redis/node-redis · error · Error

Failed to read ${filePath} from container: ${stderr}

Error message

Failed to read ${filePath} from container: ${stderr}

What it means

readFileFromContainer runs `docker exec <id> cat <filePath>` and throws when stderr is non-empty. It is used internally by loadTlsCertificates to extract ca.crt, <cert>.crt, and <cert>.key from a running Redis container into memory. Any stderr from the exec aborts the read.

Source

Thrown at packages/test-utils/lib/dockers.ts:264

/**
 * Reads a file from a Docker container directly into memory
 * @param dockerId - The Docker container ID
 * @param filePath - Path to the file inside the container
 * @returns Buffer containing the file contents
 */
async function readFileFromContainer(
  dockerId: string,
  filePath: string,
): Promise<Buffer> {
  const { stdout, stderr } = await execAsync("docker", [
    "exec",
    dockerId,
    "cat",
    filePath,
  ]);
  if (stderr) {
    throw new Error(`Failed to read ${filePath} from container: ${stderr}`);
  }
  return Buffer.from(stdout);
}

/**
 * Loads TLS certificates from a running Docker container into memory
 * @param dockerId - The Docker container ID
 * @param certName - The certificate name (used for client cert/key naming)
 * @returns TlsCertificates object with ca, cert, and key buffers
 */
async function loadTlsCertificates(
  dockerId: string,
  certName: string,
): Promise<TlsCertificates> {
  const [ca, cert, key] = await Promise.all([
    readFileFromContainer(dockerId, `${DEFAULT_TLS_PATH}/ca.crt`),
    readFileFromContainer(dockerId, `${DEFAULT_TLS_PATH}/${certName}.crt`),
    readFileFromContainer(dockerId, `${DEFAULT_TLS_PATH}/${certName}.key`),

View on GitHub (pinned to 90fd0652bc)

Solutions

1. Exec into the container to inspect the path: docker exec <id> ls -l /redis/work/tls
2. Ensure waitForTlsCertificates completed successfully before calling loadTlsCertificates
3. Check the container is still running: docker ps --filter id=<id>

Example fix

# before — file missing, cat writes to stderr
# Error: Failed to read /redis/work/tls/client.crt from container: cat: ...: No such file

# after — verify the file exists first
docker exec <id> ls -l /redis/work/tls/
# wait for cert generation, then retry

async function fileExistsInContainer(dockerId: string, filePath: string): Promise<boolean> {
  try {
    await execAsync('docker', ['exec', dockerId, 'test', '-f', filePath]);
    return true;
  } catch {
    return false;
  }
}

try {
  const buf = await readFileFromContainer(dockerId, filePath);
} catch (e) {
  if (e instanceof Error && /Failed to read/.test(e.message)) {
  }
  throw e;
}

When it happens

Trigger: The TLS cert file does not yet exist at the expected path (/redis/work/tls/<file>); the container exited before the cat; the path is wrong for the image's TLS layout; permission denied reading the key file.

Common situations: Calling loadTlsCertificates before the container's cert-generation step finished; image version that stores certs under a different directory; container crashed during startup.

Related errors

• TLS certificates not available after ${maxWaitMs}ms
• Config file not found at path: ${path}
• All ports are in use
• docker run error - ${stderr}
• docker rm error - ${stderr}

AI-assisted analysis of redis/node-redis@90fd0652bc (2026-08-11). Data as JSON: /api/errors/b9f5b731bf03f739. Report an issue: GitHub.