tag fix change to prefix prod or dev string

tag fix change to prefix prod or dev string. We are adding addtional tag
with the prefix existing tags will remain same.

buildspec.yml

@@ -27,11 +27,13 @@ phases:
         if [[ $AWS_REGION = "eu-west-1" ]]
         then
             TAG_1=latest
+            TAG_PREFIX="prod"
         else
-            TAG_1=${CODEBUILD_WEBHOOK_TRIGGER:7}
+            TAG_1=${CODEBUILD_WEBHOOK_HEAD_REF##*/}
+            # assigns branch name for dev build it will be dev
+            TAG_PREFIX=TAG_1
         fi
       - TAG_2=$VERSION
-      - TAG_3=${CODEBUILD_WEBHOOK_HEAD_REF##*/}
 
   build:
     commands:
@@ -51,11 +53,11 @@ phases:
       - docker push $REPOSITORY_URI:$TAG_1
       - docker push $REPOSITORY_URI:$TAG_2
       - |
-        if [[ -z "$TAG_3" ]]
+        if [[ -z "$TAG_PREFIX" ]]
         then
-              echo "\$TAG_3 is empty"
+              echo "\$TAG_PREFIX is empty"
         else
-              docker tag $REPOSITORY_URI:latest $REPOSITORY_URI:$TAG_3-$VERSION
-              docker push $REPOSITORY_URI:$TAG_3-$VERSION
+              docker tag $REPOSITORY_URI:latest $REPOSITORY_URI:$TAG_PREFIX-$VERSION
+              docker push $REPOSITORY_URI:$TAG_PREFIX-$VERSION
         fi
       - echo completed pushing image to ecr