同一容器部署Alertmanager与Unsee及Nginx反向代理故障排查

Hey there! Let’s figure out why your /unsee endpoint is throwing that ERR_INVALID_RESPONSE error—especially since you confirmed Unsee works perfectly when curling http://127.0.0.1:8080. The issue almost certainly lies in how Nginx is proxying requests to Unsee, so let’s break this down step by step.

Common Configuration Fixes to Try #

1. Fix Proxy Path Handling #

If your Nginx location /unsee block doesn’t handle URI paths correctly, Unsee might get malformed requests it can’t respond to. For example, omitting the trailing slash in proxy_pass makes Nginx pass the /unsee prefix to Unsee, which doesn’t expect it (since Unsee serves content from its own root /).

Use this corrected location block:

location /unsee/ {
    # Forward requests to Unsee's local port
    proxy_pass http://127.0.0.1:8080/;
    
    # Add critical headers to help Unsee process the request properly
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
}

Notice the trailing slash in both location /unsee/ and proxy_pass—this tells Nginx to strip the /unsee prefix when forwarding requests to Unsee, matching how Unsee expects to receive traffic.

2. Check Nginx Error Logs for Clues #

Nginx’s error logs will give you specific details about what’s failing. Run this command to view the latest errors in real time:

tail -f /var/log/nginx/error.log

Look for messages like "connection refused" (if Unsee isn’t listening on 127.0.0.1:8080) or "invalid response from upstream" (if Unsee rejects the request format).

3. Verify Unsee’s Binding Address #

Double-check that Unsee is configured to listen on 0.0.0.0:8080 or 127.0.0.1:8080. If it’s only bound to a specific container IP that Nginx can’t reach, that would cause a failure. Your curl test to 127.0.0.1:8080 suggests this is probably fine, but it’s worth confirming in Unsee’s config file.

Test Your Changes #

After updating your Nginx configuration:

1. Validate the config to catch syntax errors:

   nginx -t
   

2. Reload Nginx to apply the changes:

   nginx -s reload
   

3. Try accessing /unsee again in your browser—this should resolve the ERR_INVALID_RESPONSE error.

内容的提问来源于stack exchange，提问作者Simply Seth