Docker image of Mule Runtime Engine Community Edition (aka Kernel) 4 (current version is 4.2.1) intended to implement microservices and REST APIs with Mule.

• Where to get help:
  • Mule Runtime 4.2
• Where to report problems:
  • GitHub
• Supported architectures:
  • amd64

Mule Runtime is a lightweight Enterprise Service Bus (ESB) used for Integrations, building APIs, implementing Microservices, Data extraction, and Transformation.

This image supports any Mule App requiring Mule Runtime engine version 4 Kernel. However, our primary purpose is to implement microservices and REST APIs in Mule. Also, with optimization for running in Cloud with Kubernetes clusters and/or Istio, Service Mesh, or similar technologies.

Mule Runtime requires JDK 8 and since version 4.2.0, is also supporting JDK 11. Support for JDK 11 is coming in a future version.

Currently, two Linux distros are supported: Ubuntu Bionic (18.04), and Alpine. See the image section for further details.

Since Jdk8u191, the JVM has been updated to be aware that is running within a Docker container. JVM now includes the option -XX:+UseContainerSupport which is enabled by default. For this reason, usual JVM options for memory heap such as -Xms and -Xmx are not set in the image and it is recommended that you define the memory limits in the Docker container instead. For example, this command will run a container limited to 1GB of RAM:

docker run --rm -m 1g --name mymule-service -p 8081:8081 trellixa/mule

To gain more fine grained control over the memory used for Java Heap within the Docker container, JVM also defines three new options:

• -XX:InitialRAMPercentage
• -XX:MaxRAMPercentage
• -XX:MinRAMPercentage

The Mule Container is started using these options for the heap:

-XX:+UseContainerSupport -XX:MinRAMPercentage=50.0 -XX:MaxRAMPercentage=60.0

The image exposes a single port, port 8081, for Mule Applications to use.

Four volumes are defined in the image to allow easy installation and configuration of your Mule apps: logs, conf, apps, domains.

All mount points are relative to the $MULE_HOME environment variable as show below:

# Define mount points.
VOLUME ["${MULE_HOME}/logs", "${MULE_HOME}/conf", "${MULE_HOME}/apps", "${MULE_HOME}/domains"]

Where MULE_HOME value is /opt/mule.

Vanilla installations of Mule standalone use Tanuki Wrapper to start the Mule Container either as a Windows or Linux service. Also, to monitor the health of the Runtime and automatically restart it if needed. However, in this image, the Mule Container is started without using the Wrapper script. Indeed, using the Wrapper with Docker container would be redundant, Docker already provides Container level support to control Mule successfully. Furthermore, in a Microservice architecture, it is likely that the containers are managed by Kubernetes or similar, or are part of a Service Mesh using Istio, Consul, Kong, or similar.

On the other hand, Tanuki Wrapper depends on GNU glibc library which is normally not provided in Linux Alpine distro. So, by not using the wrapper, we are removing the dependency of the image with this library.

Finally, to facilitate the migration of any existing Mule deployment that you might have, the wrapper.conf file is still processed and all the Java parameters wrapper.java.additional.* are used when launching the JVM with MuleContainer.

There are tree types of images supported, all with the same Mule Runtime version 4.2.1 and OpenJDK 8 (HotSpot) version:

Note: Alpine is not officially supported by Mulesoft but Ubuntu 18.04 is supported. See: Software requirements

1. Starting a container

   To start a new container using this image, run:

   docker run --rm -m 1g --name mymule-service -p 8081:8081 trellixa/mule

   This will create a new container named mymule-service with 1GB of memory for the container mapped to port 8081.

   1. Starting a container based on Linux Alpine slim image

      To start a new container with alpine-slim image, run:

      docker run --rm -m 1g --name mymule-service -p 8081:8081 trellixa/mule:4.2.1-alpine-slim

      This will create a new container named mymule-service with 1GB of memory for the container mapped to port 8081 based on Linux Alpine and OpenJDK slim version. Image size is ~254MB.

   2. Starting a container based on Ubuntu slim image

      To start a new container with ubuntu-slim image, run:

      docker run --rm -m 1g --name mymule-service -p 8081:8081 trellixa/mule:4.2.1-ubuntu-slim

      This will create a new container named mymule-service with 1GB of memory for the container mapped to port 8081 based on Ubuntu and OpenJDK slim version. Image size is ~354MB. Ie. 100MB bigger than Alpine image but smaller by ~100MB with respect to the default Ubuntu image.

2. Deploying a Mule App

   After starting the Container, copy the Mule app into the $MULE_HOME/apps folder.

   docker cp my-mule-application.jar mymuleapp:/opt/mule/apps/.

   This will deploy the Mule app my-mule-application.jar into the mymule-service container previously created.

   In addition, the container can have the apps volume mounted with the Mule app(s) already in it.

   docker run --rm -m 1g --name mymule-service -p 8081:8081 -v my-vol-with-mule-apps:/opt/mule/apps trellixa/mule

   In this way, there is no need to copy the application to the container after running the container.

3. Deploying a Mule App from new Docker image

   Another option, you can create a new image containing you Mule app and using this image as base.

   FROM trellixa/mule
   COPY mymuleapp.jar $MULE_HOME/apps
   # Uncomment to pass any extra Java or Application parameter. For instance, the 'env' variable
   #CMD ["-Denv=qa"]

4. Passing extra parameters

   Any extra argument od the docker run command will be used as parameter to the Mule container. So, the command:

   docker run --rm -m 1g --name mymule-service -p 8081:8081 trellixa/mule -Denv=qa

   will set the env variable to 'qa' for Mule.

5. Getting the logs

   You can mount a volume with the logs when running the container. For example:

   docker run --rm -m 1g --name mymule-service -p 8081:8081 -v my-mule-logs:/opt/mule/logs trellixa/mule

6. Changing the configuration

   To change Mule Container configuration, edit or copy the $MULE_HOME/conf/mule-container.conf file. Note that the conf folder is also one of the mount points defined in the image. So, Mule can be configured using:

   docker run --rm -m 1g --name mymule-service -p 8081:8081 -v my-mule-conf:/opt/mule/conf trellixa/mule

View license information for the Dockerfile(s) and associated scripts which are licensed under the Apache License, Version 2.0.

Licenses for the products installed within the image:

• Mule Runtime Kernel edition is licensed by Mulesoft under the Common Public Attribution License (CPAL).

As with all Docker images, these likely also contain other software which may be under other licenses (such as Bash, etc from the base distribution, along with any direct or indirect dependencies of the primary software being contained).

As for any pre-built image usage, it is the image user's responsibility to ensure that any use of this image complies with any relevant licenses for all software contained within.