Multi-stage docker build support (using --target in build) does not appear to work

[Jason Ryan]

docker build --target build_stage_target -t build_name . 

Running the above command in my pipelines does not produce the desired results. The --target flag is apparently ignored, and the build runs all stages before and after the specified stage.

Is this indeed not supported or could I be doing something wrong?

[Maxim Ugryumov · Accepted solution]

This is really an issue 😭
@Jason Ryandid you solve the problem?

[Jason Ryan]

Sadly I did not :( 

[Maxim Ugryumov]

Ok, thanks!

[Maxim Ugryumov]

Hi @Jason Ryan 👋

In our team we found the answer. This is not a Bitbucket issue, but the Docker itself. BuildKit fixes this bug in multi-stage builds in the legacy docker build engine.

So, just enable the BuildKit by inserting the line

- export DOCKER_BUILDKIT=1

before the docker build command and the image will be built with the specified target.

So simple, bro))

[Jason Ryan]

Fascinating. Thank you for sharing!