Support build args without explicit value #1417
Merged
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This PR fixes #1408.
When a build arg key is specified without an explicit value, the value should be taken from the corresponding environment variable on the host.
When the corresponding environment variable on the host is unset, the build arg should be ignored to avoid masking a possible default value specified in the Dockerfile. To pass an empty string as build arg, use the form
VAR=
on the CLI/as an environment variable.