Durability Profile Contract

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Bedrock.Durability provides a machine-checkable contract for evaluating and enforcing durability profile requirements.

For consolidated operator guidance across profile checks, S3 persistence, WAL boundaries, and migration sequencing, see guides/durability-foundation.md.

API

Checks

The profile currently evaluates:

  1. desired_replication_factor >= 3
  2. desired_logs >= 3
  3. coordinator persistence enabled (coordinator.persistent == true, or implied by a coordinator path when unset)
  4. persistent coordinator.path
  5. persistent log path
  6. persistent materializer path

Result Shape

profile/1 returns a %Bedrock.Durability.Profile{}:

  • status - :ok | :failed

  • checks - map of check name to %{status, expected, actual, reason}
  • reasons - list of failure reason atoms
  • evaluated_at_ms - evaluation timestamp

Enforcement

require/2 supports two modes:

  • :strict - returns {:error, {:durability_profile_failed, reasons}} when profile fails.
  • :relaxed - returns :ok even when profile fails.

This allows downstream adapters to fail fast in strict deployments while still supporting gradual rollout in relaxed mode.

Runtime Startup Enforcement

The internal cluster supervisor enforces this profile at startup:

  • :strict mode (default): raises and fails startup when checks fail.
  • :relaxed mode: logs warning and continues.
  • unsupported values resolve to :strict.

Mode configuration is additive:

  • top-level :durability_mode (:strict | :relaxed)

  • or durability: [mode: :strict | :relaxed]

Explicit development override:

config :bedrock, MyCluster,
  durability_mode: :relaxed

Desired sizing parameters can be provided via:

  • coordinator cluster config (parameters.desired_replication_factor, parameters.desired_logs)
  • or node config fallback (durability: [...]).

Telemetry Events

Profile evaluations emit one of:

  • [:bedrock, :durability, :profile, :ok]
  • [:bedrock, :durability, :profile, :failed]

Measurements:

  • failed_checks - number of failed checks

Metadata:

  • status - :ok | :failed

  • reasons - list of failure reason atoms

  • target_type - input type (:cluster_module | :node_config | :profile_input)

  • target_module - cluster module when applicable