How can variable values be passed to a template during its creation?

When creating an image (for example, a Docker image), variable values can be passed in several ways:

1. Via build arguments

   • Using the ARG directive in the Dockerfile and the --build-arg parameter during build.
   • Allows passing values that are only available during the image build.

   Example Dockerfile:

   ARG APP_VERSION=1.0
   FROM python:3.9
   RUN echo "Application version: $APP_VERSION"
   

   Build command:

docker build --build-arg APP_VERSION=2.0 -t myapp:2.0 .

2. **Via environment variables**
   - Using the `ENV` directive in the Dockerfile to set variables that will be available in the container at runtime.

   Example:
   ```Dockerfile
   ENV APP_ENV=production

3. Via configuration files or templates
   • Using template engines or scripts that substitute variable values into configuration files before building the image.

Thus, to pass variable values into an image during its creation, ARG and --build-arg are most commonly used in Docker.