plugin-contract-guard

Development

Invariants and change procedure for the target-plugin / extension system — plugin manifests, admin plugin/extension catalog and instance APIs, secret redaction, external-plugin install policy. Use when editing crates/targets (manifest, plugin, control_plane, catalog, runtime), crates/extension-schema, or rustfs/src/admin plugin_contract.rs / plugins_*.rs / extensions.rs / target_descriptor.rs.

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Plugin & Extension Contract Guard

The "plugin system" spans four surfaces that must stay consistent:

Surface	Location
Manifests & registry	`crates/targets/src/{manifest,plugin}.rs`
Install/enable planning (control plane)	`crates/targets/src/control_plane.rs`
Extension schemas	`crates/extension-schema/src/lib.rs`, `crates/targets/src/catalog/extension.rs`
Admin API contract	`rustfs/src/admin/plugin_contract.rs`, `handlers/{plugins_catalog,plugins_instances,extensions,target_descriptor}.rs`

Hard invariants (verify before merging)

Secrets have one source of truth. Secret config keys are declared only in the plugin manifest (TargetPluginManifest.secret_fields, crates/targets/src/manifest.rs) and flow to admin via AdminTargetSpec.secret_fields. Never add a hand-maintained per-service secret table in a handler; if redaction misses a field, fix the manifest.
Redaction must round-trip. Instance GET responses replace secret values with ***redacted*** (REDACTED_SECRET_VALUE in plugins_instances.rs). Instance PUT restores the stored secret when it receives that placeholder back (restore_redacted_secret_values). Any new read or write path for target config must keep both halves: redact on the way out, restore the placeholder on the way in. The placeholder literal must never be persisted.
Fixtures never reach production responses. example_external_webhook_plugin() (crates/targets/src/catalog/mod.rs) is a test/demo fixture for control-plane planning tests. Production catalog/extension handlers must not include it; regression tests (plugin_catalog_never_exposes_example_or_external_fixtures, extension_catalog_never_exposes_example_or_external_fixtures) enforce it.
External plugin flow is planning-only and deny-by-default. plan_external_target_plugin_action returns decisions, it executes nothing. TargetPluginExternalFlowGate::default() is fully closed and TargetPluginInstallPolicy::default().allowed_download_hosts is empty — keep it that way; tests opt in via explicit policies. Install validation requires https, an allowlisted host, a full 64-hex-char sha256 digest, signature and provenance URIs, and an artifact matching the host target_triple.
Custom target types must not collide. Unknown target types get an interned unique custom:<type> plugin id (custom_plugin_id in manifest.rs). Custom plugins with secrets must register via TargetPluginDescriptor::with_manifest and declare secret_fields; ::new derives a manifest with no secrets.

Changing the admin JSON contract

Shapes are locked twice in plugin_contract.rs tests: insta snapshots (rustfs/src/admin/snapshots/) plus literal json! assertions. Update both deliberately; a shape change is a console-facing API change.
Field naming is snake_case, except discovery blocks (runtimeCapabilities, clusterSnapshot, extensionsCatalog) which are camelCase by cross-endpoint convention (same shape in system.rs, console.rs, pools.rs). Do not "fix" that inconsistency locally.
Contract types deliberately duplicate rustfs_targets types (anti-corruption layer). Add a From impl; do not serialize internal types directly.

Handler conventions

Every new admin plugin/extension route needs authorization at the top of call and an include_str! guard test asserting it (repo-wide pattern — see plugin_instance_handlers_require_admin_authorization_contract).
Reads use GetBucketTargetAction (instances) or ServerInfoAdminAction (catalogs); writes use SetBucketTargetAction.
Refresh persisted module switches once per request (refresh_persisted_module_switches), then evaluate the sync module_disabled_block_reason per domain — do not re-read the store per domain or per instance.

Generic bounds

Event-payload generics use the PluginEvent blanket trait (crates/targets/src/plugin.rs). Do not respell Send + Sync + 'static + Clone + Serialize + DeserializeOwned.