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esh-pfi-infrastructure/configs/restic/esh-vm-db/README.md
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vh a5691ce796 restic(esh-vm-db): a backup that exited 0 nightly while keeping an April dump
Work by a parallel session on 2026-09-12; committed here with the rest of the
day's changes. Rationale in persistent-memory.d/2026-09-12-esh-vm-db-restic-repair.md.

The only visible symptom was a systemd-failed unit from a Sep 6 repository
network timeout after boot. The real fault was quieter and much worse: the
pre-backup hook logged failures as WARN and returned zero, so pg_dumpall could
fail every single night -- it used TCP localhost and wanted a password nobody
supplied -- while restic dutifully backed up the stale April 23 dump still
sitting in the staging directory and reported success. Mongo was fine, which
is part of why it went unnoticed.

Postgres now dumps over the /var/run/postgresql socket with peer auth and -w,
and both database failures now fail the backup rather than masking it, while
still preserving any prior per-DB dump rather than truncating to nothing. An
ERRORS counter replaces the warn-and-continue path, and the staging directory
is overridable via RESTIC_STAGE_DIR so the new test can exercise it.

Adds backup.contract.md, retry.conf and test_pre_backup.py -- three red-green
regression tests covering the failure modes above. systemd drop-ins on both
jobs add network-online ordering plus Restart=on-failure with a 5m delay and a
3-per-hour limit, which addresses the original boot-timeout symptom.

Verified against a real run: snapshot bc5eeaff at 07:01 PDT with a fresh 3.46MB
PG dump, retrieved from the repository with decompression and completion marker
checked (not a full restore). Repository check passed, 99 snapshots. The old
hook and stale dump are preserved root-only at /var/lib/restic/repair-20260912.
2026-09-12 22:12:24 -07:00

7.5 KiB

restic / esh-vm-db

Two-database host at the ESH site (PostgreSQL 15 + MongoDB). Covered at the VM-image layer by PBS-ANA via esh-pve (or whichever ESH hypervisor owns this VM — confirm on next inventory pass). This restic profile adds DB-level granularity via pre-backup dumps.

What's backed up

Path Purpose
/etc Host config — systemd, ssh, chrony, apt, pg_hba.conf, mongod.conf
/root Root's ad-hoc scripts, shell history, ssh keys
/home User homes (lkraven + any DB-admin locals)
/var/lib/restic/stage pg_dumpall.sql.gz + mongodump/ produced by pre-backup.sh

What's not backed up (by design)

  • /var/lib/postgresql — raw PGDATA. Live-capture risk; pg_dumpall in pre-backup covers it consistently.
  • /var/lib/mongodb — raw mongo dbPath. Same reasoning; mongodump covers it.
  • NFS mount /mnt/backup (from esh-nas — not ours to mirror).

Pre-backup hook

pre-backup.sh runs as root before restic. It:

  1. Checks pg_isready on :5432 — if OK, runs pg_dumpall piped through gzip to $STAGE/pg_dumpall.sql.gz
  2. Checks mongo ping via mongosh — if OK, runs mongodump into $STAGE/mongodump/

PostgreSQL uses the local Unix socket and peer authentication as postgres, not TCP localhost. Dumps are staged before replacement. If either DB dump fails, the hook returns nonzero and aborts the backup, preserving that DB's previous dump. The two databases are not a single transactional snapshot. RESTIC_STAGE_DIR supports isolated regression tests.

Repair verified 2026-09-12

Weekly check failed September 6 on a repository connection timeout after boot. Nightly backup returned success despite PostgreSQL TCP authentication failures, reusing a dump last modified April 23. Fixed socket authentication, propagated both DB failures, and added network-online ordering plus bounded retries to both services (5-minute delay, maximum 3 starts per hour).

Deploy with playbooks/esh-vm-db-restic-repair.yaml. Service drop-ins survive regeneration of resticprofile's main units. Previous hook and PG dump retained under /var/lib/restic/repair-20260912/ (root-only).

Fresh snapshot bc5eeaff at 07:01 PDT contains today's 3,460,215-byte compressed PG dump. Retrieved FROM repository, decompressed successfully, and verified its cluster-dump completion marker. This is not a full database restore test. Mongo dump also completed. Weekly check rerun at 07:02 passed: 99 snapshots, configured 10% data sample (19 packs), no errors. Both jobs Result=success, no failed systemd units, timers active, PostgreSQL/MongoDB remain active. Inactive/dead between scheduled runs is normal for these finite jobs.

Tests: python3 configs/restic/esh-vm-db/test_pre_backup.py — three passing regressions for successful peer-auth dump and preservation/failure propagation for each database. No DB authentication policy or service restarts changed.

Deploy (one-time)

1. Create rest-server-ana htpasswd entry

Do NOT use sudo for .htpasswd writes on ana-docker. The file is NFS-mounted from ana-nas and owned by uid 1000 (the rest-server user, which equals lkraven). Sudo-root on the client gets squashed to nobody on the NFS server and can't read/write the file. lkraven writes it natively, using the docker group for the bcrypt helper.

# Pick password in password manager first
HTPW='<new-pw-saved-to-pw-manager>'

ssh -t ana-docker "docker run --rm httpd:2.4-alpine htpasswd -nbB esh-vm-db '$HTPW' | \
                   tee /tmp/htline.txt > /dev/null && \
                   sed -i '/^esh-vm-db:/d' /mnt/backup/restic/repo/ana/.htpasswd && \
                   cat /tmp/htline.txt >> /mnt/backup/restic/repo/ana/.htpasswd && \
                   rm /tmp/htline.txt && \
                   grep ^esh-vm-db: /mnt/backup/restic/repo/ana/.htpasswd && \
                   docker restart rest-server"
unset HTPW

2. Install secrets on esh-vm-db

ssh -t esh-vm-db 'sudo install -d -o root -g root -m 0700 /etc/restic /var/lib/restic /var/lib/restic/stage'

# restic.env — URL-encode the password if it has special chars
ssh -t esh-vm-db "sudo bash -c '
  read -sp \"htpasswd pw for rest-server-ana: \" HTPW; echo
  cat > /etc/restic/restic.env <<EOF
RESTIC_REPOSITORY=rest:http://esh-vm-db:\$HTPW@10.250.50.70:8000/esh-vm-db/
EOF
  chmod 600 /etc/restic/restic.env
'"

# Repo passphrase (prints once — save to password manager)
ssh -t esh-vm-db 'sudo bash -c "
  openssl rand -base64 48 | tr -d \"\\n\" > /etc/restic/password
  chmod 600 /etc/restic/password
  echo === SAVE THIS TO PASSWORD MANAGER NOW ===
  cat /etc/restic/password
  echo
"'

3. Initialize the repo

ssh -t esh-vm-db 'sudo bash -c "
  set -a; . /etc/restic/restic.env; set +a
  RESTIC_PASSWORD_FILE=/etc/restic/password restic init
"'

4. Install prerequisites (restic, resticprofile, mongosh client)

ssh -t esh-vm-db 'which restic || sudo apt-get install -y restic; \
                  which mongosh || echo "NOTE: mongosh not found; pre-backup mongo ping will fail safely — install via MongoDB APT repo if needed"; \
                  curl -sfL https://raw.githubusercontent.com/creativeprojects/resticprofile/master/install.sh | sudo sh -s -- -b /usr/local/bin; \
                  /usr/local/bin/resticprofile --version'

5. Deploy profile + hook

scp configs/restic/esh-vm-db/profiles.yaml esh-vm-db:/tmp/
scp configs/restic/esh-vm-db/pre-backup.sh esh-vm-db:/tmp/

ssh -t esh-vm-db 'sudo install -o root -g root -m 0644 /tmp/profiles.yaml /etc/restic/profiles.yaml && \
                  sudo install -o root -g root -m 0755 /tmp/pre-backup.sh /etc/restic/pre-backup.sh && \
                  rm /tmp/profiles.yaml /tmp/pre-backup.sh'

6. Schedule + verify

ssh -t esh-vm-db 'sudo resticprofile --config /etc/restic/profiles.yaml schedule --all && \
                  systemctl list-timers "resticprofile*" --no-pager'

# First manual run
ssh -t esh-vm-db 'sudo resticprofile --config /etc/restic/profiles.yaml backup --verbose'

Expect first run to land ~50-200 MB (mostly the mongodump directory + pg_dumpall). Cross-check from Backrest UI on ana-docker.

Restore

Full host config

ssh -t esh-vm-db 'sudo resticprofile --config /etc/restic/profiles.yaml restore latest --target /tmp/restore --path /etc'

Just the PG dump

ssh -t esh-vm-db 'sudo resticprofile --config /etc/restic/profiles.yaml restore latest --target /tmp/restore --path /var/lib/restic/stage/pg_dumpall.sql.gz'
# Then: gunzip + psql < pg_dumpall.sql

Just a mongo DB

ssh -t esh-vm-db 'sudo resticprofile --config /etc/restic/profiles.yaml restore latest --target /tmp/restore --path /var/lib/restic/stage/mongodump'
# Then: mongorestore /tmp/restore/var/lib/restic/stage/mongodump/

Gotchas

  • mongosh must be installed or the mongo pre-backup step silently skips (logged as WARN). Install from the MongoDB APT repo if not already present — the stock Debian mongodb-clients package is out of date and doesn't include mongosh.
  • Mongo authentication — if mongod ever gets auth enabled (it's currently open to 0.0.0.0 with no auth, which is its own concern), mongodump will need --username/--password flags. Reference in pre-backup.sh when that change happens.
  • pg_hba.conf — pg_dumpall requires local postgres superuser access. Currently works via sudo -u postgres + peer auth on the local socket. If pg_hba.conf ever changes peer → md5 for local, the hook needs a ~postgres/.pgpass entry.