terorie/netem-agent repository overview

⁠Docker netem agent

netem-agent is a container that artificially slows down a Docker network. I use it to test the behavior of distributed systems when exposed to real-world networking conditions.

• Easily emulate properties of WANs in a Docker network via netem⁠
  • Delay packets with jitter
  • Introduce packet loss, reordering, etc.
• Works in Swarm mode, Requires no special preparation of the target containers
  • Unlike e.g. pumba⁠, a powerful chaos-testing tool which needs the iproute2 package in the target containers.
• Relies on standard Linux tooling

⁠How does it work?

It uses dockerveth⁠ in the host network context to map all selected containers to their veth interfaces.

Then, it activates the NetEm traffic control facilities on those interfaces.

⁠Configuration

Requirements:

• Linux machine
• Preparation of target containers not required
• Access to the Docker daemon
• NET_ADMIN capability on agent and elevated privileges (TODO Make it work with less privileges)
• Access to Docker network namespaces
• Host networking enabled on agent
• Running as regular Docker container, not Swarm service

Example:

docker run -it --rm \
  --name netem-agent \
  --cap-add=NET_ADMIN \
  --privileged \
  --net=host \
  -v /var/run/docker.sock:/var/run/docker.sock:ro \
  -v /var/run/docker/netns:/var/run/netns:ro \
  terorie/netem-agent \
  --name='^dummy.*' \
  --delay=100ms \
  --jitter=50ms

⁠Options

• --interval Update interval
• --name Container name regex filters (optional, by default delaying all containers)
• --delay Outgoing packets delay
• --jitter Delay jitter
• --delete Delete all delays and exit

⁠Attributions

• dockerveth⁠ for getting the veth interfaces of containers
• miller⁠ for crafting with CSV
• Developed at Nimiq for testing of the Albatross network⁠