WebLogic autodeploy with Docker Compose

Docker Compose is a handy tool that allows you to quickly spin up a development environment consisting of many containers. In the context of docker images, the typical strategy is to build a new image with a new version of the application and deploy it to an external environment. For the needs of the development environment, you can accelerate it by reusing the same container to deploy a new iteration of the application.

In the case of WebLogic, the server offers an automatic deployment feature. All you have to do is place the artifact or an exploded archive in the autodeploy directory. With the help of Docker volumes, you can binding application artifacts to the place of automatic deployment.

When building, artifacts are usually generated in the build (Gradle) or target (Maven) directory. However, directly linking this path is not the best idea for several reasons:

1. It contains non-deployable subdirectories.
2. A missing artifact will turn into an empty subdirectory.
3. With each mvn clean, the volume bind may appear to be lost until the next restart (filesystem-specific).

Therefore, a reliable configuration not requiring manual intervention is to bind the volume to the parent directory.

project/
├─ src/
│  ├─ main/
│  │  ├─ java/
│  │  │  ├─ .../
│  │  ├─ webapp/
│  │  │  ├─ WEB-INF/
│  │  │  │  ├─ web.xml
├─ target/
│  ├─ classes
│  ├─ wlsdemo
│  ├─ wlsdemo.war
├─ src/
│  ├─ index.css
│  ├─ index.js
├─ docker-compose.yml
├─ domain.properties
├─ pom.xml

In the sample tree above, to bind the project folder to the /project directory inside the container, use the following docker-compose.yml:

version: '3'
services:
  weblogic:
    build: ./
    environment:
      - "debugFlag=true"
      - "DEBUG_PORT=*:8453"
    ports:
      - "7001:7001" #admin_listen_port
      - "9002:9002" #secure administration_port
      - "8453:8453" #custom debug port
    volumes:
      - ./:/project
      - ./:/u01/oracle/properties

You can implement automatic artifact deployment using a soft link. Take a look at the Dockerfile below. It is auto-build by the docker-compose.yml. The exploded archive generated by the maven-war-plugin/maven-ear-plugin during the package phase can also be interchanged with a full artifact.

# Requires license acceptation at https://container-registry.oracle.com/ Middleware > WebLogic
FROM container-registry.oracle.com/middleware/weblogic:14.1.1.0-dev-11
RUN mkdir -p /u01/oracle/user_projects/domains/base_domain/autodeploy/ \
    && /usr/bin/ln -s /project/target/wlsdemo \
    /u01/oracle/user_projects/domains/base_domain/autodeploy/wlsdemo

The modification of the classes subfolder is monitored on an ongoing basis and causes the class loader to reload. The documentation also describes a complete redeployment through updating the REDEPLOY file (under the WEB-INF/META-INF of the exploded WAR/EAR artifact). Automate it with the maven-antrun-plugin placed as the last one during the package.

    <build>
        <finalName>${artifactId}</finalName>
        <plugins>
            <!--...-->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-antrun-plugin</artifactId>
                <version>3.0.0</version>
                <executions>
                    <execution>
                        <id>touch-redeploy-file</id>
                        <phase>package</phase>
                        <goals>
                            <goal>run</goal>
                        </goals>
                        <configuration>
                            <target>
                                <touch file="${project.build.directory}/${project.artifactId}/WEB-INF/REDEPLOY"
                                       verbose="true" />
                            </target>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
</build>

In the example, I used the debugFlag and DEBUG_PORT environment variables. These are handled by the /u01/oracle/user_projects/domains/base_domain/bin/setDomainEnv.sh script. In short, this configures the debugger mode on all network interfaces (JDK 9+). Now you can debug and take advantage of the JPDA hot swap facilitated by your favorite IDE (IntelliJ > Edit Configuration > Remote JVM Debug).

The domain.properties file is required for a clean image without custom initialization scripts. It should contain the admin username and password in the following format:

username=myadminusername
password=myadminpassword12#

If you want to wait for the JVM debugger to attach, configure the JAVA_OPTIONS environment variable directly instead of the debugFlag.

Be careful with custom port mapping. It may require -Dweblogic.rjvm.enableprotocolswitch=true to establish a t3 connection.