Fix installation of linuxdeploy-plugin-native_packages

Author: TheAssassin

ci/build.sh

@@ -137,7 +137,16 @@ if [[ "${BUILD_LITE:-}" == "" ]]; then
         --output native_packages
     )
 
-    pipx install git+https://github.com/linuxdeploy/linuxdeploy-plugin-native_packages
+    # tools like pipx would have side effects on the build host and it's generally a bit overkill for our purpose
+    if which python3.13 &> /dev/null; then
+        # python3.13, installed from the deadsnakes PPA for the Docker builds
+        python3() {
+            python3.13 "$@"
+        }
+    fi
+    python3 -m venv venv
+    venv/bin/pip install git+https://github.com/linuxdeploy/linuxdeploy-plugin-native_packages
+    export PATH="$PWD/venv/bin:$PATH"
 else
     linuxdeploy_extra_args+=(
         --custom-apprun "$REPO_ROOT"/resources/appimagelauncher-lite-AppRun.sh

ci/install-deps.sh

@@ -25,6 +25,31 @@ esac
 
 set -x
 
+# this array collects all the packages we want to install
+# running as few operations as possible is a runtime optimization
+packages=()
+
+# install 32-bit build dependencies and multilib/cross compilers for binfmt-bypass's 32-bit preload library
+# must be done before apt-get update, otherwise the packages cannot be found during installation
+if [[ "$DOCKER_PLATFORM" == "linux/amd64" ]]; then
+    dpkg --add-architecture i386
+    packages+=(
+        libc6-dev:i386
+    )
+elif [[ "$DOCKER_PLATFORM" == "linux/arm64/v8" ]]; then
+    dpkg --add-architecture armhf
+    packages+=(
+        libc6-dev:armhf
+    )
+fi
+
+# allow setup of PPA
+apt-get update
+apt-get install -y software-properties-common
+
+# we depend on the deadsnakes PPA to provide a sufficiently recent Python to linuxdeploy-plugin-native_packages
+add-apt-repository -y ppa:deadsnakes/ppa
+
 packages=(
     libcurl4-openssl-dev
     libfuse-dev
@@ -71,26 +96,13 @@ packages=(
     libzstd-dev
 
     # linuxdeploy-plugin-native_packages
-    pipx
+    # see also above re. deadsnakes PPA
+    python3.13-venv
 )
 
-# install 32-bit build dependencies and multilib/cross compilers for binfmt-bypass's 32-bit preload library
-if [[ "$DOCKER_PLATFORM" == "linux/amd64" ]]; then
-    dpkg --add-architecture i386
-    packages+=(
-        libc6-dev:i386
-    )
-elif [[ "$DOCKER_PLATFORM" == "linux/arm64/v8" ]]; then
-    dpkg --add-architecture armhf
-    packages+=(
-        libc6-dev:armhf
-    )
-fi
-
 # headless install
 export DEBIAN_FRONTEND=noninteractive
 
-apt-get update
 apt-get -y --no-install-recommends install "${packages[@]}"
 
 # install more recent CMake