Debugging Containers Without Shell Access: Quick Tips

1. Run Commands Inside the Container’s Namespace

Every container runs in isolated namespaces. Use nsenter to “enter” these namespaces from the host:

# Get the container’s PID (Docker example)
PID=$(docker inspect -f ‘{{.State.Pid}}’ your_…


This content originally appeared on DEV Community and was authored by Mark Nefedov

1. Run Commands Inside the Container’s Namespace

Every container runs in isolated namespaces. Use nsenter to "enter" these namespaces from the host:

# Get the container’s PID (Docker example)
PID=$(docker inspect -f '{{.State.Pid}}' your_container)  

# Inspect processes inside the container’s PID namespace
sudo nsenter -p -t $PID ps aux  

# Check network sockets in the container’s network namespace
sudo nsenter -n -t $PID ss -tnlp

Replace ps or ss with any host-installed tool (e.g., tcpdump, strace).

2. Access Container Files via /proc

Container filesystems are mounted under /proc/$PID/root:

# View container files
ls /proc/$PID/root/etc/nginx/  

# Edit configs directly from the host
vim /proc/$PID/root/app/config.yaml

Why This Works

https://www.man7.org/linux/man-pages/man7/namespaces.7.html


This content originally appeared on DEV Community and was authored by Mark Nefedov


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