Add conditional mode to ReferenceExpression with polyglot codegen support by danegsta · Pull Request #14919 · microsoft/aspire

danegsta · 2026-03-03T22:10:35Z

Description

Extends ReferenceExpression with a conditional mode that models ternary-style values in connection strings and other reference expressions. This enables proper manifest publishing and polyglot code generation for conditional logic like TLS ssl=true in Redis connection strings, replacing the closure-based DeferredValueProvider.

ReferenceExpression conditional mode

ReferenceExpression.CreateConditional(condition, conditionMatch, whenTrue, whenFalse) creates a conditional expression that evaluates an IValueProvider condition against a given "truthy" string value and selects between two ReferenceExpression branches. Key design:

Single type: Conditional state lives as internal fields on ReferenceExpression rather than a separate type. IsConditional, Condition, WhenTrue, WhenFalse properties expose the state.
Auto-generated names: The manifest entry name is derived from the condition's ValueExpression at construction time (e.g., {redis.bindings.tcp.tlsEnabled} → cond-redis-bindings-tcp-tlsenabled), eliminating the need for explicit naming.
Manifest integration: Written as value.v0 entries in the manifest, referenced via {name.value} in connection strings.

Unified ATS wire format

Conditional expressions use the same $expr marker as value-mode expressions. The presence of a condition property distinguishes the two modes:

Value mode: { "$expr": { "format": "...", "valueProviders": [...] } }
Conditional mode: { "$expr": { "condition": <$handle>, "matchValue": <string>, "whenTrue": <$expr>, "whenFalse": <$expr> } }

All 5 polyglot language base files (TypeScript, Go, Python, Java, Rust) support:

createConditional() factory method for client-side construction
toJSON() serialization using the unified $expr format
Server-side unmarshalling via ReferenceExpressionRef in AtsMarshaller

Redis TLS

Re-enables TLS by default for Redis container endpoints. EndpointReference.GetTlsValue now returns a conditional ReferenceExpression instead of using a closure-based DeferredValueProvider, making it compatible with polyglot code generation.

Example

ReferenceExpression.CreateConditional(
    condition: primaryEndpoint.Property(EndpointProperty.TlsEnabled),
    matchValue: bool.TrueString,
    whenTrue: ReferenceExpression.Create($",ssl=true"),
    whenFalse: ReferenceExpression.Empty);

Fixes #13645

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 <para/> and <code/> elements on your triple slash comments?
    - Yes
    - No
- No
Does the change make any security assumptions or guarantees?
- Yes
- No
Does the change require an update in our Aspire docs?
- Yes
  - Link to aspire.dev issue:
    - New issue
- No

github-actions · 2026-03-03T22:10:44Z

🚀 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/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 14919

Or

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Copilot

Pull request overview

Adds a new lazy/deferred value provider to support reference-expression fragments that depend on state only known later in the lifecycle (notably Redis TLS), and updates Redis endpoint/URI scheme handling to be scheme-driven rather than hard-coded.

Changes:

Introduces DeferredValueProvider (runtime + manifest expression callbacks) and an EndpointReference.TlsValue(...) helper.
Adds EndpointAnnotation.TlsEnabled / EndpointReference.TlsEnabled and wires Redis TLS to endpoint annotations (including ssl=true connection string fragment).
Updates Redis tests/manifests to use binding {...scheme} and default Redis endpoint scheme to redis (and rediss when TLS is enabled).

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tests/Aspire.Hosting.Tests/DeferredValueProviderTests.cs	New unit tests covering deferred provider behavior and interaction with `ReferenceExpressionBuilder`.
tests/Aspire.Hosting.Redis.Tests/ConnectionPropertiesTests.cs	Updates expected Redis URI manifest expression to use `{...scheme}` binding.
tests/Aspire.Hosting.Redis.Tests/AddRedisTests.cs	Updates Redis endpoint scheme expectations and adds TLS/dynamic-resolution coverage.
src/Aspire.Hosting/ApplicationModel/EndpointReference.cs	Adds `TlsEnabled` and `TlsValue(...)` to support TLS-dependent dynamic fragments.
src/Aspire.Hosting/ApplicationModel/EndpointAnnotation.cs	Adds `TlsEnabled` flag for endpoint-level TLS state.
src/Aspire.Hosting/ApplicationModel/DeferredValueProvider.cs	Adds new general-purpose deferred value provider implementation.
src/Aspire.Hosting.Redis/RedisResource.cs	Switches TLS handling to endpoint-based TLS state and scheme-driven URI/connection string fragments.
src/Aspire.Hosting.Redis/RedisBuilderExtensions.cs	Sets Redis primary endpoint scheme to `redis` and updates TLS enablement to mutate endpoint annotation state.

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src/Aspire.Hosting/ApplicationModel/DeferredValueProvider.cs

src/Aspire.Hosting/ApplicationModel/EndpointReference.cs

src/Aspire.Hosting.Redis/RedisResource.cs

github-actions · 2026-03-03T22:42:54Z

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src/Aspire.Hosting.Redis/RedisResource.cs

src/Aspire.Hosting.Redis/RedisBuilderExtensions.cs

src/Aspire.Hosting.Redis/RedisResource.cs

src/Aspire.Hosting.Redis/RedisBuilderExtensions.cs

src/Aspire.Hosting/ApplicationModel/DeferredValueProvider.cs

src/Aspire.Hosting/ApplicationModel/EndpointAnnotation.cs

src/Aspire.Hosting/ApplicationModel/EndpointReference.cs

…egressions in output.

davidfowl · 2026-03-04T09:02:34Z

How does this affect the typescript support?

cc @sebastienros @IEvangelist

…disTls

Replace DeferredValueProvider with ConditionalReferenceExpression, a new type that models conditional values in connection strings (e.g., TLS ssl=true/empty). The CRE auto-generates its manifest name from the condition's ValueExpression at construction time. Key changes: - ConditionalReferenceExpression type with Create() factory, auto-name generation via condition sanitization, and manifest value.v0 support - EndpointReference.GetTlsValue returns CRE instead of using closure - ManifestPublishingContext writes CRE entries as value.v0 resources - Polyglot create()/toJSON() in all 5 ATS base files (TS, Go, Python, Java, Rust) with $condExpr JSON serialization format - ConditionalReferenceExpressionRef for server-side $condExpr unmarshalling in AtsMarshaller - Redis connection string tests updated with pattern matching to handle auto-generated CRE names and verify manifest value entries Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The MarshalToJson_ConditionalReferenceExpression_PreservesValueAfterRoundTrip test was asserting an exact name ('test-tls') but names are now auto-generated from the condition's ValueExpression. Use StartsWith assertion instead. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…disTls

Replace wrapIfHandle (a deserialization helper) with proper serialization logic in ReferenceExpression.toJSON() for the condition field. Remove the now-unnecessary import. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

davidfowl · 2026-03-08T00:11:48Z

src/Aspire.Hosting.CodeGeneration.Rust/Resources/base.rs

    }
 }

+impl<'de> Deserialize<'de> for ReferenceExpression {


@sebastienros this is why we should delete all other language 😄

I've had to walk back several overzealous copilot changes such as this. It seems that it gets a bit carried away once it starts trying to update all the languages.

davidfowl · 2026-03-08T00:25:51Z

docker and kubernetes both have special ReferenceExpression logic as well.

The EndToEnd tests are incompatible with TLS-enabled Redis. Opt out of the developer certificate for the Redis resource in TestProgram. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…mpose, and Kubernetes publish contexts - Azure App Service: Handle conditional expressions with Bicep ternary fallback for parameter-based conditions - Docker Compose: Convert ProcessValue to async, resolve conditions statically at generation time via GetValueAsync - Kubernetes: Resolve conditions via GetValueAsync with ValueProviderContext at generation time - Add tests with both static and parameter-based conditions for all three contexts with Verify snapshots Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…sher When a conditional ReferenceExpression's condition is a ParameterResource, emit a Helm ternary expression (e.g., {{ ternary "val1" "val2" (eq .Values.parameters.x "True") | quote }}) instead of resolving statically. This defers evaluation to helm install/upgrade time, allowing users to override the condition parameter in values.yaml. - Add BuildHelmTernary helper in KubernetesResource - Add HelmFlowControlPattern regex for ternary expression detection - Update ShouldDoubleQuoteString to render ternary as plain YAML - Non-parameter conditions still resolve statically at generation time Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The is HelmValue type check failed because ProcessValueAsync's Format=={0} optimization converts HelmValues to strings via ToString(). Changed to detect Helm expressions in string content using ContainsHelmExpression() instead. Added HelmExtensionsTests with Theory tests for ShouldDoubleQuoteString and HelmFlowControlPattern regex. Added fallback integration test verifying that conditionals with parameter branches fall back to static resolution. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Replace static fallback with Go template {{ if eq ... }}...{{ else }}...{{ end }} syntax when conditional branches contain Helm expressions. This preserves deploy-time dynamism for parameter-based conditions even when branches reference other parameters. Key changes: - BuildHelmTernary → BuildHelmConditional with ternary for literals, if/else for expression branches, static fallback for complex cases - TryFormatBranch: scalar expressions get | quote, literals wrapped as {{ "literal" | quote }} to avoid bare quotes in YAML plain scalars - AllocateBranchParameters: stores branch parameter values in AdditionalConfigValues to populate values.yaml without case-insensitive key collisions in ToConfigMap's processedKeys - HelmFlowControlPattern regex now matches {{ if in addition to {{ ternary - ShouldDoubleQuoteString checks flow control before ScalarExpressionPattern Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Re-generated the verified snapshot by running the test against the current codebase. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Conditional expressions now expose the union of both branches' ValueProviders, enabling publish contexts to discover all referenced parameters and resources without inspecting WhenTrue/WhenFalse directly. Guard RegisterFormattedParameters against the parallel array mismatch (ValueProviders is now non-empty but ManifestExpressions/StringFormats remain empty for conditionals) by recursing into each branch. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…egistration The hash-based conditional name (XxHash32 of condition + branches) is now stable, so caching the built ReferenceExpression in RedisResource is unnecessary. Fix RegisterConditionalExpressions to register the expression itself when it is conditional, not just nested conditionals in ValueProviders. With ValueProviders now containing the union of both branches' providers (parameters, endpoints, etc.), the top-level conditional was no longer being discovered through the nested provider scan. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Align with the TypeScript base.ts which already uses the current $expr key for reference expression serialization. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…rences Validate that ValueProviders returns the union of both branches' providers, References includes condition + all branch references, nested conditionals propagate providers through the chain, and duplicate conditionals produce identical hash-based names. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

karolz-ms · 2026-03-09T18:35:43Z

We should make sure that the new ConditionalExpression plays well with the GetResourceDependenciesAsync() API. Specifically, dependencies can be introduced via whenTrue branch, whenFalse branch, and via the condition itself. We should make sure that GetResourceDependenciesAsync() correctly detects dependencies introduced by any of these ConditionalExpression parameters, and that dependencies are correctly de-duplicated if they are affecting more than one parameter. And also, in non-direct discovery mode, dependencies should be detected if condition or branches of the ConditionalExpression refers to them indirectly.

Relevant test file: https://github.com/dotnet/aspire/blob/release/13.2/tests/Aspire.Hosting.Tests/ResourceDependencyTests.cs

Add 4 test cases for resource dependency tracking with conditional reference expressions: basic branch dependencies, endpoint references, nested conditionals, and deduplication. Fix bug in ReferenceExpression.References where the condition object itself was not yielded - only its sub-references via IValueWithReferences. Since ParameterResource does not implement IValueWithReferences, the condition resource was silently dropped from dependency tracking. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

danegsta · 2026-03-09T19:01:33Z

We should make sure that the new ConditionalExpression plays well with the GetResourceDependenciesAsync() API. Specifically, dependencies can be introduced via whenTrue branch, whenFalse branch, and via the condition itself. We should make sure that GetResourceDependenciesAsync() correctly detects dependencies introduced by any of these ConditionalExpression parameters, and that dependencies are correctly de-duplicated if they are affecting more than one parameter. And also, in non-direct discovery mode, dependencies should be detected if condition or branches of the ConditionalExpression refers to them indirectly.

Relevant test file: https://github.com/dotnet/aspire/blob/release/13.2/tests/Aspire.Hosting.Tests/ResourceDependencyTests.cs

Added test coverage.

ExpressionResolver.EvalExpressionAsync had no handling for conditional ReferenceExpressions. Since conditional expressions have Format="" (empty string), the method returned null, and the dashboard silently dropped the environment variable (resolvedValue?.Value != null check). Add conditional branch to EvalExpressionAsync that evaluates the condition, selects the matching branch, and recurses — mirroring the logic already present in ReferenceExpression.GetValueAsync. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…rison Remove ternary and static fallback paths from BuildHelmConditional. All conditionals now use {{ if eq ... }}...{{ else }}...{{ end }} syntax which natively handles mixed content (literal + Helm expressions) without needing TryFormatBranch or printf workarounds. Add | lower pipe for case-insensitive comparison, matching .NET's StringComparison.OrdinalIgnoreCase used in other execution/publish paths. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Apply toLower() to condition values in Azure Container Apps and App Service Bicep ternary expressions, matching the OrdinalIgnoreCase semantics used in all other execution and publish paths. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

davidfowl · 2026-03-10T05:48:50Z

@sebastienros @mitchdenny follow up here to make sure deployment works well e2e

davidfowl · 2026-03-10T05:49:16Z

Those don’t auto run without explicit triggering

danegsta requested a review from mitchdenny as a code owner March 3, 2026 22:10

Copilot AI review requested due to automatic review settings March 3, 2026 22:10

danegsta mentioned this pull request Mar 3, 2026

Add a new Tls EndpointProperty #13778

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danegsta added 2 commits March 3, 2026 15:26

Add a new deferred value provider for tls connection properties

a8bad02

Respond to PR feedback

a5aa70a

danegsta force-pushed the danegsta/redisTls branch from 9404e2f to a5aa70a Compare March 3, 2026 23:27

danegsta added 2 commits March 3, 2026 15:35

Update comment

19280d2

Update baselines for code generation tests

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danegsta added 2 commits March 3, 2026 15:56

Update comments with links to redis scheme registrations

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Make DeferredValueProvider async, use appropriate string comparison

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github-actions bot mentioned this pull request Mar 4, 2026

[pull requests] Review required #13834

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danegsta added 2 commits March 3, 2026 17:19

Relax scheme constraints in manifest schema

fc4a4b5

Omit the manifest schema going forward. Keeps schema tests to avoid r…

42a8315

…egressions in output.

This was referenced Mar 4, 2026

[13.2-burndown] Daily Burndown Report - March 4, 2026 #14940

Closed

[13.2-burndown] Daily Burndown Report - March 5, 2026 #14972

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danegsta and others added 2 commits March 6, 2026 12:49

Merge remote-tracking branch 'upstream/release/13.2' into danegsta/re…

6c1d3e9

…disTls

danegsta changed the title ~~Add a new deferred value provider for dynamic properties in endpoint references~~ Add ConditionalReferenceExpression with polyglot codegen support Mar 7, 2026

danegsta and others added 3 commits March 6, 2026 20:42

Fix outdated code generation snapshots

c914fcf

Merge remote-tracking branch 'upstream/release/13.2' into danegsta/re…

f277a91

…disTls

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danegsta and others added 5 commits March 7, 2026 16:30

Disable HTTPS certificate for Redis in EndToEnd test AppHost

abbd868

The EndToEnd tests are incompatible with TLS-enabled Redis. Opt out of the developer certificate for the Redis resource in TestProgram. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

github-actions bot mentioned this pull request Mar 8, 2026

[13.2-burndown] Daily Burndown Report - March 8, 2026 #15052

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danegsta and others added 5 commits March 9, 2026 09:55

Resolve merge conflict in Java two-pass scanning snapshot

1f48c5b

Re-generated the verified snapshot by running the test against the current codebase. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Update Go and Rust expression key from $refExpr to $expr

0acd987

Align with the TypeScript base.ts which already uses the current $expr key for reference expression serialization. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

karolz-ms approved these changes Mar 9, 2026

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danegsta merged commit 268592d into release/13.2 Mar 10, 2026
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[13.2-burndown] Daily Burndown Report - March 10, 2026 #15097

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Merge release/13.2 into main #15151

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This was referenced Mar 18, 2026

Need to use a value provider to delay evaluating Redis connection string TLS configuration #13645

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Use DevCert for SQL Server #13131

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Description

ReferenceExpression conditional mode

Unified ATS wire format

Redis TLS

Example

Checklist

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