What's Actually Happening

Envoy filters are not being applied to traffic. Custom filters don't affect requests as expected.

The Error You'll See

  • Filter configuration not taking effect
  • Requests not being modified
  • Filter not appearing in config dump

Why This Happens

  1. 1.Filter not properly configured
  2. 2.Wrong listener binding
  3. 3.Filter order issues
  4. 4.Configuration syntax error
  5. 5.Filter disabled

Step 1: Check Envoy Config Dump

bash
curl http://localhost:9901/config_dump
curl http://localhost:9901/config_dump?include_eds

Step 2: Check Filter Configuration

bash
# In config_dump, look for:
# "http_filters" or "filters"
curl -s http://localhost:9901/config_dump | jq '.configs[0].dynamic_listeners[0].filter_chains[0].filters'

Step 3: Check Listener

bash
curl -s http://localhost:9901/config_dump | jq '.configs[].dynamic_listeners[]?.name'
curl -s http://localhost:9901/config_dump/listeners

Step 4: Verify Filter Order

yaml
# Filters are applied in order
http_filters:
  - name: my-filter
  - name: envoy.filters.http.router

Step 5: Check Filter Stats

bash
curl http://localhost:9901/stats | grep my_filter

Step 5: Check Logs

bash
# Envoy logs
docker logs envoy
# Or sidecar logs
kubectl logs deployment/myapp -c istio-proxy

Step 7: Validate Configuration

bash
envoy --mode validate -c /etc/envoy/envoy.yaml

Step 8: Check Admin Interface

bash
curl http://localhost:9901/server_info
curl http://localhost:9901/listeners
curl http://localhost:9901/clusters

Step 9: Reload Configuration

bash
curl -X POST http://localhost:9901/restart
# Or hot reload:
curl -X POST http://localhost:9901/restart?restart_type=hot_restart

Step 10: Debug Filter

yaml
# Enable debug logging
admin:
  access_log_path: /tmp/admin_access.log
  address:
    socket_address:
      protocol: TCP
      address: 0.0.0.0
      port_value: 9901
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  • [Fix Istio Traffic Not Routing](/articles/fix-istio-traffic-not-routing)