Validate environment variable names for Foundry hosted agents (#16884)

* Validate environment variable names for Foundry hosted agents

Foundry Hosted Agents only support environment variable names containing ASCII letters, digits, and underscores. Service discovery names (with dashes/dots) and other generated names would silently produce invalid agent versions at deploy time.

Add validation in HostedAgentConfiguration.ToProjectsAgentVersionCreationOptions using a source-generated regex; throw DistributedApplicationException with the offending names if any are invalid. Rename target resources in the existing publish test to non-dashed names so the test exercises the happy path.

Fixes #16858

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* PR feedback

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: eerhardt

src/Aspire.Hosting.Foundry/HostedAgent/AzureHostedAgentResource.cs

@@ -157,7 +157,7 @@ private async Task<ProjectsAgentVersion> DeployAsync(PipelineStepContext context
         var projectClient = new AIProjectClient(new Uri(projectEndpoint), credential);
         var result = await projectClient.AgentAdministrationClient.CreateAgentVersionAsync(
             Name,
-            def.ToProjectsAgentVersionCreationOptions(),
+            def.ToProjectsAgentVersionCreationOptions(Target.Name),
             cancellationToken: context.CancellationToken
         ).ConfigureAwait(false);
 

src/Aspire.Hosting.Foundry/HostedAgent/HostedAgentConfiguration.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Globalization;
+using System.Text.RegularExpressions;
 using Azure.AI.Projects.Agents;
 
 namespace Aspire.Hosting.Foundry;
@@ -15,7 +16,7 @@ namespace Aspire.Hosting.Foundry;
 /// ATS-compatible properties are exported; Azure SDK-specific members remain .NET-only.
 /// </remarks>
 [AspireExport(ExposeProperties = true)]
-public class HostedAgentConfiguration(string image)
+public partial class HostedAgentConfiguration(string image)
 {
     /// <summary>
     /// The description of the hosted agent.
@@ -112,8 +113,10 @@ public decimal Memory
     /// <summary>
     /// Converts this configuration to an <see cref="ProjectsAgentVersionCreationOptions"/> instance.
     /// </summary>
-    public ProjectsAgentVersionCreationOptions ToProjectsAgentVersionCreationOptions()
+    internal ProjectsAgentVersionCreationOptions ToProjectsAgentVersionCreationOptions(string targetResourceName)
     {
+        ValidateEnvironmentVariableNames(EnvironmentVariables.Keys, targetResourceName);
+
         var def = new HostedAgentDefinition(
             ContainerProtocolVersions,
             cpu: CpuString,
@@ -143,4 +146,26 @@ public ProjectsAgentVersionCreationOptions ToProjectsAgentVersionCreationOptions
         }
         return options;
     }
+
+    private static void ValidateEnvironmentVariableNames(IEnumerable<string> environmentVariableNames, string? targetResourceName)
+    {
+        var invalidNames = environmentVariableNames
+            .Where(static name => !EnvironmentVariableNameRegex().IsMatch(name))
+            .Order(StringComparer.Ordinal)
+            .ToArray();
+
+        if (invalidNames.Length == 0)
+        {
+            return;
+        }
+
+        throw new DistributedApplicationException(
+            $"Foundry hosted agent for target resource '{targetResourceName}' contains environment variable names that are not supported by Foundry Hosted Agents. " +
+            $"Environment variable names must contain only ASCII letters, digits, or underscores. " +
+            $"Invalid name(s): '{string.Join("', '", invalidNames)}'");
+    }
+
+    // hosted agent environment variables must contain only letters, digits, or underscores.
+    [GeneratedRegex("^[A-Za-z0-9_]+$")]
+    private static partial Regex EnvironmentVariableNameRegex();
 }

tests/Aspire.Hosting.Azure.Tests/FoundryExtensionsTests.cs

@@ -288,11 +288,11 @@ public async Task PublishAsHostedAgent_ResolvesExternalContainerAppReference()
         var project = builder.AddFoundry("account")
             .AddProject("my-project");
 
-        var weatherAgent = builder.AddProject<Project>("weather-agent", launchProfileName: null)
+        var weatherAgent = builder.AddProject<Project>("weatheragent", launchProfileName: null)
             .WithEndpoint(targetPort: 9000, scheme: "http", name: "http", isExternal: true)
             .WithComputeEnvironment(env);
 
-        var advisorAgent = builder.AddProject<Project>("advisor-agent", launchProfileName: null)
+        var advisorAgent = builder.AddProject<Project>("advisoragent", launchProfileName: null)
             .WithReference(weatherAgent)
             .WaitFor(weatherAgent)
             .PublishAsHostedAgent(project);
@@ -314,7 +314,7 @@ public async Task PublishAsHostedAgent_ResolvesExternalContainerAppReference()
             NullLogger<FoundryExtensionsTests>.Instance,
             cts.Token);
 
-        Assert.Equal("https://weather-agent.example.azurecontainerapps.io", environmentVariables["services__weather-agent__http__0"]);
+        Assert.Equal("https://weatheragent.example.azurecontainerapps.io", environmentVariables["services__weatheragent__http__0"]);
     }
 
     [Fact]
@@ -469,3 +469,4 @@ private sealed class Project : IProjectMetadata
     }
 
 }
+

tests/Aspire.Hosting.Foundry.Tests/HostedAgentConfigurationTests.cs

@@ -67,7 +67,7 @@ public void ToProjectsAgentVersionCreationOptions_ProducesValidOptions()
             Cpu = 1.0m,
         };
 
-        var options = config.ToProjectsAgentVersionCreationOptions();
+        var options = config.ToProjectsAgentVersionCreationOptions("target");
 
         Assert.NotNull(options);
         Assert.Equal("Test agent", options.Description);
@@ -83,6 +83,21 @@ public void EnvironmentVariables_CanBeAdded()
         Assert.Equal("VALUE", config.EnvironmentVariables["KEY"]);
     }
 
+    [Fact]
+    public void ToProjectsAgentVersionCreationOptions_ThrowsForInvalidEnvironmentVariableNames()
+    {
+        var config = new HostedAgentConfiguration("myimage:latest");
+        config.EnvironmentVariables["VALID_NAME_1"] = "value";
+        config.EnvironmentVariables["INVALID-NAME"] = "value";
+        config.EnvironmentVariables["invalid.name"] = "value";
+
+        var ex = Assert.Throws<DistributedApplicationException>(() => config.ToProjectsAgentVersionCreationOptions("target"));
+
+        Assert.Equal(
+            "Foundry hosted agent for target resource 'target' contains environment variable names that are not supported by Foundry Hosted Agents. Environment variable names must contain only ASCII letters, digits, or underscores. Invalid name(s): 'INVALID-NAME', 'invalid.name'",
+            ex.Message);
+    }
+
     [Fact]
     public void DefaultMetadata_ContainsDeployedByAndOn()
     {