Fix: send failure notifications for config init errors

[le-lenn]

What?

Fixes #696

How I tested this

1. create notification-docker-compose.yml

services:
  gotify:
    image: gotify/server:latest
    ports:
      - "8080:80"
    environment:
      - GOTIFY_DEFAULTUSER_PASS=custom
    volumes:
      - gotify_data:/app/data

  backup:
    build: .
    entrypoint: ["/usr/bin/backup"]
    depends_on:
      - gotify
    environment:
      BACKUP_FILENAME: test.tar.gz
      NOTIFICATION_LEVEL: error
      NOTIFICATION_URLS: gotify://gotify/${GOTIFY_TOKEN}?disableTLS=true
      AWS_S3_BUCKET_NAME: missing-bucket
      AWS_ACCESS_KEY_ID_FILE: /tmp/missing
      AWS_SECRET_ACCESS_KEY_FILE: /tmp/missing
    volumes:
      - backup_data:/backup:ro
      - backup_archive:/archive

volumes:
  backup_data:
  backup_archive:
  gotify_data:

2. Start Gotify:
   • docker compose -f notification-docker-compose.yml up -d gotify
3. Create a Gotify token:
   • TOKEN=$(curl -sSLX POST -H 'Content-Type: application/json' -d '{"name":"test"}' http://admin:custom@localhost:8080/application | jq -r
     '.token')
4. Run the failing backup with notifications:
   • GOTIFY_TOKEN=$TOKEN docker compose -f notification-docker-compose.yml up --build --exit-code-from backup backup
5. Verify a message arrived:
   • curl -sSL http://admin:custom@localhost:8080/message | jq -r '.messages'

Should look like this:

[
  {
    "id": 1,
    "appid": 2,
    "message": "Running docker-volume-backup failed with error: main.(*script).init: error creating s3 storage backend: s3.NewStorageBackend: AWS_S3_BUCKET_NAME is defined, but no credentials were provided\n\nLog output of the failed run was:\n\n",
    "title": "Failure running docker-volume-backup at 2025-12-21T17:39:28Z",
    "priority": 0,
    "date": "2025-12-21T17:39:28.49883576Z"
  }
]

[le-lenn]

Tests ran locally without errors. Although I had to change a bunch of stuff because of being on a mac and having differing docker desktop setting:

diff --git a/test/docker-compose.yml b/test/docker-compose.yml
index eb4445b..b8f23ca 100644
--- a/test/docker-compose.yml
+++ b/test/docker-compose.yml
@@ -3,6 +3,8 @@ services:
     hostname: manager
     privileged: true
     image: offen/docker-volume-backup:test-sandbox
+    environment:
+      DOCKER_CONFIG: /tmp/docker-config
     healthcheck:
       test: ["CMD", "docker", "info"]
       interval: 1s
@@ -10,7 +12,7 @@ services:
       retries: 50
     volumes:
       - ./:/code
-      - ${HOME}/.docker/config.json:/root/.docker/config.json
+      - docker_config:/tmp/docker-config
       - ${TARBALL:-.}:/cache/image.tar.gz
       - docker_volume_backup_test_sandbox_image:/var/lib/docker/image
       - docker_volume_backup_test_sandbox_containerd:/var/lib/docker/containerd
@@ -20,7 +22,7 @@ services:
     hostname: worker1
     volumes:
       - ./:/code
-      - ${HOME}/.docker/config.json:/root/.docker/config.json
+      - docker_config:/tmp/docker-config
       - ${TARBALL:-.}:/cache/image.tar.gz
       - docker_volume_backup_test_sandbox_image:/var/lib/docker/image
       - docker_volume_backup_test_sandbox_containerd_1:/var/lib/docker/containerd
@@ -31,7 +33,7 @@ services:
     hostname: worker2
     volumes:
       - ./:/code
-      - ${HOME}/.docker/config.json:/root/.docker/config.json
+      - docker_config:/tmp/docker-config
       - ${TARBALL:-.}:/cache/image.tar.gz
       - docker_volume_backup_test_sandbox_image:/var/lib/docker/image
       - docker_volume_backup_test_sandbox_containerd_2:/var/lib/docker/containerd
@@ -43,3 +45,4 @@ volumes:
   docker_volume_backup_test_sandbox_containerd:
   docker_volume_backup_test_sandbox_containerd_1:
   docker_volume_backup_test_sandbox_containerd_2:
+  docker_config:
diff --git a/test/test.sh b/test/test.sh
index c695326..208c7db 100755
--- a/test/test.sh
+++ b/test/test.sh
@@ -29,7 +29,7 @@ if [ ! -z "$MATCH_PATTERN" ]; then
   find_args="$find_args -name $MATCH_PATTERN"
 fi
 
-for dir in $(find $find_args | sort); do
+for dir in $(gfind $find_args | sort); do
   dir=$(echo $dir | cut -c 3-)
   echo "################################################"
   echo "Now running ${dir}"
@@ -58,7 +58,7 @@ for dir in $(find $find_args | sort); do
     docker exec $svc /bin/sh -c "docker load -i /cache/image.tar.gz"
   done
 
-  for executable in $(find $dir -type f -executable | sort); do
+  for executable in $(gfind $dir -type f -executable | sort); do
     context="manager"
     if [ -f "$executable.context" ]; then
         context=$(cat "$executable.context")

[m90]

I went through the commit history and it seems the deadlock I remembered is gone for a while now (and I missed that it's now possible to do what this PR does). One of your changes made me find a slight inconsistency in error handling in runScript which I fixed on your branch.

Once this is green, it's ready to go, thanks for fixing.

[le-lenn]

Thanks for creating the “offen” collective. I like the concept!