Automate SOPS encryption in Git

Note: While the following worked, the entire setup felt fragile. Plus, I realized there was little point in encrypting the source code in my repository, given the repository is hosted locally on my home network where I already have encryption at rest. So, I reverted this stuff after trying it for a few days.

Initial setup #

Ensure the Age private key is available in the right place (i.e. ~/.config/sops/age/keys.txt).

Update .gitattributes in the repository to look something like this:

# For some reason, fall back needs to be at the top.
secret/* filter=sops

secret/*.env filter=sops-dotenv
secret/*.json filter=sops-json

secret/*.yaml filter=sops-yaml
secret/*.yml filter=sops-yaml

Run the following in the repository:

# Fallback
git config --local filter.sops.clean "sops encrypt /dev/stdin"
git config --local filter.sops.smudge "sops decrypt /dev/stdin"
git config --local filter.sops.required true

git config --local filter.sops-dotenv.clean "sops encrypt --input-type dotenv --output-type dotenv /dev/stdin"
git config --local filter.sops-dotenv.smudge "sops decrypt --input-type dotenv --output-type dotenv /dev/stdin"
git config --local filter.sops-dotenv.required true

git config --local filter.sops-json.clean "sops encrypt --input-type json --output-type json /dev/stdin"
git config --local filter.sops-json.smudge "sops decrypt --input-type json --output-type json /dev/stdin"
git config --local filter.sops-json.required true

git config --local filter.sops-yaml.clean "sops encrypt --input-type yaml --output-type yaml /dev/stdin"
git config --local filter.sops-yaml.smudge "sops decrypt --input-type yaml --output-type yaml /dev/stdin"
git config --local filter.sops-yaml.required true

On a new machine #

Again, ensure the key is present in the right place as above.
Clone, but don’t checkout, the repository: git clone --no-checkout ...
Apply all the config --local ... commands from above.
Checkout: git checkout --.