skaffold init for Java applications

[saturnism]

Expected behavior

skaffold init on a Java project (with Maven or Gradle) will produce the default skaffold.yaml with the corresponding Jib builder configuration.

Actual behavior

skaffold init requires Dockerfile to be present and fails with:
FATA[0001] one or more valid Dockerfiles must be present to run skaffold; please provide at least one Dockerfile and try again

However, Dockerfile is not needed for Jib.

Information

• Skaffold version: 0.17
• Operating system: OSX

Steps to reproduce the behavior

1. Create a new Java project that uses either Maven or Gradle.
2. Run skaffold init

[saturnism]

/cc @balopat @coollog @loosebazooka @dgageot

[dgageot]

That's a duplicate of #1093 but I'm going to keep your ticket because it's more detailed :-)

[coollog]

Some options for when there might be a mix of Dockerfiles and Maven/Gradle.

• default to Dockerfile if present, choose between Dockerfiles if multiple
• default to Maven/Gradle if pom.xml/mvnw/build.gradle/gradlew detected, choose between Maven/Gradle if both present
• survey with choices for use Dockerfile, jibGradle, or jibMaven

I think we should go with the survey with all the choices since otherwise, it would be hard to differentiate which artifact should use which.

[loosebazooka]

I like the survey idea.

Is skaffold init designed to only work for single artifacts at the moment? I imagine it would get pretty complex pretty fast if it started searching for one or more artifacts to configure.

[briandealwis]

I wondered about handling multi-module projects. I guess we could look for locations with a pom.xml or .mvn directory, and then try jib:_skaffold-package-goals. And similarly for Gradle.

[dgageot]

This can be close, we are waiting for #2842 to make this feature active.