wave I was wondering about something when writing lambdas u Pulumi Community #typescript

:wave: I was wondering about something, when writi...

bright-wall-79582

02/14/2023, 12:35 PM

👋 I was wondering about something, when writing lambdas using Typescript and wanting to define it using

aws.lambda.Function

, do I have to bundle the typescript code or can I just point it to a directory?

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|- application
|  | - index.ts
|- infrastructure
| | - pulumi.ts

I was following the samples doing this:

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export const exampleFunction = new aws.lambda.Function('actionRunnerLambda', {
  role: lambdaRole.arn,
  runtime: 'nodejs18.x',
  handler: 'index.handler',
  code: new AssetArchive({
    '.': new FileArchive('./application/')
  })
})

Where

index.ts

exports a “handler” function. However, when trying to upload this I get that it can’t find the handler “index.handler”. I need to use the

Function

to defined the Lambda as I need to specify things like the runtime and environment variables. This I can not do if I use for instance

createFunctionFromEventHandler

. I was wondering if I have to compile the typescript first and then point the file archive there?

brave-planet-10645

02/14/2023, 2:58 PM

If you use a

callbackFunction

resource then yes you can point it at the handler

brave-planet-10645

02/14/2023, 3:02 PM

Most of our examples have the code within the resource, but you can do something like this https://gist.github.com/pierskarsenbarg/75040eeeee9d97d6f21289215df6bf84

brave-planet-10645

02/14/2023, 3:02 PM

(that’s old code, hence the node v12)

brave-planet-10645

02/14/2023, 3:03 PM

You can use the

CallbackFunction

pretty much everywhere in the AWS provider where you specify a

Function

resource

brave-planet-10645

02/14/2023, 3:04 PM

Worth noting that the way Pulumi serialises the code, you can’t do the usual best practices like having database connections outside of the main handler code

brave-planet-10645

02/14/2023, 3:05 PM

But you can have them inside the handler code like this:

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import * as aws from "@pulumi/aws";
import { BucketEvent } from "@pulumi/aws/s3";

export const onObjectCreatedLambda = (e: BucketEvent) => {
    const db = new aws.sdk.DynamoDB.DocumentClient();
    for (const rec of e.Records || []) {
        const key = rec.s3.object.key;
        let params = {
            TableName: process.env.TABLENAME || "",
            Item: {
                'objectkey': key,
                'timestamp': new Date().toISOString()
            }
        };
        db.put(params, function (err, data) {
            if (err) {
                console.log("Error", err);
            } else {
                console.log(`Written ${key} to db`);
            }
        });
    }
};

bright-wall-79582

02/14/2023, 3:23 PM

ahh, thanks a lot for explaining this. it did the trick of course 🙂

bright-wall-79582

03/16/2023, 12:48 PM

I have run into a new snag, which is that I continue to get problems with using libraries and Pulumi refusing to serialize. errors such as this:

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which could not be serialized because it was a native code function.

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arrow function captured 'this'. Assign 'this' to another name outside function and capture that.

is the only way to get around these to revert to using Function and then use FileAssets?

brave-planet-10645

03/16/2023, 5:20 PM

Yes that’s correct. The AWS SDK is built in to the Pulumi AWS Provider SDK, but you can’t serialise other packages. So yes, you’ll need to use Function with FileAssets and ensure that everything is bundled up (you can use things like webpack for this)

bright-wall-79582

03/17/2023, 7:41 AM

it would be only certain dependencies it doesn’t like though? as I have some which work just fine. I guess I will have to switch it then, and try to solve the issue I had with never being able to find the handler function when using those assets resources 😅 💦

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