diff --git a/CHANGELOG.md b/CHANGELOG.md
index b32065a..c1e0c1e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,16 @@
 Task 6.0.3
 - Fix minimum agent requirement to `2.206.1` ([#13](https://github.com/qetza/replacetokens-task/issues/13)).
 - Fix paths in sources incompatible with `fast-glob` syntax on win32 ([#16](https://github.com/qetza/replacetokens-task/issues/16)).
+- Add agent OS in telemetry ([#5](https://github.com/qetza/replacetokens-task/issues/5)).
+
+Task 5.3.1
+- Add agent OS in telemetry ([#5](https://github.com/qetza/replacetokens-task/issues/5)).
+
+Task 4.4.1
+- Add agent OS in telemetry ([#5](https://github.com/qetza/replacetokens-task/issues/5)).
+
+Task 3.12.1
+- Add agent OS in telemetry ([#5](https://github.com/qetza/replacetokens-task/issues/5)).
 
 ## 5.0.2
 Task 6.0.2
diff --git a/README.md b/README.md
index 3a72e9e..556dd91 100644
--- a/README.md
+++ b/README.md
@@ -319,6 +319,7 @@ The following **anonymous** data is send:
 - the **hash** of your collection id
 - the **hash** of your project id and pipeline definition id
 - the hosting (`server` or `cloud`)
+- the agent OS (`Windows`, `macOS` or `Linux`)
 - the inputs values for
   - _addBOM_
   - _charsToEscape_
diff --git a/tasks/ReplaceTokensV3/CHANGELOG.md b/tasks/ReplaceTokensV3/CHANGELOG.md
index 5d7cb6d..ccc5b8c 100644
--- a/tasks/ReplaceTokensV3/CHANGELOG.md
+++ b/tasks/ReplaceTokensV3/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## 3.12.1
+- Add agent OS in telemetry ([#5](https://github.com/qetza/replacetokens-task/issues/5)).
+
 ## 3.12.0
 - Add support for `indent` transformation with indent size and indent first line parameters ([326](https://github.com/qetza/vsts-replacetokens-task/issues/326)).
 - Add support for `REPLACETOKENS_TELEMETRY_OPTOUT` environment variable.
diff --git a/tasks/ReplaceTokensV3/README.md b/tasks/ReplaceTokensV3/README.md
index 2b277b5..33e3764 100644
--- a/tasks/ReplaceTokensV3/README.md
+++ b/tasks/ReplaceTokensV3/README.md
@@ -240,6 +240,7 @@ The following **anonymous** data is send:
 - the **hash** of your project id and pipeline definition id
 - the pipeline type (`build` or `release`)
 - the hosting (`server` or `services`)
+- the agent OS (`Windows`, `macOS` or `Linux`)
 - the input values for
   - _actionOnMissing_
   - _charsToEscape_
diff --git a/tasks/ReplaceTokensV3/index.ts b/tasks/ReplaceTokensV3/index.ts
index 928f617..80a7ab9 100644
--- a/tasks/ReplaceTokensV3/index.ts
+++ b/tasks/ReplaceTokensV3/index.ts
@@ -520,6 +520,19 @@ async function run() {
       .digest('hex');
     telemetryEvent.pipelineType = tl.getVariable('release.releaseid') ? 'release' : 'build';
     telemetryEvent.serverType = !serverType || serverType.toLowerCase() !== 'hosted' ? 'server' : 'cloud';
+    telemetryEvent.os = (() => {
+      const os = tl.getVariable('Agent.OS');
+      switch (os) {
+        case 'Windows_NT':
+          return 'Windows';
+        case 'Darwin':
+          return 'macOS';
+        case 'Linux':
+          return 'Linux';
+        default:
+          return os || 'unknown';
+      }
+    })();
 
     // load inputs
     const root: string = tl.getPathInput('rootDirectory', false, true);
diff --git a/tasks/ReplaceTokensV3/task.json b/tasks/ReplaceTokensV3/task.json
index 16b9213..b928770 100644
--- a/tasks/ReplaceTokensV3/task.json
+++ b/tasks/ReplaceTokensV3/task.json
@@ -13,7 +13,7 @@
   "version": {
     "Major": 3,
     "Minor": 12,
-    "Patch": 0
+    "Patch": 1
   },
   "instanceNameFormat": "Replace tokens in $(targetFiles)",
   "minimumAgentVersion": "2.105.0",
diff --git a/tasks/ReplaceTokensV3/telemetry.ts b/tasks/ReplaceTokensV3/telemetry.ts
index c5d46b0..0369ea7 100644
--- a/tasks/ReplaceTokensV3/telemetry.ts
+++ b/tasks/ReplaceTokensV3/telemetry.ts
@@ -73,7 +73,8 @@ export default function trackEvent(event: TelemetryEvent, proxyUrl?: string): st
             inlineVariables: event.inlineVariables,
             enableRecursion: event.enableRecursion,
             useLegacyEmptyFeature: event.useLegacyEmptyFeature,
-            useDefaultValue: event.useDefaultValue
+            useDefaultValue: event.useDefaultValue,
+            os: event.os
           }
         }
       }
@@ -170,4 +171,5 @@ export interface TelemetryEvent {
   enableRecursion: boolean;
   useLegacyEmptyFeature: boolean;
   useDefaultValue: boolean;
+  os: string;
 }
diff --git a/tasks/ReplaceTokensV3/tests/L0.ts b/tasks/ReplaceTokensV3/tests/L0.ts
index cfc3645..09fd436 100644
--- a/tasks/ReplaceTokensV3/tests/L0.ts
+++ b/tasks/ReplaceTokensV3/tests/L0.ts
@@ -56,6 +56,7 @@ describe('ReplaceTokens v3 L0 suite', function () {
     process.env['SYSTEM_COLLECTIONID'] = 'col01';
     process.env['SYSTEM_TEAMPROJECTID'] = 'project01';
     process.env['SYSTEM_DEFINITIONID'] = 'def01';
+    process.env['AGENT_OS'] = 'Windows_NT';
 
     if (fs.existsSync(tmp)) removeFolder(tmp);
 
@@ -67,6 +68,7 @@ describe('ReplaceTokens v3 L0 suite', function () {
     delete process.env['SYSTEM_COLLECTIONID'];
     delete process.env['SYSTEM_TEAMPROJECTID'];
     delete process.env['SYSTEM_DEFINITIONID'];
+    delete process.env['AGENT_OS'];
   });
 
   afterEach(() => {
@@ -165,7 +167,7 @@ describe('ReplaceTokens v3 L0 suite', function () {
 
           tr.stdout.should.include('telemetry sent');
           tr.stdout.should.match(
-            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"3\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"failed"}}}}/
+            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"3\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"failed","os":"Windows"}}}}/
           );
         },
         tr,
@@ -190,7 +192,7 @@ describe('ReplaceTokens v3 L0 suite', function () {
 
           tr.stdout.should.include('telemetry sent');
           tr.stdout.should.match(
-            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"3\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"succeed","tokenPrefix":"#{","tokenSuffix":"}#","pattern":"#\\\\{\\\\s\*\(\(\?:\(\?!#\\\\{\)\(\?!\\\\s\*\\\\}#\)\.\)\*\)\\\\s\*\\\\}#","encoding":"auto","keepToken":false,"actionOnMissing":"warn","writeBOM":true,"verbosity":"normal","variableFiles":0,"rules":1,"rulesWithInputWildcard":0,"rulesWithOutputPattern":0,"rulesWithNegativePattern":0,"duration":\d+(?:\.\d+)?,"tokenReplaced":1,"tokenFound":1,"fileProcessed":1,"useLegacyPattern":false,"enableTransforms":false,"transformPrefix":"\(","transformSuffix":"\)","transformPattern":"\\\\s\*\(\.\*\)\\\\\(\\\\s\*\(\(\?:\(\?!\\\\\(\)\(\?!\\\\s\*\\\\\)\)\.\)\*\)\\\\s\*\\\\\)\\\\s\*","transformExecuted":0,"defaultValue":"","defaultValueReplaced":0,"actionOnNoFiles":"continue","inlineVariables":0,"enableRecursion":false,"useLegacyEmptyFeature":false,"useDefaultValue":false}}}}/
+            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"3\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"succeed","tokenPrefix":"#{","tokenSuffix":"}#","pattern":"#\\\\{\\\\s\*\(\(\?:\(\?!#\\\\{\)\(\?!\\\\s\*\\\\}#\)\.\)\*\)\\\\s\*\\\\}#","encoding":"auto","keepToken":false,"actionOnMissing":"warn","writeBOM":true,"verbosity":"normal","variableFiles":0,"rules":1,"rulesWithInputWildcard":0,"rulesWithOutputPattern":0,"rulesWithNegativePattern":0,"duration":\d+(?:\.\d+)?,"tokenReplaced":1,"tokenFound":1,"fileProcessed":1,"useLegacyPattern":false,"enableTransforms":false,"transformPrefix":"\(","transformSuffix":"\)","transformPattern":"\\\\s\*\(\.\*\)\\\\\(\\\\s\*\(\(\?:\(\?!\\\\\(\)\(\?!\\\\s\*\\\\\)\)\.\)\*\)\\\\s\*\\\\\)\\\\s\*","transformExecuted":0,"defaultValue":"","defaultValueReplaced":0,"actionOnNoFiles":"continue","inlineVariables":0,"enableRecursion":false,"useLegacyEmptyFeature":false,"useDefaultValue":false,"os":"Windows"}}}}/
           );
         },
         tr,
diff --git a/tasks/ReplaceTokensV4/CHANGELOG.md b/tasks/ReplaceTokensV4/CHANGELOG.md
index 7c7dcc1..85f38c7 100644
--- a/tasks/ReplaceTokensV4/CHANGELOG.md
+++ b/tasks/ReplaceTokensV4/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## 4.4.1
+- Add agent OS in telemetry ([#5](https://github.com/qetza/replacetokens-task/issues/5)).
+
 ## 4.4.0
 - Add support for `indent` transformation with indent size and indent first line parameters ([326](https://github.com/qetza/vsts-replacetokens-task/issues/326)).
 - Add support for `REPLACETOKENS_TELEMETRY_OPTOUT` environment variable.
diff --git a/tasks/ReplaceTokensV4/README.md b/tasks/ReplaceTokensV4/README.md
index aad28a4..45db8e9 100644
--- a/tasks/ReplaceTokensV4/README.md
+++ b/tasks/ReplaceTokensV4/README.md
@@ -278,6 +278,7 @@ The following **anonymous** data is send:
 - the **hash** of your project id and pipeline definition id
 - the pipeline type (`build` or `release`)
 - the hosting (`server` or `services`)
+- the agent OS (`Windows`, `macOS` or `Linux`)
 - the input values for
   - _actionOnMissing_
   - _charsToEscape_
diff --git a/tasks/ReplaceTokensV4/index.ts b/tasks/ReplaceTokensV4/index.ts
index e93c1e6..ca53996 100644
--- a/tasks/ReplaceTokensV4/index.ts
+++ b/tasks/ReplaceTokensV4/index.ts
@@ -520,6 +520,19 @@ async function run() {
       .digest('hex');
     telemetryEvent.pipelineType = tl.getVariable('release.releaseid') ? 'release' : 'build';
     telemetryEvent.serverType = !serverType || serverType.toLowerCase() !== 'hosted' ? 'server' : 'cloud';
+    telemetryEvent.os = (() => {
+      const os = tl.getVariable('Agent.OS');
+      switch (os) {
+        case 'Windows_NT':
+          return 'Windows';
+        case 'Darwin':
+          return 'macOS';
+        case 'Linux':
+          return 'Linux';
+        default:
+          return os || 'unknown';
+      }
+    })();
 
     // load inputs
     const root: string = tl.getPathInput('rootDirectory', false, true);
diff --git a/tasks/ReplaceTokensV4/task.json b/tasks/ReplaceTokensV4/task.json
index 3847cf2..597effa 100644
--- a/tasks/ReplaceTokensV4/task.json
+++ b/tasks/ReplaceTokensV4/task.json
@@ -13,7 +13,7 @@
   "version": {
     "Major": 4,
     "Minor": 4,
-    "Patch": 0
+    "Patch": 1
   },
   "releaseNotes": "Added output variables (breaking change).<br/>Added token pattern dropdown (breaking change).",
   "instanceNameFormat": "Replace tokens in $(targetFiles)",
diff --git a/tasks/ReplaceTokensV4/telemetry.ts b/tasks/ReplaceTokensV4/telemetry.ts
index ac97b26..0d678a6 100644
--- a/tasks/ReplaceTokensV4/telemetry.ts
+++ b/tasks/ReplaceTokensV4/telemetry.ts
@@ -74,7 +74,8 @@ export default function trackEvent(event: TelemetryEvent, proxyUrl?: string): st
             inlineVariables: event.inlineVariables,
             enableRecursion: event.enableRecursion,
             useLegacyEmptyFeature: event.useLegacyEmptyFeature,
-            useDefaultValue: event.useDefaultValue
+            useDefaultValue: event.useDefaultValue,
+            os: event.os
           }
         }
       }
@@ -172,4 +173,5 @@ export interface TelemetryEvent {
   enableRecursion: boolean;
   useLegacyEmptyFeature: boolean;
   useDefaultValue: boolean;
+  os: string;
 }
diff --git a/tasks/ReplaceTokensV4/tests/L0.ts b/tasks/ReplaceTokensV4/tests/L0.ts
index 6c9fb1f..3726a27 100644
--- a/tasks/ReplaceTokensV4/tests/L0.ts
+++ b/tasks/ReplaceTokensV4/tests/L0.ts
@@ -56,6 +56,7 @@ describe('ReplaceTokens v4 L0 suite', function () {
     process.env['SYSTEM_COLLECTIONID'] = 'col01';
     process.env['SYSTEM_TEAMPROJECTID'] = 'project01';
     process.env['SYSTEM_DEFINITIONID'] = 'def01';
+    process.env['AGENT_OS'] = 'Windows_NT';
 
     if (fs.existsSync(tmp)) removeFolder(tmp);
 
@@ -67,6 +68,7 @@ describe('ReplaceTokens v4 L0 suite', function () {
     delete process.env['SYSTEM_COLLECTIONID'];
     delete process.env['SYSTEM_TEAMPROJECTID'];
     delete process.env['SYSTEM_DEFINITIONID'];
+    delete process.env['AGENT_OS'];
   });
 
   afterEach(() => {
@@ -165,7 +167,7 @@ describe('ReplaceTokens v4 L0 suite', function () {
 
           tr.stdout.should.include('telemetry sent');
           tr.stdout.should.match(
-            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"4\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"failed"}}}}/
+            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"4\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"failed","os":"Windows"}}}}/
           );
         },
         tr,
@@ -190,7 +192,7 @@ describe('ReplaceTokens v4 L0 suite', function () {
 
           tr.stdout.should.include('telemetry sent');
           tr.stdout.should.match(
-            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"4\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"succeed","tokenPrefix":"#{","tokenSuffix":"}#","pattern":"#\\\\{\\\\s\*\(\(\?:\(\?!#\\\\{\)\(\?!\\\\s\*\\\\}#\)\.\)\*\)\\\\s\*\\\\}#","encoding":"auto","keepToken":false,"actionOnMissing":"warn","writeBOM":true,"verbosity":"normal","variableFiles":0,"rules":1,"rulesWithInputWildcard":0,"rulesWithOutputPattern":0,"rulesWithNegativePattern":0,"duration":\d+(?:\.\d+)?,"tokenReplaced":1,"tokenFound":1,"fileProcessed":1,"useLegacyPattern":false,"enableTransforms":false,"transformPrefix":"\(","transformSuffix":"\)","transformPattern":"\\\\s\*\(\.\*\)\\\\\(\\\\s\*\(\(\?:\(\?!\\\\\(\)\(\?!\\\\s\*\\\\\)\)\.\)\*\)\\\\s\*\\\\\)\\\\s\*","transformExecuted":0,"defaultValue":"","defaultValueReplaced":0,"tokenPattern":"default","actionOnNoFiles":"continue","inlineVariables":0,"enableRecursion":false,"useLegacyEmptyFeature":false,"useDefaultValue":false}}}}/
+            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"4\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"succeed","tokenPrefix":"#{","tokenSuffix":"}#","pattern":"#\\\\{\\\\s\*\(\(\?:\(\?!#\\\\{\)\(\?!\\\\s\*\\\\}#\)\.\)\*\)\\\\s\*\\\\}#","encoding":"auto","keepToken":false,"actionOnMissing":"warn","writeBOM":true,"verbosity":"normal","variableFiles":0,"rules":1,"rulesWithInputWildcard":0,"rulesWithOutputPattern":0,"rulesWithNegativePattern":0,"duration":\d+(?:\.\d+)?,"tokenReplaced":1,"tokenFound":1,"fileProcessed":1,"useLegacyPattern":false,"enableTransforms":false,"transformPrefix":"\(","transformSuffix":"\)","transformPattern":"\\\\s\*\(\.\*\)\\\\\(\\\\s\*\(\(\?:\(\?!\\\\\(\)\(\?!\\\\s\*\\\\\)\)\.\)\*\)\\\\s\*\\\\\)\\\\s\*","transformExecuted":0,"defaultValue":"","defaultValueReplaced":0,"tokenPattern":"default","actionOnNoFiles":"continue","inlineVariables":0,"enableRecursion":false,"useLegacyEmptyFeature":false,"useDefaultValue":false,"os":"Windows"}}}}/
           );
         },
         tr,
diff --git a/tasks/ReplaceTokensV5/CHANGELOG.md b/tasks/ReplaceTokensV5/CHANGELOG.md
index c89901f..c6511de 100644
--- a/tasks/ReplaceTokensV5/CHANGELOG.md
+++ b/tasks/ReplaceTokensV5/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## 5.3.1
+- Add agent OS in telemetry ([#5](https://github.com/qetza/replacetokens-task/issues/5)).
+
 ## 5.3.0
 - Add support for `indent` transformation with indent size and indent first line parameters ([326](https://github.com/qetza/vsts-replacetokens-task/issues/326)).
 - Add support for `REPLACETOKENS_TELEMETRY_OPTOUT` environment variable.
diff --git a/tasks/ReplaceTokensV5/README.md b/tasks/ReplaceTokensV5/README.md
index ef6bdcc..7cb29dd 100644
--- a/tasks/ReplaceTokensV5/README.md
+++ b/tasks/ReplaceTokensV5/README.md
@@ -276,6 +276,7 @@ The following **anonymous** data is send:
 - the **hash** of your project id and pipeline definition id
 - the pipeline type (`build` or `release`)
 - the hosting (`server` or `services`)
+- the agent OS (`Windows`, `macOS` or `Linux`)
 - the input values for
   - _actionOnMissing_
   - _charsToEscape_
diff --git a/tasks/ReplaceTokensV5/index.ts b/tasks/ReplaceTokensV5/index.ts
index 064b751..e154981 100644
--- a/tasks/ReplaceTokensV5/index.ts
+++ b/tasks/ReplaceTokensV5/index.ts
@@ -519,6 +519,19 @@ async function run() {
       .digest('hex');
     telemetryEvent.pipelineType = tl.getVariable('release.releaseid') ? 'release' : 'build';
     telemetryEvent.serverType = !serverType || serverType.toLowerCase() !== 'hosted' ? 'server' : 'cloud';
+    telemetryEvent.os = (() => {
+      const os = tl.getVariable('Agent.OS');
+      switch (os) {
+        case 'Windows_NT':
+          return 'Windows';
+        case 'Darwin':
+          return 'macOS';
+        case 'Linux':
+          return 'Linux';
+        default:
+          return os || 'unknown';
+      }
+    })();
 
     // load inputs
     const root: string = tl.getPathInput('rootDirectory', false, true);
diff --git a/tasks/ReplaceTokensV5/task.json b/tasks/ReplaceTokensV5/task.json
index b660542..ada9230 100644
--- a/tasks/ReplaceTokensV5/task.json
+++ b/tasks/ReplaceTokensV5/task.json
@@ -13,7 +13,7 @@
   "version": {
     "Major": 5,
     "Minor": 3,
-    "Patch": 0
+    "Patch": 1
   },
   "releaseNotes": "Migrate to Node10 handler (breaking change).<br/>Add Node16 handler.",
   "instanceNameFormat": "Replace tokens in $(targetFiles)",
diff --git a/tasks/ReplaceTokensV5/telemetry.ts b/tasks/ReplaceTokensV5/telemetry.ts
index 80e1ac6..e5c8566 100644
--- a/tasks/ReplaceTokensV5/telemetry.ts
+++ b/tasks/ReplaceTokensV5/telemetry.ts
@@ -74,7 +74,8 @@ export default function trackEvent(event: TelemetryEvent, proxyUrl?: string): st
             inlineVariables: event.inlineVariables,
             enableRecursion: event.enableRecursion,
             useLegacyEmptyFeature: event.useLegacyEmptyFeature,
-            useDefaultValue: event.useDefaultValue
+            useDefaultValue: event.useDefaultValue,
+            os: event.os
           }
         }
       }
@@ -175,4 +176,5 @@ export interface TelemetryEvent {
   enableRecursion: boolean;
   useLegacyEmptyFeature: boolean;
   useDefaultValue: boolean;
+  os: string;
 }
diff --git a/tasks/ReplaceTokensV5/tests/L0.ts b/tasks/ReplaceTokensV5/tests/L0.ts
index a4ab251..d2b4e7d 100644
--- a/tasks/ReplaceTokensV5/tests/L0.ts
+++ b/tasks/ReplaceTokensV5/tests/L0.ts
@@ -55,6 +55,7 @@ describe('ReplaceTokens v5 L0 suite', function () {
     process.env['SYSTEM_COLLECTIONID'] = 'col01';
     process.env['SYSTEM_TEAMPROJECTID'] = 'project01';
     process.env['SYSTEM_DEFINITIONID'] = 'def01';
+    process.env['AGENT_OS'] = 'Windows_NT';
 
     if (fs.existsSync(tmp)) removeFolder(tmp);
 
@@ -66,6 +67,7 @@ describe('ReplaceTokens v5 L0 suite', function () {
     delete process.env['SYSTEM_COLLECTIONID'];
     delete process.env['SYSTEM_TEAMPROJECTID'];
     delete process.env['SYSTEM_DEFINITIONID'];
+    delete process.env['AGENT_OS'];
   });
 
   afterEach(() => {
@@ -164,7 +166,7 @@ describe('ReplaceTokens v5 L0 suite', function () {
 
           tr.stdout.should.include('telemetry sent');
           tr.stdout.should.match(
-            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"5\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"failed"}}}}/
+            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"5\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"failed","os":"Windows"}}}}/
           );
         },
         tr,
@@ -188,7 +190,7 @@ describe('ReplaceTokens v5 L0 suite', function () {
           tr.succeeded.should.equal(true, 'task succeeded');
           tr.stdout.should.include('telemetry sent');
           tr.stdout.should.match(
-            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"5\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"succeed","tokenPrefix":"#{","tokenSuffix":"}#","pattern":"#\\\\{\\\\s\*\(\(\?:\(\?!#\\\\{\)\(\?!\\\\s\*\\\\}#\)\.\)\*\)\\\\s\*\\\\}#","encoding":"auto","keepToken":false,"actionOnMissing":"warn","writeBOM":true,"verbosity":"normal","variableFiles":0,"rules":1,"rulesWithInputWildcard":0,"rulesWithOutputPattern":0,"rulesWithNegativePattern":0,"duration":\d+(?:\.\d+)?,"tokenReplaced":1,"tokenFound":1,"fileProcessed":1,"useLegacyPattern":false,"enableTransforms":false,"transformPrefix":"\(","transformSuffix":"\)","transformPattern":"\\\\s\*\(\.\*\)\\\\\(\\\\s\*\(\(\?:\(\?!\\\\\(\)\(\?!\\\\s\*\\\\\)\)\.\)\*\)\\\\s\*\\\\\)\\\\s\*","transformExecuted":0,"defaultValue":"","defaultValueReplaced":0,"tokenPattern":"default","actionOnNoFiles":"continue","inlineVariables":0,"enableRecursion":false,"useLegacyEmptyFeature":false,"useDefaultValue":false}}}}/
+            /\{"name":"Microsoft\.ApplicationInsights\.Dev\.\*+\.Event","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"5\.\d+\.\d+","ai\.cloud\.role":"server","ai\.internal\.sdkVersion":"replacetokens:1\.0\.0","ai\.operation\.id":"([^"]+)","ai\.operation\.name":"replacetokens-task","ai\.operation\.parentId":"\|\1","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"preview":false,"pipelineType":"build","result":"succeed","tokenPrefix":"#{","tokenSuffix":"}#","pattern":"#\\\\{\\\\s\*\(\(\?:\(\?!#\\\\{\)\(\?!\\\\s\*\\\\}#\)\.\)\*\)\\\\s\*\\\\}#","encoding":"auto","keepToken":false,"actionOnMissing":"warn","writeBOM":true,"verbosity":"normal","variableFiles":0,"rules":1,"rulesWithInputWildcard":0,"rulesWithOutputPattern":0,"rulesWithNegativePattern":0,"duration":\d+(?:\.\d+)?,"tokenReplaced":1,"tokenFound":1,"fileProcessed":1,"useLegacyPattern":false,"enableTransforms":false,"transformPrefix":"\(","transformSuffix":"\)","transformPattern":"\\\\s\*\(\.\*\)\\\\\(\\\\s\*\(\(\?:\(\?!\\\\\(\)\(\?!\\\\s\*\\\\\)\)\.\)\*\)\\\\s\*\\\\\)\\\\s\*","transformExecuted":0,"defaultValue":"","defaultValueReplaced":0,"tokenPattern":"default","actionOnNoFiles":"continue","inlineVariables":0,"enableRecursion":false,"useLegacyEmptyFeature":false,"useDefaultValue":false,"os":"Windows"}}}}/
           );
         },
         tr,
diff --git a/tasks/ReplaceTokensV6/CHANGELOG.md b/tasks/ReplaceTokensV6/CHANGELOG.md
index 7de3893..3312772 100644
--- a/tasks/ReplaceTokensV6/CHANGELOG.md
+++ b/tasks/ReplaceTokensV6/CHANGELOG.md
@@ -2,6 +2,7 @@
 ## 6.0.3
 - Fix minimum agent requirement to `2.206.1` ([#13](https://github.com/qetza/replacetokens-task/issues/13)).
 - Fix paths in sources incompatible with `fast-glob` syntax on win32 ([#16](https://github.com/qetza/replacetokens-task/issues/16)).
+- Add agent OS in telemetry ([#5](https://github.com/qetza/replacetokens-task/issues/5)).
 
 ## 6.0.2
 - Add aliases for renamed inputs to ease upgrade ([#11](https://github.com/qetza/replacetokens-task/issues/11)).
diff --git a/tasks/ReplaceTokensV6/README.md b/tasks/ReplaceTokensV6/README.md
index 3bddab4..cfebd39 100644
--- a/tasks/ReplaceTokensV6/README.md
+++ b/tasks/ReplaceTokensV6/README.md
@@ -319,6 +319,7 @@ The following **anonymous** data is send:
 - the **hash** of your collection id
 - the **hash** of your project id and pipeline definition id
 - the hosting (`server` or `cloud`)
+- the agent OS (`Windows`, `macOS` or `Linux`)
 - the inputs values for
   - _addBOM_
   - _charsToEscape_
diff --git a/tasks/ReplaceTokensV6/index.ts b/tasks/ReplaceTokensV6/index.ts
index 2160b54..718aa9c 100644
--- a/tasks/ReplaceTokensV6/index.ts
+++ b/tasks/ReplaceTokensV6/index.ts
@@ -28,7 +28,20 @@ async function run() {
     'run',
     tl.getVariable('system.collectionid'),
     `${tl.getVariable('system.teamprojectid')}${tl.getVariable('system.definitionid')}`,
-    !serverType || serverType.toLowerCase() !== 'hosted' ? 'server' : 'cloud'
+    !serverType || serverType.toLowerCase() !== 'hosted' ? 'server' : 'cloud',
+    (() => {
+      const os = tl.getVariable('Agent.OS');
+      switch (os) {
+        case 'Windows_NT':
+          return 'Windows';
+        case 'Darwin':
+          return 'macOS';
+        case 'Linux':
+          return 'Linux';
+        default:
+          return os || 'unknown';
+      }
+    })()
   );
 
   try {
diff --git a/tasks/ReplaceTokensV6/telemetry.ts b/tasks/ReplaceTokensV6/telemetry.ts
index 92cd3d0..a17deb2 100644
--- a/tasks/ReplaceTokensV6/telemetry.ts
+++ b/tasks/ReplaceTokensV6/telemetry.ts
@@ -121,7 +121,7 @@ export function useApplicationInsightsExporter(proxy?: string) {
   provider.addSpanProcessor(new SimpleSpanProcessor(new ApplicationInsightsExporter({ proxy: proxy })));
 }
 
-export function startSpan(name: string, account: string, pipeline: string, host: string) {
+export function startSpan(name: string, account: string, pipeline: string, host: string, os: string) {
   return tracer.startSpan(name, {
     attributes: {
       account: crypto
@@ -132,7 +132,8 @@ export function startSpan(name: string, account: string, pipeline: string, host:
         .createHash('sha256')
         .update(pipeline || '')
         .digest('hex'),
-      host: host
+      host: host,
+      os: os
     }
   });
 }
diff --git a/tasks/ReplaceTokensV6/tests/L0.ts b/tasks/ReplaceTokensV6/tests/L0.ts
index f4bb01e..8a27b9f 100644
--- a/tasks/ReplaceTokensV6/tests/L0.ts
+++ b/tasks/ReplaceTokensV6/tests/L0.ts
@@ -224,6 +224,7 @@ describe('ReplaceTokens v6 L0 suite', function () {
     process.env['SYSTEM_COLLECTIONID'] = 'col01';
     process.env['SYSTEM_TEAMPROJECTID'] = 'project01';
     process.env['SYSTEM_DEFINITIONID'] = 'def01';
+    process.env['AGENT_OS'] = 'Windows_NT';
 
     try {
       // act
@@ -235,7 +236,7 @@ describe('ReplaceTokens v6 L0 suite', function () {
 
         tr.stdout.should.include('telemetry sent');
         tr.stdout.should.match(
-          /\[\{"name":"\*+","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"6\.\d+\.\d+","ai\.cloud\.role":"cloud","ai\.internal\.sdkVersion":"replacetokens:2\.0\.0","ai\.operation\.id":"[^"]+","ai\.operation\.name":"replacetokens-task","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"sources":3,"add-bom":false,"encoding":"auto","escape":"auto","if-no-files-found":"ignore","log-level":"info","missing-var-action":"none","missing-var-default":"","missing-var-log":"warn","recusrive":false,"separator":"\.","token-pattern":"default","transforms":false,"transforms-prefix":"\(","transforms-suffix":"\)","variable-files":0,"variable-envs":0,"inline-variables":0,"output-defaults":1,"output-files":2,"output-replaced":3,"output-tokens":4,"output-transforms":5,"result":"success","duration":\d+(?:\.\d+)?}}}}]/
+          /\[\{"name":"\*+","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"6\.\d+\.\d+","ai\.cloud\.role":"cloud","ai\.internal\.sdkVersion":"replacetokens:2\.0\.0","ai\.operation\.id":"[^"]+","ai\.operation\.name":"replacetokens-task","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"os":"Windows","sources":3,"add-bom":false,"encoding":"auto","escape":"auto","if-no-files-found":"ignore","log-level":"info","missing-var-action":"none","missing-var-default":"","missing-var-log":"warn","recusrive":false,"separator":"\.","token-pattern":"default","transforms":false,"transforms-prefix":"\(","transforms-suffix":"\)","variable-files":0,"variable-envs":0,"inline-variables":0,"output-defaults":1,"output-files":2,"output-replaced":3,"output-tokens":4,"output-transforms":5,"result":"success","duration":\d+(?:\.\d+)?}}}}]/
         );
       }, tr);
     } finally {
@@ -243,6 +244,7 @@ describe('ReplaceTokens v6 L0 suite', function () {
       delete process.env['SYSTEM_COLLECTIONID'];
       delete process.env['SYSTEM_TEAMPROJECTID'];
       delete process.env['SYSTEM_DEFINITIONID'];
+      delete process.env['AGENT_OS'];
 
       cleanVariables(Object.keys(vars));
       cleanSecrets(Object.keys(secrets));
@@ -263,6 +265,7 @@ describe('ReplaceTokens v6 L0 suite', function () {
     process.env['SYSTEM_COLLECTIONID'] = 'col01';
     process.env['SYSTEM_TEAMPROJECTID'] = 'project01';
     process.env['SYSTEM_DEFINITIONID'] = 'def01';
+    process.env['AGENT_OS'] = 'Windows_NT';
 
     try {
       // act
@@ -274,7 +277,7 @@ describe('ReplaceTokens v6 L0 suite', function () {
 
         tr.stdout.should.include('telemetry sent');
         tr.stdout.should.match(
-          /\[\{"name":"\*+","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"6\.\d+\.\d+","ai\.cloud\.role":"cloud","ai\.internal\.sdkVersion":"replacetokens:2\.0\.0","ai\.operation\.id":"[^"]+","ai\.operation\.name":"replacetokens-task","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"result":"failed","duration":\d+(?:\.\d+)?}}}}]/
+          /\[\{"name":"\*+","time":"[^"]+","iKey":"\*+","tags":\{"ai\.application\.ver":"6\.\d+\.\d+","ai\.cloud\.role":"cloud","ai\.internal\.sdkVersion":"replacetokens:2\.0\.0","ai\.operation\.id":"[^"]+","ai\.operation\.name":"replacetokens-task","ai\.user\.accountId":"494d0aad9d06c4ddb51d5300620122ce55366a9382b3cc2835ed5f0e2e67b4d0","ai\.user\.authUserId":"b98ed03d3eec376dcc015365c1a944e3ebbcc33d30e3261af3f4e4abb107aa82"},"data":\{"baseType":"EventData","baseData":\{"ver":"2","name":"tokens\.replaced","properties":\{"os":"Windows","result":"failed","duration":\d+(?:\.\d+)?}}}}]/
         );
       }, tr);
     } finally {
@@ -282,6 +285,7 @@ describe('ReplaceTokens v6 L0 suite', function () {
       delete process.env['SYSTEM_COLLECTIONID'];
       delete process.env['SYSTEM_TEAMPROJECTID'];
       delete process.env['SYSTEM_DEFINITIONID'];
+      delete process.env['AGENT_OS'];
 
       cleanVariables(Object.keys(vars));
       cleanSecrets(Object.keys(secrets));