Cirrus: Print images that should be pruned

Over time unless they're removed, the project could grow quite a large
collection of VM images.  While generally cheap (less than a penny each,
per month), these will become a significant cost item if not kept
in-check.

Add a specialized container for handling image-pruning, but limit
it to only finding and printing (not actually deleting) images.

Also update the image-building workflow so that base-images used to
compose cache-images are also labeled with metadata.

N/B: As an additional safeguard, the service account which
     executes the new container in production *DOES NOT*
     have access to delete images.  This can be enabled
     by adding the GCE IAM role: CustomComputeImagePrune

Signed-off-by: Chris Evich <cevich@redhat.com>

contrib/imgts/Dockerfile

@@ -7,14 +7,14 @@ RUN yum -y update && \
     yum -y install google-cloud-sdk && \
     yum clean all
 
-COPY /contrib/imgts/entrypoint.sh /usr/local/bin/entrypoint.sh
 ENV GCPJSON="__unknown__" \
     GCPNAME="__unknown__" \
     GCPPROJECT="__unknown__" \
     IMGNAMES="__unknown__" \
-    TIMESTAMP="__unknown__" \
     BUILDID="__unknown__" \
     REPOREF="__unknown__"
+
+COPY ["/contrib/imgts/entrypoint.sh", "/contrib/imgts/lib_entrypoint.sh", "/usr/local/bin/"]
 RUN chmod 755 /usr/local/bin/entrypoint.sh
 
 ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]

contrib/imgts/entrypoint.sh

@@ -2,45 +2,22 @@
 
 set -e
 
-RED="\e[1;36;41m"
-YEL="\e[1;33;44m"
-NOR="\e[0m"
+source /usr/local/bin/lib_entrypoint.sh
 
-die() {
-    echo -e "$2" >&2
-    exit "$1"
-}
+req_env_var GCPJSON GCPNAME GCPPROJECT IMGNAMES BUILDID REPOREF
 
-SENTINEL="__unknown__"  # default set in dockerfile
+gcloud_init
 
-[[ "$GCPJSON" != "$SENTINEL" ]] || \
-    die 1 "Must specify service account JSON in \$GCPJSON"
-[[ "$GCPNAME" != "$SENTINEL" ]] || \
-    die 2 "Must specify service account name in \$GCPNAME"
-[[ "$GCPPROJECT" != "$SENTINEL" ]] || \
-    die 4 "Must specify GCP Project ID in \$GCPPROJECT"
-[[ -n "$GCPPROJECT" ]] || \
-    die 5 "Must specify non-empty GCP Project ID in \$GCPPROJECT"
-[[ "$IMGNAMES" != "$SENTINEL" ]] || \
-    die 6 "Must specify space separated list of GCE image names in \$IMGNAMES"
-[[ "$BUILDID" != "$SENTINEL" ]] || \
-    die 7 "Must specify the number of current build in \$BUILDID"
-[[ "$REPOREF" != "$SENTINEL" ]] || \
-    die 8 "Must specify a PR number or Branch name in \$REPOREF"
+ARGS="
+    --update-labels=last-used=$(date +%s)
+    --update-labels=build-id=$BUILDID
+    --update-labels=repo-ref=$REPOREF
+    --update-labels=project=$GCPPROJECT
+"
 
-ARGS="--update-labels=last-used=$(date +%s)"
-# optional
-[[ -z "$BUILDID" ]] || ARGS="$ARGS --update-labels=build-id=$BUILDID"
-[[ -z "$REPOREF" ]] || ARGS="$ARGS --update-labels=repo-ref=$REPOREF"
-[[ -z "$GCPPROJECT" ]] || ARGS="$ARGS --update-labels=project=$GCPPROJECT"
-
-gcloud config set account "$GCPNAME"
-gcloud config set project "$GCPPROJECT"
-echo "$GCPJSON" > /tmp/gcp.json
-gcloud auth activate-service-account --key-file=/tmp/gcp.json || rm /tmp/gcp.json
 for image in $IMGNAMES
 do
-    gcloud compute images update "$image" $ARGS &
+    $GCLOUD compute images update "$image" $ARGS &
 done
-set +e  # Actual update failures are only warnings
-wait || die 0 "${RED}WARNING:$NOR ${YEL}Failed to update labels on one or more images:$NOR '$IMGNAMES'"
+
+wait || echo "Warning: No \$IMGNAMES were specified."

contrib/imgts/lib_entrypoint.sh

@@ -0,0 +1,44 @@
+#!/bin/bash
+
+set -e
+
+RED="\e[1;36;41m"
+YEL="\e[1;33;44m"
+NOR="\e[0m"
+SENTINEL="__unknown__"  # default set in dockerfile
+# Disable all input prompts
+# https://cloud.google.com/sdk/docs/scripting-gcloud
+GCLOUD="gcloud --quiet"
+
+die() {
+    EXIT=$1
+    PFX=$2
+    shift 2
+    MSG="$@"
+    echo -e "${RED}${PFX}:${NOR} ${YEL}$MSG${NOR}"
+    [[ "$EXIT" -eq "0" ]] || exit "$EXIT"
+}
+
+# Pass in a list of one or more envariable names; exit non-zero with
+# helpful error message if any value is empty
+req_env_var() {
+    for i; do
+        if [[ -z "${!i}" ]]
+        then
+            die 1 FATAL entrypoint.sh requires \$$i to be non-empty.
+        elif [[ "${!i}" == "$SENTINEL" ]]
+        then
+            die 2 FATAL entrypoint.sh requires \$$i to be explicitly set.
+        fi
+    done
+}
+
+gcloud_init() {
+    set +xe
+    TMPF=$(mktemp -p '' .$(uuidgen)XXXX)
+    trap "rm -f $TMPF" EXIT
+    echo "$GCPJSON" > $TMPF  && \
+    $GCLOUD auth activate-service-account --project "$GCPPROJECT" --key-file=$TMPF || \
+        die 5 FATAL auth
+    rm -f $TMPF
+}