NATS "Authorization Violation" in CI

By Daniel Zoghalchali·Latchkey

The server is configured to require authentication and rejected the client connection. The credentials in the connection URL or options are missing, wrong, or use a mechanism the server is not set up for.

What this error means

The client fails with "nats: Authorization Violation" right after connecting, before any subscribe or publish succeeds.

nats: Authorization Violation

Common causes

No credentials were sent to an authenticated server

The server has user/password or token auth enabled, but the client connected anonymously.

Wrong user, password, or token

The supplied credentials do not match what the server was started with.

How to fix it

Match the server credentials in the client URL

Start the server with a known user/password and use the same in the client connection URL.

services:
  nats:
    image: nats:2.10
    command: ["--user", "app", "--pass", "app_pw"]
    ports: ['4222:4222']
env:
  NATS_URL: nats://app:app_pw@localhost:4222

Use token auth consistently

If the server uses a token, pass the same token from the client.

# server: --auth s3cr3t
NATS_URL=nats://s3cr3t@localhost:4222

How to prevent it

• Keep the server auth config and client credentials in sync.
• Inject NATS credentials from CI secrets, not committed config.
• Use one auth mechanism (user/pass or token) end to end.

Frequently asked questions

Related guides

References

• GitHub Actions documentation