Docker for Mac's Proxy GUI is a monster; avoid it by setting ENV directly in LinuxKit config

Docker-for-Mac.md

@@ -1,44 +1,63 @@
-# Attention: issues for developer scenarios!
+# Attention: don't use Docker's own GUI to set the proxy!
 
-- beware: this will probably break your Docker for Mac install in more ways than one
+- See https://github.com/docker/for-mac/issues/2467
-- docker for mac does bizarre stuff with proxies, affecting runtime and building of containers
+- In `Docker > Preferences`, in `Resources > Proxies`, make sure you're NOT using manual proxies
-- you might run into https://github.com/docker/for-mac/issues/2467 
+- Use the hack below to set the environment var directly in LinuxKit
-  - building images is affected for sure; simple "FROM ubuntu; RUN apt update" fails
+- The issue is that setting it in the GUI affects containers too (!!!), and we don't want that in this scenario
+- If you actually need an upstream proxy (for company proxy etc) this will NOT work.
 
 # Using a Docker Desktop for Mac as a client for the proxy
 
 First, know this is a MiTM, and could break with new Docker Desktop for Mac releases or during resets/reinstalls/upgrades.
 
 These instructions tested on Mac OS Catalina, and:
-- Docker Desktop for Mac `2.5.0.0` (Stable) (which provides Docker `19.03`)
 - Docker Desktop for Mac `2.4.2.0` (Edge) (which provides Docker `20.10.0-beta1`)
+- Docker Desktop for Mac `2.5.0.0` (Stable) (which provides Docker `19.03`)
 
 This assumes you have `docker-registry-proxy` running _somewhere else_, eg, on a different machine on your local network.
 
 See the main [README.md](README.md) for instructions. (If you're trying to run both proxy and client on the same machine, see below).
 
-For these examples I will assume it is successfully running on `http://192.168.1.2:3128/`
+We'll inject the CA certificates and the HTTPS_PROXY env into the Docker install inside the HyperKit VM running LinuxKit that is used by Docker Desktop for Mac.
 
-- Make sure you can access the proxy. On your Mac/Terminal (not Docker), run:
+To do that, we use a privileged container. `justincormack/nsenter1` does the job nicely. 
-  ```shell script
+
-  # with wget...
+First things first:
-  wget --quiet -O - "http://192.168.1.2:3128/"
+
-  # ... or, with curl:
+### 1) Factory Reset Docker Desktop for Mac...
-  curl "http://192.168.1.2:3128/"
+... or make sure it's pristine (just installed).
+
+- Go into Troubleshoot > "Reset to Factory defaults"
+- it will take a while to reset/restart everything and require your password.
+ 
+### 2) Inject config into Docker's VM
+
+For these examples I will assume it is successfully running on `http://192.168.1.2:3128/` -- 
+change the `export DRP_PROXY` as appropriate. Do not include slashes.
+
+Run these commands in your Mac terminal.
+
+```bash
+set -e
+export DRP_PROXY="192.168.66.100:3129" # Format IP:port, change this 
+wget -O - "http://${DRP_PROXY}/" # Make sure you can reach the proxy
+# Inject the CA certificate
+docker run -it --privileged --pid=host justincormack/nsenter1 \
+  /bin/bash -c "wget -O - http://$DRP_PROXY/ca.crt \
+ | tee -a /containers/services/docker/lower/etc/ssl/certs/ca-certificates.crt"
+
+# Preserve original config.
+docker run -it --privileged --pid=host justincormack/nsenter1 /bin/bash -c "cp /containers/services/docker/config.json /containers/services/docker/config.json.orig"
+
+# Inject the HTTPS_PROXY enviroment variable. I dare you find a better way.
+docker run -it --privileged --pid=host justincormack/nsenter1 /bin/bash -c "sed -ibeforedockerproxy -e  's/\"PATH=/\"HTTPS_PROXY=http:\/\/$DRP_PROXY\/\",\"PATH=/' /containers/services/docker/config.json"
 ```
-- Make sure your Docker Desktop for Mac install is pristine like new, go into Troubleshoot > "Reset to Factory defaults".
+
-- Inject the CA certificates into the Docker install inside the HyperKit VM running LinuxKit that is used by Docker Desktop for Mac.
+### 3) Restart, test.
-  To do that, we use a privileged container. `justincormack/nsenter1` does the job nicely: 
+
-  ```shell script
+- Restart Docker. (Quit & Open again, or just go into Preferences and give it more RAM, then Restart.) 
-  docker run -it --privileged --pid=host justincormack/nsenter1 /bin/bash -c "wget -O - http://192.168.1.2:3128/ca.crt | tee -a /containers/services/docker/lower/etc/ssl/certs/ca-certificates.crt"
-  ```
-- Go into `Docker > Preferences`, and set `Resources > Proxies` to 
-  - "Manual proxy configuration" to ON
-    - HTTP proxy: `http://192.168.1.2:3128/`
-    - HTTPS proxy: `http://192.168.1.2:3128/`
-  - (Optional) I also recommend "Enable CLI experimental features" under "Experimental Features" (since I use `buildx` a lot)
-  - Click button "Apply & Restart", wait for it to restart.
 - Try a `docker pull` now. It should be using the proxy (watch the logs on the proxy server).
+- Test that no crazy proxy has been set: `docker run -it curlimages/curl:latest http://ifconfig.me` and `docker run -it curlimages/curl:latest https://ifconfig.me` both work.
 - Important: **push**es done with this configured will either not work, or use the auth you configured on the proxy, if any. Beware, and report back.  
   
 
@@ -48,8 +67,8 @@ For these examples I will assume it is successfully running on `http://192.168.1
 
 You need to pre-pull the proxy itself and `justincormack/nsenter1`.
 
-Then set up the proxy server, and then follow the instructions above (without the Factory Reset).
+Follow the instructions above, but pre-pull after the Factory Reset.
 
-Do NOT use 127.0.0.1, instead use your machine's local LAN IP address. (Hint: there's a good chance 192.168.64.1 is useable, due the the way Docker Desktop for Mac sets networking up).
+Do NOT use 127.0.0.1, instead use your machine's local LAN IP address.
 
 Make sure to bring the proxy up after applying/restarting the Docker Engine.