CBD-4012: Do not pull aliases in couchbase-k8s-microservice-docker

Change-Id: I9b269bde050fff32790daed44d8490d6927904f2
Reviewed-on: http://review.couchbase.org/c/build-tools/+/149857
Reviewed-by: Chris Hillery <[email protected]>
Tested-by: Blair Watt <[email protected]>

Author: udkyo

k8s-microservice/jenkins/util/update-base.sh

@@ -2,12 +2,27 @@
 
 DOCKERFILE=$1
 
-# Find the last FROM line in the Dockerfile and cut off the image name
-base=$(tac ${DOCKERFILE} | grep -m1 '^FROM' | cut -d' ' -f2)
-
-if [ "${base}" = "scratch" ]; then
-    echo "Not updating 'scratch' base image"
-else
-    echo "Updating base image ${base}"
-    docker pull ${base}
-fi
+upstream_images=()
+aliases=()
+
+# Get list of images and their aliases
+while read line; do
+    if $(echo $line | grep -q "^FROM"); then
+        upstream_images+=($(echo $line | awk '{print $2}'))
+        if $(echo $line | grep -q " as "); then
+            aliases+=($(echo $line | sed "s/.* as //"))
+        fi
+    fi
+done < $DOCKERFILE
+
+# Pull all non-alias images listed in FROM instructions
+for image in "${upstream_images[@]}"; do
+    if [[ ! "${aliases[@]}" =~ "${image}" ]]; then
+        if [ "${image}" = "scratch" ]; then
+            echo "Not updating 'scratch' base image"
+        else
+            echo "Updating base image ${image}"
+            docker pull ${image}
+        fi
+    fi
+done