ci: document and fix a couple things for local Docker testing (#3672)

Signed-off-by: Reactor Scram <ReactorScram@users.noreply.github.com>
Co-authored-by: Jamil <jamilbk@users.noreply.github.com>

CONTRIBUTING.md

@@ -98,7 +98,6 @@ To start the local Firezone cluster, follow these steps:
 
 ```
 docker compose build
-docker compose up -d postgres
 docker compose run --rm elixir /bin/sh -c "cd apps/domain && mix ecto.create && mix ecto.migrate && mix ecto.seed"
 
 # Before moving to the next step, copy the Firezone account UUID from the seed step

docker-compose.yml

@@ -114,6 +114,7 @@ services:
       RUST_LOG: firezone_linux_client=trace,wire=trace,connlib_client_shared=trace,firezone_tunnel=trace,connlib_shared=trace,warn
       FIREZONE_API_URL: ws://api:8081
       FIREZONE_ID: D0455FDE-8F65-4960-A778-B934E4E85A5F
+    init: true
     build:
       target: debug
       context: rust

rust/linux-client/README.md

@@ -13,6 +13,14 @@ cargo build --release --bin firezone-linux-client
 
 You should then find a binary in `target/release/firezone-linux-client`.
 
+The releases on Github are built with musl. To build this way, use:
+
+```bash
+rustup target add x86_64-unknown-linux-musl
+sudo apt-get install musl-tools
+cargo build --release --bin firezone-linux-client --target x86_64-unknown-linux-musl
+```
+
 ## Running
 
 To run the Linux client:

scripts/tests/dns-etc-resolvconf.sh

@@ -21,6 +21,9 @@ function gateway() {
     docker compose exec -it gateway "$@"
 }
 
+# Re-up the gateway since a local dev setup may run this back-to-back
+docker compose up -d gateway
+
 echo "# check original resolv.conf"
 client sh -c "cat /etc/resolv.conf.firezone-backup"