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Extend the Rundeck Docker image

Extend the Rundeck Docker image

What is Docker?

Docker is a platform used by many organizations to run virtualized applications. In addition to managing servers that are Docker containers, it is possible to run Rundeck (or PagerDuty Process Automation) in a Docker container. The default Rundeck Docker image uses standard variablesopen in new window to configure the main Rundeck settings. However, specific, non-standard variables can be added to use third-party plugins or add specific non-standard functionality. When using Docker, the image must be complete and nothing extra can be installed once the container is started. All configuration files, required software, etc., must be incorporated when the image is built and custom configurations must be exposed via environment variables.

What is Remco?

Remco is a lightweight configuration management tool (highly influenced by confdopen in new window) that can be used in conjunction with Docker. Remco’s main benefits are:

  • Keeping local configuration files up-to-date using data stored in a key/value store like etcd or consul and processing template resources.
  • Reloading applications to pick up new config file changes.

Rundeck uses a template system to build configuration files based on environment variables. Template files such as rundeck-config.properties, framework.properties, and log4j2.properties control the main configuration aspects of Rundeck. Remco generates these templates.

Extending the base Rundeck Docker image happens for a variety of reasons, including:

  • Copying plugins/addons to the container
  • Adding or modifying configuration files (explained in this article)
  • Other files need to be copied to the image

About the Remco structure

A custom Remco template requires a defined folder structure. For example, a parent folder called remco is required, with two folders inside called resource.d and templates.

Rundeck Docker structure with Remco:

Inside the resource.d folder, .toml files must be created. These files define the source and destination path where the configuration files will be copied.

A .toml file example:

[[template]]
src = "${REMCO_TEMPLATE_DIR}/extra-rundeck-config.properties"
dst = "${REMCO_TMP_DIR}/rundeck-config/extra-rundeck-config.properties"
mode = "0644"

An example: Adding a Docker variable through Remco

Exercise Goal:

By adding remco template files, create a new rundeck.feature.joblifecycleplugin.enabled=true entry in the rundeck-config.properties file.

Exercise Steps

  1. Create rundeck-config-extra.properties file at mydocker/remco/templates/ path with the following content:
    # adding extra stuff to rundeck-config.properties file
rundeck.feature.jobLifecyclePlugin.enabled={{ getv("/rundeck/feature/joblifecycleplugin/enabled", "true") }}
  2. Create rundeck-config.properties-extra.toml file at mydocker/remco/resources.d/ path with the following content:
    [[template]]
 src = "${REMCO_TEMPLATE_DIR}/rundeck-config-extra.properties"
 dst = "${REMCO_TMP_DIR}/rundeck-config/rundeck-config-extra.properties" 
 mode = "0644"
  3. Create the docker-compose.yaml at mydocker/ path with the following content:
    version: '3'
services:
 rundeckserver:
   build:
     context: .
     dockerfile: Dockerfile
     args:
       url: http://localhost:4440
   ports:
     - "4440:4440"
   restart: always
  4. Create Dockerfile at mydocker/ path with the following content:
    FROM rundeck/rundeck:4.4.0
COPY --chown=rundeck:root remco /etc/remco
COPY --chown=rundeck:root volume/job-lifecycle-3.2.3-20200221.jar /home/rundeck/libext/
ARG url=""
ENV RUNDECK_SERVER_ADDRESS=0.0.0.0
ENV RUNDECK_GRAILS_URL=http://localhost:4440
  5. Build the custom image:
    docker-compose build
  6. Run and see the container in action:
    docker-compose up
    That adds this line in the rundeck-config.properties file:
    # adding extra stuff to rundeck-config.properties file
rundeck.feature.jobLifecyclePlugin.enabled=true

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