adding-a-trigger

Imported from windmill-labs/windmill (.agents/skills/adding-a-trigger/SKILL.md). Install upstream with npx skills add windmill-labs/windmill --skill adding-a-trigger. Copyright stays with the author.

Skill: Adding a New Trigger Type

Use this skill when adding a trigger kind that implements TriggerCrud (Kafka, GCP, Azure, MQTT, SQS, NATS, Postgres, Email…). For native triggers (Nextcloud, Google Drive — things wired through windmill-native-triggers), use the native-trigger skill instead.

The goal of this doc is to enumerate every file that needs to change. Missing any one of them leads to silent regressions: sync drops the trigger, capture button does nothing, workspace forks lose it, sidebar counters undercount. Follow the checklist top-to-bottom — each section is independent enough to be validated on its own.

Throughout this doc, substitute {kind} for the new trigger kind (azure, kafka, …), {Kind} for PascalCase (Azure, Kafka), {KIND} for SCREAMING (AZURE, KAFKA).

Reference implementations

• GCP — closest analogue to Azure. Has push + pull, OIDC auth, ARM-like resource paths, capture handler. Grep for gcp_trigger / GcpTrigger.
• Kafka — simpler (pull-only, streaming). Good for trivial integrations.
• Azure — most recently added (2026). Shared-secret push auth, Event Grid namespaces + basic topics, ARM resource discovery, Namespace-pull data-plane. Grep for azure_trigger / AzureTrigger.

1. Database migration

Create a migration: cargo sqlx migrate add -r add_{kind}_trigger from backend/. Never write timestamps manually.

The up.sql usually defines:

• An optional enum type (e.g. AZURE_MODE) if the trigger has sub-kinds
• The {kind}_trigger table with at minimum these columns (mirrored from kafka/gcp):
  • primary: (workspace_id, path)
  • script_path, is_flow, enabled, mode, permissioned_as, edited_by, email
  • edited_at, error, server_id, last_server_ping
  • error_handler_path, error_handler_args jsonb, retry jsonb
  • trigger-specific fields
• Indexes on foreign keys + any frequently-filtered columns
• Foreign key to workspace
• The RLS policies (see_own, see_member, see_folder_extra_perms_user_*, see_extra_perms_user_*, see_extra_perms_groups_*), copied from an existing trigger table

RLS: wrap every session GUC read in a scalar sub-select. Write the session reads as (select current_setting('session.user')), = any((select regexp_split_to_array(current_setting('session.groups'), ','))::text[]), ?| (select regexp_split_to_array(current_setting('session.pgroups'), ','))::text[], ? (select concat('u/', current_setting('session.user'))), etc. — not the bare current_setting(...). The GUCs are set with SET LOCAL, so the sub-select hoists them to a one-time InitPlan instead of re-evaluating per scanned row. Put the ::text[] cast outside the sub-select for the array cases: in an = any (...) context, casting inside — = any((select ...::text[])) — makes Postgres parse the operand as a row-returning subquery and fails at CREATE with operator does not exist: text = text[]. The outside cast keeps it in array-operand form. See migration 20260714230440_wrap_session_gucs_in_rls_policies for the canonical wrapped forms.

Down migration drops the table and any enum types.

2. Backend crate (windmill-trigger-{kind})

Create a new crate under backend/windmill-trigger-{kind}/ with:

• Cargo.toml: features enterprise, private if EE, standard deps
• src/lib.rs: pub use mod_ee::*; behind #[cfg(all(feature = "enterprise", feature = "private"))]
• src/mod_ee.rs: core types + helpers
• src/handler_ee.rs: TriggerCrud impl + route handlers
• src/listener_ee.rs: (only if streaming/pull-based) Listener trait impl

Required in mod_ee.rs:

• {Kind}Config struct (persisted shape, FromRow)
• {Kind}ConfigRequest struct (what API receives — usually similar to Config but with validation fields)
• {Kind}Trigger unit struct (implements the traits)
• impl TriggerJobArgs for {Kind}Trigger — sets TRIGGER_KIND, Payload, v1_payload_fn

Required in handler_ee.rs:

• #[async_trait] impl TriggerCrud for {Kind}Trigger with:
  • type Trigger = Trigger<{Kind}Config>
  • type TriggerConfigRequest = {Kind}ConfigRequest
  • const ROUTE_PREFIX: &'static str = "/{kind}_triggers";
  • const TABLE_NAME, ADDITIONAL_SELECT_FIELDS
  • get_deployed_object, validate_config, create_trigger, update_trigger, delete_trigger, test_connection
  • additional_routes (optional — mount extra endpoints for things like ARM resource listing, topic discovery)

Register the crate in backend/Cargo.toml as a workspace member and as a dep of windmill-api behind the feature flag.

3. Wire into windmill-api (feature-gated everywhere)

backend/windmill-api/src/triggers/handler.rs — mount the trigger crate:

#[cfg(all(feature = "enterprise", feature = "{kind}_trigger", feature = "private"))]
{
    use crate::triggers::{kind}::{Kind}Trigger;
    router = router.nest({Kind}Trigger::ROUTE_PREFIX, complete_trigger_routes({Kind}Trigger));
}

backend/windmill-api/src/triggers/{kind}/mod.rs — re-export the crate:

pub use windmill_trigger_{kind}::*;

backend/windmill-api/src/lib.rs — if the trigger receives inbound pushes, add a webhook route:

.nest("/{kind}/w/{workspace_id}", {
    #[cfg(all(feature = "enterprise", feature = "{kind}_trigger", feature = "private"))]
    { triggers::{kind}::handler_oss::{kind}_push_route_handler() }
    #[cfg(not(...))]
    { Router::new() }
})

4. TriggerKind enum (backend/windmill-types/src/triggers.rs)

Already has slots for most triggers but verify your variant exists:

• Add {Kind} to the TriggerKind enum
• Add match arm in to_key()
• Add match arm in from_str
• Add match arm in JobTriggerKind (if jobs need kind tagging)

5. OpenAPI (backend/windmill-api/openapi.yaml)

This file is huge and the single most-forgotten place. Add:

• /w/{workspace}/{kind}_triggers/create + /update/{path} + /delete/{path} + /get/{path} + /list + /exists/{path} + /setmode/{path} + /test paths (mirror gcp section)
• Any additional_routes your handler exposes (resource discovery, etc.)
• Schemas: {Kind}Trigger, {Kind}TriggerData, {Kind}Mode (if enum), {Kind}DeliveryConfig, helper request/response types
• Add {kind} to CaptureTriggerKind enum
• Add {kind}_used: boolean to the UsedTriggers response schema

Regenerate frontend client: npm run generate-backend-client from frontend/.

6. UsedTriggers + workspace export

backend/windmill-api-workspaces/src/workspaces.rs — add {kind}_used: bool to the UsedTriggers struct and add an EXISTS(SELECT 1 FROM {kind}_trigger …) to the get_used_triggers query.

backend/windmill-api/src/workspaces_export.rs — add export block mirroring gcp's (export lists all triggers, serializes them to YAML/JSON). The block re-uses the trigger_ignore_keys variable so the new kind automatically participates in fork-export stripping (mode field is omitted when the source workspace is a fork — keeps fork→parent merges from flipping the parent's enabled state).

Fork cloning (clone_triggers_and_schedules in workspaces.rs) — add an INSERT INTO {kind}_trigger ... SELECT ... block that copies all rows from the parent workspace, forcing mode = 'disabled'::TRIGGER_MODE. Always runs at fork creation; forgetting this means users can't carry {kind} triggers into their forks.

6.5 Hardcoded trigger-kind arrays (silent-failure hotspots)

Several files keep hardcoded arrays of trigger kind strings. Miss one and ACL checks / user offboarding / trash drop your kind:

• backend/windmill-api-groups/src/granular_acls.rs — KINDS: [&str; N]. Increment N (the compile error is cryptic otherwise). Controls which kinds accept granular ACL operations.
• backend/windmill-api-users/src/users.rs (extra_perms_tables) — which tables get extra_perms entries cleaned when a user is deleted.
• backend/windmill-api/src/offboarding.rs — three separate arrays (enumeration, fork-copy, and delete paths). All three need the new kind.
• backend/windmill-api/src/trash.rs — valid_tables for the trash / restore API.
• backend/windmill-git-sync/src/lib.rs — add a test assertion for DeployedObject::{Kind}Trigger.get_kind() == "{kind}_trigger" (the get_kind match arm itself lives in the enum impl — already required by the Rust compiler).
• backend/windmill-api-auth/src/scopes.rs — add the {Kind}Triggers variant to ScopeDomain enum + as_str match + from_str match. Required for the OAuth/token system to recognise {kind}_triggers:read|write scopes.
• backend/windmill-api/src/token.rs (build_trigger_scope_domains → TRIGGER_DOMAINS) — add ("{kind}_triggers", "{Kind display name}") so the CreateToken UI's scope selector surfaces the read / write checkboxes.

OpenAPI enums to extend (do NOT forget — generated client will allow it but server rejects as 400):

• CaptureTriggerKind enum
• Three kind enums under /w/{workspace}/acls/{get,add,remove}/{kind}/{path} (yes, same list repeated three times)

After editing any of these, run a full cargo check with your feature flag + gcp_trigger + other core flags — the KINDS: [&str; N] length mismatch only surfaces when the crate compiles.

7. Capture infrastructure (backend/windmill-api/src/capture.rs)

If the trigger supports push delivery, it also needs a capture endpoint so users can test it:

• {Kind}TriggerConfig struct (gated by feature flags)
• TriggerConfig::{Kind} variant
• set_{kind}_trigger_config function (creates the subscription/equivalent pointing at the capture URL — use your manage_{kind}_subscription helper with trigger_mode=false)
• Both real + no-op versions behind feature gates
• TriggerKind::{Kind} => set_{kind}_trigger_config(...) arm in set_config
• {kind}_payload async handler — validates auth (if any), processes payload, calls insert_capture_payload
• Route: .route("/{kind}/{runnable_kind}/{*path}", post({kind}_payload)) inside workspaced_unauthed_service — and expand the surrounding #[cfg(any(...))] to include your feature flag

8. CLI (cli/) — easy to miss, breaks sync silently

Check all of these:

cli/src/types.ts:

• Add "{kind}" to TRIGGER_TYPES array
• Add "{kind}_trigger" to getTypeStrFromPath return union
• Add match case in getTypeStrFromPath's typeEnding === chain
• Add pushTrigger("{kind}", ...) branch in pushObj

cli/src/commands/trigger/trigger.ts:

• Import {Kind}Trigger type
• Add {kind}: {Kind}Trigger to the Trigger type map
• Add {kind}: wmill.get{Kind}Trigger, update{Kind}Trigger, create{Kind}Trigger to each function map
• Add {kind}: { ... } template to triggerTemplates
• Add list{Kind}Triggers call + spread in the list aggregation
• Update --kind option descriptions to mention the new kind

cli/src/commands/sync/sync.ts:

• Add path.endsWith(".{kind}_trigger" + ext) in the file-type filter
• Add typ == "{kind}_trigger" in getTypeOrder
• Add "{kind}_trigger" to the delete-suffix regex (~line 3092)
• Add a case "{kind}_trigger" in the delete switch

cli/src/guidance/skills.ts — DO NOT EDIT DIRECTLY. It's auto-generated by system_prompts/generate.py. Instead:

• Edit system_prompts/utils.py → append ('{Kind}Trigger', '{kind}_trigger') to the SCHEMA_MAPPINGS['triggers'] list (this is the master list — the one in generate.py is duplicated and utils.py wins)
• Then run python3 system_prompts/generate.py — it regenerates cli/src/guidance/skills.ts with the schema extracted from backend/windmill-api/openapi.yaml
• Commit the regenerated file

9. Frontend — editor + drawer

Under frontend/src/lib/components/triggers/{kind}/:

• {Kind}TriggerPanel.svelte — the tile shown in the triggers listing
• {Kind}TriggerEditor.svelte — outer drawer wrapper
• {Kind}TriggerEditorInner.svelte — state + business logic; must expose:
  • openEdit(path, isFlow, defaultValues?) method
  • isEditor prop, onConfigChange + onCaptureConfigChange callbacks
  • get{Kind}Config() + get{Kind}CaptureConfig() helpers
  • captureConfig = $derived.by(untrack(() => isEditor) ? get{Kind}CaptureConfig : () => ({}))
  • $effect(() => { const args = [captureConfig, isValid] as const; untrack(() => onCaptureConfigChange?.(...args)) })
• {Kind}TriggerEditorConfigSection.svelte — form fields; use design-system components (TextInput, Select, Toggle, ToggleButtonGroup), never raw <input>
• {Kind}Capture.svelte — capture panel; wraps CaptureSection with captureType="{kind}"
• utils.ts — requestBody builders and any trigger-type-specific helpers

10. Frontend — global integration

Easy to miss:

• frontend/src/lib/components/triggers.ts — add '{kind}' to the TriggerKind union
• frontend/src/lib/components/triggers/CaptureWrapper.svelte:
  • Import {Kind}Capture
  • Add to isStreamingCapture() array (streaming = pull-style; push-style is typically false)
  • Add {:else if captureType === '{kind}'} branch with the <{Kind}Capture> render
• frontend/src/lib/components/sidebar/SidebarContent.svelte — import the icon, add the nav entry
• frontend/src/lib/components/sidebar/OperatorMenu.svelte — add the operator-mode entry
• frontend/src/routes/(root)/(logged)/+layout.svelte — destructure {kind}_used from /get_used_triggers response, push '{kind}' into usedKinds
• frontend/src/lib/components/search/GlobalSearchModal.svelte — import icon, add "Go to {Kind} ..." entry
• frontend/src/lib/components/offboarding-utils.ts — add mappings {kind}_trigger: '{kind}_triggers' and {kind}_trigger: '{kind} trigger'
• frontend/src/lib/components/icons/{Kind}Icon.svelte — single-path SVG, fill={color ?? 'currentColor'}, size prop default 16 (match existing icons — don't hardcode colors, don't use width/height props)
• frontend/src/routes/(root)/(logged)/{kind}_triggers/+page.svelte — listing page (mirror gcp_triggers/+page.svelte for push+pull, kafka_triggers for pure streaming)
• frontend/src/lib/components/CompareWorkspaces.svelte — workspace fork / compare tool. Needs: service import, editor import, {kind}Editor $state, case '{kind}' in openTriggerDetails(), entry in triggerServices object (list/delete/normalize), and <{Kind}TriggerEditor bind:this={{kind}Editor} /> in the template

10.5 AI system prompts (system_prompts/)

• system_prompts/utils.py — append ('{Kind}Trigger', '{kind}_trigger') to SCHEMA_MAPPINGS['triggers'] (master list used by code generation + CLI skills)
• system_prompts/generate.py — also has a duplicated schema_types list (~line 903) for the AI triggers skill content. Add ('{Kind}Trigger', '{kind}_trigger') there too
• system_prompts/generate.py schema_names (~line 1192) — add '{Kind}Trigger' (add 'New{Kind}Trigger' only if the OpenAPI declares one; GCP and Azure don't)
• Run python3 system_prompts/generate.py — this rewrites cli/src/guidance/skills.ts and all auto-generated/ docs. Commit the regenerated files

11. Validation

Run all of these before declaring done:

# Backend
cd backend
cargo check --features enterprise,{kind}_trigger,private   # minimal
cargo check --features enterprise,azure_trigger,private,gcp_trigger,http_trigger,mqtt_trigger,postgres_trigger,sqs_trigger,kafka,nats,smtp,websocket  # full

# SQLx offline data (never run `cargo sqlx prepare` directly — use the wrapper)
./update_sqlx.sh

# Frontend
cd frontend
npm run generate-backend-client
npm run check:fast

Smoke test in the UI: create a trigger, save, check it appears in sidebar + search, delete, re-create via CLI wmill sync.

12. Common pitfalls

• Forgetting feature gates in workspaced_unauthed_service() — the surrounding #[cfg(any(...))] expression must include your feature flag, not just the inner #[cfg] on the route
• .route(path, ...).route(path, ...) with same path and different methods — older axum replaced; use .route(path, post(h1).options(h2)) to chain methods on the same MethodRouter
• on:event directives — legacy Svelte 4, no-op in runes mode. Use callback props (onSelected, onConfigChange)
• $bindable(default_value) on optional props — banned by project CLAUDE.md. Use $bindable() + $derived(prop ?? default) instead
• CORS layer intercepting OPTIONS — tower-http CorsLayer short-circuits OPTIONS before reaching your handler. For server-to-server webhook endpoints, drop the CORS layer entirely (CORS is browser-only)
• DeliveryAttributeMappings / custom headers for auth — prefer HMAC or sha256-hashed shared secrets over opaque JWTs when the provider doesn't support signed tokens natively. Store only the hash; regenerate secret on every save
• ARM / API resource-listing cascades — if the trigger's resource type is deep (Azure: subscription → RG → namespace → topic), offer dropdowns in the UI populated from the provider's APIs using the user's credential resource
• Clearing stale selections on dependency change — when a dropdown's underlying data reloads (e.g., user changes SP or edition), clear selections that no longer match the new list
• Workspace-scoped tag compatibility — if the trigger has tags, verify forked workspaces handle them (see commit 0773b5bc85 for a historical fix)

13. EE file split

If the trigger is enterprise-only, the code lives in windmill-ee-private__worktrees/.../windmill-trigger-{kind}/src/*_ee.rs and is symlinked into the OSS tree. The windmill-ee-private__worktrees/ directory holds the real files; changes propagate via symlinks. See docs/enterprise.md for the workflow.

14. Final checklist before PR

• Migration up/down tested (revert + re-apply)
• ./update_sqlx.sh committed the updated .sqlx/ offline data
• cargo check passes with your feature flag + with all trigger features
• npm run check:fast passes
• Trigger visible in sidebar with correct icon weight (not oversized/colored — use currentColor)
• Create, edit, delete flow all work in the UI
• Capture button works (if push-capable)
• Trigger appears in /get_used_triggers → sidebar pulse
• wmill sync pull + wmill sync push both round-trip the trigger
• wmill trigger list includes it
• OpenAPI schemas are complete (no null in generated types)