Add possibility to forward custom ports

README.md

@@ -62,6 +62,28 @@ docker run -it lukechilds/dockerpi pi3
 
 > **Note:** In the Pi 2 and Pi 3 machines, QEMU hangs once the machines are powered down requiring you to `docker kill` the container. See [#4](https://github.com/lukechilds/dockerpi/pull/4) for details.
 
+## Port forwarding
+
+In some applications you may want to have access to some ports of the Raspberry Pi (e.g. for SSH connection). To do so, you can set the `QEMU_HOSTFWD` enviroment variable of the container by adding one or more entries, separated by spaces, in the standard QEMU format (`protocol::hostip:hostport-guestip:guestport`).
+
+Example using the `docker run` command to expose the SSH and MQTT ports from the Raspberry Pi to the Container (`-e` part) and from the Container to the Host (`-p` part):
+
+```
+docker run -it -e QEMU_HOSTFWD="tcp::5022-:22 tcp::1883-:1883" -p 5022:5022 -p 1883:1883 lukechilds/dockerpi
+```
+
+Example using the `docker-compose.yml` file to achieve the same result:
+
+```yml
+services:
+  dockerpi:
+    image: lukechilds/dockerpi
+    environment:
+     - QEMU_HOSTFWD=tcp::5022-:22 tcp::1883-:1883
+    ports:
+     - "5022:5022"
+     - "1883:1883"
+```
 
 ## Wait, what?
 

entrypoint.sh

@@ -25,30 +25,32 @@ if [[ "$(($image_size_in_bytes % ($GIB_IN_BYTES * 2)))" != "0" ]]; then
   qemu-img resize $image_path "${new_size_in_gib}G"
 fi
 
+for fwd in $QEMU_HOSTFWD; do hostfwd="$hostfwd,hostfwd=$fwd"; done
+
 if [ "${target}" = "pi1" ]; then
   emulator=qemu-system-arm
   kernel="/root/qemu-rpi-kernel/kernel-qemu-4.19.50-buster"
   dtb="/root/qemu-rpi-kernel/versatile-pb.dtb"
   machine=versatilepb
   memory=256m
   root=/dev/sda2
-  nic="--net nic --net user,hostfwd=tcp::5022-:22"
+  nic="--net nic --net user$hostfwd"
 elif [ "${target}" = "pi2" ]; then
   emulator=qemu-system-arm
   machine=raspi2b
   memory=1024m
   kernel_pattern=kernel7.img
   dtb_pattern=bcm2709-rpi-2-b.dtb
   append="dwc_otg.fiq_fsm_enable=0"
-  nic="-netdev user,id=net0,hostfwd=tcp::5022-:22 -device usb-net,netdev=net0"
+  nic="-netdev user,id=net0$hostfwd -device usb-net,netdev=net0"
 elif [ "${target}" = "pi3" ]; then
   emulator=qemu-system-aarch64
   machine=raspi3b
   memory=1024m
   kernel_pattern=kernel8.img
   dtb_pattern=bcm2710-rpi-3-b-plus.dtb
   append="dwc_otg.fiq_fsm_enable=0"
-  nic="-netdev user,id=net0,hostfwd=tcp::5022-:22 -device usb-net,netdev=net0"
+  nic="-netdev user,id=net0$hostfwd -device usb-net,netdev=net0"
 else
   echo "Target ${target} not supported"
   echo "Supported targets: pi1 pi2 pi3"