Merge pull request #17 from offen/local-prune

Use find instead of mc for pruning local backups

README.md

@@ -51,11 +51,12 @@ AWS_S3_BUCKET_NAME="<xxx>"
 
 # **IMPORTANT, PLEASE READ THIS BEFORE USING THIS FEATURE**:
 # The mechanism used for pruning backups is not very sophisticated
-# and applies its rules to **all files in the target directory**,
+# and applies its rules to **all files in the target directory** by default,
 # which means that if you are storing your backups next to other files,
 # these might become subject to deletion too. When using this option
 # make sure the backup files are stored in a directory used exclusively
-# for storing them or you might lose data.
+# for storing them or to configure BACKUP_PRUNING_PREFIX to limit
+# removal to certain files.
 
 # Define this value to enable automatic pruning of old backups. The value
 # declares the number of days for which a backup is kept.
@@ -71,6 +72,15 @@ AWS_S3_BUCKET_NAME="<xxx>"
 
 # BACKUP_PRUNING_LEEWAY="10m"
 
+# In case your target bucket or directory contains other files than the ones
+# managed by this container, you can limit the scope of rotation by setting
+# a prefix value. This would usually be the non-parametrized part of your
+# BACKUP_FILENAME. E.g. if BACKUP_FILENAME is `db-backup-%Y-%m-%dT%H-%M-%S.tar.gz`,
+# you can set BACKUP_PRUNING_PREFIX to `db-backup-` and make sure
+# unrelated files are not affected.
+
+# BACKUP_PRUNING_PREFIX="backup-"
+
 ########### BACKUP ENCRYPTION
 
 # Backups can be encrypted using gpg in case a passphrase is given

src/backup.sh

@@ -103,32 +103,62 @@ fi
 info "Backup finished"
 echo "Will wait for next scheduled backup."
 
-prune () {
-  target=$1
-  rule_applies_to=$(
+probe_expired () {
+  local target=$1
+  local is_local=$2
+  if [ -z "$is_local" ]; then
     mc rm $MC_GLOBAL_OPTIONS --fake --recursive --force \
       --older-than "${BACKUP_RETENTION_DAYS}d" \
-      "$target" \
-      | wc -l
-  )
+      "$target"
+  else
+    find $target* -type f -mtime $BACKUP_RETENTION_DAYS
+  fi
+}
+
+probe_all () {
+  local target=$1
+  local is_local=$2
+  if [ -z "$is_local" ]; then
+    mc ls $MC_GLOBAL_OPTIONS "$target"
+  else
+    find $target* -type f
+  fi
+}
+
+delete () {
+  local target=$1
+  local is_local=$2
+  if [ -z "$is_local" ]; then
+    mc rm $MC_GLOBAL_OPTIONS --recursive --force \
+      --older-than "${BACKUP_RETENTION_DAYS}d" \
+      "$target"
+  else
+    find $target* -delete -type f -mtime $BACKUP_RETENTION_DAYS
+  fi
+}
+
+prune () {
+  local target=$1
+  local is_local=$2
+  if [ ! -z "$BACKUP_PRUNING_PREFIX" ]; then
+    target="$target/${BACKUP_PRUNING_PREFIX}"
+  fi
+
+  rule_applies_to=$(probe_expired "$target" "$is_local" | wc -l)
   if [ "$rule_applies_to" == "0" ]; then
-    echo "No backups found older than the configured retention period of $BACKUP_RETENTION_DAYS days."
+    echo "No backups found older than the configured retention period of ${BACKUP_RETENTION_DAYS} days."
     echo "Doing nothing."
-    exit 0
+  else
+    total=$(probe_all "$target" "$is_local" | wc -l)
+
+    if [ "$rule_applies_to" == "$total" ]; then
+      echo "Using a retention of ${BACKUP_RETENTION_DAYS} days would prune all currently existing backups, will not continue."
+      echo "If this is what you want, please remove files manually instead of using this script."
+    else
+      delete "$target" "$is_local"
+      echo "Successfully pruned ${rule_applies_to} backups older than ${BACKUP_RETENTION_DAYS} days."
+    fi
   fi
-
-  total=$(mc ls $MC_GLOBAL_OPTIONS "$target" | wc -l)
-
-  if [ "$rule_applies_to" == "$total" ]; then
-    echo "Using a retention of ${BACKUP_RETENTION_DAYS} days would prune all currently existing backups, will not continue."
-    echo "If this is what you want, please remove files manually instead of using this script."
-    exit 1
-  fi
-
-  mc rm $MC_GLOBAL_OPTIONS \
-    --recursive --force \
-    --older-than "${BACKUP_RETENTION_DAYS}d" "$target"
-  echo "Successfully pruned ${rule_applies_to} backups older than ${BACKUP_RETENTION_DAYS} days."
 }
 
 if [ ! -z "$BACKUP_RETENTION_DAYS" ]; then
@@ -137,10 +167,10 @@ if [ ! -z "$BACKUP_RETENTION_DAYS" ]; then
   sleep "$BACKUP_PRUNING_LEEWAY"
   if [ ! -z "$AWS_S3_BUCKET_NAME" ]; then
     info "Pruning old backups from remote storage"
-    prune "backup-target/$bucket"
+    prune "backup-target/$AWS_S3_BUCKET_NAME"
   fi
   if [ -d "$BACKUP_ARCHIVE" ]; then
     info "Pruning old backups from local archive"
-    prune "$BACKUP_ARCHIVE"
+    prune "$BACKUP_ARCHIVE" "local"
   fi
 fi

src/entrypoint.sh

@@ -17,6 +17,7 @@ BACKUP_ARCHIVE="${BACKUP_ARCHIVE:-/archive}"
 
 BACKUP_RETENTION_DAYS="${BACKUP_RETENTION_DAYS:-}"
 BACKUP_PRUNING_LEEWAY="${BACKUP_PRUNING_LEEWAY:-10m}"
+BACKUP_PRUNING_PREFIX="${BACKUP_PRUNING_PREFIX:-}"
 BACKUP_STOP_CONTAINER_LABEL="${BACKUP_STOP_CONTAINER_LABEL:-true}"
 
 AWS_S3_BUCKET_NAME="${AWS_S3_BUCKET_NAME:-}"

test/compose/docker-compose.yml

@@ -25,6 +25,10 @@ services:
       AWS_S3_BUCKET_NAME: backup
       BACKUP_FILENAME: test.tar.gz
       BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_RETENTION_DAYS: ${BACKUP_RETENTION_DAYS:-7}
+      BACKUP_FORCE_PRUNE: ${BACKUP_FORCE_PRUNE:-}
+      BACKUP_PRUNING_LEEWAY: 5s
+      BACKUP_PRUNING_PREFIX: test
     volumes:
       - ./local:/archive
       - app_data:/backup/app_data:ro

test/compose/run.sh

@@ -29,4 +29,27 @@ fi
 
 echo "[TEST:PASS] All containers running post backup."
 
+docker-compose down
+
+# The second part of this test checks if backups get deleted when the retention
+# is set to 0 days (which it should not as it would mean all backups get deleted)
+# TODO: find out if we can test actual deletion without having to wait for a day
+BACKUP_RETENTION_DAYS="0" docker-compose up -d
+sleep 5
+
+docker-compose exec backup backup
+
+docker run --rm -it \
+  -v compose_backup_data:/data alpine \
+  ash -c '[ $(find /data/backup/ -type f | wc -l) = "1" ]'
+
+echo "[TEST:PASS] Remote backups have not been deleted."
+
+if [ "$(find ./local -type f | wc -l)" != "1" ]; then
+  echo "[TEST:FAIL] Backups should not have been deleted, instead seen:"
+  find ./local -type f
+fi
+
+echo "[TEST:PASS] Local backups have not been deleted."
+
 docker-compose down --volumes

test/swarm/docker-compose.yml

@@ -33,6 +33,8 @@ services:
       AWS_S3_BUCKET_NAME: backup
       BACKUP_FILENAME: test.tar.gz
       BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
+      BACKUP_RETENTION_DAYS: 7
+      BACKUP_PRUNING_LEEWAY: 5s
     volumes:
       - pg_data:/backup/pg_data:ro
       - /var/run/docker.sock:/var/run/docker.sock