aws-test: tag and push an alpha of the oscontainer

In #150, it was discussed that an `alpha` tag should be
made for the oscontainer (and cloud image) after it passes the tests
run in AWS.  This change accomplishes this goal by pulling the
oscontainer by commit ID, tagging it as `alpha` and pushing it to the
registry.  (After a successful test, obviously)

If the AWS tests fail, the image tagged with the ostree commit is
garbage collected and no alpha promotion happens.

Jenkinsfile.aws-test

@@ -1,5 +1,8 @@
 def NODE = "rhcos-jenkins"
 def AWS_REGION = "us-east-1"
+def API_CI_REGISTRY = "registry.svc.ci.openshift.org"
+def OS_NAME = "maipo";
+def OSCONTAINER_IMG = API_CI_REGISTRY + "/rhcos/os-${OS_NAME}"
 
 // location on the server we'll rsync to/from our $WORKSPACE
 def images = "/srv/rhcos/output/images"
@@ -23,7 +26,7 @@ node(NODE) {
 
     // We're only ever triggered by the cloud job, so we know the latest build is in latest/
     // We immediately resolve it back to the specific images/ dir
-    def version
+    def ostree_commit, version
     try {
     utils.inside_assembler_container("") {
     stage("Sync In") {
@@ -32,6 +35,7 @@ node(NODE) {
             sshUserPrivateKey(credentialsId: params.ARTIFACT_SSH_CREDS_ID, keyFileVariable: 'KEY_FILE'),
         ]) {
             utils.rsync_file_in_dest(ARTIFACT_SERVER, KEY_FILE, "${images}/cloud/latest/meta.json", "${WORKSPACE}/meta.json")
+            ostree_commit = utils.sh_capture("jq -r '.[\"ostree-commit\"]' ${WORKSPACE}/meta.json")
             version = utils.sh_capture("jq -r '.[\"ostree-version\"]' ${WORKSPACE}/meta.json")
             // resolve to original dir to avoid races in the next rsync in
             def imgv = utils.sh_capture("jq -r '.[\"image-version\"]' ${WORKSPACE}/meta.json")
@@ -48,12 +52,21 @@ node(NODE) {
                 string(credentialsId: params.S3_PRIVATE_BUCKET, variable: 'S3_PRIVATE_BUCKET'),
                 string(credentialsId: params.AWS_CI_ACCOUNT, variable: 'AWS_CI_ACCOUNT'),
                 string(credentialsId: params.S3_PUBLIC_BUCKET, variable: 'S3_PUBLIC_BUCKET'),
+                usernameColonPassword(credentialsId: params.REGISTRY_CREDENTIALS, variable: 'CREDS'),
             ]) {
                 def ami_intermediate = utils.sh_capture("jq -r .HVM ${WORKSPACE}/aws-${AWS_REGION}.json")
+
+                // login to registry and setup container storage
+                def (registryUser, registryPass) = "${CREDS}".split(':')
+                utils.registry_login(registryUser, registryPass, "${API_CI_REGISTRY}")
+                utils.prep_container_storage("${WORKSPACE}")
+
                 currentBuild.description = "version=${version} ami=${ami_intermediate}"
                 sh """
                     # Do testing with intermediate aws image passed in by cloud job
                     if ! kola -b rhcos -p aws --aws-type t2.small --tapfile rhcos-aws.tap --aws-ami ${ami_intermediate} --aws-region ${AWS_REGION} -j ${NUM_VMS} run; then
+                        # if the tests fail, GC the container image tagged with the ostree commit
+                        skopeo delete docker://${OSCONTAINER_IMG}:${ostree_commit}
                         exit 1
                     fi
 
@@ -71,6 +84,10 @@ node(NODE) {
                     aws s3 cp --acl public-read \
                         ${WORKSPACE}/aws-${AWS_REGION}.json \
                         s3://${S3_PUBLIC_BUCKET}/aws-${AWS_REGION}-tested.json
+
+                    # Copy the container image to alpha, then GC the image tagged with the ostree commit
+                    skopeo copy docker://${OSCONTAINER_IMG}:${ostree_commit} docker://${OSCONTAINER_IMG}:alpha
+                    skopeo delete docker://${OSCONTAINER_IMG}:${ostree_commit}
                 """
             }
         }