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Extending Docker Configuration

Extending Docker Configuration

Remco is used to generate the Rundeck
configuration files from templates. It supports different key/value sources such as vault, etcd, and dynamodb.
All configuration backends are combined into a unified keyspace. This allows storing parts of the
configuration space in different backends. The default configuration uses environment variables.

Extending the configuration involves building a derived image
with additional template files.

Configuration Layout

.
├── Dockerfile
├── remco
   ├── config.toml
   ├── resources.d
   │   ├── artifact-repositories-private.yaml.toml
   │   ├── framework.properties.toml
   │   ├── grails-config.properties.toml
   └── templates
       ├── artifact-repositories-private.yaml
       ├── framework.properties
       ├── grails-config.properties
       ├── jaas-loginmodule.conf
       ├── log4j2.properties

The above is an abridged layout of the remco configuration files in the Rundeck image source directory.
The three primary components for the configuration system are:

  • config.toml Where the config backends and resource includes are configured
  • remco/resources.d Directory that includes the resources files declaring the templates
  • remco/templates Directory where the templates are stored

Template Resources

[[template]]
    src         = "${REMCO_TEMPLATE_DIR}/framework.properties"
    dst         = "${RUNDECK_HOME}/etc/framework.properties"
    mode        = "0644"

The template resource files declare:

  • src The source template file
  • dst Where the template will be rendered on disk
  • mode The file mode for the created file

Config Merging

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

In the above example the destination is the special temporary directory ${REMCO_TMP_DIR}/rundeck-config/.
All files in this directory will be merged into rundeck-config.properties before Rundeck starts.

Special Destination Directories

All template files rendered into special destination directories
are merged into common Rundeck configuration files before Rundeck starts.
The special template destination directories are:

  • ${REMCO_TMP_DIR}/rundeck-config/ -> rundeck-config.properties
  • ${REMCO_TMP_DIR}/framework/ -> framework.properties

Extending Configuration

Extending the configuration by building a new Docker image derived from the Rundeck image is a snap.
The following example is taken from the Docker Zoo Config Exhibit.

Starting with the following layout:

.
├── docker-compose.yml
├── Dockerfile
├── README.md
└── remco
    ├── resources.d
    │   └── plugin-http-tours-framework.properties.toml
    └── templates
        └── plugin-http-tours-framework.properties

The plugin-http-tours-framework.properties.toml file contents are:

[[template]]
    src         = "${REMCO_TEMPLATE_DIR}/plugin-http-tours-framework.properties"
    dst         = "${REMCO_TMP_DIR}/framework/plugin-http-tours-framework.properties"
    mode        = "0644"

This file declares the input template source and an output destination to the special
directory ${REMCO_TMP_DIR}/framework/. This contents of the rendered template will
be merged into framework.properties at startup.

The template contents are as follows:

{% if exists("/rundeck/tour/endpoint") %}

framework.plugin.TourLoader.httptours.tourEndpoint={{ getv("/rundeck/tour/endpoint") }}
framework.plugin.TourLoader.httptours.tourManifestName={{ getv("/rundeck/tour/manifest","tour-manifest.json") }}
framework.plugin.TourLoader.httptours.toursSubpath={{ getv("/rundeck/tour/subpath","tours") }}

{% endif %}

This template adds configuration for a new plugin.

The following line from the Dockerfile includes the new remco configurations in the derived Docker image:

COPY --chown=rundeck:root remco /etc/remco