How to access the filesystem

This guide shows you how to access the filesystem from Apibara indexers. After reading this guide, you'll be able to use the Deno filesystem API from within your indexer.

Consider the following indexer that reads a list of smart contract addresses from a file.

const addresses = await Deno.readTextFile("/path/to/file.txt");
console.log(addresses);

export const config = {
  streamUrl: "https://sepolia.starknet.a5a.ch",
  startingBlock: 10_000,
  network: "starknet",
  filter: {
    header: { weak: false },
  },
  sinkType: "console",
  sinkOptions: {},
};

export default async function transform(_block) {
  return [];
}

If you run it you will get the following error.

apibara run indexer.ts -A dna_xxx

sink configuration error
├╴at /dna/sinks/sink-common/src/error.rs:142:14
├╴failed to load configuration from script
│
╰─▶ indexer script operation failed
    ├╴at /dna/script/src/script.rs:339:22
    ├╴failed to run indexer event loop
    ╰╴error: Error: Requires read access to "/path/to/file.txt", run again with the --allow-read flag
          at Object.readTextFile (ext:deno_fs/30_fs.js:751:29)
          at file:///path/to/indexer.ts:1:30

You can grant access to the file with the --allow-read flag. Without arguments, the flag grants access to any directory and file. You can restrict access with a comma-separated list of files and directories.

The Apibara CLI provides write access to the filesystem using the --allow-write flag. This flag works exactly the same as the read flag.