Deploying Java EE Application to Docker Swarm Cluster
Follow these simple steps to get your Java application deployed.
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Join For FreeWhat is Docker Swarm?
Docker Swarm provides native clustering to Docker. Clustering using Docker Swarm 0.2.0 provides a basic introduction to Docker Swarm, and how to create a simple three node cluster. As a refresher, the key components of Docker Swarm are shown below:
In short, Swarm Manager is a pre-defined Docker Host, and is a single point for all administration. Additional Docker hosts are identified as Nodes and communicate with the Manager using TCP. By default, Swarm uses hosted Discovery Service, based on Docker Hub, using tokens to discover nodes that are part of a cluster. Each node runs a Node Agent that registers the referenced Docker daemon, monitors it, and updates the Discovery Service with the node’s status. The containers run on a node.
That blog provide complete details, but a quick summary to create the cluster is shown below:
# Create cluster
TOKEN=`docker run swarm create`
# Creating Swarm master
docker-machine create -d virtualbox --swarm --swarm-master --swarm-discovery token://$TOKEN swarm-master
# Creating swarm node 01
docker-machine create -d virtualbox --swarm --swarm-discovery token://$TOKEN swarm-node-01
Create swarm node 02
docker-machine create -d virtualbox --swarm --swarm-discovery token://$TOKEN swarm-node-02
Listing the cluster shows:
NAME ACTIVE DRIVER STATE URL SWARM
swarm-master virtualbox Running tcp://192.168.99.106:2376 swarm-master (master)
swarm-node-01 virtualbox Running tcp://192.168.99.107:2376 swarm-master
swarm-node-02 * virtualbox Running tcp://192.168.99.108:2376 swarm-master
It has one master and two nodes.
Deploy a Java EE application to Docker Swarm
All hosts in the cluster are accessible using a single, virtual host. Swarm serves the standard Docker API, so any tool that communicates with a single Docker host communicate can scale to multiple Docker hosts by communicating to this virtual host.
Docker Container Linking Across Multiple Hosts explains how to link containers across multiple Docker hosts. It deploys a Java EE 7 application to WildFly on one Docker host, and connects it with a MySQL container running on a different Docker host. We can deploy both of these containers using the virtual host, and they will then be deployed to the Docker Swarm cluster.
Lets get started!
MySQL on Docker Swarm
- Start the MySQL container
docker run --name mysqldb -e MYSQL_USER=mysql -e MYSQL_PASSWORD=mysql -e MYSQL_DATABASE=sample -e MYSQL_ROOT_PASSWORD=supersecret -p 3306:3306 -d mysql
- Status of the container can be seen as:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES b49d627a0431 mysql:latest "/entrypoint.sh mysq 5 minutes ago Up 4 minutes 192.168.99.107:3306->3306/tcp swarm-node-01/mysqldb
- It shows the container is running on
swarm-node-01
. Make sure you are connected to the Docker Swarm cluster usingeval $(docker-machine env --swarm swarm-master)
. - Find IP address of the host where this container is started:
~> docker inspect --format '{{ .Node.Ip }}' $(docker ps -q --filter 'name=*mysqldb*') 192.168.99.107
WildFly on Docker Swarm
~> docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ab5717083812 arungupta/wildfly-mysql-javaee7:host "/opt/jboss/wildfly/ 25 minutes ago Up 25 minutes 192.168.99.108:8080->8080/tcp swarm-node-02/mywildfly
b49d627a0431 mysql:latest "/entrypoint.sh mysq 34 minutes ago Up 33 minutes 192.168.99.107:3306->3306/tcp swarm-node-01/mysqldb
Enjoy!
Published at DZone with permission of Arun Gupta, DZone MVB. See the original article here.
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