tcwg-cleanup-stale-containers.sh: Simplify image removal

The current code seems to miss some of the dependencies of dangling
images, so we attempt to delete a used image.

Rather than being more careful in not attempting to delete used images,
we non-forcefully attempt to delete all images, and ignore failures.

Change-Id: I240ab7faf6f21d7f60451375992805fcc9124f60

1 files changed, 12 insertions, 23 deletions

diff --git a/tcwg-cleanup-stale-containers.sh b/tcwg-cleanup-stale-containers.sh
index d5d999d9..18710eb8 100755
--- a/tcwg-cleanup-stale-containers.sh
+++ b/tcwg-cleanup-stale-containers.sh
@@ -174,29 +174,18 @@ if [ ${#rm_volumes[@]} != 0 ]; then
     fi
 fi
 
-rm_images=()
-for image in $($DOCKER images -q -f dangling=true); do
-    if ! $DOCKER ps -a --format "{{.Image}}" | grep -q $image; then
-	rm_images=("${rm_images[@]}" $image)
-    fi
-done
-
-if [ ${#rm_images[@]} != 0 ]; then
-    echo "Removing unused images"
-    if $cleanup_images; then
-	for image in "${rm_images[@]}"; do
-	    $DOCKER rmi $image &
-	    res=0; wait $! || res=$?
-	    if [ $res != 0 ]; then
-		echo "WARNING: $DOCKER rmi $image -- exit status: $res"
-		status=$(($status|8))
-	    fi
-	done
-    else
-	echo "Increasing exit code to indicate unused images"
-	status=$(($status|8))
-        echo "DRY_RUN: NOT REMOVING UNTAGGED IMAGES"
-    fi
+if $cleanup_images; then
+    for image in $($DOCKER images -q -f dangling=true); do
+	# Try to remove $image.  The command will fail if the image is
+	# used by something.
+	$DOCKER rmi $image &
+	res=0; wait $! || res=$?
+	if [ $res = 0 ]; then
+	    echo "Removed image $image"
+	fi
+    done
+else
+    echo "DRY_RUN: NOT REMOVING UNTAGGED IMAGES"
 fi
 
 # This is a workaround for https://issues.jenkins-ci.org/browse/JENKINS-49097.