How can I use a file from the local disk in Pulumi?

Question

I am trying to use a long policy document for AWS in Pulumi that sits on disk.

const policyDocument = new pulumi.asset.FileAsset("./policy.json");

However, when I try to use the variable later like this:

export const jobPolicy = new aws.iam.Policy(`${ jobName }-policy`, {
  path: `/${ stage }`,
  description: `Policy for ETL job ${ jobName }`,
  policy: JSON.stringify(policyDocument)
});

I get the following:

 + policy     : "{\"__pulumiAsset\":true,\"path\":{}}"

Is there a way to somehow use a JSON file in Pulumi + TypeScript?

I also tried:

import * as fs from 'fs';
const policyDocument  = fs.readFileSync('policy.json', 'utf8');

The result is:

Error: ENOENT: no such file or directory, open 'policy.json'
at Object.openSync (node:fs:585:3)

Answer 1

A pulumi.asset.FileAsset creates new resources, with inputs and outputs. It's generally used to create lambda functions.

The policy parameter takes a standard TypeScript string, so you were on the right lines using fs.readFileSync, but I think you forgot to add the path to the json file. You could probably do:

const policyDocument  = fs.readFileSync('./policy.json','utf8');

Notice the ./ there. However, a safer way is to resolve the directory using path. Try something like this

import * as pulumi from "@pulumi/pulumi";
import * as aws from "@pulumi/aws";
import * as fs from 'fs';
import * as path from "node:path";

const policyDocument = fs.readFileSync(path.resolve(__dirname, 'policy.json'), 'utf8');

const jobPolicy = new aws.iam.Policy('file-policy', {
    policy: policyDocument
});