[copilot] fix disk space usage (#10574)

Context: https://github.com/dotnet/android/actions/runs/19085458511

Copilot is running out of disk space, but it has a second drive at `/mnt/` we could be using.

* Create a symlink `./bin` -> `/mnt/bin` for all build output.

* Set env vars for `/mnt/android-archives` and `/mnt/android-toolchain`

Author: jonathanpeppers

.github/workflows/copilot-setup-steps.yml

@@ -6,13 +6,38 @@ jobs:
   copilot-setup-steps:
     runs-on: ubuntu-latest
     timeout-minutes: 120
+    env:
+      AndroidToolchainCacheDirectory: /mnt/android-archives
+      AndroidToolchainDirectory: /mnt/android-toolchain
 
     steps:
     - name: Checkout repository
       uses: actions/checkout@v4
       with:
         submodules: recursive
 
+    - name: Log disk space (after checkout)
+      uses: ./.github/workflows/log-disk-space
+
+    - name: Setup build directories on secondary disk
+      run: |
+        echo "Setting up Android toolchain on /mnt (secondary disk with 66G+ free)"
+        
+        # Create directories with sudo and set ownership
+        sudo mkdir -p /mnt/android-archives
+        sudo mkdir -p /mnt/android-toolchain
+        sudo mkdir -p /mnt/bin
+        sudo chown $USER:$USER /mnt/android-archives /mnt/android-toolchain /mnt/bin
+        
+        # Remove bin directory if it exists and create symlink to use the secondary disk
+        rm -rf ./bin
+        ln -s /mnt/bin ./bin
+        
+        echo "Android toolchain directories configured:"
+        ls -la /mnt
+        ls -lah bin
+        df -h /mnt
+
     - name: Setup .NET
       uses: actions/setup-dotnet@v4
       with:
@@ -25,6 +50,11 @@ jobs:
         make jenkins PREPARE_CI=1 PREPARE_AUTOPROVISION=1 CONFIGURATION=Debug
       timeout-minutes: 60
 
+    - name: Log disk space (after android build)
+      uses: ./.github/workflows/log-disk-space
+      with:
+        detailed: 'true'
+
     - name: Upload logs
       uses: actions/upload-artifact@v4
       if: steps.android-build.outcome == 'failure'

.github/workflows/log-disk-space/action.yml

@@ -0,0 +1,68 @@
+name: Log Disk Space
+description: Logs disk space usage on the runner
+inputs:
+  detailed:
+    description: 'Whether to include detailed disk analysis (true/false)'
+    required: false
+    default: 'false'
+runs:
+  using: composite
+  steps:
+  - name: Display disk space
+    shell: bash
+    run: |
+      MAX_LINES=20
+      
+      echo "=== Disk Space Usage ==="
+      df -h
+      echo ""
+      echo "=== Inode Usage ==="
+      df -i
+      echo ""
+      echo "=== Disk Usage Summary ==="
+      df -h / | tail -1 | awk '{print "Used: " $3 " / " $2 " (" $5 " full)"}'
+      echo ""
+      echo "=== /mnt disk info ==="
+      echo "Permissions:"
+      ls -la / | grep mnt
+      echo "Contents:"
+      ls -la /mnt 2>/dev/null || echo "/mnt is empty or not accessible"
+      echo "Disk usage:"
+      df -h /mnt
+
+      # Detailed analysis if requested
+      if [ "${{ inputs.detailed }}" = "true" ]; then
+        echo ""
+        echo "=== DETAILED ANALYSIS ==="
+        echo ""
+        echo "=== Largest directories in /home/runner ==="
+        sudo du -h /home/runner 2>/dev/null | sort -rh | head -$MAX_LINES || true
+        echo ""
+        echo "=== Largest directories in /opt ==="
+        sudo du -h /opt 2>/dev/null | sort -rh | head -$MAX_LINES || true
+        echo ""
+        echo "=== Workspace breakdown (top level) ==="
+        du -h --max-depth=1 . 2>/dev/null | sort -rh || true
+        echo ""
+        echo "=== Workspace breakdown (2 levels deep) ==="
+        du -h --max-depth=2 . 2>/dev/null | sort -rh | head -$MAX_LINES || true
+        echo ""
+        echo "=== bin directory ==="
+        du -sh ./bin/* 2>/dev/null | sort -rh | head -$MAX_LINES || echo "No bin"
+        echo ""
+        echo "=== external directory ==="
+        du -sh ./external/* 2>/dev/null | sort -rh | head -$MAX_LINES || echo "No external"
+        echo ""
+        echo "=== Android toolchain directories ==="
+        du -sh /mnt/android-archives 2>/dev/null || echo "No android-archives"
+        du -sh /mnt/android-toolchain 2>/dev/null || echo "No android-toolchain"
+        echo ""
+        echo "=== /mnt disk usage ==="
+        du -h --max-depth=1 /mnt 2>/dev/null | sort -rh || true
+        echo ""
+        echo "=== Docker usage ==="
+        docker system df 2>/dev/null || echo "Docker not available"
+        echo ""
+        echo "=== Temp directories ==="
+        du -sh /tmp /var/tmp 2>/dev/null || true
+      fi