Add step to wait for launcher files to be ready (#576)

Adds a small bash script and calls it in CI to block the CI from progressing until the launcher release files are uploaded.

.github/workflows/build.yml

@@ -20,6 +20,10 @@ jobs:
   build-northstar:
     runs-on: ubuntu-20.04
     steps:
+      - name: Wait for launcher release build to be ready
+        timeout-minutes: 30 # Only wait for 30 minutes. If we take longer, something probably broke
+        run:
+          bash wait_dl.sh
       - name: Download compiled launcher
         run:
           wget "https://github.com/R2Northstar/NorthstarLauncher/releases/download/${{ env.NORTHSTAR_VERSION }}/northstar-launcher.zip"

wait_for_launcher_dl.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+
+# Check if contains command line arg
+if [ -z "$1" ]; then
+    echo "Missing command-line argument."
+    exit 1
+fi
+
+url="https://github.com/R2Northstar/NorthstarLauncher/releases/tag/$1"
+wait_time_seconds=60
+
+# Loop until the response code changes
+while true; do
+    response=$(curl --silent --output /dev/null --write-out "%{http_code}" $url)
+    if [ $response -ne 200 ]; then
+        echo "Response is not 200. Retrying in $wait_time_seconds seconds."
+        sleep $wait_time_seconds
+    else
+        echo "Site is accessible with response code $response."
+        break
+    fi
+done
+
+# 10 second sleep just in case we hit some weird race condition
+# where files are still being uploaded but release is done
+sleep 10