Buildkite plugins, Docker, and shared environment variables

Plugins are reusable and composable pieces of functionality that extend and adapt CI/CD workflows, improving productivity and efficiency. However, dependencies can make things complex as plugins need to be defined together and in a specific order to achieve the desired result. Environment variables aren't automatically available to Docker containers, so multiple plugins sharing environment variables should be defined within a single "plugins" step. When using plugins with Docker, it is important to explicitly define required environment variables in the plugin script or use argument variables for Docker Compose.