Include zep as a small binary in your Docker image using multi-stage builds:
# build layer
FROM ghcr.io/aasaam/zep:latest as zep
# final layer
FROM yourimage
COPY --from=zep /usr/bin/zep /usr/local/bin/zep
Then in your entrypoint script:
#!/bin/sh
set -e
# Use zep to process your template file
/usr/local/bin/zep /path/to/your/template > final-config.ext
# Run your application
/run/my/awesome-process