buildstream.buildelement module

The BuildElement class is a convenience element one can derive from for implementing the most common case of element.

Description of assemble activities

This element will perform the following steps to assemble an element:

Stage dependencies

The dependencies in the Scope.BUILD scope will be staged at the root of the sandbox

Integrate dependencies

The integration commands taken from the bst public domain of each dependency will be run in the sandbox to create and update caches. Typically ldconfig among other things is run in this step.

Stage sources

Sources are now staged according to their configuration into the %{build-root} directory (normally /buildstream/build) inside the sandbox.

Run commands

Commands are now run in the sandbox.

Commands are taken from the element configuration specified by the given BuildElement subclass, which can in turn be overridden by the user in element declarations (.bst files).

Commands are run in the following order:

  • configure-commands: Commands to configure how the element will build
  • build-commands: Commands to build the element
  • install-commands: Commands to install the results into %{install-root}
  • strip-commands: Commands to strip debugging symbols installed binaries

In addition to the above command domains, each command list is checked for a pre- and post- command domain. So for instance, an element declaration can append or prepend commands without overriding the existing defaults provided by the element type

Example

config:
  pre-configure-commands:
  - echo "Do something before default configure-commands"

Working Directory

Note that by default the working directory is where the sources are staged in %{build-root}, but this can be overridden to build inside of a subdirectory of the build directory using the command-subdir variable in an element declaration. e.g.:

variables:
  command-subdir: src

The above fragment will cause all commands to be run in the src/ subdirectory of the staged sources.

Result collection

Finally, the resulting build artifact is collected from the the %{install-root} directory (which is normally configured as /buildstream/install) inside the sandbox.

All build elements must install into the %{install-root} using whatever semantic the given build system provides to do this. E.g. for standard autotools packages we simply do make DESTDIR=%{install-root} install.

class BuildElement(context, project, artifacts, meta)

Bases: buildstream.element.Element

configure(node)
preflight()
get_unique_key()
configure_sandbox(sandbox)
stage(sandbox)
assemble(sandbox)