new: [postgres] add automatic backup every hours

Signed-off-by: Valentin Lab <valentin.lab@kalysto.org>

postgres/build/Dockerfile

@@ -38,4 +38,6 @@ COPY --from=builder /bin/pgm /bin
 
 RUN apk add /tmp/mbuffer-2018*.apk --allow-untrusted
 
+RUN apk add gzip
+
 RUN ln -sf /usr/bin/mbuffer /usr/bin/buffer

postgres/hooks/schedule_command-relation-joined

@@ -7,11 +7,13 @@
 ##  - the target of the link is launched first, and get a chance to ``relation-set``
 ##  - both side of the scripts get to use ``relation-get``.
 
+. lib/common
+
 set -e
 
 ## XXXvlab: should use container name here so that it could support
 ## multiple postgres
-label=pg-backup-$SERVICE_NAME
+label=${SERVICE_NAME}-pg-backup
 DST=$CONFIGSTORE/$TARGET_SERVICE_NAME/etc/cron/$label
 schedule=$(relation-get schedule)
 
@@ -20,10 +22,6 @@ if ! echo "$schedule" | egrep '^\s*(([0-9/,*-]+\s+){4,4}[0-9/,*-]+|@[a-z]+)\s*$'
     exit 1
 fi
 
-## XXXvlab: how is this meant to works if there's multiples postgres (about PGHOST=?) ?
-## Warning: using '\' in heredoc will be removed in the final cron file, which
-##   is totally wanted: cron does not support multilines.
-
 exclude_dbs=$(relation-get exclude-dbs 2>/dev/null) || true
 exclude_dbs=$(echo "$exclude_dbs" | shyaml get-values 2>/dev/null |
                   nspc) || true
@@ -31,20 +29,16 @@ exclude_dbs=$(echo "$exclude_dbs" | shyaml get-values 2>/dev/null |
 ## Warning: 'docker -v' will use HOST directory even if launched from
 ##   'cron' container.
 file_put "$DST" <<EOF
+COMPOSE_LAUNCHER_OPTS=$COMPOSE_LAUNCHER_OPTS
+
 $schedule     root  lock $label -D -p 10 -c "\
     docker run --rm \
-        -e PGHOST=\$POSTGRES_PORT_5432_TCP_ADDR \
+        -e PGHOST=${SERVICE_NAME} \
         -e exclude_dbs=\"$exclude_dbs\" \
-        -v /root/.pgpass:/root/.pgpass \
-        -v \"$BASE_CHARM_PATH/resources/bin/pg-backup:/usr/sbin/pg-backup\" \
+        -v \"$LOCAL_DB_PASSFILE\":/root/.pgpass \
+        -v \"$HOST_CHARM_STORE/${CHARM_REL_PATH#${CHARM_STORE}/}/resources/bin/pg-backup:/usr/sbin/pg-backup\" \
         -v \"$SERVICE_DATASTORE/var/backups/pg:/var/backups/pg\" \
         --entrypoint pg-backup \
         \"$DOCKER_BASE_IMAGE\"" 2>&1 | ts '\%F \%T \%Z' >> /var/log/cron/pg-backup_script.log
 EOF
 chmod +x "$DST"
-
-config-add "\
-$MASTER_TARGET_SERVICE_NAME:
-  links:
-    - $MASTER_BASE_SERVICE_NAME
-"

postgres/metadata.yml

@@ -3,4 +3,13 @@ maintainer: "Valentin Lab <valentin.lab@kalysto.org>"
 data-resources:
   - /var/lib/postgresql/data
 provides:
-  postgres-database:
+  postgres-database:
+
+uses:
+  schedule-command:
+    constraint: optional
+    auto: pair
+    solves:
+      backup: "Automatic regular backups"
+    default-options:
+      schedule: "31 * * * *"  ## schedule backup every hour

postgres/resources/bin/pg-backup

@@ -23,14 +23,15 @@ for db in $dbs; do
     (( start = SECONDS ))
     echo "Dumping database $db..." >&2
     pg_dump -Ox "$db" | gzip --rsyncable > "$dst.inprogress"
-    errlvl="$?"
+    errlvl="${PIPESTATUS[0]}"
     ## Atomic replace
     (( elapsed = SECONDS - start ))
     if [ "$errlvl" != "0" ]; then
         echo "  !! Error when dumping database $db." >&2
+        rm "$dst.inprogress"
     else
-        echo "  ..dumped $db to $dst ($(du -sh "$dst" | cut -f 1) in ${elapsed}s)" >&2
+        mv "$dst.inprogress" "$dst"
+        printf "  ..dumped %-35s (%12s in %10s)\n" "${dst##*/}" "$(du -sh "$dst" | cut -f 1)" "${elapsed}s" >&2
     fi
-    mv "$dst.inprogress" "$dst"
 done