Docker Volume Mounts for Development: Avoiding Baked Code Issues

When to use

When deploying applications in Docker containers where code or configuration changes need to be reflected immediately without rebuilding the entire image. Prevents the common mistake of "baking in" code at build time and then wondering why file updates don't appear in the running container.

Prerequisites

Docker installed and running on the server
Application deployed in a Docker container
Need to iterate on code/configuration without full image rebuilds

Steps

Identify files/directories that need live updates (e.g., transcription files, AD text configs)
Instead of copying files into the image at build time, use Docker volume mounts in your docker-compose.yml or docker run command:
```
volumes:
  - /opt/video-accessibility/data:/app/data
  - /opt/video-accessibility/config:/app/config
```
For direct docker run: docker run -v /opt/video-accessibility/data:/app/data ...
Update files on the host machine in the mounted directory
Changes appear immediately in the running container without rebuilding the image

Key Configuration

Dockerfile: Remove COPY instructions for files that change frequently; use VOLUME declarations instead
docker-compose.yml: Add volumes section mapping host paths to container paths
Permissions: Ensure the container user has write permissions to mounted directories

Gotchas

Code baked into Docker images with COPY or ADD commands will not reflect host-side changes—the container uses the image snapshot
If changes don't appear, verify the volume mount path is correct and the container was restarted after mounting changes
File permissions between host and container can cause issues; use explicit user IDs if needed
Volume mounts only work for data/config; for code changes during development, either use volume mounts or implement a proper CI/CD pipeline for production

Source

Project: video-accessibility-old

2.1 KiB Raw Permalink Blame History