Syncing Dev Configs into Docker Containers

You spin up a Docker container for development and immediately hit a wall. No Git configuration. No shell aliases. No SSH keys. The container is a blank slate, and you are stuck running git config --global user.name for the hundredth time.

Most developers reach for volume mounts as a quick fix. But volume mounts have serious limitations: they expose plaintext secrets, break when paths differ between host and container, and do not work across different host operating systems.

The simplest approach is mounting config files directly into the container:

This works for simple cases but falls apart quickly. Your SSH keys are mounted as plaintext. If the container runs as a different user, permissions break. And you need to remember which files to mount every time.

Instead of mounting files, install ConfigSync inside the container and pull your configs at runtime. This keeps secrets encrypted until they are needed and works identically regardless of the host OS.

Then pull your configs when the container starts, using a token passed as an environment variable:

For multi-container development setups, add ConfigSync to your entrypoint in Docker Compose. Every service that needs dev configs gets them automatically:

The --filter flag lets each service pull only the configs it needs. Your app container gets everything; the worker only needs Git configuration.

ConfigSync includes a dedicated Docker module that syncs your Docker configuration itself. The ~/.docker/config.json file contains registry authentication tokens, and the Docker module encrypts these before syncing.

This means when you pull on a new machine or inside a container, your private registry access is already configured. No more docker login on every new environment.

The ideal container development workflow with ConfigSync looks like this: build your image once with ConfigSync installed, pass your token at runtime, and pull only the modules each container needs. Your Git identity, SSH keys, shell config, and registry credentials all arrive encrypted and are decrypted only inside the running container.

No more volume mount spaghetti. No more plaintext secrets in Docker commands. Just one tool that gives every container your full development environment.