Add a script to tag docker images as stable or by their git tag version (#6808)

* Add a script to tag docker images as stable or by their git tag version
* Apply suggestions from code review

Co-authored-by: Victor Farazdagi <simple.square@gmail.com>
* Always use HEAD

scripts/tag-versioned-docker-images.sh

@@ -0,0 +1,66 @@
+#!/bin/bash
+
+# This script is used to tag docker images with a specific commit or tag the
+# docker images as ":stable" with the --stable flag.
+
+# List of docker tags to update with git versioned tag.
+DOCKER_IMAGES=(
+  # Beacon chain images
+  "gcr.io/prysmaticlabs/prysm/beacon-chain"
+  "index.docker.io/prysmaticlabs/prysm-beacon-chain"
+  # Validator images
+  "gcr.io/prysmaticlabs/prysm/validator"
+  "index.docker.io/prysmaticlabs/prysm-validator"
+  # Slasher images
+  "gcr.io/prysmaticlabs/prysm/slasher"
+  "index.docker.io/prysmaticlabs/prysm-slasher"
+)
+
+
+# Check that the current commit has an associated git tag.
+TAG=$(git describe --tags HEAD)
+TAG_COMMIT=$(git rev-list -n 1 "$TAG")
+CURRENT_COMMIT=$(git rev-parse HEAD)
+
+if [ "$TAG_COMMIT" != "$CURRENT_COMMIT" ]
+then
+  echo "Current commit does not have an associated tag."
+  exit 1
+fi
+
+TAG_AS_STABLE=0
+
+for arg in "$@"
+do
+    case $arg in
+        -s|--stable)
+        TAG_AS_STABLE=1
+        shift # Remove --stable from processing
+        ;;
+        *)
+        OTHER_ARGUMENTS+=("$1")
+        shift # Remove generic argument from processing
+        ;;
+    esac
+done
+
+if [ "$TAG_AS_STABLE" = "1" ]
+then
+  TAG="stable"
+fi
+
+HEAD=HEAD-$(git rev-parse --short=6 HEAD)
+
+for image in "${DOCKER_IMAGES[@]}"
+do
+  SRC="$image:$HEAD"
+  DST="$image:$TAG"
+  echo "Pulling $SRC"
+  docker pull "$SRC"
+  echo "Tagging $SRC as $DST"
+  docker tag "$SRC" "$DST"
+  echo "Pushing $DST"
+  docker push "$DST"
+done
+
+exit 0