Allow multiple schedules in the same container (#78)

* Allow mounting of config directory for multiple schedules

* Add docs for conf.d feature

* Fix behavior on multiple files

* Define default case first in entrypoint script

README.md

@@ -28,6 +28,7 @@ It handles __recurring or one-off backups of Docker volumes__ to a __local direc
   - [Manually triggering a backup](#manually-triggering-a-backup)
   - [Update deprecated email configuration](#update-deprecated-email-configuration)
   - [Using a custom Docker host](#using-a-custom-docker-host)
+  - [Run multiple backup schedules in the same container](#run-multiple-backup-schedules-in-the-same-container)
 - [Recipes](#recipes)
   - [Backing up to AWS S3](#backing-up-to-aws-s3)
   - [Backing up to Filebase](#backing-up-to-filebase)
@@ -653,6 +654,32 @@ DOCKER_HOST=tcp://docker_socket_proxy:2375
 
 In case you are using a socket proxy, it must support `GET` and `POST` requests to the `/containers` endpoint. If you are using Docker Swarm, it must also support the `/services` endpoint. If you are using pre/post backup commands, it must also support the `/exec` endpoint.
 
+### Run multiple backup schedules in the same container
+
+Multiple backup schedules with different configuration can be configured by mounting an arbitrary number of configuration files (using the `.env` format) into `/etc/dockervolumebackup/conf.d`:
+
+```
+version: '3'
+
+services:
+  # ... define other services using the `data` volume here
+  backup:
+    image: offen/docker-volume-backup:latest
+    volumes:
+      - data:/backup/my-app-backup:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+      - ./configuration:/etc/dockervolumebackup/conf.d
+
+volumes:
+  data:
+```
+
+A separate cronjob will be created for each config file.
+If a configuration value is set both in the global environment as well as in the config file, the config file will take precedence.
+The `backup` command expects to run on an exclusive lock, so it is your responsibility to make sure the invocations do not overlap.
+In case you need your schedules to overlap, you need to create a dedicated container for each schedule instead.
+When changing the configuration, you currently need to manually restart the container for the changes to take effect.
+
 ## Recipes
 
 This section lists configuration for some real-world use cases that you can mix and match according to your needs.

entrypoint.sh

@@ -5,10 +5,21 @@
 
 set -e
 
+if [ ! -d "/etc/dockervolumebackup/conf.d" ]; then
   BACKUP_CRON_EXPRESSION="${BACKUP_CRON_EXPRESSION:-@daily}"
 
   echo "Installing cron.d entry with expression $BACKUP_CRON_EXPRESSION."
   echo "$BACKUP_CRON_EXPRESSION backup 2>&1" | crontab -
+else
+  echo "/etc/dockervolumebackup/conf.d was found, using configuration files from this directory."
+
+  for file in /etc/dockervolumebackup/conf.d/*; do
+    source $file
+    BACKUP_CRON_EXPRESSION="${BACKUP_CRON_EXPRESSION:-@daily}"
+    echo "Appending cron.d entry with expression $BACKUP_CRON_EXPRESSION and configuration file $file"
+    (crontab -l; echo "$BACKUP_CRON_EXPRESSION /bin/sh -c 'set -a; source $file; set +a && backup' 2>&1") | crontab -
+  done
+fi
 
 echo "Starting cron in foreground."
 crond -f -l 8

test/compose/docker-compose.yml

@@ -21,7 +21,7 @@ services:
     volumes:
       - webdav_backup_data:/var/lib/dav
 
-  backup: &default_backup_service
+  backup:
     image: offen/docker-volume-backup:${TEST_VERSION:-canary}
     hostname: hostnametoken
     depends_on:

test/confd/.gitignore

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

test/confd/backup.env

@@ -0,0 +1,2 @@
+BACKUP_FILENAME="conf.tar.gz"
+BACKUP_CRON_EXPRESSION="*/1 * * * *"

test/confd/docker-compose.yml

@@ -0,0 +1,22 @@
+version: '3'
+
+services:
+  backup:
+    image: offen/docker-volume-backup:${TEST_VERSION:-canary}
+    restart: always
+    volumes:
+      - ./local:/archive
+      - app_data:/backup/app_data:ro
+      - ./backup.env:/etc/dockervolumebackup/conf.d/00backup.env
+      - ./never.env:/etc/dockervolumebackup/conf.d/10never.env
+      - /var/run/docker.sock:/var/run/docker.sock
+
+  offen:
+    image: offen/offen:latest
+    labels:
+      - docker-volume-backup.stop-during-backup=true
+    volumes:
+      - app_data:/var/opt/offen
+
+volumes:
+  app_data:

test/confd/never.env

@@ -0,0 +1,2 @@
+BACKUP_FILENAME="never.tar.gz"
+BACKUP_CRON_EXPRESSION="0 0 5 31 2 ?"

test/confd/run.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+
+set -e
+
+cd $(dirname $0)
+
+mkdir -p local
+
+docker-compose up -d
+
+# sleep until a backup is guaranteed to have happened on the 1 minute schedule
+sleep 100
+
+docker-compose down --volumes
+
+if [ ! -f ./local/conf.tar.gz ]; then
+  echo "[TEST:FAIL] Config from file was not used."
+  exit 1
+fi
+echo "[TEST:PASS] Config from file was used."
+
+if [ -f ./local/never.tar.gz ]; then
+  echo "[TEST:FAIL] Unexpected file was found."
+  exit 1
+fi
+echo "[TEST:PASS] Unexpected cron did not run."