When I first decided to deploy my backend with Redis using Coolify, I thought it would be straightforward. Redis in one container, the backend in another—what could go wrong? Spoiler alert: everything.
The Setup
Locally, everything was perfect. Redis and BullMQ worked like a dream. But as soon as I deployed, my backend decided it wanted nothing to do with Redis. The dreaded error:
ECONNREFUSED: Failed to connect
errno: 103
syscall: "connect"That’s when I knew I was in for a long day (or two).
Troubleshooting Steps
1. Testing Network Connectivity
My first thought was, "Maybe Docker networking is the issue?" So I pinged the Redis container from within the backend container. Success! They could see each other. This confirmed that Docker’s networking magic was working just fine.
But BullMQ? It was still sitting in the corner, arms crossed, refusing to connect.
2. The “Blame BullMQ” Phase
“Maybe it’s BullMQ,” I thought. Developers love to blame the tools, right? So I swapped it out for ioredis. Surely, this will work, I told myself.
Spoiler: It didn’t.
At this point, I had a moment of existential dread. Was it me? Was it Redis? Was it Docker? Was it… fate?
3. Double-Checking Environment Variables
When all else fails, blame the .env file. I triple-checked every environment variable:
REDIS_HOST: ✅REDIS_PORT: ✅REDIS_USERNAMEandREDIS_PASSWORD: ✅
Everything looked correct. I even redeployed the backend to ensure the changes applied. No dice.
At this point, I was beginning to think my .env file was just a modern-day Horcrux.
4. Recreating Redis
Frustrated but still clinging to hope, I deleted the Redis database and recreated it from scratch with default settings. I updated my backend credentials and redeployed, ready for victory.
Guess what? The error laughed in my face. Again.
A New Approach: Manual Setup
Desperation breeds creativity. I manually spun up a Redis container outside of Coolify and connected it to the Coolify Docker network. Then, I updated my backend configuration to use the Redis container’s IP address instead of its name.
And finally… it worked!
Well, sort of. I quickly realized that using the IP address was a terrible idea. Why? Because container IPs change after a reboot. I had fixed the issue temporarily but set myself up for future headaches.
Final Adjustment: Switching to Container DNS
The aha moment came when I decided to use Docker’s DNS system. Instead of relying on the IP address, I updated my backend to reference the Redis container by its name. This way, the connection would persist even if the container restarted.
Finally, BullMQ was happy. Redis was happy. And most importantly, I was happy.
Lessons Learned
Looking back, this journey taught me a few valuable lessons:
- Networking Matters: Always verify that containers are on the same Docker network.
- Library-Specific Behavior: Not all libraries handle connections the same way. Be prepared to test alternatives.
- Environment Variables Are Key: Double-check them and redeploy to apply changes.
- Use Docker DNS: Relying on container names rather than IPs is a best practice for Dockerized applications.
Conclusion
This journey was equal parts frustrating and educational. Debugging in Dockerized environments can feel like trying to solve a Rubik’s Cube with one hand tied behind your back. But with patience, methodical troubleshooting, and a bit of programmer humor, I managed to untangle the mess.
So, if you ever find yourself battling Docker, Redis, or BullMQ, remember: the solution might be just one DNS name away. And if not? Well, at least you’ll have a story to tell. 😄