Containers | Building a local development environmentContainers, Docker Compose, Local Development, DLM with Containers ·
Docker-Compose, Flyway and a T-SQL runner to help you get up and running with a local development environment.
In my introductory posts on docker and docker-compose. We managed to set up an empty SQL Server container, but in the real world, that is not very useful.
Okay great - we can create SQL Server containers now let us build on that to create a ready-to-go development environment with
Let us take a moment to talk about the objective. We need a SQL Server, a database and something to deploy code to it (build). We will define a service (an instance of a container) in our compose file for each of these tasks.
SQL Server using image
A simple T-SQL Script runner
Flyway for Build/Deployment
Flyway cannot create a database it expects the database to exist before deploying the code. This is why we use
aletasystems/tsqlrunner which is a custom-image based on
We have configured our SQL-Server as follows.
- Running on port 14333
- Password is set in a
We now need to initialise SQL server using the container
aletasystems/tsqlrunner.Our initialisation process is really simple, execute a create database script against the master database.
First a quick tour on how
- In your compose file, you map a local directory containing TSQL files to the containers
- The local directory follows the convention of
- The runner will first run the scripts in
master\filename(in alphabetical order)
- Then process each database and script (again in alphabetical order)
With this information, we place a create database TSQL script file (
We now add
inittools service to our
docker-compose file, we configure it as below.
- The SQL Server it connects to is the
dbservice we defined earlier
- It users the username
saand password (again it is taken from our
- We give it the path to the SQL Scripts to run.
We will use flyway to deploy our code, but you can plugin an alternative that suits your need. I found flyway the easiest to work with, it is a fantastic tool and I hope to write/talk about it in the future.
I won’t get into too much detail about how flyway works as that deserves it own post, but if you are interested you can read How Flyway works
volumesshows flyway where the
commandtells it what we want to do along with the various parameters
Some useful commands:
- To re-run flyway with the latest changes to source code
docker-compose restart flyway
- To view the flyway log
docker-compose logs -f flyway
How did we control order?
We used the
depends_on property to tell each service what it depends on. This is not exactly true, as it is (and from what I understand) the moment a service comes online, docker believes it is ready - which can be problematic as SQL Server takes a few seconds to become accessible.
It is therefore important that your services have a retry/delay mechanism built-in. Flyway has an additional parameter
aletasystems/tsqlrunner has a modest retry mechanism