### A Jenkins pipeline to sync tidb docker images from Dockerhub to GCR.
- jenkins-slave-pod.yaml: defines the slave pod template to be used to run the pipeline.
- Dockerfile: defines the Docker image to be used to create the slave pod. 
- Jenkinsfile: the Jenkins pipeline definitions.
  
### How does it work:
- The pipeline monitors: https://github.com/pingcap/pingcap.github.io/blob/src/data/tidb_download_pkg.json; when the new push committed to the 'src' branch, the pipeline is triggered.
- The pipeline compares the difference from the last commit against 'tidb_download_pkg.json', and grabs the new lines which contain the new tags, then pulls the images with new tags from dockerhub, and pushes them to GCR eventually.
- The pipeline has been tested under 'yan-test' project, which resides in our Jenkins cluster.
- The Github webhook is yet to be created as it would require permissions.