sbt eagerly tries to connect to Docker daemon when starting

[ignasi35]

Reproducible Test Case

Create a new project based on lagom-java.g8 using Lagom 1.3.10

sbt -Dsbt.version=0.13.16 new https://github.com/lagom/lagom-java.g8

Start the application and interact with it. Stop the application. Upgrade the plugin version to 1.4.0-SNAPSHOT and start the application again.

NOTE: same issue applies migrating from 1.4.0-M2 to 1.4.0-SNAPSHOT.

Actual Behavior

$ sbt
[info] Loading global plugins from /Users/ignasi/.sbt/0.13/plugins
[info] Loading project definition from /Users/ignasi/wip/support/hello/project
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
[info] Set current project to hello (in build file:/Users/ignasi/wip/support/hello/)
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

Expected Behavior

None of the above.

[TimMoore]

This is a consequence of a bug in sbt-native-packager 1.3.1, fixed in 1.3.2 (sbt/sbt-native-packager#1058).

I had updated Play (in 2.6.7) to depend on sbt-native-packager 1.3.1 because of other improvements to the way it builds Docker images (playframework/playframework#7975). Unfortunately this was found, fixed and released in the time between when I opened the pull request and when it was merged, but we only noticed this later.

We've already updated to 1.3.2 in the Play 2.6.x branch (playframework/playframework#8002) so we will pick up this fix when Play 2.6.8 is released and we update.

Because we'll need 2.6.8 before 1.4.0-RC1 is released anyway, I don't think it's worth trying to work around this in another way.