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Add Java polyglot AppHost parity#15470

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Add Java polyglot AppHost parity#15470
sebastienros wants to merge 10 commits intomainfrom
sebros/java-empty-apphost-template

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@sebastienros sebastienros commented Mar 21, 2026 •
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Description

This PR brings Java polyglot AppHost support much closer to the existing TypeScript experience.

Summary:

  • adds Java validation apphosts across playground/polyglot/Java/** to mirror the TypeScript playground coverage
  • improves generated Java SDK ergonomics for unions, callbacks, optional/nullability handling, and direct resource overloads
  • adds a runnable playground/JavaAppHost sample
  • adds Java CI validation in tests.yml and the polyglot validation Docker/scripts, including a dedicated Java playground validation script
  • replaces the previous Java Express/React CLI template with Empty (Java AppHost) behind the experimental Java feature flag
  • adds scoped .gitignore entries for Java playground build outputs

Motivation/context:

  • Java polyglot support was lagging behind TypeScript in generated surface area, playground coverage, CLI scaffolding, and CI validation.
  • This change closes those gaps so Java can serve as a practical experimental AppHost language with much better compile-time validation.

Limitation:
If we want to generate compact source files (https://openjdk.org/jeps/512) like file-based apps in C# we need to explore the currently unique .java sdk file into split classes which would generate a lot of fils in the .modules folder. That wouldn't change the size of the git repo (objects would be reused) but can feel very overwhelming. Like node_modules feel. Current generated code is also compatbile with jdk 17 while jep512 requires jdk 25.

To enable the java support, type aspire config set -g features.experimentalPolyglot:java true

Checklist

  • Is this feature complete?
    • Yes. Ready to ship.
    • No. Follow-up changes expected.
  • Are you including unit tests for the changes and scenario tests if relevant?
    • Yes
    • No
  • Did you add public API?
    • Yes
      • If yes, did you have an API Review for it?
        • Yes
        • No
      • Did you add <remarks /> and <code /> elements on your triple slash comments?
        • Yes
        • No
    • No
  • Does the change make any security assumptions or guarantees?
    • Yes
      • If yes, have you done a threat model and had a security review?
        • Yes
        • No
    • No
  • Does the change require an update in our Aspire docs?

@sebastienros
Add Java polyglot apphost parity
a8cfa2a 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot AI review requested due to automatic review settings March 21, 2026 04:28
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github-actions bot commented Mar 21, 2026 •
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🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 15470

Or

  • Run remotely in PowerShell:
iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 15470"

Copilot AI reviewed Mar 21, 2026
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Pull request overview

This PR expands Java polyglot AppHost support to better match the TypeScript experience by adding Java validation AppHosts across the polyglot playground, introducing a runnable Java sample, and wiring Java validation into CI/Docker workflows.

Changes:

  • Added multiple Java playground validation AppHosts (configs + AppHost.java + generated .modules) mirroring TypeScript coverage
  • Added a runnable playground/JavaAppHost sample (Java AppHost + Node/React frontend)
  • Added Java CI/unit-test job and Docker/scripts for Java playground validation

Reviewed changes

Copilot reviewed 86 out of 374 changed files in this pull request and generated 3 comments.

Show a summary per file
File Description
playground/polyglot/Java/Aspire.Hosting.Azure.PostgreSQL/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for Java validation AppHost SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.OperationalInsights/ValidationAppHost/aspire.config.json Adds Java AppHost config enabling experimental Java polyglot and package restore.
playground/polyglot/Java/Aspire.Hosting.Azure.OperationalInsights/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising OperationalInsights API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.OperationalInsights/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.OperationalInsights/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.Kusto/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for Kusto package.
playground/polyglot/Java/Aspire.Hosting.Azure.Kusto/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising Kusto API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.Kusto/ValidationAppHost/.modules/Transport.java Adds generated Java JSON-RPC transport for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.Kusto/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.Kusto/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.KeyVault/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for KeyVault package.
playground/polyglot/Java/Aspire.Hosting.Azure.KeyVault/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising KeyVault API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.KeyVault/ValidationAppHost/.modules/Transport.java Adds generated Java JSON-RPC transport for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.KeyVault/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.KeyVault/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.Functions/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for Functions (+ Storage dependency).
playground/polyglot/Java/Aspire.Hosting.Azure.Functions/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising Functions API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.Functions/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.Functions/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.EventHubs/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for EventHubs package.
playground/polyglot/Java/Aspire.Hosting.Azure.EventHubs/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising EventHubs API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.EventHubs/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.EventHubs/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.CosmosDB/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for CosmosDB (+ KeyVault dependency).
playground/polyglot/Java/Aspire.Hosting.Azure.CosmosDB/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising CosmosDB API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.CosmosDB/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.CosmosDB/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.ContainerRegistry/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for ContainerRegistry (+ AppContainers dependency).
playground/polyglot/Java/Aspire.Hosting.Azure.ContainerRegistry/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising ContainerRegistry API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.ContainerRegistry/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.ContainerRegistry/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.CognitiveServices/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for CognitiveServices package.
playground/polyglot/Java/Aspire.Hosting.Azure.CognitiveServices/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising CognitiveServices/OpenAI API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.CognitiveServices/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.CognitiveServices/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.ApplicationInsights/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for ApplicationInsights (+ OperationalInsights dependency).
playground/polyglot/Java/Aspire.Hosting.Azure.ApplicationInsights/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising ApplicationInsights API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.ApplicationInsights/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.ApplicationInsights/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.AppService/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for AppService package.
playground/polyglot/Java/Aspire.Hosting.Azure.AppService/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising AppService API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.AppService/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.AppService/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.AppContainers/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for AppContainers (+ OperationalInsights dependency).
playground/polyglot/Java/Aspire.Hosting.Azure.AppContainers/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising AppContainers API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.AppContainers/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.AppContainers/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/polyglot/Java/Aspire.Hosting.Azure.AppConfiguration/ValidationAppHost/aspire.config.json Adds Java validation AppHost config for AppConfiguration package.
playground/polyglot/Java/Aspire.Hosting.Azure.AppConfiguration/ValidationAppHost/AppHost.java Adds Java validation AppHost exercising AppConfiguration API surface.
playground/polyglot/Java/Aspire.Hosting.Azure.AppConfiguration/ValidationAppHost/.modules/Base.java Adds generated Java base/runtime helpers for SDK.
playground/polyglot/Java/Aspire.Hosting.Azure.AppConfiguration/ValidationAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
playground/JavaAppHost/frontend/vite.config.ts Adds Vite config including API proxy for frontend dev server.
playground/JavaAppHost/frontend/tsconfig.node.json Adds TS config for Vite/node tooling.
playground/JavaAppHost/frontend/tsconfig.json Adds TS project references setup.
playground/JavaAppHost/frontend/tsconfig.app.json Adds TS config for React app compilation.
playground/JavaAppHost/frontend/src/main.tsx Adds React entrypoint.
playground/JavaAppHost/frontend/src/index.css Adds base/reset styles and reduced-motion handling.
playground/JavaAppHost/frontend/src/App.tsx Adds sample UI fetching weather forecast via API proxy.
playground/JavaAppHost/frontend/package.json Adds frontend dependencies/scripts and Node engine constraints.
playground/JavaAppHost/frontend/index.html Adds Vite HTML entry.
playground/JavaAppHost/frontend/eslint.config.js Adds ESLint config for TS/React hooks and refresh.
playground/JavaAppHost/frontend/.dockerignore Adds Docker ignore for Node build artifacts.
playground/JavaAppHost/aspire.config.json Adds Java AppHost config for the runnable JavaAppHost sample.
playground/JavaAppHost/api/tsconfig.json Adds TS config for the API service build output.
playground/JavaAppHost/api/src/instrumentation.ts Adds OpenTelemetry NodeSDK initialization for Aspire dashboard.
playground/JavaAppHost/api/src/index.ts Adds Express API service serving forecast and optional static bundle.
playground/JavaAppHost/api/package.json Adds API dependencies including express and OpenTelemetry exporters/SDK.
playground/JavaAppHost/AppHost.java Adds runnable Java AppHost wiring Node API + Vite frontend and publish bundling.
playground/JavaAppHost/.modules/Transport.java Adds generated Java JSON-RPC transport for the JavaAppHost sample.
playground/JavaAppHost/.modules/Base.java Adds generated Java base/runtime helpers for the JavaAppHost sample.
playground/JavaAppHost/.modules/.codegen-hash Adds codegen hash for generated SDK output.
.github/workflows/tests.yml Adds Java SDK unit test job and integrates it into overall results gating.
.github/workflows/polyglot-validation/test-java.sh Updates Java polyglot validation script to create/restore/run a minimal Redis-backed Java AppHost.
.github/workflows/polyglot-validation/test-java-playground.sh Adds script to restore + javac compile all Java validation AppHosts in the playground.
.github/workflows/polyglot-validation/Dockerfile.java Updates Docker image and runs both Java validation scripts in container.
Files not reviewed (1)
  • playground/JavaAppHost/frontend/package-lock.json: Language not supported
Comments suppressed due to low confidence (1)

playground/JavaAppHost/.modules/Transport.java:1

  • The RandomAccessFile used for the Windows named pipe is a local variable that is never stored/closed. If it becomes GC-eligible, the underlying handle can be closed unexpectedly (via finalization/cleaner), breaking the transport. Store the RandomAccessFile as an instance field to keep it alive for the duration of the connection and close it when disconnecting/shutting down (or avoid RandomAccessFile entirely by opening streams directly against the pipe path if supported).

@github-actions github-actions bot mentioned this pull request Mar 21, 2026
Open
sebastienros and others added 9 commits March 20, 2026 21:46
@sebastienros
Fix Java AppHost CI regressions
266e5a0 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sebastienros
Fix Java validation flows
c7a0993 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sebastienros
Fix Java CI regressions
c0eff6e 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sebastienros
Fix polyglot apphost file path defaults
edda9d8 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sebastienros
Fix polyglot createBuilder defaults
581bd09 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sebastienros
Update Azure SQL snapshots
fd4c014 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sebastienros
Narrow Kusto log assertions
c27562f 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sebastienros
Revert narrowed Kusto log assertions
f7df302 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sebastienros
Preserve fluent Java builder return types
62ae748 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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github-actions bot commented Mar 21, 2026

🎬 CLI E2E Test Recordings — 54 recordings uploaded (commit 62ae748)

View recordings
Test Recording
AddPackageInteractiveWhileAppHostRunningDetached ▶️ View Recording
AddPackageWhileAppHostRunningDetached ▶️ View Recording
AgentCommands_AllHelpOutputs_AreCorrect ▶️ View Recording
AgentInitCommand_DefaultSelection_InstallsSkillOnly ▶️ View Recording
AgentInitCommand_MigratesDeprecatedConfig ▶️ View Recording
AspireAddPackageVersionToDirectoryPackagesProps ▶️ View Recording
AspireUpdateRemovesAppHostPackageVersionFromDirectoryPackagesProps ▶️ View Recording
Banner_DisplayedOnFirstRun ▶️ View Recording
Banner_DisplayedWithExplicitFlag ▶️ View Recording
CertificatesClean_RemovesCertificates ▶️ View Recording
CertificatesTrust_WithNoCert_CreatesAndTrustsCertificate ▶️ View Recording
CertificatesTrust_WithUntrustedCert_TrustsCertificate ▶️ View Recording
ConfigSetGet_CreatesNestedJsonFormat ▶️ View Recording
CreateAndDeployToDockerCompose ▶️ View Recording
CreateAndDeployToDockerComposeInteractive ▶️ View Recording
CreateAndPublishToKubernetes ▶️ View Recording
CreateAndRunAspireStarterProject ▶️ View Recording
CreateAndRunAspireStarterProjectWithBundle ▶️ View Recording
CreateAndRunEmptyAppHostProject ▶️ View Recording
CreateAndRunJavaEmptyAppHostProject ▶️ View Recording
CreateAndRunJsReactProject ▶️ View Recording
CreateAndRunPythonReactProject ▶️ View Recording
CreateAndRunTypeScriptEmptyAppHostProject ▶️ View Recording
CreateAndRunTypeScriptStarterProject ▶️ View Recording
CreateJavaAppHostWithViteApp ▶️ View Recording
CreateStartAndStopAspireProject ▶️ View Recording
CreateTypeScriptAppHostWithViteApp ▶️ View Recording
DescribeCommandResolvesReplicaNames ▶️ View Recording
DescribeCommandShowsRunningResources ▶️ View Recording
DetachFormatJsonProducesValidJson ▶️ View Recording
DoctorCommand_DetectsDeprecatedAgentConfig ▶️ View Recording
DoctorCommand_WithSslCertDir_ShowsTrusted ▶️ View Recording
DoctorCommand_WithoutSslCertDir_ShowsPartiallyTrusted ▶️ View Recording
GlobalMigration_HandlesCommentsAndTrailingCommas ▶️ View Recording
GlobalMigration_HandlesMalformedLegacyJson ▶️ View Recording
GlobalMigration_PreservesAllValueTypes ▶️ View Recording
GlobalMigration_SkipsWhenNewConfigExists ▶️ View Recording
GlobalSettings_MigratedFromLegacyFormat ▶️ View Recording
InvalidAppHostPathWithComments_IsHealedOnRun ▶️ View Recording
LogsCommandShowsResourceLogs ▶️ View Recording
PsCommandListsRunningAppHost ▶️ View Recording
PsFormatJsonOutputsOnlyJsonToStdout ▶️ View Recording
PublishWithDockerComposeServiceCallbackSucceeds ▶️ View Recording
RestoreGeneratesSdkFiles ▶️ View Recording
RunWithMissingAwaitShowsHelpfulError ▶️ View Recording
SecretCrudOnDotNetAppHost ▶️ View Recording
SecretCrudOnTypeScriptAppHost ▶️ View Recording
StagingChannel_ConfigureAndVerifySettings_ThenSwitchChannels ▶️ View Recording
StopAllAppHostsFromAppHostDirectory ▶️ View Recording
StopAllAppHostsFromUnrelatedDirectory ▶️ View Recording
StopNonInteractiveMultipleAppHostsShowsError ▶️ View Recording
StopNonInteractiveSingleAppHost ▶️ View Recording
StopWithNoRunningAppHostExitsSuccessfully ▶️ View Recording
TypeScriptAppHostWithProjectReferenceIntegration ▶️ View Recording

📹 Recordings uploaded automatically from CI run #23385491108

eerhardt
eerhardt reviewed Mar 23, 2026
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playground/polyglot/Java/Aspire.Hosting.Azure.AppConfiguration/ValidationAppHost/AppHost.java
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@eerhardt eerhardt Mar 23, 2026

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Do we need both the polyglot/Java and the JavaAppHost playground apps? It seems like they have a lot of overlap/duplication.

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@eerhardt eerhardt Mar 23, 2026

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Can we just have 1 combined playground app? There is a LOT of duplication in the .modules folders in all of these.

Also - playground apps aren't really here for testing. Should this breadth of scenarios be covered in tests instead?

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