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>

.cirrus.yml

@@ -261,7 +261,7 @@ meta_task:
         cpu: 1
         memory: 1
 
-    env:
+    env: &meta_env_vars
         # Space-separated list of images used by this repository state
         IMGNAMES: >-
             ${FEDORA_CACHE_IMAGE_NAME}
@@ -277,6 +277,31 @@ meta_task:
 
     timeout_in: 10m
 
+    # Cirrus-CI ignores entrypoint defined in image
+    script: '/usr/local/bin/entrypoint.sh |& ${TIMESTAMP}'
+
+
+# Remove old and disused images based on labels set by meta_task
+image_prune_task:
+
+    # Do not run this frequently
+    only_if: $CIRRUS_BRANCH == 'master'
+
+    depends_on:
+        - "meta"
+
+    container:
+        image: "quay.io/libpod/imgprune:latest"  # see contrib/imgprune
+        cpu: 1
+        memory: 1
+
+    env:
+        <<: *meta_env_vars
+        GCPJSON: ENCRYPTED[4c11d8e09c904c30fc70eecb95c73dec0ddf19976f9b981a0f80f3f6599e8f990bcef93c253ac0277f200850d98528e7]
+        GCPNAME: ENCRYPTED[7f54557ba6e5a437f11283a53e71baec9ca546f48a9835538cc54d297f79968eb1337d4596a1025b14f9d1c5723fbd29]
+
+    timeout_in: 10m
+
     script: '/usr/local/bin/entrypoint.sh |& ${TIMESTAMP}'
 
 

contrib/cirrus/build_vm_images.sh

@@ -3,7 +3,8 @@
 set -e
 source $(dirname $0)/lib.sh
 
-ENV_VARS='PACKER_BUILDS BUILT_IMAGE_SUFFIX UBUNTU_BASE_IMAGE FEDORA_BASE_IMAGE PRIOR_FEDORA_BASE_IMAGE SERVICE_ACCOUNT GCE_SSH_USERNAME GCP_PROJECT_ID PACKER_VER SCRIPT_BASE PACKER_BASE'
+BASE_IMAGE_VARS='FEDORA_BASE_IMAGE PRIOR_FEDORA_BASE_IMAGE UBUNTU_BASE_IMAGE'
+ENV_VARS="PACKER_BUILDS BUILT_IMAGE_SUFFIX $BASE_IMAGE_VARS SERVICE_ACCOUNT GCE_SSH_USERNAME GCP_PROJECT_ID PACKER_VER SCRIPT_BASE PACKER_BASE CIRRUS_BUILD_ID CIRRUS_CHANGE_IN_REPO"
 req_env_var $ENV_VARS
 # Must also be made available through make, into packer process
 export $ENV_VARS
@@ -24,6 +25,20 @@ then
 fi
 
 cd "$GOSRC/$PACKER_BASE"
+# Add/update labels on base-images used in this build to prevent premature deletion
+ARGS="
+"
+for base_image_var in $BASE_IMAGE_VARS
+do
+    # See entrypoint.sh in contrib/imgts and contrib/imgprune
+    # These updates can take a while, run them in the background, check later
+    gcloud compute images update "$image" \
+        --update-labels=last-used=$(date +%s) \
+        --update-labels=build-id=$CIRRUS_BUILD_ID \
+        --update-labels=repo-ref=$CIRRUS_CHANGE_IN_REPO \
+        --update-labels=project=$GCP_PROJECT_ID \
+        ${!base_image_var} &
+done
 
 make libpod_images \
     PACKER_BUILDS=$PACKER_BUILDS \
@@ -33,9 +48,31 @@ make libpod_images \
     PACKER_BASE=$PACKER_BASE \
     BUILT_IMAGE_SUFFIX=$BUILT_IMAGE_SUFFIX
 
+# Separate PR-produced images from those produced on master.
+if [[ "${CIRRUS_BRANCH:-}" == "master" ]]
+then
+    POST_MERGE_BUCKET_SUFFIX="-master"
+else
+    POST_MERGE_BUCKET_SUFFIX=""
+fi
+
 # When successful, upload manifest of produced images using a filename unique
 # to this build.
 URI="gs://packer-import${POST_MERGE_BUCKET_SUFFIX}/manifest${BUILT_IMAGE_SUFFIX}.json"
 gsutil cp packer-manifest.json "$URI"
 
+# Ensure any background 'gcloud compute images update' processes finish
+set +e  # need 'wait' exit code to avoid race
+while [[ -n "$(jobs)" ]]
+do
+    wait -n
+    RET=$?
+    if [[ "$RET" -eq "127" ]] || \   # Avoid TOCTOU race w/ jobs + wait
+       [[ "$RET" -eq "0" ]]
+    then
+        continue
+    fi
+    die $RET "Required base-image metadata update failed"
+done
+
 echo "Finished. A JSON manifest of produced images is available at $URI"

contrib/imgprune/Dockerfile

@@ -0,0 +1,7 @@
+FROM libpod/imgts:latest
+
+RUN yum -y update && \
+    yum clean all
+
+COPY /contrib/imgprune/entrypoint.sh /usr/local/bin/entrypoint.sh
+RUN chmod 755 /usr/local/bin/entrypoint.sh

contrib/imgprune/README.md

@@ -0,0 +1,11 @@
+![PODMAN logo](../../logo/podman-logo-source.svg)
+
+A container image for maintaining the collection of
+VM images used by CI/CD on this project and several others.
+Acts upon metadata maintained by the imgts container.
+
+Example build (from repository root):
+
+```bash
+sudo podman build -t $IMAGE_NAME -f contrib/imgprune/Dockerfile .
+```

contrib/imgprune/entrypoint.sh

@@ -0,0 +1,67 @@
+#!/bin/bash
+
+set -e
+
+source /usr/local/bin/lib_entrypoint.sh
+
+req_env_var GCPJSON GCPNAME GCPPROJECT IMGNAMES
+
+gcloud_init
+
+# For safety's sake + limit nr background processes
+PRUNE_LIMIT=10
+THEFUTURE=$(date --date='+1 hour' +%s)
+TOO_OLD='90 days ago'
+THRESHOLD=$(date --date="$TOO_OLD" +%s)
+# Format Ref: https://cloud.google.com/sdk/gcloud/reference/topic/formats
+FORMAT='value[quote](name,selfLink,creationTimestamp,labels)'
+PROJRE="/v1/projects/$GCPPROJECT/global/"
+BASE_IMAGE_RE='cloud-base'
+RECENTLY=$(date --date='30 days ago' --iso-8601=date)
+EXCLUDE="$IMGNAMES $IMAGE_BUILDER_CACHE_IMAGE_NAME" # whitespace separated values
+# Filter Ref: https://cloud.google.com/sdk/gcloud/reference/topic/filters
+FILTER="selfLink~$PROJRE AND creationTimestamp<$RECENTLY AND NOT name=($EXCLUDE)"
+TODELETE=$(mktemp -p '' todelete.XXXXXX)
+
+echo "Searching images for pruning candidates older than $TOO_OLD ($THRESHOLD):"
+$GCLOUD compute images list --format="$FORMAT" --filter="$FILTER" | \
+    while read name selfLink creationTimestamp labels
+    do
+        created_ymd=$(date --date=$creationTimestamp --iso-8601=date)
+        last_used=$(egrep --only-matching --max-count=1 'last-used=[[:digit:]]+' <<< $labels || true)
+        markmsgpfx="Marking $name (created $created_ymd) for deletion"
+        if [[ -z "$last_used" ]]
+        then # image pre-dates addition of tracking labels
+            echo "$markmsgpfx: Missing 'last-used' metadata, labels: '$labels'"
+            echo "$name" >> $TODELETE
+            continue
+        fi
+
+        last_used_timestamp=$(date --date=@$(cut -d= -f2 <<< $last_used || true) +%s || true)
+        last_used_ymd=$(date --date=@$last_used_timestamp --iso-8601=date)
+        if [[ -z "$last_used_timestamp" ]] || [[ "$last_used_timestamp" -ge "$THEFUTURE" ]]
+        then
+            echo "$markmsgpfx: Missing or invalid last-used timestamp: '$last_used_timestamp'"
+            echo "$name" >> $TODELETE
+            continue
+        fi
+
+        if [[ "$last_used_timestamp" -le "$THRESHOLD" ]]
+        then
+            echo "$markmsgpfx: Used over $TOO_OLD on $last_used_ymd"
+            echo "$name" >> $TODELETE
+            continue
+        fi
+
+        echo "NOT $markmsgpfx: last used on $last_used_ymd)"
+    done
+
+echo "Pruning up to $PRUNE_LIMIT images that were marked for deletion:"
+for image_name in $(tail -$PRUNE_LIMIT $TODELETE | sort --random-sort)
+do
+    # This can take quite some time (minutes), run in parallel disconnected from terminal
+    echo "TODO: Would have: $GCLOUD compute images delete $image_name &"
+    sleep "$[1+RANDOM/1000]s" &  # Simlate background operation
+done
+
+wait || true  # Nothing to delete: No background jobs

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
+}