Issue Type: Potential docker network issue or potential loop
Host: Debian 10 (buster) VM on vSphere7
**Docker:**20.10.17
Containers:
- tomcat:9.0.60-jdk17-openjdk-slim-buster
- postgres:13.4 (debian:buster)
The Situation:
Recently ran into an issue where the network was reporting very high load (>5Gbps+)
While troubleshooting I found netstat
was reporting several thousand HTTPS connections between the bridge and the container VIF - ESTABLISHED and CLOSE_WAIT.
There were NOT enough inbound connections to the host to account for more than ~1000 connections per minute.
Software stack is simple - webapp running in tomcat, data stored in postgres.
Port 443 is configured in Tomcat container and exposed on the host.
The Strange:
- Containers were destroyed and recreated multiple times using
docker-compose
, which claimed to remove the network. - Host VM was rebooted to add more CPU to handle the load (under the assumption Tomcat servlet was falling behind due to processing incoming data)
- Issue continued to happen.
- Accidentally jacked up
iptables
while attempting to create rules to block all, but a single in-bound connection to the host. This effectively broke docker networking. - Cleared all firewall rules.
- Restarted docker
systemctl <stop/start> docker
- After docker daemon restart, network resumed normal operation. Inbound data <200Mbps
The Questions:
- Has anyone seen similar behavior before?
- What’s are the best resources and/or tools to troubleshoot docker network issues?