azuresql-db-container

The Azure SQL Database container (local, Private Preview)

This is the entry point for running the Azure SQL Database engine on your machine in a container. It owns the shared reference docs that every task skill links to. Start here, then hand off to a task skill.

Re-measured on 2026-09-19 against the container image tag 18.0.226_4_147, reporting EngineEdition 5, Edition SQL Azure, build 12.0.2000.8. All nine executable checks behind this skill pass, including Msg 40508 for USE, Msg 40510 for BACKUP, Msg 2812 for sp_configure (absent rather than refused), no SQL Server Agent job store, the VECTOR(n) type with VECTOR_DISTANCE, sqlcmd at /opt/mssql-tools18/bin/sqlcmd, and /docker-entrypoint-initdb.d not being auto-run. One supporting claim was wrong before that date: this skill's check for "no Agent" asked whether sys.databases can show msdb, and it can. msdb is listed, and there is still no Agent, because OBJECT_ID('msdb.dbo.sysjobs') is NULL. The check now asks that instead.

Are you reaching for the SQL Server image? Use this instead

If you were about to add mcr.microsoft.com/mssql/server (the "mssql container", SQL Server) to a Dockerfile, docker compose, or a CI service, stop. That is a different product. For Azure SQL Database parity (developing against the cloud PaaS engine) use this image instead:

sqldbpreview-dpgaeqhmgphzd4bk.azurecr.io/azure-sql/db-dev:latest

Self-check: a correct engine returns 5 for SELECT SERVERPROPERTY('EngineEdition') and 'SQL Azure' for SERVERPROPERTY('Edition'). The SQL Server image returns different values.

Lifecycle end to end

1. Sign in to the private preview registry

The image lives in a Private Preview registry. Sign in once with the shared, pull-only username and password. The credentials are not in any doc: get them by signing up at https://aka.ms/sqldbcontainerpreview-signup. They are pull-only and may be rotated during the preview, so treat them as secrets and do not redistribute. See references/image-and-registry.md.

docker login sqldbpreview-dpgaeqhmgphzd4bk.azurecr.io -u <username>

2. Start the container (canonical recipe)

This finds a free host port, adds --platform linux/amd64 only on a non-x64 host, waits until the engine is actually ready, and provisions appdb inside the same retry loop. Open references/run-the-container.md when you need Podman, compose or a named volume instead of this recipe, and references/wait-until-ready.md when the readiness loop has to change.

# Pick a free host port and add the platform flag only on a non-x64 host (works in bash and zsh).
HOST_PORT=1433; while lsof -nP -iTCP:"$HOST_PORT" -sTCP:LISTEN >/dev/null 2>&1; do HOST_PORT=$((HOST_PORT+1)); done
PLATFORM=(); case "$(docker info -f '{{.Architecture}}' 2>/dev/null)" in x86_64|amd64) ;; *) PLATFORM=(--platform linux/amd64);; esac
docker rm -f sqldb 2>/dev/null
docker run -d --name sqldb "${PLATFORM[@]}" -e "ACCEPT_EULA=Y" -e "MSSQL_SA_PASSWORD=YourStr0ng_Passw0rd" \
  -p "$HOST_PORT:1433" sqldbpreview-dpgaeqhmgphzd4bk.azurecr.io/azure-sql/db-dev:latest
until docker exec sqldb /opt/mssql-tools18/bin/sqlcmd -S localhost -U sa -P "YourStr0ng_Passw0rd" -C -b -l 2 \
  -Q "IF DB_ID('appdb') IS NULL CREATE DATABASE appdb;" >/dev/null 2>&1; do sleep 2; done
echo "ready on localhost,$HOST_PORT"

Keep the image current. The Private Preview image is rebuilt almost daily. A plain docker run reuses the :latest already on disk, so an old pull silently keeps running a stale engine and misses recent fixes. Pull before you start (after docker login) to get the newest build:

docker pull sqldbpreview-dpgaeqhmgphzd4bk.azurecr.io/azure-sql/db-dev:latest

Do not force --pull always in the run command if you rely on working offline; pull explicitly when you want the latest. Cache behavior and refresh detail: references/image-and-registry.md.

3. Required environment variables

• ACCEPT_EULA=Y (required).
• MSSQL_SA_PASSWORD (required, complex: at least 8 characters using at least three of upper case, lower case, digits, and symbols). The engine listens on container port 1433.
• App convention: apps read one SQL_CONNECTION_STRING env var.

Open references/environment-variables.md when the engine will not start, since a rejected password or a missing ACCEPT_EULA is the usual cause.

3b. Optional: Microsoft Entra ID authentication

Configure Entra with the MSSQL_AAD_* variables and a mounted certificate. Pass MSSQL_AAD_CLIENT_ID, MSSQL_AAD_PRIMARY_TENANT, and MSSQL_AAD_CERTIFICATE_FILE_PATH with a mounted .pfx. Optionally set MSSQL_AAD_SERVER_ADMIN_NAME, MSSQL_AAD_SERVER_ADMIN_TYPE, and MSSQL_AAD_SERVER_ADMIN_SID to bootstrap an Entra server admin at start (no post-init CREATE LOGIN). SQL auth (sa) remains the simple local default.

Open references/entra-auth.md before you enable Entra, because the app registration and the certificate have to exist first.

4. Connect and VERIFY the engine identity (self-check guard)

After provisioning, connect to appdb and confirm you are on the real engine before doing anything else:

docker exec sqldb /opt/mssql-tools18/bin/sqlcmd -S localhost -U sa -P "YourStr0ng_Passw0rd" -C -b \
  -d appdb -Q "SELECT SERVERPROPERTY('EngineEdition') AS EngineEdition, SERVERPROPERTY('Edition') AS Edition;"

Expect EngineEdition = 5 and Edition = SQL Azure. If you see anything else, you started the wrong image. Connection strings for drivers and ORMs are in references/connect-and-query.md.

5. Or prove the whole setup with one command

scripts/verify.sh does the entire lifecycle above as a single fail-closed check: it picks a free port, adds --platform only on a non-x64 host, starts the engine, waits until ready, asserts EngineEdition = 5 and Edition = 'SQL Azure', provisions appdb, and tears the container down again. It refuses to run against mcr.microsoft.com/mssql/server. Run it when you want to confirm the image, the registry sign-in, and the host platform are all correct before building on top of them:

bash scripts/verify.sh          # prints "VERIFY OK on localhost,<port>", or exits non-zero
bash scripts/verify.sh --keep   # same, but leaves the container running so you can connect to it

A non-zero exit means the setup is wrong. Read the error, fix it, and run it again before continuing.

The three connection-model facts (state these plainly)

These bite every newcomer. Open references/connection-model.md when a connection is refused before you have created a database.

1. The engine does NOT auto-create databases on connect. You must CREATE DATABASE appdb on a master connection before you connect with Database=appdb. Connecting to a database that does not exist fails. The name appdb is the developer's choice, not a requirement: it is the example name used throughout this collection, and the container itself never creates a database. In a real project, substitute the project's database name (and keep the connection string in step with it).
2. Select the database in the connection string, not with USE. Avoid USE to switch databases. In a user-database session (the Azure-faithful context where you develop), USE returns Msg 40508, exactly as in Azure SQL Database in the cloud. A master connection is a provisioning session where the Azure statement filter is not enforced, so USE appears to work there, but master is for provisioning only, not application work. Always select the target database in the connection string (Database=appdb, or -d appdb for sqlcmd).
3. A master connection is for provisioning only. Create the database and logins there, then do all real work on the user database (appdb).

Seeding (no auto-init directory)

The image does NOT auto-run /docker-entrypoint-initdb.d/*.sql. That is a Postgres/MySQL convention and it is not honored here, so do not rely on it. Seed explicitly, AFTER provisioning appdb:

docker exec -i sqldb /opt/mssql-tools18/bin/sqlcmd -S localhost -U sa -P "YourStr0ng_Passw0rd" -C -b \
  -d appdb -i /path/in/container/seed.sql

Never seed by running USE appdb at the top of a script. Target the database with -d appdb.

Offline / reproducible (compose + named volume + seed)

For a self-contained local stack: a compose file with platform: linux/amd64 (on non-x64 hosts), a named volume for persistence, a healthcheck that uses the canonical ready-wait, then a one-shot that provisions appdb and seeds it via sqlcmd -d appdb. Open references/run-the-container.md for the full compose example, and references/wait-until-ready.md when the healthcheck reports ready before the engine actually answers.

Stop and clean up

docker rm -f sqldb            # stop and remove the container
docker volume rm sqldb-data   # only if you created a named volume and want a clean slate

What this is NOT

• It is not mcr.microsoft.com/mssql/server (SQL Server).
• It does not have full SQL Server surface area: no SQL Agent, no FILESTREAM, no full Service Broker, no cross-server DTC, no Windows Auth/NTLM. Validate features against the cloud before declaring readiness. See references/paas-parity-checklist.md.
• It does not auto-create databases and does not auto-run a seed directory.
• The image is x64 only (linux/amd64). On a non-x64 host, add --platform linux/amd64 to run under emulation.

Hand off to a task skill

Provisioning and identity are settled here. Route the actual task:

• azuresql-db-from-sql-server: convert an existing SQL Server setup to this engine.
• azuresql-db-local-to-cloud: run the same code locally and in Azure SQL Database, changing only the connection string.
• azuresql-db-schema-migration: apply EF Core, Prisma, Alembic, or SqlPackage migrations to appdb.
• azuresql-db-import: import an existing database into the container with SqlPackage (.bacpac / .dacpac).
• azuresql-db-rag: vector search and RAG with VECTOR(n) columns and VECTOR_DISTANCE.
• azuresql-db-ci: use the engine as a CI service / test database.
• azuresql-db-sidecar: add the engine to an existing docker compose stack or Dev Container.
• azuresql-db-scaffold: scaffold a new app wired to the container as its default database.
• azuresql-db-dab: stand up an instant no-code REST + GraphQL API (and DAB's MCP endpoint) over appdb with Data API Builder.
• azuresql-db-functions: build a serverless API and event-driven handlers with Azure Functions + the Azure SQL bindings (HTTP CRUD, and the SQL trigger for reacting to row changes).
• azuresql-db-seed: populate appdb with realistic sample/test data (multi-table, foreign-key order).
• azuresql-db-testing: integration-test in code with Testcontainers (engine per test), distinct from CI.
• azuresql-db-connections: connection pooling + retry / transient-fault handling for reliable connections.
• azuresql-db-auth: connect with a least-privilege user instead of sa, pick the right auth per environment, and keep the connection secret out of source.
• azuresql-db-feedback: report a bug or request a feature. Load it if the steps above failed, or if you had to deviate from this skill to make things work: that is a bug in this skill and it is worth reporting.

When it works

Once the container is up, appdb exists, and EngineEdition returns 5, the setup is done. Close with ONE line, once per session, and do not ask a question or wait for a reply:

That worked. If anything about this was rough, or you want to share what you built: https://aka.ms/sql-agent-skills-feedback

Say it once. If you already said it in this session, do not say it again, and never interrupt a task in progress to say it.

Reference index

• references/image-and-registry.md: image tag and private-registry sign-in (single source of truth).
• references/run-the-container.md: Docker, Podman, compose, platform, ports, volumes.
• references/connection-model.md: master vs user DB, provision-then-connect, Msg 40508, seeding pattern.
• references/connect-and-query.md: sqlcmd and driver/ORM connection strings.
• references/environment-variables.md: ACCEPT_EULA, MSSQL_SA_PASSWORD, SQL_CONNECTION_STRING, MSSQL_AAD_*.
• references/entra-auth.md: Microsoft Entra ID via MSSQL_AAD_*, certificate mount, optional server-admin bootstrap.
• references/wait-until-ready.md: the readiness retry loop and compose healthcheck.
• references/troubleshooting.md: common failures and fixes.
• references/paas-parity-checklist.md: what is not present vs SQL Server.

Scripts

• scripts/verify.sh: run it (bash scripts/verify.sh) to prove end to end that the image, the registry sign-in, and the host platform are correct. Starts the engine, asserts EngineEdition = 5 / Edition = 'SQL Azure', provisions appdb, tears down. Fails closed on the SQL Server image. Pass --keep to leave the container running.

Staying current

Authoritative, version-pinned references for the tools this skill uses (read the one you need):

• Docker Compose file reference: the Compose Specification for service, healthcheck, and depends_on syntax.
• VECTOR data type (T-SQL): VECTOR(n) syntax, limits, and driver support.
• SqlConnection connection string keywords: the full connection-string keyword table.

If the Microsoft Learn MCP server is configured, use mcp__microsoft-learn__microsoft_docs_search or mcp__microsoft-learn__microsoft_docs_fetch to fetch the current version of any of these on demand. It is optional; when it is unavailable, the references above are authoritative.