Added example to set task variable.

ServerTaskHelper/AzureFunctionSample/MyTaskExecutionHandler.cs

@@ -7,6 +7,7 @@
 using Microsoft.TeamFoundation.DistributedTask.WebApi;
 using Newtonsoft.Json;
 using AzureFunctionSample;
+using System.Linq;
 
 namespace MyAzureFunctionSampleFunctionHandler
 {
@@ -43,6 +44,20 @@ public async Task<TaskResult> ExecuteAsync(TaskMessage taskMessage, TaskLogger t
             {
                 // Creates the container in Azure
                 await MyApp.CreateContainer(taskLogger, myAppParameters);
+
+                using (var taskClient = new TaskClient(taskMessage.GetTaskProperties()))
+                {
+                    // set variable
+                    var variableName = "ContainerName";
+                    await taskClient.SetTaskVariable(taskId: taskMessage.GetTaskProperties().TaskInstanceId, name: variableName, value: "AzPipelineAgent", isSecret: false, cancellationToken: cancellationToken);
+
+                    // get variable
+                    var variableValue = taskClient.GetTaskVariable(taskId: taskMessage.GetTaskProperties().TaskInstanceId, name: variableName, cancellationToken: cancellationToken);
+                    message = $"Variable name: {variableName} value: {variableValue}";
+                    await taskLogger.Log(message).ConfigureAwait(false);
+                }
+
+
                 return await Task.FromResult(TaskResult.Succeeded);
             }
             catch (Exception ex)

ServerTaskHelper/DistributedTask.ServerTask.Remote.Common/TaskProgress/TaskClient.cs

@@ -82,6 +82,30 @@ public async Task AppendTimelineRecordFeedAsync(IEnumerable<string> lines)
             await taskClient.AppendTimelineRecordFeedAsync(this.taskProperties.ProjectId, this.taskProperties.HubName, this.taskProperties.PlanId, this.taskProperties.TimelineId, this.taskProperties.JobId, lines).ConfigureAwait(false);
         }
 
+        public async Task SetTaskVariable(Guid taskId, string name, string value, bool isSecret, CancellationToken cancellationToken)
+        {
+            var records = await taskClient.GetRecordsAsync(this.taskProperties.ProjectId, this.taskProperties.HubName, this.taskProperties.PlanId, this.taskProperties.TimelineId, userState: null, cancellationToken: cancellationToken).ConfigureAwait(false);
+            var taskRecord = records.FirstOrDefault(r => r.Id == taskId);
+            taskRecord.Variables[name] = new VariableValue { Value = value, IsSecret = isSecret };
+
+            await taskClient.UpdateTimelineRecordsAsync(this.taskProperties.ProjectId, this.taskProperties.HubName, this.taskProperties.PlanId, this.taskProperties.TimelineId, new List<TimelineRecord> { taskRecord }, cancellationToken).ConfigureAwait(false);
+        }
+
+        public string GetTaskVariable(Guid taskId, string name, CancellationToken cancellationToken)
+        {
+            var records = taskClient.GetRecordsAsync(this.taskProperties.ProjectId, this.taskProperties.HubName, this.taskProperties.PlanId, this.taskProperties.TimelineId, userState: null, cancellationToken: cancellationToken).Result;
+            var taskRecord = records.FirstOrDefault(r => r.Id == taskId);
+            foreach(var varaible in taskRecord.Variables)
+            {
+                if (string.Equals(varaible.Key, name, StringComparison.OrdinalIgnoreCase))
+                {
+                    return varaible.Value.Value;
+                }
+            }
+
+            return null;
+        }
+
         public void Dispose()
         {
             vssConnection?.Dispose();

ServerTaskHelper/HttpRequestSampleWithoutHandler/MyApp.cs

@@ -91,6 +91,9 @@ internal static void ExecuteAsync(string taskMessageBody, string projectId, stri
 
                     // Attache task log to the timeline record
                     UpdateTaskTimelineRecord(httpClient, authToken, planUri, projectId, hubName, planId, timelineId, taskInstanceId, taskLogObjectString);
+
+                    // Set task varaible
+                    SetTaskVariable(httpClient, authToken, planUri, projectId, hubName, planId, timelineId, taskInstanceId, "MyAppName", "TestApp", false);
                 }
             }
         }
@@ -212,8 +215,46 @@ private static void UpdateTaskTimelineRecord(HttpClient httpClient, string authT
 
             PatchData(httpClient, updateTaskTimelineRecordUrl, requestBody, authToken);
         }
-
-
+
+        private static void SetTaskVariable(HttpClient httpClient, string authToken, string planUri, string projectId, string hubName, string planId, string timelineId, string taskInstanceId, string variableName, string variableValue, bool isSecret)
+        {
+            // Get timeline records
+            const string TimelineRecordsUrl = "{0}/{1}/_apis/distributedtask/hubs/{2}/plans/{3}/timelines/{4}/records?api-version=4.1";
+
+            var timelineRecordsUrl = string.Format(TimelineRecordsUrl, planUri, projectId, hubName, planId, timelineId);
+
+            var response = GetData(httpClient, timelineRecordsUrl, authToken);
+            var timelineRecords = "";
+            if (response.StatusCode == HttpStatusCode.OK)
+            {
+                timelineRecords = response.Content.ReadAsStringAsync().Result;
+                dynamic timelineRecordsData = JsonConvert.DeserializeObject(timelineRecords);
+                JObject timelineRecord = new JObject();
+                foreach (var t in timelineRecordsData["value"])
+                {
+                    string timelineRecordId = (string)t["id"];
+                    if (string.Equals(timelineRecordId, taskInstanceId, StringComparison.OrdinalIgnoreCase))
+                    {
+                        timelineRecord = t;
+                        var taskVaraible = new JObject();
+                        taskVaraible[variableName] = new JObject(new JProperty("value", variableValue), new JProperty("isSecret", isSecret));
+                        timelineRecord.Add(new JProperty("variables", taskVaraible));
+                    }
+                }
+
+                JArray updatedTimelineRecords = new JArray();
+                updatedTimelineRecords.Add(timelineRecord);
+                var requestBodyJObject = new JObject();
+                requestBodyJObject["value"] = updatedTimelineRecords;
+                requestBodyJObject.Add(new JProperty("count", 1));
+
+                var requestBody = JsonConvert.SerializeObject(requestBodyJObject);
+
+                PatchData(httpClient, timelineRecordsUrl, requestBody, authToken);
+            }
+        }
+
+
         private static HttpResponseMessage PostData(HttpClient httpClient, string url, string requestBody, string authToken)
         {
             var buffer = System.Text.Encoding.UTF8.GetBytes(requestBody);
@@ -239,5 +280,14 @@ private static HttpResponseMessage PatchData(HttpClient httpClient, string url,
 
             return httpClient.PatchAsync(new Uri(url), byteContent).Result;
         }
+
+        private static HttpResponseMessage GetData(HttpClient httpClient, string url, string authToken)
+        {          
+            httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(
+            System.Text.ASCIIEncoding.ASCII.GetBytes(
+                string.Format("{0}:{1}", "", authToken))));
+
+            return httpClient.GetAsync(new Uri(url)).Result;
+        }
     }
 }