MongoDB lambda mongocryptd race condition fix

mongodb-fle-lambda-race-condition-fix.js

// this is the writable folder where our .pid file live
const tmpPath = path.resolve(process.env.LAMBDA_TASK_ROOT, "../../tmp");

// if the file exists our ephemeral function container got reused, so we do not need to spawn the process again
if (!fs.existsSync(tmpPath + "/mongocryptd.pid")) {
await new Promise((resolve, reject) => {
    // to prevent waiting for godot
    const safeGuard = setTimeout(() => reject(), 3000);

    const child = spawn(
    "mongocryptd",
    ["--idleShutdownTimeoutSecs=240", `--pidfilepath=${tmpPath}/mongocryptd.pid`],
    {
        // note that we need stdio in order to determine when the process is ready to accept connections
        detached: true,
    }
    );

    child.stdout.on("data", (data) => {
      // I checked the mongocryptd logs
      // id:23016 means the process is ready to accept incoming connections
      // this looks hacky, but the bson package is unable to parse the mongocryptd logs
    if (data.toString().includes(`"id":23016`)) {
        console.debug("Mongocryptd is ready to accept connecitons. Proceed to connect to cluster.");
        clearTimeout(safeGuard);
        resolve();
    }
    });

    child.stderr.on("data", (data) => {
      // you could add debug logs here
      reject(data);
    });

    child.unref();
});
}