out IP

address of the Docker Machine:

docker-machine ls NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS consul-machine - virtualbox Running tcp://192.168.99.106:2376 v1.11.1 default - virtualbox Running tcp://192.168.99.100:2376 v1.11.0 swarm-master * (swarm) virtualbox Running tcp://192.168.99.107:2376 swarm-master (master) v1.11.1 swarm-node-01 - virtualbox Running tcp://192.168.99.108:2376 swarm-master v1.11.1 swarm-node-02 - virtualbox Running tcp://192.168.99.109:2376 swarm-master v1.11.1 1 2 3 4 5 6 7 docker - machine ls NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS consul - machine - virtualbox Running tcp : //192.168.99.106:2376 v1.11.1 default - virtualbox Running tcp : //192.168.99.100:2376 v1.11.0 swarm - master * ( swarm ) virtualbox Running tcp : //192.168.99.107:2376 swarm-master (master) v1.11.1 swarm - node - 01 - virtualbox Running tcp : //192.168.99.108:2376 swarm-master v1.11.1 swarm - node - 02 - virtualbox Running tcp : //192.168.99.109:2376 swarm-master v1.11.1

If you have jq installed then IP address can be conveniently found as:

docker-machine inspect swarm-node-01 | jq ".Driver.IPAddress" "192.168.99.108" 1 2 docker - machine inspect swarm - node - 01 | jq ".Driver.IPAddress" "192.168.99.108"

Couchbase Cluster on Docker Swarm

All Couchbase server nodes are created equal. This allows the Couchbase cluster to truly scale horizontally to meet your growing application demands. Independently running Couchbase nodes can be added to a cluster by invoking the server-add CLI command. This is typically a two step process. The first step is adding one or more nodes. The second step then rebalances the cluster where the data on the existing nodes is rebalanced across the updated cluster. In our case, a single Couchbase

container is running on each Docker Machine. Lets pick IP address of any one Couchbase node, and add IP address of the other node:

docker run -it arungupta/couchbase couchbase-cli server-add --cluster=`docker-machine inspect swarm-node-01 | jq -r ".Driver.IPAddress"`:8091 --user Administrator --password password --server-add=`docker-machine inspect swarm-node-02 | jq -r ".Driver.IPAddress"` --server-add-username=Administrator --server-add-password=password SUCCESS: server-add 192.168.99.109:8091 1 2 3 4 5 6 7 8 9 10 docker run - it arungupta / couchbase couchbase - cli server - add -- cluster = ` docker - machine inspect swarm - node - 01 | jq - r ".Driver.IPAddress" ` : 8091 -- user Administrator -- password password -- server - add = ` docker - machine inspect swarm - node - 02 | jq - r ".Driver.IPAddress" ` -- server - add - username = Administrator -- server - add - password = password SUCCESS : server - add 192.168.99.109 : 8091

Couchbase Web Console for both the nodes will show a similar output:





This shows that the two nodes now form a cluster, and needs to be rebalanced.

Rebalance Couchbase Cluster

Now, lets rebalance the cluster:

docker run -it arungupta/couchbase couchbase-cli rebalance --cluster=`docker-machine inspect swarm-node-01 | jq -r ".Driver.IPAddress"`:8091 --user Administrator --password password INFO: rebalancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SUCCESS: rebalanced cluster 1 2 3 docker run - it arungupta / couchbase couchbase - cli rebalance -- cluster = ` docker - machine inspect swarm - node - 01 | jq - r ".Driver.IPAddress" ` : 8091 -- user Administrator -- password password INFO : rebalancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SUCCESS : rebalanced cluster

Couchbase Web Console will be updated to show that rebalance is happening:



And finally you’ll see a rebalanced cluster:

Scale and Rebalance Couchbase Cluster

Scale the Couchbase cluster:

docker-compose scale db=3 WARNING: The "db" service specifies a port on the host. If multiple containers for this service are created on a single host, the port will clash. Creating and starting couchbasedockerswarm_db_3 ... done 1 2 3 docker - compose scale db = 3 WARNING : The "db" service specifies a port on the host . If multiple containers for this service are created on a single host , the port will clash . Creating and starting couchbasedockerswarm_db_3 . . . done

Check that the container is running on a different Docker Machine:

docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 02f94e2bbd3e arungupta/couchbase "/entrypoint.sh /opt/" 9 seconds ago Up 8 seconds swarm-master/couchbasedockerswarm_db_3 4c8c149f4e34 arungupta/couchbase "/entrypoint.sh /opt/" About an hour ago Up About an hour swarm-node-02/couchbasedockerswarm_db_1 d3b6a1dbddb5 arungupta/couchbase "/entrypoint.sh /opt/" About an hour ago Up About an hour swarm-node-01/couchbasedockerswarm_db_2 1 2 3 4 5 docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 02f94e2bbd3e arungupta / couchbase "/entrypoint.sh /opt/" 9 seconds ago Up 8 seconds swarm - master / couchbasedockerswarm_db_3 4c8c149f4e34 arungupta / couchbase "/entrypoint.sh /opt/" About an hour ago Up About an hour swarm - node - 02 / couchbasedockerswarm_db_1 d3b6a1dbddb5 arungupta / couchbase "/entrypoint.sh /opt/" About an hour ago Up About an hour swarm - node - 01 / couchbasedockerswarm_db_2

As mentioned earlier, scaling a Couchbase cluster is a two-step process. This is so because typically you’ll add multiple servers and then rebalance the cluster. However, in cases where you only need to add a single Couchbase node and then rebalance,

the rebalance command can be used achieve that. In our case, this is done as shown:

docker run -it arungupta/couchbase couchbase-cli rebalance --cluster=`docker-machine inspect swarm-node-01 | jq -r ".Driver.IPAddress"`:8091 --user Administrator --password password --server-add=`docker-machine inspect swarm-master | jq -r ".Driver.IPAddress"` --server-add-username=Administrator --server-add-password=password SUCCESS: server-add 192.168.99.107:8091 INFO: rebalancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SUCCESS: rebalanced cluster 1 2 3 4 docker run - it arungupta / couchbase couchbase - cli rebalance -- cluster = ` docker - machine inspect swarm - node - 01 | jq - r ".Driver.IPAddress" ` : 8091 -- user Administrator -- password password -- server - add = ` docker - machine inspect swarm - master | jq - r ".Driver.IPAddress" ` -- server - add - username = Administrator -- server - add - password = password SUCCESS : server - add 192.168.99.107 : 8091 INFO : rebalancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SUCCESS : rebalanced cluster

The rebalanced cluster now looks like:



This blog showed how you can easily create and scale a Couchbase Cluster using Docker Swarm, Machine and Compose. Enjoy! Further reading …