c932667cd2
- Remove redundant chars and all errors caused by RST->MD conversion. e.g. [/#, /\, \<, />, etc.] - Fix broken inter-document links - Fix outbound links no-longer active or changed - Fix lists - Fix code blocks - Correct apostrophes - Replace redundant inline note marks for code with code marks - Fix broken image links - Remove non-functional title links - Correct broken cross-docs links - Improve readability Note: This PR does not try to fix/amend: - Grammatical errors - Lexical errors - Linguistic-logic errors etc. It just aims to fix main structural or conversion errors to serve as a base for further amendments that will cover others including but not limited to those mentioned above. Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer) Update: - Fix backtick issues Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
1.3 KiB
page_title: Images page_description: Definition of an image page_keywords: containers, lxc, concepts, explanation, image, container
Image
Introduction
In Docker terminology, a read-only Layer is called an image. An image never changes.
Since Docker uses a Union File System, the processes think the whole file system is mounted read-write. But all the changes go to the top-most writeable layer, and underneath, the original file in the read-only image is unchanged. Since images don't change, images do not have state.
Parent Image
Each image may depend on one more image which forms the layer beneath it. We sometimes say that the lower image is the parent of the upper image.
Base Image
An image that has no parent is a base image.
Image IDs
All images are identified by a 64 hexadecimal digit string (internally a 256bit value). To simplify their use, a short ID of the first 12 characters can be used on the command line. There is a small possibility of short id collisions, so the docker server will always return the long ID.