Bump base image to Ubuntu 24.04 LTS

docs/source/configuration/system.md

@@ -7,7 +7,11 @@
 A list of packages in the [`.deb`](<https://en.wikipedia.org/wiki/Deb_(file_format)>) format that should be installed. The `.deb` files are downloaded from the server configured in the Docker base image.
 
 ```{note}
-If a `Dockerfile` is not used to change the Docker base image, the base image  is [Ubuntu](https://ubuntu.com/) [22.04 LTS (Jammy Jellyfish)](https://releases.ubuntu.com/jammy/). All `.deb` files availables are listed in [Ubuntu Packages](https://packages.ubuntu.com/jammy/).
+If a `Dockerfile` is not used to change the Docker base image, the base image  is [Ubuntu](https://ubuntu.com/) [24.04 LTS (Noble Numbat)](https://releases.ubuntu.com/noble/). All `.deb` files availables are listed in [Ubuntu Packages](https://packages.ubuntu.com/noble/).
+```
+
+```{versionchanged}
+Base ubuntu image upgraded from 22.04 to 24.04 in October, 2025
 ```
 
 We use `apt.txt`, for example, to install LaTeX in our

docs/source/design.md

@@ -49,7 +49,8 @@ Many ingredients go into making an image from a repository:
 
 `repo2docker` controls the first two, the user controls the third one. The current
 policy for the version of the base image is that we will use the current LTS
-version Jammy Jellyfish (22.04) for the foreseeable future.
+version (24.04) until the start to be build challenges associated with the age of the base system,
+at which point it will be increased to the 'current' LTS when that occurs - typically between 2-5 years from the age of release.
 
 The version of `repo2docker` used to build an image can influence which packages
 are installed by default and which features are supported during the build

docs/source/howto/breaking_changes.md

@@ -2,6 +2,12 @@
 
 Repo2docker occasionally has to make breaking changes in how repositories are built.
 
+## Upgrade of base image from Ubuntu 22.04 to 24.04
+
+The base image used by repo2docker was [upgraded from Ubuntu 22.04 to Ubuntu 24.04](https://github.com/jupyterhub/repo2docker/pull/1287) October 2025 (2025.10).
+
+This is unlikely to affect you unless you are using {ref}`apt.txt <apt-txt>`.
+
 ## Upgrade of base image from Ubuntu 18.04 to 22.04
 
 The base image used by repo2docker was [upgraded from Ubuntu 18.04 to Ubuntu 22.04](https://github.com/jupyterhub/repo2docker/pull/1287) in version 2023.10.0 due to Ubuntu 18.04 going out of support.

repo2docker/app.py

@@ -459,7 +459,7 @@ def _dry_run_changed(self, change):
     )
 
     base_image = Unicode(
-        "docker.io/library/buildpack-deps:jammy",
+        "docker.io/library/buildpack-deps:24.04",
         config=True,
         help="""
         Base image to use when building docker images.