Seed CLI telemetry session IDs from CI workflow context

.github/workflows/add-lockdown-label.yml

@@ -13,6 +13,9 @@ permissions:
   actions: write # For managing the operation state cache
   issues: write
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   add-label:
     runs-on: ubuntu-latest

.github/workflows/add-servicing-consider-label.yml

@@ -13,6 +13,9 @@ permissions:
   contents: read
   pull-requests: write
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   add-servicing-label:
     runs-on: ubuntu-latest

.github/workflows/aot-size-analysis.yml

@@ -31,6 +31,7 @@ on:
 permissions: read-all
 
 env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
   AZDO_ORG: dnceng-public
   AZDO_PROJECT: public
   AZDO_PIPELINE_ID: "101"

.github/workflows/backport.yml

@@ -15,6 +15,9 @@ permissions:
   pull-requests: write
   actions: write
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   backport:
     uses: dotnet/arcade/.github/workflows/backport-base.yml@main

.github/workflows/check-vendored-files.yml

@@ -33,6 +33,9 @@ concurrency:
   group: vendored-files-check
   cancel-in-progress: false
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   validate:
     name: Validate manifest

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

@@ -18,6 +18,8 @@ jobs:
 
   copilot-setup-steps:
     runs-on: ubuntu-latest
+    env:
+      DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:

.github/workflows/detect-netsdk-diagnostics.yml

@@ -25,6 +25,9 @@ on:
 
 permissions: read-all
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   detect-diagnostics:
     name: Detect New NETSDK Diagnostic Codes

.github/workflows/fix-completions-on-comment.yml

@@ -13,6 +13,7 @@ permissions:
   contents: read
 
 env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
   REPO_NAME: ${{ github.event.repository.name }}
   RUN_URL: https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}
 

.github/workflows/inter-branch-merge-flow.yml

@@ -9,6 +9,9 @@ permissions:
   contents: write
   pull-requests: write
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   Merge:
     uses: dotnet/arcade/.github/workflows/inter-branch-merge-base.yml@main

.github/workflows/labeler-cache-retention.yml

@@ -21,6 +21,7 @@ on:
         default: "ACTIVE"
 
 env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
   CACHE_KEY: ${{ inputs.cache_key || 'ACTIVE' }}
 
 jobs:

.github/workflows/labeler-predict-issues.yml

@@ -23,6 +23,7 @@ on:
         default: "ACTIVE"
 
 env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
   # Do not allow failure for jobs triggered automatically (as this causes red noise on the workflows list)
   ALLOW_FAILURE: ${{ github.event_name == 'workflow_dispatch' }}
 

.github/workflows/labeler-predict-pulls.yml

@@ -36,6 +36,7 @@ on:
         default: "ACTIVE"
 
 env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
   # Do not allow failure for jobs triggered automatically (this can block PR merge)
   ALLOW_FAILURE: ${{ github.event_name == 'workflow_dispatch' }}
 

.github/workflows/labeler-promote.yml

@@ -30,6 +30,9 @@ on:
 permissions:
   actions: write
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   promote-issues:
     if: ${{ inputs.issues }}

.github/workflows/labeler-train.yml

@@ -45,6 +45,7 @@ on:
         default: "staged"
 
 env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
   CACHE_KEY: ${{ inputs.cache_key_suffix }}
   REPOSITORY: ${{ github.repository }}
   LABEL_PREFIX: "Area-"

.github/workflows/pr-analysis.yml

@@ -5,6 +5,9 @@ on:
 permissions:
   contents: read
   pull-requests: read
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   allowed-labels:
     runs-on: ubuntu-latest

.github/workflows/remove-lockdown-label.yml

@@ -12,6 +12,9 @@ permissions:
     actions: write
     pull-requests: write
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
     remove-labels:
         # Only run on the main repository, not forks

.github/workflows/stale.yml

@@ -5,6 +5,7 @@ on:
   workflow_dispatch: # Allow manual trigger for testing
 
 env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
   KBE_LABEL: 'Known Build Error'
   STALE_LABEL: 'stale'
   KEEP_OPEN_LABEL: 'keep-open'

.github/workflows/update-man-pages.yml

@@ -9,6 +9,9 @@ permissions:
   contents: write
   pull-requests: write
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   update-man-pages:
     runs-on: ubuntu-latest

.github/workflows/update-static-web-assets-baselines.yml

@@ -11,6 +11,9 @@ on:
 permissions:
   contents: read
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   metadata:
     name: Fetch Pull Request Metadata

.github/workflows/update-xlf-on-comment.yml

@@ -13,6 +13,7 @@ permissions:
   contents: read
 
 env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
   REPO_NAME: ${{ github.event.repository.name }}
   RUN_URL: https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}
 jobs:

.github/workflows/validate-pat-pool.yml

@@ -8,6 +8,9 @@ on:
 # No GitHub API permissions needed
 permissions: {}
 
+env:
+  DOTNET_CLI_TELEMETRY_SESSIONID: gha-${{ github.repository_id }}-${{ github.run_id }}-${{ github.run_attempt }}
+
 jobs:
   validate:
     environment: copilot-pat-pool

.vsts-ci.yml

@@ -35,6 +35,8 @@ variables:
 - template: /eng/pipelines/templates/variables/sdk-defaults.yml
 # Variables used: DncEngInternalBuildPool
 - template: /eng/common/templates-official/variables/pool-providers.yml
+- name: DOTNET_CLI_TELEMETRY_SESSIONID
+  value: azdo-$(System.CollectionId)-$(System.TeamProjectId)-$(Build.BuildId)
 # Helix testing requires a token when internally run.
 # Variables used: HelixApiAccessToken
 - group: DotNet-HelixApi-Access

.vsts-pr.yml

@@ -34,6 +34,8 @@ variables:
 - template: /eng/pipelines/templates/variables/sdk-defaults.yml
 # Variables used: DncEngPublicBuildPool
 - template: /eng/common/templates/variables/pool-providers.yml
+- name: DOTNET_CLI_TELEMETRY_SESSIONID
+  value: azdo-$(System.CollectionId)-$(System.TeamProjectId)-$(Build.BuildId)
 
 resources:
   containers:

documentation/project-docs/telemetry.md

@@ -33,6 +33,11 @@ The .NET SDK telemetry can be disabled using the following environment variable:
   - Values: `false`, `0`, or `no` to allow messages
   - Default: `false` (messages are displayed)
   - Note: This flag does not affect telemetry collection itself
+- **`DOTNET_CLI_TELEMETRY_SESSIONID`**: Seeds the initial telemetry session ID
+  - When set, the CLI uses this value instead of generating a new GUID for the first `TelemetryClient` created in the process
+  - This is useful for correlating multiple `dotnet` invocations that belong to the same CI workflow, job, or higher-level user session
+  - If not set, the CLI generates a new GUID per process as before
+
 
 - **`DOTNET_CLI_TELEMETRY_DISABLE_TRACE_EXPORT`**: Set to `1`, `true`, or `yes` to disable exporting trace
   telemetry to Azure Monitor (both persistence and upload). Metrics/OTLP export and the local disk log are
@@ -125,7 +130,7 @@ Every telemetry event automatically includes these common properties:
 | **Product Type** | Type of .NET product | Product identifier |
 | **Libc Release** | Libc release information | Libc release version |
 | **Libc Version** | Libc version information | Libc version number |
-| **SessionId** | Unique session identifier | GUID |
+| **SessionId** | Unique session identifier | GUID or CI-specific correlation identifier |
 
 ## Telemetry Events
 

src/Cli/dotnet/README.md

@@ -85,3 +85,7 @@ Specifies the location of the servicing index to use by the shared host when loa
 `DOTNET_CLI_TELEMETRY_OPTOUT`
 
 Specifies whether data about the .NET Core tools usage is collected and sent to Microsoft. **true** to opt-out of the telemetry feature (values true, 1 or yes accepted); otherwise, **false** (values false, 0 or no accepted). If not set, it defaults to **false**, that is, the telemetry feature is on.
+
+`DOTNET_CLI_TELEMETRY_SESSIONID`
+
+Seeds the initial telemetry session identifier for the current `dotnet` process. When set, multiple `dotnet` invocations can share the same value to correlate telemetry across a CI workflow or other higher-level session.

src/Cli/dotnet/Telemetry/TelemetryClient.cs

@@ -191,7 +191,11 @@ public TelemetryClient(string? sessionId, IEnvironmentProvider? environmentProvi
             s_tracerProvider ??= s_tracerProviderBuilder.Build();
         }
 
-        CurrentSessionId ??= !string.IsNullOrEmpty(sessionId) ? sessionId : Guid.NewGuid().ToString();
+        var initialSessionId = !string.IsNullOrEmpty(sessionId)
+            ? sessionId
+            : environmentProvider.GetEnvironmentVariable(EnvironmentVariableNames.DOTNET_CLI_TELEMETRY_SESSIONID);
+
+        CurrentSessionId ??= !string.IsNullOrEmpty(initialSessionId) ? initialSessionId : Guid.NewGuid().ToString();
         s_commonProperties = new TelemetryCommonProperties().GetTelemetryCommonProperties(CurrentSessionId);
     }
 

test/dotnet.Tests/CommandTests/MSBuild/GivenMsbuildForwardingApp.cs

@@ -3,7 +3,11 @@
 
 #nullable disable
 
+using Microsoft.DotNet.Cli;
 using Microsoft.DotNet.Cli.Commands.MSBuild;
+using Microsoft.DotNet.Cli.Telemetry;
+using Microsoft.DotNet.Cli.Utils;
+using Moq;
 
 namespace Microsoft.DotNet.Cli.MSBuild.Tests
 {
@@ -19,7 +23,7 @@ public GivenMsbuildForwardingApp()
         public void DotnetExeIsExecuted()
         {
             var msbuildPath = "<msbuildpath>";
-            new MSBuildForwardingApp(new string[0], msbuildPath)
+            new MSBuildForwardingApp(Array.Empty<string>(), msbuildPath)
                 .GetProcessStartInfo().FileName.Should().EndWith("dotnet.exe");
         }
 
@@ -28,7 +32,7 @@ public void DotnetExeIsExecuted()
         public void DotnetIsExecuted()
         {
             var msbuildPath = "<msbuildpath>";
-            new MSBuildForwardingApp(new string[0], msbuildPath)
+            new MSBuildForwardingApp(Array.Empty<string>(), msbuildPath)
                 .GetProcessStartInfo().FileName.Should().EndWith("dotnet");
         }
 
@@ -39,7 +43,7 @@ public void DotnetIsExecuted()
         public void ItSetsEnvironmentalVariables(string envVarName)
         {
             var msbuildPath = "<msbuildpath>";
-            var startInfo = new MSBuildForwardingApp(new string[0], msbuildPath).GetProcessStartInfo();
+            var startInfo = new MSBuildForwardingApp(Array.Empty<string>(), msbuildPath).GetProcessStartInfo();
             startInfo.Environment.ContainsKey(envVarName).Should().BeTrue();
         }
 
@@ -48,7 +52,7 @@ public void ItSetsMSBuildExtensionPathToExistingPath()
         {
             var msbuildPath = "<msbuildpath>";
             var envVar = "MSBuildExtensionsPath";
-            new DirectoryInfo(new MSBuildForwardingApp(new string[0], msbuildPath)
+            new DirectoryInfo(new MSBuildForwardingApp(Array.Empty<string>(), msbuildPath)
                                 .GetProcessStartInfo()
                                 .Environment[envVar])
                 .Should()
@@ -60,7 +64,7 @@ public void ItSetsMSBuildSDKsPathToExistingPath()
         {
             var msbuildPath = "<msbuildpath>";
             var envVar = "MSBuildSDKsPath";
-            new DirectoryInfo(new MSBuildForwardingApp(new string[0], msbuildPath)
+            new DirectoryInfo(new MSBuildForwardingApp(Array.Empty<string>(), msbuildPath)
                                 .GetProcessStartInfo()
                                 .Environment[envVar])
                 .Should()
@@ -72,7 +76,7 @@ public void ItSetsOrIgnoresTelemetrySessionId()
         {
             var msbuildPath = "<msbuildpath>";
             var envVar = "DOTNET_CLI_TELEMETRY_SESSIONID";
-            var startInfo = new MSBuildForwardingApp(new string[0], msbuildPath)
+            var startInfo = new MSBuildForwardingApp(Array.Empty<string>(), msbuildPath)
                 .GetProcessStartInfo();
 
             string sessionId = startInfo.Environment[envVar];
@@ -83,16 +87,49 @@ public void ItSetsOrIgnoresTelemetrySessionId()
             //  for session ID, so ignore if they already set it
             if (sessionId != "test")
             {
-                (sessionId == null || Guid.TryParse(sessionId, out _))
-                    .Should().BeTrue("DOTNET_CLI_TELEMETRY_SESSIONID should be null or current session id");
+                (sessionId == null || Guid.TryParse(sessionId, out _) || sessionId == TelemetryClient.CurrentSessionId)
+                    .Should().BeTrue("DOTNET_CLI_TELEMETRY_SESSIONID should be null, current session id, or a guid");
+            }
+        }
+
+        [TestMethod]
+        [DoNotParallelize]
+        public void ItUsesSeededTelemetrySessionId()
+        {
+            const string sessionId = "gha-12345-1";
+            var msbuildPath = "<msbuildpath>";
+            var environmentProvider = new Mock<IEnvironmentProvider>(MockBehavior.Strict);
+
+            TelemetryClient.DisabledForTests = true;
+            TelemetryClient.DisabledForTests = false;
+
+            try
+            {
+                environmentProvider
+                    .Setup(p => p.GetEnvironmentVariableAsBool(EnvironmentVariableNames.TELEMETRY_OPTOUT, It.IsAny<bool>()))
+                    .Returns(false);
+                environmentProvider
+                    .Setup(p => p.GetEnvironmentVariable(EnvironmentVariableNames.DOTNET_CLI_TELEMETRY_SESSIONID))
+                    .Returns(sessionId);
+
+                _ = new TelemetryClient(sessionId: null, environmentProvider: environmentProvider.Object);
+
+                var startInfo = new MSBuildForwardingApp(Array.Empty<string>(), msbuildPath)
+                    .GetProcessStartInfo();
+
+                startInfo.Environment["DOTNET_CLI_TELEMETRY_SESSIONID"].Should().Be(sessionId);
+            }
+            finally
+            {
+                TelemetryClient.DisabledForTests = true;
             }
         }
 
         [TestMethod]
         public void ItDoesNotSetCurrentWorkingDirectory()
         {
             var msbuildPath = "<msbuildpath>";
-            var startInfo = new MSBuildForwardingApp(new string[0], msbuildPath)
+            var startInfo = new MSBuildForwardingApp(Array.Empty<string>(), msbuildPath)
                 .GetProcessStartInfo().WorkingDirectory.Should().Be("");
         }