Extending image

This image can be extended using source-to-image.

For example to build customized image my-image:x.y with configuration in ~/image-configuration/ run:

$ s2i build ~/image-configuration/ image:x.y my-image:x.y

The directory passed to s2i build should contain one or more of the following directories:

service-config/

when running run-service command contained service.conf file is used for service configuration

pre-init/

contained shell scripts (*.sh) are sourced before service is started

init/

contained shell scripts (*.sh) are sourced after service is started

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During s2i build all provided files are copied into /opt/app-root/src directory in the new image. If some configuration files are present in destination directory, files with the same name are overwritten. Also only one file with the same name can be used for customization and user provided files are preferred over default files in /usr/share/container-scripts/- so it is possible to overwrite them.

Same configuration directory structure can be used to customize the image every time the image is started using docker run. The directory have to be mounted into /opt/app-root/src/ in the image (-v ./image-configuration/:/opt/app-root/src/). This overwrites customization built into the image.

Example

This repository contains the example to demonstrate the workflow.

Build the s2i builder image:

$ make build

Build new extended image:

$ s2i build ./examples/extending-image/ image:x.y new-image

Run new image:

$ docker run new-image

You should see that two extra scripts were executed : init-extended.sh and pre-init-extended.sh. The set-config.sh script takes care about using correct configuration file for the service. In this example configuration file from examples folder is used in the container, not the default one.

Credits

Pattern of creating s2i images is inspired by sclorg MongoDB container.

Development Notes

This repository is temporary and hopefully will be merged with container-image-template in the future.