Change uv caching approach (#19)

Now control uv cache location with enviroment variables

Author: coretl

.devcontainer.json

@@ -6,10 +6,13 @@
     },
     "remoteEnv": {
         // Allow X11 apps to run inside the container
-        "DISPLAY": "${localEnv:DISPLAY}"
+        "DISPLAY": "${localEnv:DISPLAY}",
+        // Put things that allow it in the persistent cache
+        "UV_CACHE_DIR": "/cache/uv",
+        "UV_PYTHON_CACHE_DIR": "/cache/uv-python"
     },
-    // Create the config folder for the user modifiable terminal-config and the uv cache
-    "initializeCommand": "mkdir -p ${localEnv:HOME}/.config/terminal-config ${localEnv:HOME}/.cache/uv",
+    // Create the config folder for the user modifiable terminal-config
+    "initializeCommand": "mkdir -p ${localEnv:HOME}/.config/terminal-config",
     "runArgs": [
         // Allow the container to access the host X11 display and EPICS CA
         "--net=host",
@@ -23,11 +26,11 @@
             "target": "/user-terminal-config",
             "type": "bind"
         },
-        // Keep a persistent cross container cache for uv
+        // Keep a persistent cross container cache
         {
-            "source": "${localEnv:HOME}/.cache/uv",
-            "target": "/root/.cache/uv",
-            "type": "bind"
+            "source": "devcontainer-shared-cache",
+            "target": "/cache",
+            "type": "volume"
         }
     ],
     // Mount the parent as /workspaces so we can pip install peers as editable

Dockerfile

@@ -46,9 +46,3 @@ RUN /root/terminal-config/ensure-user-terminal-config.sh && \
 # Install uv using the official image
 # See https://docs.astral.sh/uv/guides/integration/docker/#installing-uv
 COPY --from=ghcr.io/astral-sh/uv:0.9 /uv /uvx /bin/
-
-# We recommend mounting in a cache for uv, so silence warnings about it being on a different volume
-# and cache python interpreter downloads in the same directory
-# https://docs.astral.sh/uv/guides/integration/docker/#caching
-ENV UV_LINK_MODE=copy
-ENV UV_PYTHON_CACHE_DIR=/root/.cache/uv/python

README.md

@@ -46,6 +46,8 @@ History is also stored in this directory, in `.bash_eternal_history` and `.zsh_e
 
 See [this repo's `.devcontainer.json`](./.devcontainer.json) for an example on how to use as a devcontainer. Or clone this repo, open in vscode and click "reopen in container"
 
+If you are considering using this for a pure python project devcontainer, consider using https://github.com/DiamondLightSource/python-copier-template
+
 ## How to use in the build stage of a Dockerfile
 
 If you are using this during the build stage of a Dockerfile, then you should select the upstream `ubuntu` container for the runtime.