foxglove-sdk/docker-compose.netem.yml at main · foxglove/foxglove-sdk · GitHub

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# Compose override that adds a netem sidecar to the LiveKit service for
# simulating degraded network conditions (latency, jitter, packet loss) on
# WebRTC UDP traffic.
#
# Usage:
#   docker compose -f docker-compose.yaml -f docker-compose.netem.yml up -d --wait
#
# The sidecar shares the LiveKit container's network namespace and applies tc
# netem rules to all network interfaces. This shapes all egress from LiveKit —
# including RTC media/data packets sent back to test clients. Applying to all
# interfaces (not just eth0) is necessary because rootless Podman with pasta
# networking forwards published-port traffic through the loopback interface.
#
# Configure via the NETEM_ARGS environment variable. It accepts any arguments
# valid after `tc qdisc replace dev <iface> root netem`. Defaults to moderate
# impairment (80ms delay, 20ms jitter, 2% packet loss).
#
# Examples:
#   # Good network
#   NETEM_ARGS="delay 20ms 5ms" docker compose -f docker-compose.yaml -f docker-compose.netem.yml up -d --wait
#
#   # Poor wifi
#   NETEM_ARGS="delay 150ms 50ms loss 5%" docker compose -f docker-compose.yaml -f docker-compose.netem.yml up -d --wait
#
#   # Severe degradation with bandwidth cap
#   NETEM_ARGS="delay 300ms 100ms loss 10% rate 500kbit" docker compose -f docker-compose.yaml -f docker-compose.netem.yml up -d --wait
#
#   # Packet reordering (common trigger for WebRTC jitter buffer issues)
#   NETEM_ARGS="delay 50ms 10ms reorder 25% loss 1%" docker compose -f docker-compose.yaml -f docker-compose.netem.yml up -d --wait
#
# Requirements:
#   - Linux host: works natively.
#   - macOS host: requires Docker Desktop >= 4.27 (sch_netem kernel module fix).
#   - GitHub Actions: works on ubuntu-latest runners.

services:
  livekit:
    ports:
      - "9999:9999/udp" # UDP echo for netem packet loss testing

  netem:
    image: alpine:3
    network_mode: "service:livekit"
    cap_add:
      - NET_ADMIN
    environment:
      NETEM_ARGS: "${NETEM_ARGS:-delay 80ms 20ms loss 2%}"
    entrypoint: ["/bin/sh", "-c"]
    command:
      - |
        apk add --no-cache iproute2 socat > /dev/null 2>&1
        # Start a UDP echo server for packet loss testing. Each received
        # datagram is echoed back through the netem-shaped egress path.
        socat UDP-RECVFROM:9999,fork EXEC:/bin/cat &
        # Apply netem to all interfaces. This covers both Docker (eth0)
        # and Podman rootless/pasta (lo) port forwarding paths.
        # Use "replace" instead of "add" to handle pre-existing qdiscs.
        for iface in $$(ls /sys/class/net/); do
          tc qdisc replace dev "$$iface" root netem $${NETEM_ARGS} 2>/dev/null && \
            echo "netem applied to $$iface: $${NETEM_ARGS}"
        done
        tc -s qdisc show
        # Keep the container alive so the qdisc rules persist.
        exec sleep infinity
    healthcheck:
      test: ["CMD-SHELL", "tc qdisc show | grep -q netem"]
      interval: 2s
      timeout: 5s
      retries: 10
    depends_on:
      livekit:
        condition: service_started