Improving Docker Image Creation #2012
Description
Currently the Docker image for DB Sync is large, complex, and discourages customization. Given the majority of our users are using the docker image, I would like to revisit this strategy.
Introduction
Docker images are built from the NixOS module. While this approach does have benefits in reproduceability, it also presents several challenges:
- Image Size: Recent releases are 1GB+, even though the binary is less that 100MB
- Nix specific: Store paths confuse non-Nix users
- Bundled Configs: Included network configuration makes customization difficult
The NixOS module has significant complexity, mostly bash wrappers that inject network-specific configuration from the Cardano Operations Book.
A while back, we added configuration options to tune DB Sync to each user's specific needs. While convenient, the batteries-included approach make customization more difficult.
Proposed Solution
Instead of building the Docker images with Nix, I propose we take a hybrid approach:
- Build static binaries with Nix
- Use a simple Dockerfile to copy artifacts to the Docker image
Example Workflow
# Create a static executable
nix build .#cardano-db-sync-linux
# Copy the executable to docker context
cp -L result/bin/cardano-db-sync docker/
# Build the docker image
docker build docker
Configuration Files
The configuration files would not be available in the image. Instead, users have two options:
- Option 1: Mount the configs in a data volume
- Option 2: Create a derived image with the configs baked in
The latest configuration files are available in the Cardano Operations Book, which matches the workflow for non-containerized installations.
Benefits
- 10x smaller images: 100MB instead of 1GB
- Standard Docker Experience: Easier for non-nix users to debug
- Explicit Configuration: Straightforward customization for all users