self-hosted-runners: make Actions Runner path customizable

Some Azure VM types have a temporary disk which is local to the VM and
therefore provides _much_ faster disk IO than the OS Disk (or any other
attached disk).

Hosted GitHub Actions runners also leverage this disk and do their work
in D:/a/_work, so let's use it too if we can. It leads to a ~25% speed
increase when doing heavy IO operations.

Ref: https://learn.microsoft.com/en-us/azure/virtual-machines/managed-disks-overview#temporary-disk
Ref:
https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners#supported-runners-and-hardware-resources
Signed-off-by: Dennis Ameling (he/him) <[email protected]>

Author: dennisameling

.github/workflows/create-azure-self-hosted-runners.yml

@@ -134,6 +134,15 @@ jobs:
           | jq --raw-output .token)
         echo "::add-mask::$ACTIONS_RUNNER_TOKEN"
         echo ACTIONS_RUNNER_TOKEN=$ACTIONS_RUNNER_TOKEN >> $GITHUB_ENV
+
+        # The Azure VM type we use has blazing-fast local, temporary storage available as the D:\ drive.
+        # The only downside is that, after dellocation, the contents of this disk (including the Actions Runner),
+        # are destroyed. Let's only use it when we don't immediately deallocate the VM.
+        if [[ "${{ env.DEALLOCATE_IMMEDIATELY }}" == "true" ]]; then
+          echo "ACTIONS_RUNNER_PATH=C:\a" >> $GITHUB_ENV
+        else
+          echo "ACTIONS_RUNNER_PATH=D:\a" >> $GITHUB_ENV
+        fi
         
     - name: Azure Login
       uses: azure/login@v1
@@ -144,7 +153,7 @@ jobs:
       with:
         resourceGroupName: ${{ secrets.AZURE_RESOURCE_GROUP }}
         template: ./azure-self-hosted-runners/azure-arm-template.json
-        parameters: ./azure-self-hosted-runners/azure-arm-template-example-parameters.json githubActionsRunnerRegistrationUrl="${{ env.ACTIONS_RUNNER_REGISTRATION_URL }}" githubActionsRunnerToken="${{ env.ACTIONS_RUNNER_TOKEN }}" postDeploymentPsScriptUrl="${{ env.POST_DEPLOYMENT_SCRIPT_URL }}" virtualMachineName=${{ steps.generate-vm-name.outputs.vm_name }} virtualMachineSize=${{ env.AZURE_VM_TYPE }} publicIpAddressName1=${{ steps.generate-vm-name.outputs.vm_name }}-ip adminUsername=${{ secrets.AZURE_VM_USERNAME }} adminPassword=${{ secrets.AZURE_VM_PASSWORD }} stopService={{ env.DEALLOCATE_IMMEDIATELY }}
+        parameters: ./azure-self-hosted-runners/azure-arm-template-example-parameters.json githubActionsRunnerRegistrationUrl="${{ env.ACTIONS_RUNNER_REGISTRATION_URL }}" githubActionsRunnerToken="${{ env.ACTIONS_RUNNER_TOKEN }}" postDeploymentPsScriptUrl="${{ env.POST_DEPLOYMENT_SCRIPT_URL }}" virtualMachineName=${{ steps.generate-vm-name.outputs.vm_name }} virtualMachineSize=${{ env.AZURE_VM_TYPE }} publicIpAddressName1=${{ steps.generate-vm-name.outputs.vm_name }}-ip adminUsername=${{ secrets.AZURE_VM_USERNAME }} adminPassword=${{ secrets.AZURE_VM_PASSWORD }} stopService={{ env.DEALLOCATE_IMMEDIATELY }} githubActionsRunnerPath="${{ env.ACTIONS_RUNNER_PATH }}"
 
     - name: Deallocate the VM for later use
       if: env.DEALLOCATE_IMMEDIATELY == 'true'

azure-self-hosted-runners/azure-arm-template.json

@@ -16,6 +16,12 @@
                 "description": "GitHub Actions Runner registration token for the org/repo. Note that these tokens are only valid for one hour after creation!"
             }
         },
+        "githubActionsRunnerPath": {
+            "type": "string",
+            "metadata": {
+                "description": "Path to the Actions Runner. Keep this path short to prevent Long Path issues, e.g. D:\\a"
+            }
+        },
         "postDeploymentPsScriptUrl": {
             "type": "string",
             "minLength": 6,
@@ -256,7 +262,7 @@
                         "value": "[parameters('location')]"
                     },
                     "arguments": {
-                        "value": "[concat('-GitHubActionsRunnerToken ', parameters('githubActionsRunnerToken'), ' -GithubActionsRunnerRegistrationUrl ', parameters('githubActionsRunnerRegistrationUrl'), ' -GithubActionsRunnerName ', parameters('virtualMachineName'), ' -StopService ', parameters('stopService'))]"
+                        "value": "[concat('-GitHubActionsRunnerToken ', parameters('githubActionsRunnerToken'), ' -GithubActionsRunnerRegistrationUrl ', parameters('githubActionsRunnerRegistrationUrl'), ' -GithubActionsRunnerName ', parameters('virtualMachineName'), ' -StopService ', parameters('stopService'), ' -GitHubActionsRunnerPath ', parameters('githubActionsRunnerPath'))]"
                     }
                 }
             },

azure-self-hosted-runners/post-deployment-script.ps1

@@ -16,7 +16,11 @@ param (
     # Stop Service immediately (useful for spinning up runners preemptively)
     [Parameter(Mandatory=$false)]
     [ValidateSet('true', 'false')]
-    [string]$StopService = 'true'
+    [string]$StopService = 'true',
+
+    # Path to the Actions Runner. Keep this path short to prevent Long Path issues, e.g. D:\a
+    [Parameter(Mandatory=$true)]
+    [string]$GitHubActionsRunnerPath
 )
 
 Write-Output "Starting post-deployment script."
@@ -33,8 +37,6 @@ $GitHubActionsRunnerVersion = "2.300.2"
 $GithubActionsRunnerArch = "arm64"
 $GithubActionsRunnerHash = "9409e50d9ad33d8031355ed079b8f56cf3699f35cf5d0ca51e54deed432758ef"
 $GithubActionsRunnerLabels = "self-hosted,Windows,ARM64"
-# Keep this path short to prevent Long Path issues
-$GitHubActionsRunnerPath = "C:\a"
 
 # ======================
 # WINDOWS DEVELOPER MODE