This commit finishes the first step for migrating our complete build and
release pipeline to Concourse CI.
We're creating here a new "Release" jobs group in our pipeline.
We can now release Milestones from our pipeline with:
* the "stage-milestone" job, which creates and tags a new Milestone
version on the source repository, builds the artifacts and deploys them
in a staging repository and updates the version to the next SNAPSHOT.
* the "promote-milestone" fetches the build information from the staging
repository and promotes the released milestone in the official milestone
repository.
Interactions with the Artifactory and Bintray REST APIs are done using
the https://github.com/spring-io/concourse-release-scripts project.
Closes gh-22490
This commit adds the Concourse build infrastructure under the "ci/"
folder. It contains:
* "images/", the definitions of container images used in the pipeline
* "pipeline.yml" the build pipeline definition
* "parameters.yml" the parameters for the pipeline definition
* "tasks/" the tasks used by the build pipeline
* "scripts/" scripts used by pipeline tasks
This first iteration of the Concourse pipeline builds CI container
images for JDK8, JDK11, JDK14 and JDK15.
These images are used for building and publishing the master branch of
Spring Framework using JDK8. Other JDK variants are sanity checks and
don't actually publish the produced artifacts.
See gh-22490
