Docker's Layers
Filevine Tech Talk
May 25th, 2023
What is Docker?
Docker is a tool that allows developers to package their applications into containers.
What is a Container?
A container is a standard unit of software that packages up code and all its dependencies so the application runs reliably from one computing environment to another.
What is a Layer?
A layer is a read-only file along with metadata that is stacked on top of another. When you make a change to a file or metadata, a new layer is created (copy-on-write).
What is an OCI Layer?
OCI layers follow the OCI specification for storing and identifying layers and images.
https://github.com/opencontainers/image-spec/blob/main/spec.md
Layers are immutable
- Secrets will persist
- Size will persist
- ...even if you can't get to it anymore
Layers allow for caching
If it's been done before, do it no more
Principles in practice
Demo