[inf-1oop]

main currently ships a validator that cannot start

#26 set PRYSM_VERSION=v7.1.8, but the validator command still passes --db-backup-output-dir, which Prysm removed in v7:

Incorrect Usage: flag provided but not defined: -db-backup-output-dir

The container then crash-loops. This is not latent — it affects anyone who pulls main and starts a validator today. I hit it for real upgrading contango-validator-1, where it cost ~2.5 minutes of missed duties.

Reproduced against gcr.io/prysmaticlabs/prysm/validator:v7.1.8 with the exact flag set main renders:

flag set	result on v7.1.8
main today	Incorrect Usage: flag provided but not defined: -db-backup-output-dir
this PR	INFO main: Prysm Validator started version=Prysm/v7.1.8/51b5a75...

Three fixes, all in docker-compose.yml

1. Drop the two dead backup flags

--db-backup-output-dir is gone in v7. --enable-db-backup-webhook goes with it — v7 keeps it only in config/features/deprecated_flags.go as a hidden no-op, so it logs is deprecated and has no effect on every start and does nothing.

2. validator-backup actually backs something up

The service POSTs to the validator's /db/backup webhook — which is precisely what the deprecated flag used to enable. The call returns success while backing up nothing.

That matters more than a normal dead feature: the README tells operators to run it before upgrading, and slashing protection history lives in that database. A backup step that silently no-ops is worse than no backup step, because it buys false confidence before the one operation where you need the file.

It now runs slashing-protection-history export, which writes the standard EIP-3076 file that any client can import.

One constraint, spelled out in a comment in the file: it must run with the validator stopped, because validator.db is a bolt database with a single-writer lock.

docker compose stop validator
docker compose --profile backup run --rm validator-backup
docker compose --profile node --profile validator --profile init up -d validator

3. Restart policy for geth, beacon, validator

Only stats and caddy used the x-restart anchor. Without it, an OOM kill or crash stops attesting until a human notices — an operator fleet has already hit this, with a geth OOM-killed during an archive sync sitting dead for two days while the node still reported "up".

Verification

• main's rendered flag set fails immediately on v7.1.8 with the error above
• this PR's flag set reaches Prysm Validator started
• validator slashing-protection-history export exists in v7.1.8 and accepts --slashing-protection-export-dir
• docker compose config clean across the node, validator, init and backup profiles
• the running upgrade on contango-validator-1 (canonical validator v7.1.8 + v7.1.8-vega.1 beacon) has been performing all duties — attestations, aggregates, sync committee messages and contributions, and block proposals — for 4+ hours

Deliberately not in this PR

These came out of the same upgrade but need testing rather than review, so they belong to the validator rollout session:

• --enable-doppelganger is absent from the repo. It is a real anti-double-signing control and operators are hand-rolling it in overrides. Shipping it costs ~2 epochs of missed attestations per start, which deserves a deliberate decision.
• The override trap. Compose replaces command: rather than merging, so an operator override restating the validator command silently bypasses every future fix here — fix: point the validator REST endpoint at the beacon HTTP port #28's REST fix was in the repo and inert on the node for exactly this reason. Fixes 3 (and doppelganger) reduce the reason to keep an override at all; the README should also state the rule.
• v5→v7 renamed log strings (Submitted new sync message → Submitted sync committee messages). Any alerting that greps validator logs goes quiet and looks healthy. This fooled my own checks twice.
• No rollback path. A v7→v5 validator downgrade is unsupported and untested.

🤖 Generated with Claude Code

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