JSON summaries

Every worker writes a structured per-run summary under /var/log after it finishes. They are intended for external monitoring without requiring a push gateway: scrape the file or have your webhook endpoint receive the same document.

Files are written via *.tmp + mv so a node-exporter / log forwarder scrape never sees a partial document.

Common fields (every worker)

Field	Type	Description
job	string	One of backup, check, prune, replicate, restore, snapshot-export.
hostname	string	Container hostname. Set explicitly in Compose / Kubernetes for stable labels.
release	string	${VERSION}-${restic_base} baked at build time, e.g. 2.2.2-0.18.1.
started_at	string	ISO 8601 in container TZ.
finished_at	string	ISO 8601 in container TZ.
started_epoch	integer	Unix epoch seconds at start.
finished_epoch	integer	Unix epoch seconds at finish.
duration_seconds	integer	Wall-clock duration.
exit_code	integer	Worker exit code. 0 = success.
repository	string	Masked Restic repository URL (mask_repository).

Per-worker schemas

last-backup.json

/bin/backup produces, in addition to the common fields:

Field	Type	Description
backup_root_dir	string	Value of BACKUP_ROOT_DIR at runtime.
restic_tag	string	The tag passed to restic backup.
snapshot_id	string | omitted	Short snapshot ID when restic produced one.
files_new	integer | omitted	Files added in this snapshot.
files_changed	integer | omitted	Files changed since the previous snapshot.
files_unmodified	integer | omitted	Files that were unchanged.
dirs_new / dirs_changed / dirs_unmodified	integer | omitted	Same for directories.
bytes_added	string | omitted	Bytes added, human-formatted (1.234 MiB).
bytes_stored	string | omitted	Bytes stored in this snapshot, human-formatted.

Numeric extras only appear when restic actually printed them. Failed backups before restic emitted its summary line will have only the common fields and exit_code.

{
  "job": "backup",
  "hostname": "backup-node",
  "release": "2.2.2-0.18.1",
  "started_at": "2026-05-11T02:00:00+0200",
  "finished_at": "2026-05-11T02:05:12+0200",
  "started_epoch": 1762828800,
  "finished_epoch": 1762829112,
  "duration_seconds": 312,
  "exit_code": 0,
  "repository": "s3:https://s3.example.com/***@bucket/restic",
  "backup_root_dir": "/data",
  "restic_tag": "backup-node-data",
  "snapshot_id": "a1b2c3d4",
  "files_new": 12,
  "files_changed": 4,
  "files_unmodified": 21034,
  "bytes_added": "1.234 MiB"
}

last-check.json

Common fields only. restic check does not emit headline metrics worth extracting; repository is the helpful one.

last-prune.json

Common fields only.

last-replicate.json

Field	Type	Description
replicate_jobs_processed	integer	Number of job rows parsed and dispatched.
replicate_jobs_failed	integer	Number that failed (counting recoveries).

{
  "job": "replicate",
  "hostname": "backup-node",
  "release": "2.2.2-0.18.1",
  "started_at": "2026-05-11T09:00:00+0200",
  "finished_at": "2026-05-11T09:11:23+0200",
  "duration_seconds": 683,
  "exit_code": 0,
  "replicate_jobs_processed": 3,
  "replicate_jobs_failed": 0
}

last-restore.json

Field	Type	Description
snapshot	string	Snapshot ID restored.
target	string	Restore target path.
dry_run	boolean	true when --dry-run was passed.
cancelled	boolean	true when the operator typed q/quit or hit Ctrl+C.
include_zero_match	boolean	true when --include matched 0 files/dirs.
files_restored	integer | omitted	From restic's Summary: line.
bytes_restored	string | omitted	Human-formatted bytes restored.
elapsed_human	string | omitted	Human-formatted restore duration (from restic, may differ slightly from duration_seconds).

Exit codes:

• 0 on success.
• 3 when include_zero_match=true.
• 130 when cancelled=true.

last-snapshot-export.json

Field	Type	Description
snapshot	string	Snapshot ID exported.
archive	string	Final archive path (or null when --dry-run).
work_dir	string	Temporary work directory used (auto-generated or operator-supplied).
dry_run	boolean	true when --dry-run was passed.
include_zero_match	boolean	true when --include matched 0 files/dirs.
archive_size_bytes	integer | omitted	Size of the archive on disk; only when not --dry-run.
files_restored / bytes_restored / elapsed_human	–	Same as restore.

{
  "job": "snapshot-export",
  "hostname": "backup-node",
  "release": "2.2.2-0.18.1",
  "started_at": "2026-05-11T15:30:00+0200",
  "finished_at": "2026-05-11T15:31:12+0200",
  "duration_seconds": 72,
  "exit_code": 0,
  "repository": "rclone:jottacloud:backups",
  "snapshot": "5a3f2c8b",
  "archive": "/restore/snapshot-export-5a3f2c8b-20260511-153000.tar.gz",
  "archive_size_bytes": 595132416,
  "work_dir": "/tmp/snapshot-export.pFKmAM",
  "dry_run": false,
  "include_zero_match": false,
  "files_restored": 4523,
  "bytes_restored": "567.89 MiB",
  "elapsed_human": "1m12s"
}

Reading the files

docker exec restic-backup-helper cat /var/log/last-backup.json
docker exec restic-backup-helper cat /var/log/last-backup.json | jq '.duration_seconds, .files_new, .bytes_added'

The file is also POSTed to WEBHOOK_URL when set — see Webhooks.

Stability promise

Field names and types are part of the public API surface; we treat changes the same way we treat env-var changes:

• Adding new fields is a MINOR bump.
• Renaming or removing a field is a MAJOR bump.

So a parser written today will still work for the entire 2.x lifecycle.