Add a Docker Compose example with Haproxy and an echo server (#7)

.dockerignore

@@ -0,0 +1,4 @@
+.dockerignore
+.git
+.github
+.gitignore

README.md

@@ -83,6 +83,10 @@ Example invocation:
 sudo ./go-mmproxy -l 0.0.0.0:25577 -4 127.0.0.1:25578 -6 [::1]:25578 --allowed-subnets ./net-prefixes.txt
 ```
 
+### Docker examples
+
+You can find an example Dockerfile and a Docker Compose setup in the [docker-example directory](https://github.com/kzemek/go-mmproxy/tree/main/docker-example).
+
 ## Benchmark
 
 ### Setup

docker-example/Dockerfile

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+FROM golang:1.21 AS builder
+RUN apt-get update && apt-get install -y iptables iproute2 && apt-get clean
+WORKDIR /app/src/go-mmproxy
+COPY . .
+RUN CGO_ENABLED=0 go build -v
+ENTRYPOINT ["sh", "-x", "docker-example/entrypoint.sh"]

docker-example/Dockerfile.echo

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+FROM ubuntu
+RUN apt-get update && apt-get install -y ncat iproute2 tcpdump inetutils-ping iptables && apt-get clean

docker-example/docker-compose.yml

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+services:
+  echo:
+    build:
+      context: .
+      dockerfile: Dockerfile.echo
+    command: ip route replace default via 10.5.5.3 && ncat -kvnl -e /bin/cat 0.0.0.0 9000
+    cap_add: [ NET_ADMIN ]
+    networks:
+      backend:
+        ipv4_address: 10.5.5.2
+
+  go-mmproxy:
+    build:
+      context: ../
+      dockerfile: docker-example/Dockerfile
+    command: ./go-mmproxy -l 0.0.0.0:1234 -4 10.5.5.2:9000 -p tcp -v 2 -mark 123
+    privileged: true
+    networks:
+      backend:
+        ipv4_address: 10.5.5.3
+      default:
+
+
+  haproxy:
+    image: haproxy:2.9
+    ports: [ 8000:8000 ]
+    volumes:
+      - ./haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg
+
+networks:
+  backend:
+    ipam:
+      config:
+        - subnet: 10.5.5.0/24
+          gateway: 10.5.5.1

docker-example/entrypoint.sh

@@ -0,0 +1,12 @@
+echo 1 > /proc/sys/net/ipv4/conf/all/route_localnet
+
+# Outgoing packets
+iptables -t mangle -A OUTPUT -m mark --mark 123 -j CONNMARK --save-mark
+iptables -t mangle -A OUTPUT -m mark --mark 123 -j MARK --set-mark 0
+# Incoming packets
+iptables -t mangle -A PREROUTING -m connmark --mark 123 -j CONNMARK --restore-mark
+
+ip rule add fwmark 123 lookup 100
+ip route add local 0.0.0.0/0 dev lo table 100
+
+env "$@"

docker-example/haproxy.cfg

@@ -0,0 +1,7 @@
+frontend myfrontend
+  bind :8000
+  default_backend mybackend
+
+backend mybackend
+  balance roundrobin
+  server go-mmproxy-v1 go-mmproxy:1234 send-proxy