I'm looking into buildpacks to create container images without Dockerfiles. One benefit should be that buildpacks are managed and are updated quite fast if some vulnerabilities are found. So it should relief the developer from that task. However, how do I know when the buildpacks I use are updated? Maybe they are also now longer compatible to my code?
When you run a command like pack build, it will automatically attempt to download the latest/newest version of the buildpacks you are using (technically it attempts to download the newest "builder" version). You can control/override this with the --pull-policy option, which can be set to always, never, or if-not-present.
Knowing if a new version is available may depend on the buildpacks and builder you are using. You could attempt a docker pull of the builder image or a pack buildpack pull. If it does not pull anything, then there is no update.
In addition, the Buildpack Registry contains release information for buildpacks that have been published there.