Sync records to a webhook

Send every create, update and delete in a collection to an external service, and let the record be indexed as normal.

Trigger: record.index:<nsid>. Needs: happyview-http. Script variables: WEBHOOK_URL.

The receiving service should treat each request as “set the state of this URI”, keyed by uri. The same record can reach this script more than once, so a service that appends a row per request will see duplicates. See Create scripts may run more than once.

Lua

local json = require("internal.json")
local http = require("happyview.http")

function handle(input, ctx)
  local res = http.post(ctx.env.WEBHOOK_URL, {
    headers = { ["Content-Type"] = "application/json" },
    body = json.encode({
      action = input.action,
      uri = input.uri,
      did = input.did,
      record = input.record,
    }),
  })

  if res.status >= 400 then
    error("webhook answered " .. res.status)
  end

  -- `record` is absent on delete; `true` lets the delete proceed.
  return input.record or true
end

JavaScript

import http from "happyview.http";

export default async function handle(input, ctx) {
  const res = await http.post(ctx.env.WEBHOOK_URL, {
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({
      action: input.action,
      uri: input.uri,
      did: input.did,
      record: input.record,
    }),
  });

  if (res.status >= 400) {
    throw new Error(`webhook answered ${res.status}`);
  }

  // `record` is absent on delete; `true` lets the delete proceed.
  return input.record ?? true;
}

TypeScript

import http from "happyview.http";

interface RecordEvent {
  action: "create" | "update" | "delete";
  uri: string;
  did: string;
  record?: Record<string, unknown>;
}

interface Context {
  env: Record<string, string>;
}

export default async function handle(input: RecordEvent, ctx: Context) {
  const res = await http.post(ctx.env.WEBHOOK_URL, {
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({
      action: input.action,
      uri: input.uri,
      did: input.did,
      record: input.record,
    }),
  });

  if (res.status >= 400) {
    throw new Error(`webhook answered ${res.status}`);
  }

  // `record` is absent on delete; `true` lets the delete proceed.
  return input.record ?? true;
}

How it works

1. record.index catches creates, updates and deletes for the collection, unless a more specific record.create, record.update or record.delete script exists for an action.
2. The script posts the event to the URL in the WEBHOOK_URL script variable.
3. http.post returns a 4xx or 5xx answer as an ordinary result, so the script checks status and raises for it.
4. It returns the record so indexing goes ahead unchanged. A script that returns nothing would stop the record from being indexed.

If the request fails or the webhook answers with an error status, the script fails. A record script is retried up to 4 times in total and then dead-lettered, and the record is indexed anyway. Wrap the call in pcall (Lua) or try/catch (JavaScript and TypeScript) if you would rather log the failure and carry on.

Record scripts run before indexing, so a slow webhook slows down indexing for everything behind it. Keep the endpoint fast, or have the script create a background job and do the call from there.