Builder Management
New
Introduced in 0.24.0
builder:report [<app>] [<flag>] # Displays a builder report for one or more apps
builder:set <app> <key> (<value>) # Set or clear a builder property for an app
Builders are a way of customizing how an app is built from a source, allowing users flexibility in how artifacts are created for later scheduling.
Usage
Builder selection
Dokku supports the following built-in builders:
builder-dockerfile: Builds apps using aDockerfileviadocker build. See the dockerfile builder documentation for more information on how this builder functions.builder-herokuish: Builds apps with Heroku's v2a Buildpack specification viagliderlabs/herokuish. See the herokuish builder documentation for more information on how this builder functions.builder-pack: Builds apps with Cloud Native Buildpacks via thepack-clitool. See the cloud native buildpacks builder documentation for more information on how this builder functions.
Builders run a detection script against a source code repository, and the first detected builder will be used to build the app artifact. The exception to this is when a Dockerfile is detected and the app is also able to use either herokuish or pack-cli for building, in which case one of the latter will be chosen.
Overriding the auto-selected builder
If desired, the builder can be specified via the builder:set command by speifying a value for selected. The selected builder will always be used.
The default value may be set by passing an empty value for the option:
The selected property can also be set globally. The global default is an empty string, and auto-detection will be performed when no value is set per-app or globally.
The default value may be set by passing an empty value for the option.
Changing the build directory
Warning
Please keep in mind that setting a custom build directory will result in loss of any changes to the top-level directory, such as the git.keep-git-dir property.
When deploying a monorepo, it may be desirable to specify the specific build directory to use for a given app. This can be done via the builder:set command. If a value is specified and that directory does not exist within the repository, the build will fail.
The default value may be set by passing an empty value for the option:
The build-dir property can also be set globally. The global default is empty string, and the global value is used when no app-specific value is set.
The default value may be set by passing an empty value for the option.
Displaying builder reports for an app
You can get a report about the app's builder status using the builder:report command:
=====> node-js-app builder information
Builder build dir: custom
Builder computed build dir: custom
Builder computed selected: herokuish
Builder global build dir:
Builder global selected: herokuish
Builder selected: herokuish
=====> python-sample builder information
Builder build dir:
Builder computed build dir:
Builder computed selected: dockerfile
Builder global build dir:
Builder global selected: herokuish
Builder selected: dockerfile
=====> ruby-sample builder information
Builder build dir:
Builder computed build dir:
Builder computed selected: herokuish
Builder global build dir:
Builder global selected: herokuish
Builder selected:
You can run the command for a specific app also.
You can pass flags which will output only the value of the specific information you want. For example:
Custom builders
To create a custom builder, the following triggers must be implemented:
builder-build:- arguments:
BUILDER_TYPEAPPSOURCECODE_WORK_DIR - description: Creates a docker image named with the output of
common#get_app_image_name $APP. builder-detect:- arguments:
APPSOURCECODE_WORK_DIR - description: Outputs the name of the builder (without the
builder-prefix) to use to build the app. builder-release:- arguments:
BUILDER_TYPEAPPIMAGE_AG - description: A post-build, pre-release trigger that can be used to post-process the image. Usually simply tags and labels the image appropriately.
Custom plugins names must have the prefix builder- or builder overriding via builder:set may not function as expected.
Builders can use any tools available on the system to build the docker image, and may even be used to schedule building off-server. The only current requirement is that the image must exist on the server at the end of the builder-build command, though this requirement may be relaxed in a future release.
For a simple example of how to implement this trigger, see builder-pack, which utilizes a cli tool - pack-cli - to generate an OCI image that is compatible with Docker and can be scheduled by the official scheduling plugins.