Tag Archives: microservice

Microservice using Docker stack deploy – WildFly, Java EE and Couchbase

There is plenty of material on microservices, just google it! I gave a presentation on refactoring monolith to microservices at Devoxx Belgium a couple of years back and it has good reviews:

This blog will show how Docker simplifies creation and shutting down of a microservice.

All code used in this blog is at github.com/arun-gupta/couchbase-javaee.

Microservice Definition using Compose

Docker 1.13 introduced a v3 of Docker Compose. The changes in the syntax are minimal but the key difference is addition of deploy attribute. This attribute allows to specify replicas, rolling update and restart policy for the container.

Our microservice will start a WldFly application server with a Java EE application pre-deployed. This application will talk to a Couchbase database to CRUD application data.

Here is the Compose definition:

In this Compose file:

  1. Two services in this Compose are defined by the name db and web attributes
  2. Image name for each service defined using image attribute
  3. The arungupta/couchbase:travel image starts Couchbase server, configures it using Couchbase REST API, and loads travel-sample bucket with ~32k JSON documents.
  4. The arungupta/couchbase-javaee:travel image starts WildFly and deploys application WAR file built from https://github.com/arun-gupta/couchbase-javaee. Clone that project if you want to build your own image.
  5. envrionment attribute defines environment variables accessible by the application deployed in WildFly. COUCHBASE_URI refers to the database service. This is used in the application code as shown at https://github.com/arun-gupta/couchbase-javaee/blob/master/src/main/java/org/couchbase/sample/javaee/Database.java.
  6. Port forwarding is achieved using ports attribute
  7. depends_on attribute in Compose definition file ensures the container start up order. But application-level start up needs to be ensured by the applications running inside container. In our case, WildFly starts up rather quickly but takes a few seconds for the database to start up. This means the Java EE application deployed in WildFly is not able to communicate with the database. This outlines a best practice when building micro services applications: you must code defensively and ensure in your application initialization that the micro services you depend on have started, without assuming startup order. This is shown in the database initialization code at https://github.com/arun-gupta/couchbase-javaee/blob/master/src/main/java/org/couchbase/sample/javaee/Database.java. It performs the following checks:

    1. Bucket exists
    2. Query service of Couchbase is up and running
    3. Sample bucket is fully loaded

This application can be started using docker-compose up -d command on a single host. Or a cluster of Docker engines in swarm-mode using docker stack deploy command.

Setup Docker Swarm-mode

Initialize Swarm mode using the following command:

This starts a Swarm Manager. By default, manager node are also worker but can be configured to be manager-only.

Find some information about this one-node cluster using the command docker info command:

This cluster has 1 node, and that is manager.

Alternatively, a multi-host cluster can be easily setup using Docker for AWS.

Deploy Microservice

The microservice can be started as:

This shows the output:

WildFly and Couchbase services are started on this node. Each service has a single container. If the Swarm mode is enabled on multiple nodes then the containers will be distributed across multiple nodes.

A new overlay network is created. This allows multiple containers on different hosts to communicate with each other.

Verify that the WildFly and Couchbase services are running using docker service ls:

Logs for the service can be seen using docker service logs -f webapp_web:

Make sure to wait for the last log statement to show.

Access Microservice

Get 10 airlines from the microservice:

This shows the results as:

Docker for Java Developers workshop is a self-paced hands-on lab and allows you to get started with Docker easily.

Get a single resource:

Create a new resource:

Update a resource:

Delete a resource:

Detailed output from each of these commands is at github.com/arun-gupta/couchbase-javaee.

Delete Microservice

The microservice can be removed using  the command docker stack rm webapp:

Want to get started with Couchbase? Look at Couchbase Starter Kits.

Want to learn more about running Couchbase in containers?

Source: https://blog.couchbase.com/2017/february/microservice-using-docker-stack-deploy-wildfly-javaee-couchbase

Microservices using WildFly Swarm, Docker and Couchbase

Containers, Microsoervices, and NoSQL provide an awesome threesome for building your modern applications. These applications need to be agile, meet constantly evolving customer demands, be pervasive, and should work across mobile, web and IoT platforms.

This blog will explain a simple microservices stack using WildFly Swarm, Docker, and Couchbase. Complete code and instructions in this blog are documented at: github.com/arun-gupta/wildfly-swarm-couchbase.

Let’s understand the key components of this stack first!

wildfly-swarm-logo

WildFly Swarm allows to package and run JavaEE applications by packaging them with just enough of the server runtime to java -jar your application. With built-in service discovery, single sign-on using Keycloak, monitoring using Hawkular, and many more features, WildFly Swarm provides all the necessary components to develop your microservice.

docker-for-mac

Docker for Mac provides native support for running Docker containers on Mac OSX. It relies upon Hypervisor.framework in OSX. Docker engine runs in an Alpine Linux distribution on top of an xhyve Virtual Machine, and even the VM is managed by Docker. There is no need for Docker Machine or VirtualBox, and it integrates with OSX security sandbox model. DockerCon 2016 removed the private beta restriction from Docker for Mac, and so its available for everybody now.

Couchbase Logo

NoSQL provides the agility and flexibility of schema-less databases. This allows the application to evolve independently and rapidly without going through cumbersome database migrations. Couchbase offers true horizontal scaling with homogenous architecture, as opposed to non-scalable master/slave architecture. It also offers auto-sharding, SQL-like query language for JSON (N1QL), mobile database and synchronization with the backend server, and much more.

The complete sample application in this blog is at: github.com/arun-gupta/wildfly-swarm-couchbase.

WildFly Swarm Application

Let’s look at the Java EE REST endpoint:

It uses standard JAX-RS annotation to convert a POJO into a REST endpoint. Couchbase Java API provide a fluent API and used N1QL statement to query the documents and return the results. The N1QL statement returns the first 10 elements from the query result. Learn more about N1QL syntax in this interactive tutorial.

Database abstraction is defined as:

This is a singleton EJB that is eagerly initialized. It uses Couchbase Java SDK to connect to Couchbase. Database endpoint can be specified using the COUCHBASE_URI environment variable.

Next up is pom.xml for configuring the WildFly Swarm and Couchbase Java Client:

It uses WildFly Swarm “bill of materials” to pull in all the dependencies. Only the specific dependencies needed for the build are specified in <dependencies>. These are then packaged in the “fat jar”.

WildFly Swarm Maven plugin is used to package and run the application:

COUCHBASE_URI is used to read the host of where Couchbase database server is running.

Run Couchbase Server

Run the Couchbase server using Docker for Mac:

The arungupta/couchbase is built upon the standard Couchbase image and uses Couchbase REST API to configure the server.

Wait for a couple of minutes for the sample bucket to be populated with the JSON documents.

Invoke the Couchbase CLI tool cbq create a primary index on the sample bucket:

This will show the output as:

This output shows that result of creating index was successful.

One of the advantages of running Docker for Mac is that all the containers are accessible at localhost. This means Couchbase Web Console can be accessed at localhost:8091.

couchbase-web-console-docker-mac-wildfly-swarm-microsoervice

This screen ensures that Couchbase is configured  correctly.

Run WildFly Swarm Microservice

 

Package and run the self-contained microservice as:

If Couchbase is running on a different host, then the command will change to:

It shows the output as:

Now the application can be accessed as:

And a formatted output looks like:

So you built a simple microservice using WildFly Swarm accessing a Couchbase database running as a Docker container.

Now, ideally this WildFly Swarm service should be packaged as a Docker image and then that Docker image would serve as the service. A Maven profile with the name docker is already added to pom.xml but issue #3 is making that scenario fail.

Microservices References

Source: blog.couchbase.com/2016/june/microservices-wildfly-swarm-docker-couchbase