Docker Machine, Swarm and Compose for multi-container and multi-host applications with Couchbase and WildFly

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This blog will explain how to create multi-container application deployed on multiple hosts using Docker. This will be achieved using Docker Machine, Swarm and Compose.

Yes, all three tools together makes this blog that much more interesting!

Docker Swarm Machine Compose

The diagram explains the key components:

  • Docker Machine is used to provision multiple Docker hosts
  • Docker Swarm will be used to create a multi-host cluster
  • Each node in Docker Swarm cluster is registered/discovered using Consul
  • Multi-container application will be deployed using Docker Compose
  • WildFly and Couchbase are provisioned on different hosts
  • Docker multi-host networking is used for WildFly and Couchbase to communicate

In addition, Maven is used to configure Couchbase and deploy application to WildFly.

Latest instructions at Docker for Java Developers.

No story, just pure code, lets do it!

Create Discovery Service using Docker Machine

  1. Create a Machine that will host discovery service:
  2. Connect to this Machine:
  3. Run Consul service using the following Compose file:
    This Compose file is available at https://github.com/arun-gupta/docker-images/blob/master/consul/docker-compose.yml.
    Started container can be verified as:

Create Docker Swarm Cluster using Docker Machine

Swarm is fully integrated with Machine, and so is the easiest way to get started.

  1. Create a Swarm Master and point to the Consul discovery service:
    Few options to look here:

    1. --swarm configures the Machine with Swarm
    2. --swarm-master configures the created Machine to be Swarm master
    3. --swarm-discovery defines address of the discovery service
    4. --cluster-advertise advertise the machine on the network
    5. --cluster-store designate a distributed k/v storage backend for the cluster
    6. --virtualbox-disk-size sets the disk size for the created Machine to 5GB. This is required so that WildFly and Couchbase image can be downloaded on any of the nodes.
  2. Find some information about this machine:
    Note that the disk size is 5GB.
  3. Connect to the master by using the command:
  4. Find some information about the cluster:
  5. Create a new Machine to join this cluster:
    Notice no --swarm-master is specified in this command. This ensure that the created Machines are worker nodes.
  6. Create a second Swarm node to join this cluster:
  7. List all the created Machines:
    The machines that are part of the cluster have cluster’s name in the SWARM column, blank otherwise. For example,consul-machine is a standalone machine where as all other machines are part of the swarm-master cluster. The Swarm master is also identified by (master) in the SWARM column.
  8. Connect to the Swarm cluster and find some information about it:

    Note, --swarm is specified to connect to the Swarm cluster. Otherwise the command will connect to swarm-masterMachine only.

    This shows the output as:

    There are 3 nodes – one Swarm master and 2 Swarm worker nodes. There is a total of 4 containers running in this cluster – one Swarm agent on master and each node, and there is an additional swarm-agent-master running on the master. This can be verified by connecting to the master and listing all the containers.

  9. List nodes in the cluster with the following command:

Start Application Environment using Docker Compose

Make sure you are connected to the cluster by giving the command eval "$(docker-machine env --swarm swarm-master)".

  1. List all the networks created by Docker so far:
    Docker create three networks for each host automatically:

    Network Name Purpose
    bridge Default network that containers connect to. This is docker0 network in all Docker installations.
    none Container-specific networking stack
    host Adds a container on hosts networking stack. Network configuration is identical to the host.

    This explains a total of nine networks, three for each node, as shown in this Swarm cluster.

  2. Use Compose file to start WildFly and Couchbase:

    In this Compose file:

    1. Couchbase service has a custom container name defined by container_name. This name is used when creating a new environment variable COUCHBASE_URI during WildFly startup.
    2. arungupta/wildfly-admin image is used as it binds WildFly’s management to all network interfaces, and in addition also exposes port 9990. This enables WildFly Maven Plugin to be used to deploy the application.Source for this file is at https://github.com/arun-gupta/docker-images/blob/master/wildfly-couchbase-javaee7/docker-compose.yml.

    This application environment can be started as:

    --x-networking creates an overlay network for the Swarm cluster. This can be verified by listing networks again:

    Three new networks are created:

    1. Containers connected to the multi-host network are automatically connected to the docker_gwbridge network. This network allows the containers to have external connectivity outside of their cluster, and is created on each worker node.
    2. A new overlay network wildflycouchbasejavaee7 is created. Connect to different Swarm nodes and check that the overlay network exists on them.

      Lets begin with master:

      Next, with swarm-node-01:

      Finally, with swarm-node-02:

      As seen, wildflycouchbasejavaee7 overlay network exists on all Machines. This confirms that the overlay network created for Swarm cluster was added to each host in the cluster. docker_gwbridge only exists on Machines that have application containers running.

      Read more about Docker Networks.

  3. Verify that WildFly and Couchbase are running:

Configure Application and Database

  1. Clone https://github.com/arun-gupta/couchbase-javaee.git. This workspace contains a simple Java EE application that is deployed on WildFly and provides a REST API over travel-sample bucket in Couchbase.
  2. Couchbase server can be configured using REST API. The application contains a Maven profile that allows to configure Couchbase server with travel-sample bucket. This can be invoked as:
  3. Deploy the application to WildFly by specifying three parameters:
    1. Host IP address where WildFly is running
    2. Username of a user in WildFly’s administrative realm
    3. Password of the user specified in WildFly’s administrative realm

Access Application

Now that WildFly and Couchbase server have started, lets access the application. You need to specify IP address of the Machine where WildFly is running:

Complete set of REST API for this application is documented at github.com/arun-gupta/couchbase-javaee.

Latest instructions at Docker for Java Developers.

Enjoy!

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16 thoughts on “Docker Machine, Swarm and Compose for multi-container and multi-host applications with Couchbase and WildFly”

  1. Awesome start… that’s exactly what I was looking for… Maybe you could extend it to use docker-machine to control hosts in any given Data Center using the generic driver. That would make this look like a production deployment :) Thanks a lot!

  4. Nice tutorial that doesn’t assume anything. Thanks for taking the time to write it. I’ve some questions though:

    1) How do I rejoin the swarm if I’d left? The instructions in the tutorial require creating a new machine and the official docs use a pre-generated cluster id for registration, not Consul.
    2) It appears that even though the application (Wildfly + Couchbase) is running on all 3 nodes, Couchbase is running a single host, single container scenario. In other words, the 3 instances of Couchbase are not in a cluster as far as Couchbase is concerned. Is that correct?
    3) Please consider extending the tutorial by adding at least one other method of registration and discovery as shown in the official docs.

  5. Abhijit,

    Thanks for your feedback!

    This application is using a single instance of Couchbase. A future blog will talk about how to create a scalable cluster on Docker.

    Can you file bugs at https://github.com/javaee-samples/docker-java for your requests?

    Arun

  6. > Can you file bugs…
    Done.
    https://github.com/javaee-samples/docker-java/issues/131

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  10. Thanks for this very good article.Unfortunately docker compose on windows does’nt have the –x-networking option yet (1.6.2)

  12. Hi Arun, I filed the issue, and got a quick reply.
    As from docker-compose 1.6.0, networking is the default mode, and the experimental –x-networking flag has been removed and that’s a preety good news !

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