TL;DR

dksnap allows you to create and manage snapshots of docker containers. We expect this to be especially useful for developers working with database containers locally. Check dksnap out on GitHub!

Local Development & Test Data

One of the best things about working at Kelda is that we get to talk with tons of developers who are in the weeds building microservices every day. We hear about all the benefits of containerized development and some of the challenges as well. One such challenge is managing test data during local development and testing.

First, some context: most of the developers we're working with are using Docker locally to work on one or more containers that depend on a database of some sort. In production, of course, they use a production database managed by the ops team. However, when working locally, accessing the production database typically isn't feasible. Instead, devs tend to grab a Postgres, MySQL, or Mongo container from Docker Hub.

The trouble begins when that database needs to be populated with data, this typically requires annoying manual setup work that can take quite a long time to get right. Once all the work has been done to get the database container set up just right, the last thing you want is to have to do it again. However, eventually, tests get run, data gets stale, containers get restarted, life happens, and you end up back where you started – with a bunch of manual setup work in front of you.

dksnap

dksnap is a tool that allows you to create, view, and rollback snapshots of containers in real-time without needing to fiddle with bash scripts or memorize complicated docker commands.

Once you've set up your container precisely the way you like, you can create a snapshot. That done, you can manipulate your data however you'd like, knowing that you can instantly revert to a previously working state in seconds.

In addition to the core snapshot functionality, dksnap allows you to replace a running container using any snapshot that you've created, and provides a tree view of all your snapshots along with a diff that shows you how they've changed over time.

dksnap has three key features that aren't easily replicated with the standard Docker CLI.

• First, it's volume aware. Most database containers use volumes which docker commit doesn't capture.
• Second, it's database aware. dksnap knows how to talk to Mongo, Postgres, and MySQL, allowing it to dump and restore data politely, and giving it the ability to show diffs between different snapshot versions.
• Last but not least, it has a simple and intuitive user interface that hides the complexity required for docker snapshots.

Try dksnap

Getting started with dksnap is simple. This tool is a single go binary that you can install by running the following in a terminal:

<code>curl https://kelda.io/install-dksnap.sh | sh</code>

Or, if you prefer, download the latest release and copy it to your $PATH.

If you've already got containers running on your local machine, dksnap opens a new terminal GUI that allows you to create, replace, and view snapshots of your containers.

Otherwise, if you'd like to try out dksnap, we've created a simple demo along with step-by-step instructions so that you can see how it works.

<code># Download the demo.
git clone https://github.com/kelda/dksnap.git
cd dksnap/demo

# Start the example application. 
# You can access it in your browser at localhost:8080.
docker-compose up -d

# Use dksnap to create snapshots of the entries in the Mongo database.
dksnap</code>

Get Involved

dksnap is currently in alpha. It is ready for daily use but is still undergoing substantial development. If you find this useful or interesting, please consider joining the community and providing us with your thoughts.

Here are some ways that you can get involved:

• Start using dksnap today with your work or personal projects.
• Fork the repo and poke around.
• If you have any suggestions, open an issue.
• Join the slack.

We look forward to hearing from you!

Previously published at https://kelda.io/blog/dksnap-docker-snapshots-for-development-and-test-data/