TestBuildEnvUsage2 was flagged in https://github.com/docker/docker/issues/19425
as one of the slowest integration tests. It's slow because it has some
comprehensive builder test cases that end up creating a lot of layers.
Even with a busybox base image, this can be expensive. It's not possible
to build "FROM scratch" because the test cases need the shell to ensure
environment variables are set correctly.
Some of the ENV and RUN statements can be combined. This causes fewer
layers to get created. Doing this produces a marginal improvement in the
runtime.
Before:
PASS: docker_cli_build_test.go:3956: DockerSuite.TestBuildEnvUsage2 43.619s
After:
PASS: docker_cli_build_test.go:3956: DockerSuite.TestBuildEnvUsage2 31.286s
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
74fafa5dd2