allow local storage of backups

README.md

@@ -1,8 +1,8 @@
 # docker-volume-backup
 
-Backup Docker volumes to any S3 compatible storage.
+Backup Docker volumes locally or to any S3 compatible storage.
 
-The [offen/docker-volume-backup](https://hub.docker.com/r/offen/docker-volume-backup) Docker image can be used as a sidecar container to an existing Docker setup. It handles recurring backups of Docker volumes to any S3 compatible storage and rotates away old backups if configured.
+The [offen/docker-volume-backup](https://hub.docker.com/r/offen/docker-volume-backup) Docker image can be used as a sidecar container to an existing Docker setup. It handles recurring backups of Docker volumes to a local directory or any S3 compatible storage (or both) and rotates away old backups if configured.
 
 ## Configuration
 
@@ -30,15 +30,33 @@ AWS_S3_BUCKET_NAME="<xxx>"
 # This is the FQDN of your storage server, e.g. `storage.example.com`.
 # Do not set this when working against AWS S3. If you need to set a
 # specific protocol, you will need to use the option below.
+
 # AWS_ENDPOINT="<xxx>"
 
 # The protocol to be used when communicating with your storage server.
 # Defaults to "https". You can set this to "http" when communicating with
 # a different Docker container on the same host for example.
+
 # AWS_ENDPOINT_PROTO="https"
 
+# In addition to backing up you can also store backups locally. Pass in
+# a local path to store your backups here if needed. You likely want to
+# mount a local folder or Docker volume into that location when running
+# the container. Local paths can also be subject to pruning of old
+# backups as defined below.
+
+# BACKUP_ARCHIVE="/archive"
+
 ########### BACKUP PRUNING
 
+# **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**,
+# 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.
+
 # Define this value to enable automatic pruning of old backups. The value
 # declares the number of days for which a backup is kept.
 
@@ -108,6 +126,10 @@ services:
       # to stop the container
       - /var/run/docker.sock:/var/run/docker.sock:ro
       - data:/backup/my-app-backup:ro
+      # If you mount a local directory or volume to `/archive` a local
+      # copy of the backup will be stored there. You can override the
+      # location inside of the container by setting `BACKUP_ARCHIVE`
+      # - /path/to/local_backups:/archive
 volumes:
   data:
 ```

src/backup.sh

@@ -77,13 +77,24 @@ if [ "$CONTAINERS_TO_STOP_TOTAL" != "0" ]; then
   fi
 fi
 
+copy_backup () {
+  mc cp $MC_GLOBAL_OPTIONS "$BACKUP_FILENAME" "$1"
+}
+
 if [ ! -z "$AWS_S3_BUCKET_NAME" ]; then
   info "Uploading backup to remote storage"
   echo "Will upload to bucket \"$AWS_S3_BUCKET_NAME\"."
-  mc cp $MC_GLOBAL_OPTIONS "$BACKUP_FILENAME" "backup-target/$AWS_S3_BUCKET_NAME"
+  copy_backup "backup-target/$AWS_S3_BUCKET_NAME"
   echo "Upload finished."
 fi
 
+if [ -d "$BACKUP_ARCHIVE" ]; then
+  info "Copying backup to local archive"
+  echo "Will copy to \"$BACKUP_ARCHIVE\"."
+  copy_backup "$BACKUP_ARCHIVE"
+  echo "Finished copying."
+fi
+
 if [ -f "$BACKUP_FILENAME" ]; then
   info "Cleaning up"
   rm -vf "$BACKUP_FILENAME"
@@ -92,16 +103,12 @@ fi
 info "Backup finished"
 echo "Will wait for next scheduled backup."
 
-if [ ! -z "$BACKUP_RETENTION_DAYS" ]; then
-  info "Pruning old backups"
-  echo "Sleeping ${BACKUP_PRUNING_LEEWAY} before checking eligibility."
-  sleep "$BACKUP_PRUNING_LEEWAY"
-  bucket=$AWS_S3_BUCKET_NAME
-
+prune () {
+  target=$1
   rule_applies_to=$(
-    mc rm $MC_GLOBAL_OPTIONS --fake --recursive -force \
+    mc rm $MC_GLOBAL_OPTIONS --fake --recursive --force \
       --older-than "${BACKUP_RETENTION_DAYS}d" \
-      "backup-target/$bucket" \
+      "$target" \
       | wc -l
   )
   if [ "$rule_applies_to" == "0" ]; then
@@ -110,7 +117,7 @@ if [ ! -z "$BACKUP_RETENTION_DAYS" ]; then
     exit 0
   fi
 
-  total=$(mc ls $MC_GLOBAL_OPTIONS "backup-target/$bucket" | wc -l)
+  total=$(mc ls $MC_GLOBAL_OPTIONS "$target" | wc -l)
 
   if [ "$rule_applies_to" == "$total" ]; then
     echo "Using a retention of ${BACKUP_RETENTION_DAYS} days would prune all currently existing backups, will not continue."
@@ -119,7 +126,21 @@ if [ ! -z "$BACKUP_RETENTION_DAYS" ]; then
   fi
 
   mc rm $MC_GLOBAL_OPTIONS \
-    --recursive -force \
-    --older-than "${BACKUP_RETENTION_DAYS}d" "backup-target/$bucket"
+    --recursive --force \
+    --older-than "${BACKUP_RETENTION_DAYS}d" "$target"
   echo "Successfully pruned ${rule_applies_to} backups older than ${BACKUP_RETENTION_DAYS} days."
+}
+
+if [ ! -z "$BACKUP_RETENTION_DAYS" ]; then
+  info "Pruning old backups"
+  echo "Sleeping ${BACKUP_PRUNING_LEEWAY} before checking eligibility."
+  sleep "$BACKUP_PRUNING_LEEWAY"
+  if [ ! -z "$AWS_S3_BUCKET_NAME" ]; then
+    info "Pruning old backups from remote storage"
+    prune "backup-target/$bucket"
+  fi
+  if [ -d "$BACKUP_ARCHIVE" ]; then
+    info "Pruning old backups from local archive"
+    prune "$BACKUP_ARCHIVE"
+  fi
 fi

src/entrypoint.sh

@@ -12,10 +12,12 @@ set -e
 cat <<EOF > env.sh
 BACKUP_SOURCES="${BACKUP_SOURCES:-/backup}"
 BACKUP_CRON_EXPRESSION="${BACKUP_CRON_EXPRESSION:-@daily}"
-BACKUP_FILENAME=${BACKUP_FILENAME:-"backup-%Y-%m-%dT%H-%M-%S.tar.gz"}
+BACKUP_FILENAME="${BACKUP_FILENAME:-backup-%Y-%m-%dT%H-%M-%S.tar.gz}"
+BACKUP_ARCHIVE="${BACKUP_ARCHIVE:-/archive}"
 
 BACKUP_RETENTION_DAYS="${BACKUP_RETENTION_DAYS:-}"
 BACKUP_PRUNING_LEEWAY="${BACKUP_PRUNING_LEEWAY:-10m}"
+BACKUP_STOP_CONTAINER_LABEL="${BACKUP_STOP_CONTAINER_LABEL:-true}"
 
 AWS_S3_BUCKET_NAME="${AWS_S3_BUCKET_NAME:-}"
 AWS_ENDPOINT="${AWS_ENDPOINT:-s3.amazonaws.com}"
@@ -23,14 +25,16 @@ AWS_ENDPOINT_PROTO="${AWS_ENDPOINT_PROTO:-https}"
 
 GPG_PASSPHRASE="${GPG_PASSPHRASE:-}"
 
-BACKUP_STOP_CONTAINER_LABEL="${BACKUP_STOP_CONTAINER_LABEL:-true}"
-
 MC_GLOBAL_OPTIONS="${MC_GLOBAL_OPTIONS:-}"
 EOF
 chmod a+x env.sh
 source env.sh
 
-mc $MC_GLOBAL_OPTIONS alias set backup-target "$AWS_ENDPOINT_PROTO://$AWS_ENDPOINT" "$AWS_ACCESS_KEY_ID" "$AWS_SECRET_ACCESS_KEY"
+if [ ! -z "$AWS_ACCESS_KEY_ID" ] && [ ! -z "$AWS_SECRET_ACCESS_KEY" ]; then
+  mc $MC_GLOBAL_OPTIONS alias set backup-target \
+    "$AWS_ENDPOINT_PROTO://$AWS_ENDPOINT" \
+    "$AWS_ACCESS_KEY_ID" "$AWS_SECRET_ACCESS_KEY"
+fi
 
 # Add our cron entry, and direct stdout & stderr to Docker commands stdout
 echo "Installing cron.d entry with expression $BACKUP_CRON_EXPRESSION."

test/compose/.gitignore

@@ -0,0 +1 @@
+local

test/compose/docker-compose.yml

@@ -26,6 +26,7 @@ services:
       BACKUP_FILENAME: test.tar.gz
       BACKUP_CRON_EXPRESSION: 0 0 5 31 2 ?
     volumes:
+      - ./local:/archive
       - app_data:/backup/app_data:ro
       - /var/run/docker.sock:/var/run/docker.sock
 

test/compose/run.sh

@@ -4,6 +4,8 @@ set -e
 
 cd $(dirname $0)
 
+mkdir -p local
+
 docker-compose up -d
 sleep 5
 
@@ -13,7 +15,11 @@ docker run --rm -it \
   -v compose_backup_data:/data alpine \
   ash -c 'tar -xf /data/backup/test.tar.gz && test -f /backup/app_data/offen.db'
 
-echo "[TEST:PASS] Found relevant files in untared backup."
+echo "[TEST:PASS] Found relevant files in untared remote backup."
+
+tar -xf ./local/test.tar.gz -C /tmp && test -f /tmp/backup/app_data/offen.db
+
+echo "[TEST:PASS] Found relevant files in untared local backup."
 
 if [ "$(docker-compose ps -q | wc -l)" != "3" ]; then
   echo "[TEST:FAIL] Expected all containers to be running post backup, instead seen:"