App Hash contagion

[julienrbrt]

If any consumer chain is nondeterministic, it will affect other chains. The whole system (provider and other consumer chains) could become unstable or even halt.

[Pantani]

WDYT about implementing a quarantine mechanism?

We can create a health track inside modules/provider.go

• Track each consumer chains success/failure
• Monitor AppHash across the blocks
• Maintain health status: HEALTHY, DEGRADED, QUARANTINED

automatically isolate and quarantine the chain inside the abci/multiplexer.go

• After N consecutive failures (configurable, default: 3), quarantine the chain
• Exclude quarantined chains from AppHash aggregation
• Skip transactions for quarantined chains (return error to users)
• Continue processing healthy chains normally

and the fallback/recovery mechanism inside modules/provider.go

• Governance message to manually reset chain health after fixes
• Automatic quarantine expiry (configurable, default: 100 blocks) triggers a review event
• Emit events for monitoring/alerting

[julienrbrt]

Yes, that is exactly why we will track app hashes in the new ABCI call.