My colcon configuration

colcon.yaml

_definitions:
  - &base-paths
      # don't look at packages outside the src subdirectory
      base-paths:      [/opt/ros/master/src]
  - &build-base
      build-base:       /opt/ros/master/build
  - &test-base
      test-base:        /opt/ros/master/build
  - &test-result-base
      test-result-base: /opt/ros/master/test-results
  - &install-base
      install-base:     /opt/ros/master/install
  - &build-test-settings
      # leads to shorter PATH and other environment variables from sourcing your workspace
      merge-install: true
      # my computer has lots of cores
      parallel-workers: 3

"": # applies to all colcon subcommands
  log-base: /opt/ros/master/log
build:
  <<: [*base-paths, *build-base, *install-base, *test-result-base, *build-test-settings]
    # makes it so some edits (e.g. python and launch files) don't require rebuilding the package
  # but also leads to a long pythonpath
  # symlink-install: true
  symlink-install: false

  # don't make uninstall targets. I never use them anyway
  ament-cmake-args: [-DAMENT_CMAKE_UNINSTALL_TARGET=OFF]
  cmake-args: [
    --no-warn-unused-cli,
    # choose the appropriate build configuration:

    # -DCMAKE_BUILD_TYPE=Release
    -DCMAKE_BUILD_TYPE=RelWithDebInfo # when running for performance profiling
    # -DCMAKE_BUILD_TYPE=Debug            # when running for debugging
    ]
  # if a package fails, still try building the rest
  continue-on-error: true
extension-points:
  all: true
extensions:
  all: true
graph:
  <<: [*base-paths, *build-base]
info:
  <<: [*base-paths, *build-base]
metadata: {}
list:
  <<: [*base-paths, *build-base]
test:
  <<: [*build-test-settings, *base-paths, *build-base, *test-result-base, *install-base]
test-result:
  <<: [*test-result-base]
  # Don't just give the totals - tell us which tests failed and why
  verbose: true 
version-check: {}