Add an onError handler to run which is called when a step permanently fails
#43
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#45 should address this with |
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jpwilliams
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…ean examples (#45) ## Breaking changes ### Function creation helpers removed The following function creation methods have been removed and should be replaced by using `Inngest#createFunction`: - `createFunction` - `createScheduledFunction` - `createStepFunction` - `Inngest#createScheduledFunction` - `Inngest#createStepFunction` ```ts import { createFunction } from "inngest"; createFunction("Example", "app/user.created", () => {}); // becomes import { Inngest } from "inngest"; const inngest = new Inngest({ name: "App" }); inngest.createFunction("Example", "app/user.created", () => {}); ``` ```ts import { createScheduledFunction } from "inngest"; createScheduledFunction("Example", "* * * * *", () => {}); // or inngest.createScheduledFunction // becomes import { Inngest } from "inngest"; const inngest = new Inngest({ name: "App" }); inngest.createFunction("Example", { cron: "* * * * *" }, () => {}); ``` ```ts import { createStepFunction } from "inngest"; createStepFunction("Example", "* * * * *", () => {}); // or inngest.createStepFunction // becomes import { Inngest } from "inngest"; const inngest = new Inngest({ name: "App" }); inngest.createFunction("Example", { cron: "* * * * *" }, async ({ tools }) => { // Use a tool to create a step function }); ``` ### Step functions are now asynchronous In order to provide the full power of asynchronous JavaScript, step functions are now required to be async functions, and all step tooling will return promises instead of synchronously. If you're using TypeScript, you'll be guided through the changes at each stage. For example, trying to access `.id` of the new `Promise<User>` will throw an error telling you that it must first be awaited. ```ts import { createStepFunction } from "inngest"; import { userDb } from "./db"; import { email } from "./email"; export default createStepFunction( "Example", "app/user.created", ({ event, tools }) => { const user = tools.run("Get user email", () => userDb.get(event.userId)); // We run synchronously, so wait for the email to be send before the alert is sent tools.run("Send email", () => email.sendEmail(user.email, "Welcome!")); tools.run("Send alert to staff", () => email.sendAlert("New user created!") ); } ); ``` This would be converted to the following: ```ts import { inngest } from "./client"; import { userDb } from "./db"; import { email } from "./email"; export default inngest.createFunction( // use client instead of helper { name: "Example", fns: { ...userDb, ...email } }, // can pass functions to wrap in tools.run() "app/user.created", async ({ event, fns: { getUser, sendEmail, sendAlert }}) => { const user = await getUser(event.userId); // use fns directly that have been passed // We don't await these, so they are run in parallel now sendEmail(user.email, "Welcome!"); sendAlert("New user created!"); } ); ``` ### Custom handlers require a `stepId` In order to provide the parallel functionality in this PR, all handlers created using `InngestCommHandler` must provide a `stepId` parameter when attempting to run a function. This should be accessed via the query string using the exported `queryKeys.StepId` enum. ```diff run: async () => { if (req.method === "POST") { return { fnId: url.searchParams.get(queryKeys.FnId) as string, + stepId: url.searchParams.get(queryKeys.StepId) as string, ``` ## Features ### Pass functions to wrap as retriable steps When creating a function, you can now pass a `fns` key to automatically wrap all found functions in `tools.run()` step tooling, automatically providing your existing functionality with retries and durability. ```ts import { inngest } from "./client"; import { userDb } from "./db"; import { email } from "./email"; export default inngest.createFunction( { name: "Example", fns: { ...userDb, ...email } }, "app/user.created", async ({ event, fns: { getUser, sendEmail}}) => { const user = await getUser(event.userId); sendEmail(user.email, "Welcome!"); } ); ``` ## Fixes - `user` key in event payloads can now be any value, to ensure conflicting generated events are accepted; see #87 for further discussion ## Related changes/issues based on this PR - #66 - #73 - #74 - #75 - #76 - #69 - #43 ## SDK changes - [x] Refactor step function tooling to be `async` - [x] Unify `createFunction`, `createScheduledFunction`, and `createStepFunction` under a single `createFunction` method - [x] ~Preserve complex client-less `createFunction` helper~ > Prefer instantiation with a client for now. - [x] Add error-handling capabilities by giving the SDK the ability to send back a serialised `error` as well as `data` - [x] Allow use of regular JS tooling (`.then()`, `try/catch`, etc) in step functions without gotchas - [x] ~Create a new `StepOpCode` for a no-op other than `None`~ We just return an empty array. - [x] Add ability to pass steps in as "just functions" to avoid wrapping all user code in `tools.run()` - [x] ~Add ability to pass steps in as "just functions" to a `new Inngest()` client, which is merged with any steps passed directly to `inngest.createFunction()`~ > Defer this to be implemented with #66, as this will alter generics for `Inngest` and `InngestFunction` to aid with this change. - [x] Hash synchronous groups of steps and throw errors if synchronous step order doesn't match - [x] Allow triggering steps using `stepId` query param instead of op position codes - [x] Add new `StepPlanned` (or similar) op code for back compat - [ ] Create `step` alias for `tools` and deprecate `tools` - [ ] Add a large warning when the a step function resolves, but some tooling is still pending; we want to highlight for users that to be safe they should make sure to await in serverless environments ## Examples <details> <summary>See examples</summary> ```ts // Any type of function uses the same method. // declare createFunction: (nameOrFunctionOpts, eventNameOrTriggerOpts, fn) => void; inngest.createFunction("...", "demo/event.sent", () => {}); inngest.createFunction("...", { event: "demo/event.sent" }, () => {}); inngest.createFunction("...", { cron: "* * * * *" }, () => {}); ``` ```ts // A step function uses the same method; just use a tool. inngest.createFunction("...", "demo/event.sent", ({ tools: { run } }) => { run("Step", () => {}); }); ``` ```ts // Step functions now use async functions - easier to map complex flows. inngest.createFunction("...", "demo/event.sent", async ({ tools: { run } }) => { const randomNumber = await run("Get random number", () => Math.random()); await run("Send random number", () => sendEmail("...", randomNumber)); }); ``` ```ts // With async support, fire-and-forget parallel steps are easy to create - just // trigger them all and SDK will let Inngest know of all of the pending actions. inngest.createFunction("...", "demo/event.sent", async ({ tools: { run } }) => { run("Send email", () => sendEmail("...")); run("Send another email", () => sendEmail("...")); run("Send yet another email", () => sendEmail("...")); }); // This means that the response from the SDK to Inngest is always an array of // upcoming steps. // // In this case, the first call would return all three actions, as we're not // awaiting them; the SDK gets a single synchronous tick of the event loop to // decide what is next. [ { op: "Step", name: "Send email", run: true }, { op: "Step", name: "Send another email", run: true }, { op: "Step", name: "Send yet another email", run: true }, ]; ``` ```ts // Step functions can handle errors too, meaning we can use usual tools like // try/catch. inngest.createFunction("...", "demo/event.sent", async ({ tools: { run } }) => { try { await run("Step", () => {}); } catch (err) { await run("Send error to Tim", () => sendEmail("...", err)); } }); // Or perhaps we want to silently handle an error case and not have it affect // other steps. inngest.createFunction("...", "demo/event.sent", async () => { await run("Send email", () => sendEmail("...")).catch(() => { run("Send error to Tim", () => sendEmail("...", err)); }); }); ``` ```ts // Tools such as `Promise.all` are fine too. inngest.createFunction("...", "demo/event.sent", async ({ tools: { run } }) => { await Promise.all([ run("Send email", () => sendEmail("...")), run("Send another email", () => sendEmail("...")), ]); }); ``` ```ts // We can even create parallel chains of steps that trigger immediately, follow // their own path, then eventually come back together. inngest.createFunction("...", "demo/event.sent", async ({ tools: { run } }) => { const fooStep = run("Foo", () => fooSomething()) .then((data) => run("Foo again", () => fooSomethingElse(data))) .then((data) => run("Foo again again", () => fooSomethingElse(data))); const barStep = run("Bar", () => barSomething()) .then((data) => run("Bar again", () => barSomethingElse(data))) .then((data) => run("Bar again again", () => barSomethingElse(data))); const [foo, bar] = await Promise.all([fooStep, barStep]); await run("Send email", () => sendEmail("...", { foo, bar })); }); ``` ```ts // Wrapping all user code in `run()` can be a bit verbose. One of the initial // goals of the SDK was that steps were "just functions". If we pass those to // our Inngest function then we can shim them with `run()` automatically, which // makes the code look _super_ clean. // // The TS types and runtime JS will non-destructively filter the input and add // shims, meaning you could pass entire structures/classes in with no bother, // like we do here with `userDb` and `email` which may export more than just // functions. We even retain the function's comments! import * as userDb from "./dbs/user"; import * as email from "./email"; inngest.createFunction( { name: "...", fns: { ...email, ...userDb } }, "demo/event.sent", async ({ event, fns: { sendEmail, getUserById } }) => { const user = await getUserById(event.user.id); await sendEmail(user.email, "..."); } ); // This can really help clean up functions with lots of steps, like our example // of parallel paths above. inngest.createFunction( { name: "...", fns: { ...fooLib, ...barLib, ...email } }, "demo/event.sent", async ({ tools: { run } }) => { const fooStep = fooSomething() .then(fooSomethingElse) .then(fooSomethingElse); const barStep = barSomething() .then(barSomethingElse) .then(barSomethingElse); const [foo, bar] = await Promise.all([fooStep, barStep]); await sendEmail("...", { foo, bar }); } ); ``` ```ts // Sometimes, a user may want to bundle async actions together in a single step, // for example when something must be fetched from the DB right before sending // an email. // // If this is unique to this Inngest function, we can always use `tools.run()` // to run in-line code. If we wanted to create a reusable step, however, we just // make a regular function. const sendEmailToUser = async (userId: string, body: string) => { const user = await getUserById(userId); await sendEmail(user.email, body); }; inngest.createFunction( { name: "...", fns: { sendEmailToUser, something } }, "demo/event.sent", async ({ event }) => { await something(); await sendEmailToUser(event.user.id, "..."); } ); ``` ```ts // If we were to create a library of reusable steps, a _future_ option that is // not in this PR could be to pass steps in to the Inngest constructor to // provide the tooling for every function automatically. const inngest = new Inngest<Events>({ name: "...", fns: { ...email, ...userDb, ...postDb }, }); inngest.createFunction( "...", "demo/event.sent", async ({ event, fns: { getUserById, getPostsByTag, sendEmail } }) => { const user = await getUserById(event.user.id); const posts = await getPostsByTag(user.favouriteTag); await sendEmail(user.email, posts); } ); ``` </details>
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jpwilliams
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Mar 31, 2023
…n fails (#133) ## Summary INN-821 This is the SDK side of inngest/inngest#370. From that PR: > This [PR] outlines the ability to create functions called automatically any time functions permanently fail. Failure functions can be their own step functions and should be called with the latest error and the incoming event. This allows users to run any logic necessary for eg. cleanup, alerting, logging, etc. For users, this ensures `inngest.createFunction()` provides some syntactical sugar over simply creating a new function that listens for the correct `inngest/function.failed` event. ```ts inngest.createFunction( { name: "Send welcome email", fns: { ...emailer } }, { event: "app/user.created" }, async ({ event, fns: { sendEmail } }) => { await sendEmail({ type: "welcome", to: event.data.email }); }, async ({ err, event }) => { await sendEmail({ type: "alert", to: "[email protected]", subject: `Welcome email failed to send to ${event.event.data.email}`, body: `Error: ${err.message}` }); } ); ``` Future per-step error handling via `.catch()`, `try`/`catch`, etc., could be preferable for some functions; the example above is short enough to be cleaner with a `try`/`catch` block. For larger functions, however, this ensures you don't have to wrap your entire function in a `try`/`catch` block or otherwise reorganise your code to be able to catch errors. We had previously discussed using an `onFailure` option in the function options to define this alongside `name`, `retries`, etc. I prefer that approach for discoverability, but we need to infer types from the options object to build the handler, so we're moving back to mirroring the `Promise.then(onResolve, onReject)` signature instead. ## Related - Closes inngest/inngest#370 - #43 ## Todo - [ ] Example and integration tests - [ ] Documentation
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Added in #133. |
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See inngest/inngest#370 for discussion.
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