Allow user to specify custom download cache directory

Contributes to #10.

Author: TheAssassin

README.md

@@ -16,6 +16,26 @@ Python plugin for linuxdeploy. Sets up miniconda inside an AppDir, and installs
 There are many variables available to alter the behavior of the plugin. The current list can be obtained by calling the plugin with `--help`.
 
 
+## Customize caching behavior
+
+By default, linuxdeploy-plugin-conda redownloads the miniconda installer on every execution. This is not an issue for most people, as the installers are only 50-80 MiB in size. However, it is usually not necessary to redownload the file every time, especially while developing scripts based on the conda plugin.
+
+Therefore, you can set a custom directory via the environment variable `$CONDA_DOWNLOAD_DIR`, into which downloaded files are stored then. The plugin makes use of some `wget` parameters to ensure that the file is only downloaded when it is incomplete (`-c`) or there is a newer version available (`-N`).
+
+Example:
+
+```bash
+> export CONDA_DOWNLOAD_DIR=/my/own/directory
+> ./linuxdeploy-x86_64.AppImage --plugin conda [...]
+[...]
+Using user-specified download directory: /my/own/directory
+[...]
+```
+
+Relative paths work as well.
+
+
+
 ## Example
 
 This generates a working FreeCAD AppImage from Conda ingredients, including Qt and PyQt:

linuxdeploy-plugin-conda.sh

@@ -60,15 +60,29 @@ if [ "$CONDA_PACKAGES" == "" ]; then
     echo "WARNING: \$CONDA_PACKAGES not set, no packages will be installed!"
 fi
 
+# the user can specify a directory into which the conda installer is downloaded
+# if they don't specify one, we use a temporary directory
+# if one is specified, the installer will not be re-downloaded unless it has changed
+if [ "$CONDA_DOWNLOAD_DIR" != "" ]; then
+    # resolve path relative to cwd
+    if [[ "$CONDA_DOWNLOAD_DIR" != /* ]]; then
+        CONDA_DOWNLOAD_DIR="$(readlink -f "$CONDA_DOWNLOAD_DIR")"
+    fi
 
-# create temporary directory into which downloaded files are put
-TMPDIR=$(mktemp -d)
+    echo "Using user-specified download directory: $CONDA_DOWNLOAD_DIR"
+    mkdir -p "$CONDA_DOWNLOAD_DIR"
+else
+    # create temporary directory into which downloaded files are put
+    CONDA_DOWNLOAD_DIR="$(mktemp -d)"
 
-_cleanup() {
-    rm -rf "$TMPDIR"
-}
+    _cleanup() {
+        if [ -d "$CONDA_DOWNLOAD_DIR"]; then
+            rm -rf "$CONDA_DOWNLOAD_DIR"
+        fi
+    }
 
-trap _cleanup EXIT
+    trap _cleanup EXIT
+fi
 
 if [ -d "$APPDIR"/usr/conda ]; then
     echo "Error: directory exists: $APPDIR/usr/conda"
@@ -80,22 +94,25 @@ ARCH=${ARCH:-x86_64}
 # install Miniconda, a self contained Python distribution, into AppDir
 case "$ARCH" in
     "x86_64")
-        miniconda_url=https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh
+        miniconda_installer_filename=Miniconda3-latest-Linux-x86_64.sh
         ;;
     "i386"|"i686")
-        miniconda_url=https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86.sh
+        miniconda_installer_filename=Miniconda3-latest-Linux-x86.sh
         ;;
     *)
         echo "Error: Unknown Miniconda arch: $ARCH"
         exit 1
         ;;
 esac
 
-(cd "$TMPDIR" && wget "$miniconda_url")
+pushd "$CONDA_DOWNLOAD_DIR"
+    miniconda_url=https://repo.continuum.io/miniconda/"$miniconda_installer_filename"
+    wget -N -c "$miniconda_url"
+popd
 
 # install into usr/conda/ instead of usr/ to make sure that the libraries shipped with conda don't overwrite or
 # interfere with libraries bundled by other plugins or linuxdeploy itself
-bash "$TMPDIR"/Miniconda3-latest-Linux-*.sh -b -p "$APPDIR"/usr/conda -f
+bash "$CONDA_DOWNLOAD_DIR"/"$miniconda_installer_filename" -b -p "$APPDIR"/usr/conda -f
 
 # activate environment
 . "$APPDIR"/usr/conda/bin/activate
@@ -162,3 +179,4 @@ if [ "$CONDA_SKIP_CLEANUP" == "" ]; then
     rm -rf lib/python?.?/site-packages/{setuptools,pip}
     popd
 fi
+