docker-data-api-builder

name	docker-data-api-builder
description	Docker Compose orchestration of SQL Server, Data API Builder, SQL Commander, and MCP Inspector. Use when asked to create docker-compose.yml, set up local containers, or run DAB without Aspire.

Docker SQL Server + DAB + MCP Inspector (Local Dev)

This skill provides a minimal, repeatable workflow for running SQL Server, Data API Builder (DAB), SQL Commander, and MCP Inspector together in Docker Compose for local development and testing.

Included script template

• docker.ps1 — starts compose, waits for SQL health, builds dacpac, and publishes schema.
  • Use this instead of running docker compose up -d alone when schema deployment is required.

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Core Mental Model

• One docker-compose.yml controls the full stack. Never use raw docker run.
• Containers talk by service name, not localhost.
• DAB reads config from /App/dab-config.json — mount it read-only.
• SQL Server must be healthy before DAB starts — use healthcheck + depends_on: condition: service_healthy.
• MCP Inspector requires a special URL to auto-connect to DAB's /mcp endpoint.

---

Prerequisites

• Docker Desktop running
• A dab-config.json in the workspace root (use @env('DATABASE_CONNECTION_STRING'))
• Non-default SQL Server host port (assume 1433 is in use)

MVP rule: Only add database.sql / sample-data.sql if the user explicitly asks.

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Quick Workflow (Checklist)

1. Pick a cute Compose project name (e.g., bloom-tracker).
2. Create .env with passwords/connection strings (gitignored).
3. Create .gitignore with .env, **\bin, and **\obj entries.
4. Create docker-compose.yml using the template below.
5. Start services with docker compose up -d.
6. Wait for SQL Server to be healthy — run docker compose ps and confirm sql-2025 shows (healthy).
7. Build and deploy the database schema before opening SQL Commander or DAB:

   dotnet build database/database.sqlproj
   sqlpackage /Action:Publish /SourceFile:database/bin/Debug/database.dacpac /TargetConnectionString:"Server=localhost,14330;Database=<DbName>;User Id=sa;Password=<password>;TrustServerCertificate=true" /p:BlockOnPossibleDataLoss=false
   

8. Open SQL Commander or MCP Inspector only after the schema is deployed.

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Templates

.env (example)

# Never commit this file
SA_PASSWORD=YourStrong@Passw0rd
DATABASE_CONNECTION_STRING=Server=sql-2025;Database=TodoDb;User Id=sa;Password=YourStrong@Passw0rd;TrustServerCertificate=true
SQL_COMMANDER_CONNECTION_STRING=Server=sql-2025;Database=TodoDb;User Id=sa;Password=YourStrong@Passw0rd;TrustServerCertificate=true

Note: For container-to-container connections, use Server=sql-2025 (the service name), not localhost. CRITICAL: Never use $ in passwords — Docker Compose interprets $ as a variable reference in .env files (e.g., Pa$$word becomes Paword). Use only alphanumeric characters, !, @, #, %, ^, &, *.

docker-compose.yml

name: bloom-tracker  # change to match your use case

services:
  sql-2025:
    image: mcr.microsoft.com/mssql/server:2025-latest
    container_name: sql-2025
    restart: unless-stopped
    environment:
      - ACCEPT_EULA=Y
      - MSSQL_SA_PASSWORD=${SA_PASSWORD}
    ports:
      - "14330:1433"  # non-default host port
    volumes:
      - sql-2025-data:/var/opt/mssql
    healthcheck:
      test: /opt/mssql-tools18/bin/sqlcmd -S localhost -U sa -P "${SA_PASSWORD}" -C -Q "SELECT 1" || exit 1
      interval: 10s
      timeout: 5s
      retries: 10
      start_period: 30s

  sql-cmdr:
    image: jerrynixon/sql-commander:latest
    container_name: sql-cmdr
    restart: unless-stopped
    environment:
      - ConnectionStrings__db=${SQL_COMMANDER_CONNECTION_STRING}
    ports:
      - "8080:8080"
    depends_on:
      sql-2025:
        condition: service_healthy

  api-server:
    image: mcr.microsoft.com/azure-databases/data-api-builder:latest
    container_name: api-server
    restart: unless-stopped
    environment:
      - DATABASE_CONNECTION_STRING=${DATABASE_CONNECTION_STRING}
    ports:
      - "5000:5000"
    volumes:
      - ./dab-config.json:/App/dab-config.json:ro
    depends_on:
      sql-2025:
        condition: service_healthy

  mcp-inspector:
    image: ghcr.io/modelcontextprotocol/inspector:latest
    container_name: mcp-inspector
    restart: unless-stopped
    environment:
      - HOST=0.0.0.0
      - MCP_AUTO_OPEN_ENABLED=false
      - DANGEROUSLY_OMIT_AUTH=true
    ports:
      - "6274:6274"
      - "6277:6277"
    depends_on:
      - api-server

volumes:
  sql-2025-data:
    external: false

MCP Inspector auto-connect URL

http://localhost:6274/?transport=streamable-http&serverUrl=http%3A%2F%2Fapi-server%3A5000%2Fmcp

Important: http://localhost:6274 alone won't auto-connect.

---

Minimal DAB MCP Config (reference)

Ensure dab-config.json enables MCP and uses env vars:

{
  "$schema": "https://github.com/Azure/data-api-builder/releases/download/v2.0.8/dab.draft.schema.json",
  "data-source": {
    "database-type": "mssql",
    "connection-string": "@env('DATABASE_CONNECTION_STRING')"
  },
  "runtime": {
    "rest": { "enabled": true, "path": "/api" },
    "graphql": { "enabled": true, "path": "/graphql", "allow-introspection": true },
    "mcp": { "enabled": true, "path": "/mcp" },
    "host": { "mode": "development" }
  }
}

---

Verification

• docker compose ps shows all services running
• SQL container health is healthy
• DAB responds at http://localhost:5000/health — open this in the browser to verify DAB is running and show the user it's working
• MCP Inspector opens via the special URL and lists tools

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Troubleshooting

SA login fails (Error 18456, State 8)

• SQL Server only sets SA_PASSWORD on first volume initialization. If the volume already exists from a prior run with a different password, changing .env has no effect.
• Fix: Run docker compose down -v to remove volumes, then docker compose up -d to recreate from scratch.
• Prevention: Before running docker compose up -d, always run docker compose down -v to ensure a clean state. This avoids stale password mismatches.

DAB can't connect to SQL Server

• TrustServerCertificate=true is required — SQL Commander will not connect without it (locally or in Azure)
• Use Server=sql-2025 (service name) inside containers
• Confirm SQL container is healthy before DAB starts

SQL Commander or DAB fails with "Cannot open database" (Error 4060)

• The SQL Server container is running and healthy, but the database hasn't been created yet.
• SQL Server's healthcheck only verifies the engine accepts connections — it does NOT verify specific databases exist.
• Fix: Build and deploy the database schema with sqlpackage /Action:Publish before using SQL Commander or DAB.
• Prevention: Always run sqlpackage after docker compose up -d and before opening any service that depends on the database.

MCP Inspector opens but doesn't connect

• Use the special auto-connect URL (not plain localhost:6274)
• Verify DAB is running and /mcp is enabled

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Consistency Rules (MVP)

1. Always use docker-compose.yml (no raw docker run).
2. Always use non-default SQL ports on the host.
3. Always mount dab-config.json read-only (:ro) for local development only.
4. Always use healthcheck + depends_on: condition: service_healthy.
5. Always include SQL Commander and MCP Inspector in the compose stack.
6. Use service names for container-to-container connections.
7. Ask before adding schema or seed files (database.sql, sample-data.sql).
8. Prefer a dedicated SQL login for app connections; only use sa to bootstrap if needed.

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