# Vert.x Docker Images

Execute Vert.x applications in Docker containers.

== Introduction

https://www.docker.com/[Docker] lets you deploy applications inside lightweight and isolated software containers.
Applications run side by side in isolated Linux containers. If you never used Docker before check this online https://docs.docker.com/get-started/[tutorial].

Vert.x provides Docker images that you can use to run your applications. Two Docker images are provided:

* `vertx/vertx4` is the base image you need to extend to run your own application
* `vertx/vertx4-exec` is providing the `vertx` command to your system without having to install `vert.x` yourself.

The images are available from https://hub.docker.com/u/vertx/[Docker Hub].

This guide presents how to use these two images but also how to automate Docker image creation using Maven, generate
Fabric8 metadata and use _fat jars_.

== The base image

The base image (`vertx/vertx4`) lets you run your vert.x application in a Docker container. For this, you must
_extend_ the image to deploy your own application - _i.e._ create your own `Dockerfile` inheriting from
`vertx/vertx4`. Your application is then  launched using the `vertx` command (but in the container).

=== Deploying a Groovy verticle in a docker container

Running a groovy verticle in a docker container is not much different. Instead of the `hello-verticle.js` from the
previous example, we now have a `hello-verticle.groovy`:

.hello-verticle.groovy
[source, groovy]
----
vertx.createHttpServer().requestHandler({ request ->
    request.response().end("Groovy world")
}).listen(8080)
----

So, in the `Dockerfile` we just change the verticle file name:

.Dockerfile
[source]
----
# Extend vert.x image
FROM vertx/vertx4

# Set the name of the verticle to deploy
ENV VERTICLE_NAME hello-verticle.groovy

# Set the location of the verticles
ENV VERTICLE_HOME /usr/verticles

EXPOSE 8080

# Copy your verticle to the container
COPY $VERTICLE_NAME $VERTICLE_HOME/

# Launch the verticle
WORKDIR $VERTICLE_HOME
ENTRYPOINT ["sh", "-c"]
CMD ["exec vertx run $VERTICLE_NAME -cp $VERTICLE_HOME/*"]
----

The build and run instructions are very close to the previous ones:

[source]
----
> docker build -t sample/vertx-groovy .
....
> docker run -t -i -p 8080:8080 sample/vertx-groovy
----

=== Deploying a Java verticle in a docker container

So, now let's see how to deploy a Java verticle. Again it's not different from the previous examples, except that we
copy the verticle _jar_ file to the container. Let's take the following verticle:

.io.vertx.sample.hello.HelloVerticle
[source, java]
----
package io.vertx.sample.hello;

import io.vertx.core.AbstractVerticle;

public class HelloVerticle extends AbstractVerticle {

  @Override
  public void start() throws Exception {
    vertx.createHttpServer().requestHandler(request -> {
      request.response().end("Hello Java world");
    }).listen(8080);
  }
}
----

Let's now imagine that this verticle is packaged into the `target/hello-verticle-1.0.-SNAPSHOT.jar` jar file. So the
`Dockerfile` needs to copy this file but also gives to vert.x the verticle class name:

.Dockerfile
----
# Extend vert.x image
FROM vertx/vertx4

#                                                       <1>
ENV VERTICLE_NAME io.vertx.sample.hello.HelloVerticle
ENV VERTICLE_FILE target/hello-verticle-1.0-SNAPSHOT.jar

# Set the location of the verticles
ENV VERTICLE_HOME /usr/verticles

EXPOSE 8080

# Copy your verticle to the container                   <2>
COPY $VERTICLE_FILE $VERTICLE_HOME/

# Launch the verticle
WORKDIR $VERTICLE_HOME
ENTRYPOINT ["sh", "-c"]
CMD ["exec vertx run $VERTICLE_NAME -cp $VERTICLE_HOME/*"]
----
<1> Unlike the previous examples, here we set the verticle class name and the jar file
<2> The jar file is copied.

Build and run instructions do not change:

[source]
----
> docker build -t sample/vertx-java .
....
> docker run -t -i -p 8080:8080 sample/vertx-java
----

=== Configuration

The previous `Dockerfile`s did not configure vert.x. Let's see how such configuration can be added.

==== Configuring the Java Virtual Machine

You can configure the Java Virtual Machine using the `JAVA_OPTS` environment variable. So in the `Dockerfile` adds:

[source]
----
ENV JAVA_OPTS "-Dfoo=bar"
----

==== VERTX_OPTS

System variables specific to vert.x can be configured using the `VERTX_OPTS` environment variable:

[source]
----
ENV VERTX_OPTS "-Dvertx.options.eventLoopPoolSize=26 -Dvertx.options.deployment.worker=true"
----

==== Classpath

You can configure the classpath of the application using either the `-cp` parameter of the vert.x command or the
`CLASSPATH` environment variable:

[source]
----
ENV CLASSPATH "/usr/verticles/libs/foo.jar:/usr/verticles/libs/bar.jar:"
----

==== Logging

To configure the `logging.properties` file (that let you customize JUL loggers`), set the `VERTX_JUL_CONFIG`
environment variables:

[source]
----
COPY ./logging.properties $VERTICLE_HOME/                       <1>
ENV VERTX_JUL_CONFIG $VERTICLE_HOME/logging.properties          <2>
----
<1> Copy your `logging.properties` file
<2> Set the `VERTX_JUL_CONFIG` environment variable

==== Clustering

You can provide your own `cluster.xml` file, and add it to the classpath. To build a dynamic classpath from all the
file contained in `$VERTICLE_HOME` you can use:

[source]
----
COPY ./cluster.xml $VERTICLE_HOME/
# ...
CMD [export CLASSPATH=`find $VERTICLE_HOME -printf '%p:' | sed 's/:$//'`; exec vertx run $VERTICLE_NAME"]
----

Notice the `export CLASSPATH=...;` part in the `CMD` instruction. It builds the value of the `CLASSPATH` variable from
the content of the `$VERTICLE_HOME` directory. This tricks is useful to compute large and dynamic classpath.

=== Build Docker Images with Maven

There are a couple of Maven plugins to build your Docker images during your Maven build process. This example uses the
https://github.com/spotify/docker-maven-plugin[docker-maven-plugin] from Spotify.

First, create your Java project as usual. So your sources are located in `src/main/java`... Then create a
`src/main/docker` directory and create a `Dockerfile` inside:

[source]
----
.
├── pom.xml
├── src
│   └── main
│       ├── docker
│       │   └── Dockerfile
│       └── java
│           └── io
│               └── vertx
│                   └── example
│                       └── HelloWorldVerticle.java
├── target
----

In the `pom.xml` file add the following plugin configuration

[source, xml]
----
<groupId>com.spotify</groupId>
<artifactId>docker-maven-plugin</artifactId>
<version>0.2.8</version>
<executions>
  <execution>
    <id>docker</id>
    <phase>package</phase>
    <goals>
      <goal>build</goal>
    </goals>
  </execution>
</executions>
<configuration>
  <dockerDirectory>${project.basedir}/src/main/docker</dockerDirectory>
  <!-- Configure the image name -->
  <imageName>sample/vertx-hello</imageName>
  <resources>
    <resource>
      <targetPath>/verticles</targetPath>
      <directory>${project.build.directory}</directory>
      <includes>
        <include>${project.artifactId}-${project.version}.jar</include>
      </includes>
    </resource>
    <!-- don't forget to also add all the dependencies required by your application -->
  </resources>
</configuration>
</plugin>
----

The plugin copies the listed content into `target/docker`. Each resource is copied into the set `targetPath`. So edit
 the `src/main/docker/Dockerfile` and add the following content:

[source]
----
FROM vertx/vertx4

ENV VERTICLE_HOME /usr/verticles
ENV VERTICLE_NAME io.vertx.example.HelloWorldVerticle

COPY ./verticles $VERTICLE_HOME

ENTRYPOINT ["sh", "-c"]
CMD ["exec vertx run $VERTICLE_NAME -cp $VERTICLE_HOME/*"]
----

It's basically the same content as we saw above. The copy is a bit different as the plugin have placed
files in the same directory as the `Dockerfile`.

Once configured the image is built using: `mvn clean package`

=== Build Docker Images for Fabric 8

http://fabric8.io/[Fabric 8] is an open source set of micro-services that run on top of Kubernetes and OpenShift V3 to
 provide management, continuous delivery and iPaas facilities. You can execute vert.x application on top of Fabric 8
 by packaging them into a Docker image. However, additional metadata is required. In this example, we are going to
 use the https://github.com/rhuss/docker-maven-plugin[docker-maven-plugin] from Roland Huß.

Let's set up the following structure:

[source]
----
.
├── pom.xml
├── src
│   └── main
│       ├── docker
│       │   └── assembly.xml
│       └── java
│           └── io
│               └── vertx
│                   └── example
│                       └── HelloWorldVerticle.java
└── target
----

Unlike the maven plugin from Spotify, this plugin takes an `assembly.xml` as input. The file lists all the files that
 need to be copied to the docker container such as:

[source, xml]
----
 <assembly>
   <dependencySets>
     <dependencySet>
       <includes>
         <include>:${project.artifactId}</include>
       </includes>
       <outputDirectory>.</outputDirectory>
     </dependencySet>
   </dependencySets>
 </assembly>
----

The rest of the `Dockerfile configuration is given in the `pom.xml` file. Add the following plugin to the `pom.xml`
 file:

[source,xml]
----
 <plugin>
  <groupId>org.jolokia</groupId>
  <artifactId>docker-maven-plugin</artifactId>
  <version>0.11.5</version>
  <executions>
    <execution>
      <id>build</id>
      <phase>package</phase>
      <goals>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <images>
      <image>
        <name>${docker.image}</name>
        <build>
          <from>vertx/vertx4</from>
          <tags>
            <tag>${project.version}</tag>
          </tags>
          <ports>
            <port>8080</port>
          </ports>
          <command>vertx run io.vertx.example.HelloWorldVerticle -cp
            /usr/verticles/${project.artifactId}-${project.version}.jar
          </command>
          <assembly>
            <mode>dir</mode>
            <basedir>/usr/verticles</basedir>
            <descriptor>assembly.xml</descriptor>
          </assembly>
        </build>
      </image>
    </images>
  </configuration>
 </plugin>
----

To configure the container more finely, check the
https://github.com/rhuss/docker-maven-plugin/blob/master/doc/manual.md[manual]. All the _instructions_ we put in the
`Dockerfile` can be set from the plugin.

NOTE: The previous `pom.xml` file use a properties called `docker.image` setting the image name. Don't forget to set
it in your pom.xml` file.

Once you have this configuration in place, we need a second plugin to generate the metadata required by Fabric8:

[source, xml]
----
<plugin>
<groupId>io.fabric8</groupId>
<artifactId>fabric8-maven-plugin</artifactId>
<version>2.1.4</version>
<executions>
  <execution>
    <id>json</id>
    <phase>generate-resources</phase>
    <goals>
      <goal>json</goal>
    </goals>
  </execution>
  <execution>
    <id>attach</id>
    <phase>package</phase>
    <goals>
      <goal>attach</goal>
    </goals>
  </execution>
</executions>
</plugin>
----

Once set up, you can build your docker image with: `mvn clean package`. It creates the `kubernates.json` file
required by Fabric8. Then push your image on the Docker Registry provided by Fabric8:

[source, sh]
----
docker push $DOCKER_REGISTRY/sample/vertx-hello
----

Don't forget to set the `DOCKER_REGISTRY` url to point on the registry managed by Fabric8. The last step is to
_apply_ it with:

[source,sh]
----
mvn io.fabric8:fabric8-maven-plugin:2.1.4:apply
----

== The executable image

The `vertx/vertx4-exec` image provides the `vertx` command to the host. So no need to install vert.x on your machine,
 you can just use this docker image.

For instance:

[source, shell]
----
> docker run -i -t vertx/vertx4-exec -version
4.2.1
----

To run a verticle:

[source, shell]
----
docker run -i -t -p 8080:8080 \
    -v $PWD:/verticles vertx/vertx4-exec \
    run io.vertx.sample.RandomGeneratorVerticle \
    -cp /verticles/MY_VERTICLE.jar
----

This command mounts the current directory (`PWD`) into `/verticles` and then launch the `vertx run` command. Notice the
`-cp` parameter reusing the `/verticles` directory.

=== Customizing the stack

The `vertx/vertx4-exec` image provides the default "full" Vert.x stack. You may want to customize this stack and create
 your own exec image. First, create a `vertx-stack.json` file:

[source,json]
----
{
  "variables": {
    "vertx.version": "3.3.3"
  },
  "dependencies": [
    {
      "groupId": "io.vertx",
      "artifactId": "vertx-web",
      "version": "${vertx.version}",
      "included": true
    }
  ]
}
----

You can list any dependency you need, not just the Vert.x artifacts
(refer to the http://vertx.io/docs/vertx-stack-manager/stack-manager/[Stack Manager documentation] for details).

Then write a `Dockerfile` for your custom executable image:

----
FROM vertx/vertx4-exec                                     <1>

COPY vertx-stack.json ${VERTX_HOME}/vertx-stack.json       <2>

RUN vertx resolve && rm -rf ${HOME}/.m2                    <3>
----
<1> Extend the Vert.x executable image
<2> Replace the stack file in the Vert.x command installation
<3> Resolve dependencies

You should know be able to build your custom executable image:

[source,shell]
----
docker build -t mycompany/my-vertx4-exec .
----

And run your verticle:

[source,shell]
----
docker run -i -t -p 8080:8080 \
    -v $PWD:/verticles mycompany/my-vertx4-exec \
    run io.vertx.sample.RandomGeneratorVerticle \
    -cp /verticles/MY_VERTICLE.jar
----

== Deploying a fat jar

It is also possible to deploy a Vert.x application packaged as a _fat jar_ into a docker container. For this you
don't need the images provided by Vert.x, you can directly use a base _Java_ image. Let's have a look.

First, be sure your application is packaged as a _fat jar_. Then, use the following `Dockerfile`:

[source]
----
FROM openjdk:8-jre-alpine                                           <1>

ENV VERTICLE_FILE hello-verticle-fatjar-3.0.0-SNAPSHOT-fat.jar      <2>

# Set the location of the verticles
ENV VERTICLE_HOME /usr/verticles

EXPOSE 8080

# Copy your fat jar to the container
COPY target/$VERTICLE_FILE $VERTICLE_HOME/                          <3>

# Launch the verticle
WORKDIR $VERTICLE_HOME
ENTRYPOINT ["sh", "-c"]
CMD ["exec java -jar $VERTICLE_FILE"]                               <4>
----
<1> Extend the image providing OpenJDK 8, use the one you want
<2> Set the `VERTICLE_FILE` to point on the _fat jar_
<3> Copy the _Fat jar_ from _target_. Change it if you don't use Maven.
<4> Launch the application using the `java` executable (instead of `vertx`

It's basically the same `Dockerfile` as before. However, this time we extend `java:8` instead of the `vertx/vertx4`
image. Then we copy the fat jar to the container, and launch it with the `java` executable. All the configuration
settings presented above are still valid.

Build and run the container with:

[source]
----
> docker build -t sample/vertx-java-fat .
....
> docker run -t -i -p 8080:8080 sample/vertx-java-fat
----
