How to access the network

This guide shows you how to access the network from Apibara indexers. In other words, this is how to use fetch or functions that use fetch.

For this guide, we are going to make a simple JSON-RPC. Notice that in practice making JSON-RPC requests inside your indexer will considerably slow down indexing speed.

indexer.ts

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) {
  const response = await fetch("https://free-rpc.nethermind.io/sepolia-juno/", {
    method: "POST",
    body: JSON.stringify({
      jsonrpc: "2.0",
      id: 1,
      method: "starknet_specVersion",
      params: [],
    }),
  });
  const { result } = await response.json();
  console.log(result);
  return [];
}

If you try to run this indexer, you will get the following error. This is because by default indexers cannot make network requests.

Terminal

apibara run indexer.ts -A dna_xxx

2024-02-13T13:51:53.897835Z  INFO acquiring persistence lock
2024-02-13T13:51:53.897877Z  INFO lock acquired
2024-02-13T13:51:53.911828Z  INFO status server listening on 0.0.0.0:43991
2024-02-13T13:51:54.198360Z  INFO handle block batch block=900000 status=finalized
fatal sink error
├╴at /dna/sinks/sink-common/src/error.rs:152:14
├╴failed to transform batch data
├╴error while streaming data
│
╰─▶ indexer script operation failed
    ├╴at /dna/script/src/script.rs:339:22
    ├╴failed to run indexer event loop
    ╰╴error: Error: Requires net access to "free-rpc.nethermind.io", run again with the --allow-net flag
          at opFetch (ext:deno_fetch/26_fetch.js:73:14)
          at mainFetch (ext:deno_fetch/26_fetch.js:182:59)
          at ext:deno_fetch/26_fetch.js:465:9
          at new Promise (<anonymous>)
          at fetch (ext:deno_fetch/26_fetch.js:428:18)
          at transform (file:///path/to/indexer.ts:13:25)
          at [script]:14:39

Allow specific hostnames

The best option is to allow specific hostnames. You can do this by using the --allow-net option and specifying a comma-separated list of allowed hostnames. While not always required, you should use the --allow-net flag before the script path.

Terminal

apibara run --allow-net=infura.com,free-rpc.nethermind.io indexer.ts -A dna_xxx

2024-02-13T13:57:11.529777Z  INFO acquiring persistence lock
2024-02-13T13:57:11.529817Z  INFO lock acquired
2024-02-13T13:57:11.543764Z  INFO status server listening on 0.0.0.0:44903
2024-02-13T13:57:11.825759Z  INFO handle block batch block=900000 status=finalized
0.6.0
2024-02-13T13:57:11.918706Z  INFO []

Notice that free-rpc.nethermind.io and nethermind.io are two distinct hostnames.

Allow all hostnames

If you want to grant access to all hostnames, use the --allow-net flag without any argument. This option is less secure but more convenient.

Terminal

apibara run --allow-net indexer.ts -A dna_xxx

2024-02-13T13:57:11.529777Z  INFO acquiring persistence lock
2024-02-13T13:57:11.529817Z  INFO lock acquired
2024-02-13T13:57:11.543764Z  INFO status server listening on 0.0.0.0:44903
2024-02-13T13:57:11.825759Z  INFO handle block batch block=900000 status=finalized
0.6.0
2024-02-13T13:57:11.918706Z  INFO []

Top-level await support

Apibara indexers support awaiting at the top level.

indexer.ts


const response = await fetch("https://my-endpoint.org");
const someRemoteObject = await response.json();

export const config = { ... };