I am building a Docker image with the following base image in the Dockerfile:
FROM python:3.12-slim-bookworm
My build command is docker build . --no-cache=true.
The build logs are:
[+] Building 78.3s (17/17) FINISHED docker:desktop-linux
=> [internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 741B 0.0s
=> [internal] load metadata for docker.io/library/python:3.12-slim-bookworm 1.8s
=> [auth] library/python:pull token for registry-1.docker.io 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 1.80kB 0.0s
=> [ 1/10] FROM docker.io/library/python:3.12-slim-bookworm@sha256:eb53cb99a609b86da6e239b16e1f2aed5e10cfbc538671fc4631093a00f133f2
...
After the image is built, Docker Desktop shows that it is built with the base image FROM python:3-slim, and that python:3-slim has a newer image available, as shown in my screenshot.
According to this answer https://stackoverflow.com/a/74141798/23361424, since the build command includes --no-cache=true, it should pull the newest available image.
However, the sha256 digest from the build logs eb53cb99a609b86da6e239b16e1f2aed5e10cfbc538671fc4631093a00f133f2 and the digest from the latest (as of today) python:3-slim image https://hub.docker.com/layers/library/python/3-slim/images/sha256-4e7d6f2672bd4a834eac99973679c7e73fbcd475d439b7569512bf478ed39c78?context=explore are different.
I solved the problem with this build command: docker build . --no-cache.
The official documentation for docker build and its options is here: https://docs.docker.com/engine/reference/commandline/image_build/#options
Apparently docker build . --no-cache=true uses the cache.
