Add default OTEL telemetry settings to dab init config generation

[Copilot]

Why make this change?

dab init generates config with no telemetry section, requiring users to manually edit config or run dab add-telemetry to enable standard OpenTelemetry workflows. This is friction for .NET/Aspire and containerized scenarios where OTEL env vars are already set by the orchestrator.

What is this change?

Adds default OpenTelemetry config to TryCreateRuntimeConfig() using @env() references for standard OTEL environment variables. The generated config now includes:

"telemetry": {
  "open-telemetry": {
    "enabled": true,
    "endpoint": "@env('OTEL_EXPORTER_OTLP_ENDPOINT')",
    "headers": "@env('OTEL_EXPORTER_OTLP_HEADERS')",
    "service-name": "@env('OTEL_SERVICE_NAME')"
  }
}

Additionally, runtime config loading and OTLP exporter setup are hardened to gracefully handle missing OTEL env vars:

• src/Cli/ConfigGenerator.cs — Added TelemetryOptions with OpenTelemetryOptions to the RuntimeConfig constructed during init.
• src/Config/FileSystemRuntimeConfigLoader.cs — Changed TryLoadKnownConfig to use EnvironmentVariableReplacementFailureMode.Ignore so missing @env() env vars don't crash config loading — they remain as literal @env(...) strings.
• src/Service/Startup.cs — Added Uri.TryCreate validation in the OTLP exporter setup guard condition. If the endpoint is null, empty, or an unresolved @env(...) placeholder (not a valid URI), OTLP exporter setup is skipped entirely and a warning is logged. Updated warning message to reference "endpoint URI" instead of "connection string".
• src/Service/Program.cs — Applied the same Uri.TryCreate validation for the logger factory OTLP setup, replacing the previous !string.IsNullOrWhiteSpace + new Uri() pattern.
• 31 Verify snapshot files — Updated to reflect the new telemetry section.
• src/Cli.Tests/EndToEndTests.cs — E2E tests that deserialize init-generated config with doReplaceEnvVar: true now use EnvironmentVariableReplacementFailureMode.Ignore matching production behavior. TestAddTelemetry assertion updated since telemetry is no longer null after init.

How was this tested?

• Integration Tests
• Unit Tests

All 43 InitTests pass. EndToEndTests.TestInitForCosmosDBNoSql passes. E2E tests for TestInitializingRestAndGraphQLGlobalSettings, TestEnablingMultipleCreateOperation, and TestAddTelemetry updated to accommodate new defaults.

Sample Request(s)

dab init --database-type mssql --connection-string "Server=localhost;Database=mydb;"

Generated dab-config.json now includes the telemetry.open-telemetry section with @env() references. If the OTEL env vars are set at runtime (e.g., by Aspire or a container orchestrator), telemetry export works automatically. If unset, the @env() values remain as literal strings, the endpoint fails Uri.TryCreate validation, and OTLP setup is gracefully skipped.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>dab init should automatically include default OTEL settings </issue_title>
<issue_description>## Problem
Currently, when running dab init, the generated dab-config.json does NOT include default configuration for OpenTelemetry telemetry using the standard OTEL_* environment variables (such as OTEL_EXPORTER_OTLP_ENDPOINT, OTEL_SERVICE_NAME, etc.). This makes DAB out-of-the-box telemetry support useless compared to typical .NET applications and Aspire scenarios.

Proposal

When dab init is run in the CLI, if the telemetry section is being generated (or whenever the user chooses to include telemetry), automatically add the following default values to dab-config.json:

"telemetry": {
  "open-telemetry": {
    "enabled": true,
    "endpoint": "@env('OTEL_EXPORTER_OTLP_ENDPOINT')",
    "headers": "@env('OTEL_EXPORTER_OTLP_HEADERS')",
    "exporter-protocol": "@env('OTEL_EXPORTER_OTLP_PROTOCOL')",
    "service-name": "@env('OTEL_SERVICE_NAME')"
  }
}

These defaults should follow the documented OTEL env variable mapping, so users can use standard .NET/OTEL workflows with container orchestrators and Aspire. If the env vars are not set at runtime, the config values should remain as-is or fall back gracefully.

Benefit

• Aligns DAB telemetry configuration with the "expected" .NET/Aspire experience
• Simplifies Aspire integration and containerized telemetry export
• Reduces user error/misconfiguration
• DAB users don't need to hand-edit config to enable standard OTEL telemetry flows

Implementation Guidance

• Extend CLI config template logic to include the above section when telemetry is requested/enabled
• Consider surfacing a CLI flag to toggle inclusion of OTEL env mappings
• Document the behavior in dab init help and in DAB docs

---

This is a feature request for improved developer out-of-the-box experience. See OpenTelemetry config docs for reference.</issue_description>

<agent_instructions>introduce as little code as possible. </agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes dab init should automatically include default OTEL settings  #3161

---

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[Copilot]

Pull request overview

This PR updates dab init config generation to include default OpenTelemetry settings (via @env() references to standard OTEL_* environment variables) and refreshes CLI tests/snapshots to reflect the new generated config shape.

Changes:

• Add default runtime.telemetry.open-telemetry block to init-generated RuntimeConfig.
• Update CLI E2E tests to tolerate unset OTEL_* env vars during deserialization and adjust assertions for non-null telemetry.
• Refresh Verify snapshots for init-generated configs to include the new telemetry section.

Reviewed changes

Copilot reviewed 33 out of 33 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/Cli/ConfigGenerator.cs	Adds default OpenTelemetry telemetry options to the RuntimeConfig produced by dab init.
src/Cli.Tests/EndToEndTests.cs	Updates env-var replacement settings and telemetry assertions to accommodate new init defaults.
src/Cli.Tests/Snapshots/EndToEndTests.TestInitForCosmosDBNoSql.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.CosmosDbNoSqlDatabase.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.CosmosDbPostgreSqlDatabase.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.EnsureCorrectConfigGenerationWithDifferentAuthenticationProviders_171ea8114ff71814.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.EnsureCorrectConfigGenerationWithDifferentAuthenticationProviders_2df7a1794712f154.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.EnsureCorrectConfigGenerationWithDifferentAuthenticationProviders_59fe1a10aa78899d.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.EnsureCorrectConfigGenerationWithDifferentAuthenticationProviders_b95b637ea87f16a7.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.EnsureCorrectConfigGenerationWithDifferentAuthenticationProviders_daacbd948b7ef72f.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.GraphQLPathWithoutStartingSlashWillHaveItAdded.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.MsSQLDatabase.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.RestPathWithoutStartingSlashWillHaveItAdded.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.TestInitializingConfigWithoutConnectionString.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.TestSpecialCharactersInConnectionString.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_0546bef37027a950.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_0ac567dd32a2e8f5.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_0c06949221514e77.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_18667ab7db033e9d.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_2f42f44c328eb020.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_3243d3f3441fdcc1.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_53350b8b47df2112.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_6584e0ec46b8a11d.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_81cc88db3d4eecfb.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_8ea187616dbb5577.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_905845c29560a3ef.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_b2fd24fab5b80917.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_bd7cd088755287c9.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_d2eccba2f836b380.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_d463eed7fe5e4bbe.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_d5520dd5c33f7b8d.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_eab4a6010e602b59.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.
src/Cli.Tests/Snapshots/InitTests.VerifyCorrectConfigGenerationWithMultipleMutationOptions_ecaa688829b4030e.verified.txt	Snapshot updated to include Telemetry.OpenTelemetry section.

[Aniruddh25]

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