aspire-data-api-builder

name	aspire-data-api-builder
description	Guide for .NET Aspire orchestration of SQL Server + Data API Builder + SQL Commander + MCP Inspector. Use when asked to create an Aspire-based DAB environment.

.NET Aspire + Data API Builder (Single-File Orchestration)

This skill provides a minimal workflow for running SQL Server, Data API Builder (DAB), SQL Commander, and MCP Inspector using .NET Aspire's single-file AppHost pattern for local development.

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Core Mental Model

• One apphost.cs file orchestrates everything — no project files, no Docker Compose
• aspire run starts all services with health checks, dependencies, and telemetry
• Aspire injects OTEL env vars (OTEL_EXPORTER_OTLP_ENDPOINT, OTEL_SERVICE_NAME) automatically — do NOT add "headers": "@env('OTEL_EXPORTER_OTLP_HEADERS')" to dab-config.json telemetry config unless the env var is set, or DAB will crash loop
• Containers talk by service name, not localhost
• DAB reads config from bind-mounted file — mount dab-config.json read-only
• SQL Server must be healthy before DAB starts — use .WaitFor() for the database, .WaitForCompletion() for SQL projects
• Aspire Dashboard provides visual monitoring, logs, and metrics at http://localhost:15888

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Prerequisites

• .NET 10+ SDK — verify with dotnet --version
• Aspire CLI 13+ — install: dotnet tool install -g aspire — verify: aspire --version
• Docker Desktop running — SQL Server runs in container
• dab-config.json in workspace root using @env('MSSQL_CONNECTION_STRING')

MVP rule: Only add database schema/seed scripts if user explicitly asks.

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Quick Workflow (Checklist)

1. Create .env with connection string (gitignored).
2. Create apphost.cs using the template below.
3. Run with aspire run.
4. Access services via Aspire Dashboard.

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Templates

.env (example)

# Never commit this file
SA_PASSWORD=YourStrong@Passw0rd
MSSQL_CONNECTION_STRING=Server=sql-server;Database=MyDb;User Id=sa;Password=YourStrong@Passw0rd;TrustServerCertificate=true

Critical: Add .env, **\bin, and **\obj to .gitignore before creating secrets.

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apphost.cs (minimal template)

// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

#:sdk Aspire.AppHost.Sdk@13.0.0
#:package Aspire.Hosting.SqlServer@13.0.0
#:package CommunityToolkit.Aspire.Hosting.SqlDatabaseProjects@9.8.1-beta.420
#:package CommunityToolkit.Aspire.Hosting.Azure.DataApiBuilder@9.8.1-beta.420
#:package CommunityToolkit.Aspire.Hosting.McpInspector@9.8.0

var builder = DistributedApplication.CreateBuilder(args);

var options = new
{
    SqlDatabase = "MyDb",
    DabConfig = "dab-config.json",
    DabImage = "latest",
    SqlCmdrImage = "latest"
};

var sqlServer = builder
    .AddSqlServer("sql-server")
    .WithDataVolume("sql-data")
    .WithEnvironment("ACCEPT_EULA", "Y")
    .WithLifetime(ContainerLifetime.Persistent);

var sqlDatabase = sqlServer
    .AddDatabase(options.SqlDatabase);

var dabServer = builder
    .AddContainer("data-api", image: "azure-databases/data-api-builder", tag: options.DabImage)
    .WithImageRegistry("mcr.microsoft.com")
    .WithBindMount(source: new FileInfo(options.DabConfig).FullName, target: "/App/dab-config.json", isReadOnly: true)
    .WithHttpEndpoint(targetPort: 5000, name: "http")
    .WithEnvironment("MSSQL_CONNECTION_STRING", sqlDatabase)
    .WithUrls(context =>
    {
        context.Urls.Clear();
        context.Urls.Add(new() { Url = "/graphql", DisplayText = "GraphQL", Endpoint = context.GetEndpoint("http") });
        context.Urls.Add(new() { Url = "/swagger", DisplayText = "Swagger", Endpoint = context.GetEndpoint("http") });
        context.Urls.Add(new() { Url = "/health", DisplayText = "Health", Endpoint = context.GetEndpoint("http") });
    })
    .WithOtlpExporter()
    .WithParentRelationship(sqlDatabase)
    .WithHttpHealthCheck("/health")
    .WaitFor(sqlDatabase);

var sqlCommander = builder
    .AddContainer("sql-cmdr", "jerrynixon/sql-commander", options.SqlCmdrImage)
    .WithImageRegistry("docker.io")
    .WithHttpEndpoint(targetPort: 8080, name: "http")
    .WithEnvironment("ConnectionStrings__db", sqlDatabase)
    .WithUrls(context =>
    {
        context.Urls.Clear();
        context.Urls.Add(new() { Url = "/", DisplayText = "Commander", Endpoint = context.GetEndpoint("http") });
    })
    .WithParentRelationship(sqlDatabase)
    .WithHttpHealthCheck("/health")
    .WaitFor(sqlDatabase);

var mcpInspector = builder
    .AddMcpInspector("mcp-inspector")
    .WithMcpServer(dabServer)
    .WithParentRelationship(dabServer)
    .WithEnvironment("NODE_TLS_REJECT_UNAUTHORIZED", "0")
    .WaitFor(dabServer)
    .WithUrls(context =>
    {
        context.Urls.First().DisplayText = "Inspector";
    });

await builder.Build().RunAsync();

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dab-config.json (minimal)

{
  "$schema": "https://dataapibuilder.azureedge.net/schemas/latest/dab.draft.schema.json",
  "data-source": {
    "database-type": "mssql",
    "connection-string": "@env('MSSQL_CONNECTION_STRING')"
  },
  "runtime": {
    "rest": {
      "enabled": true,
      "path": "/api"
    },
    "graphql": {
      "enabled": true,
      "path": "/graphql"
    },
    "host": {
      "mode": "development",
      "cors": {
        "origins": ["*"],
        "allow-credentials": false
      }
    },
    "mcp": {
      "enabled": true
    }
  },
  "entities": {}
}

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Running the Stack

Start Services

aspire run

This command:

• Builds and restores packages
• Starts SQL Server container
• Waits for SQL health check
• Starts DAB container with bind-mounted config
• Starts SQL Commander
• Starts MCP Inspector
• Opens Aspire Dashboard

Aspire Dashboard: http://localhost:15888

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Access Services

Service	URL	Purpose
Aspire Dashboard	http://localhost:15888	Monitor all services, logs, metrics
DAB GraphQL	Click "GraphQL" link in dashboard	Query data via GraphQL
DAB Swagger	Click "Swagger" link in dashboard	REST API documentation
DAB Health	Click "Health" link in dashboard	Service health status
SQL Commander	Click "Commander" link in dashboard	SQL query tool
MCP Inspector	Click "Inspector" link in dashboard	Test MCP endpoints

Note: Aspire assigns dynamic ports. Use dashboard links instead of hardcoded URLs.

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Stop Services

Press Ctrl+C in terminal where aspire run is active, or:

docker stop $(docker ps -q)

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Adding Database Schema (Optional)

To deploy a SQL schema on startup using a SQL Database Project, add this before var dabServer:

var sqlDatabaseProject = builder
    .AddSqlProject<Projects.database>("sql-project")
    .WithReference(sqlDatabase);

Then change dabServer and sqlCommander to wait for the SQL project to complete deployment (not just start):

// Use WaitForCompletion — SQL projects are run-to-completion resources
.WaitForCompletion(sqlDatabaseProject);

Critical: Use .WaitForCompletion() for SQL projects, not .WaitFor(). The SQL project container exits after deploying the dacpac — .WaitFor() only waits for it to enter Running state, which may be before deployment finishes. This causes DAB to fail with "Invalid object name" errors.

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Troubleshooting

aspire: command not found

Fix:

dotnet tool install -g aspire

SQL Server container fails to start

Check Docker:

docker ps -a
docker logs <container-id>

DAB can't connect to SQL Server

Verify connection string in .env uses service name sql-server, not localhost:

MSSQL_CONNECTION_STRING=Server=sql-server;Database=MyDb;...

DAB fails with "Invalid object name 'dbo.TableName'"

Cause: Race condition — DAB started before the SQL project finished deploying the schema. Using .WaitFor(sqlDatabaseProject) only waits for Running state, not completion.

Fix: Change .WaitFor(sqlDatabaseProject) to .WaitForCompletion(sqlDatabaseProject). SQL projects are run-to-completion resources that exit after dacpac deployment.

// WRONG — may start before dacpac finishes
.WaitFor(sqlDatabaseProject)

// CORRECT — waits for deployment to complete
.WaitForCompletion(sqlDatabaseProject)

DAB crash loop with @env() telemetry headers

Aspire automatically injects OTEL_EXPORTER_OTLP_ENDPOINT and OTEL_SERVICE_NAME into containers, but not OTEL_EXPORTER_OTLP_HEADERS. If your dab-config.json includes:

"headers": "@env('OTEL_EXPORTER_OTLP_HEADERS')"

DAB will enter a fatal deserialization crash loop because all @env() references must resolve to a value. The headers field is only needed when the OTLP endpoint requires authentication (e.g., cloud APM services) — local Aspire doesn't.

Fix: Remove the headers field from dab-config.json telemetry config when running with Aspire locally. Only add it when targeting an authenticated OTLP collector, and ensure the referenced environment variable is set.

Port conflicts

Aspire auto-assigns ports. If dashboard doesn't open, check terminal output for actual URL.

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Aspire vs Docker Compose

Feature	Aspire	Docker Compose
Definition	Single C# file	YAML file
Language	C#	YAML
Dependencies	.WaitFor() + health checks	depends_on + healthcheck
Monitoring	Built-in dashboard with logs, metrics, traces	External tools required
Service Discovery	Automatic	Manual with service names
Hot Reload	Yes with --watch	No
Debugging	Native .NET debugging	Container debugging only

Use Aspire when:

• You're already in a .NET project
• You want integrated telemetry and monitoring
• You need complex startup orchestration

Use Docker Compose when:

• You need multi-language support
• You want standard container orchestration
• Aspire isn't installed

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Configuration Details

Service Names (DNS)

Containers reference each other by service name:

• SQL Server: sql-server
• DAB: data-api
• SQL Commander: sql-cmdr
• MCP Inspector: mcp-inspector

Volumes

SQL Server data persists in Docker volume sql-data:

docker volume ls | Select-String sql-data

To reset database:

aspire run  # Stop with Ctrl+C
docker volume rm <volume-name>
aspire run  # Restart

Health Checks

• SQL Server: Default SQL health check
• DAB: GET /health (must return 200)
• SQL Commander: GET /health

Services won't start until dependencies are healthy.

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Reference

• Aspire Sample (Official)
• Aspire CLI Reference
• Aspire Dashboard Docs
• DAB Configuration

For Azure deployment, see the azure-data-api-builder skill.