Try detecting the NDK version automatically

.github/workflows/android.yml

@@ -31,6 +31,14 @@ jobs:
       matrix:
         api-level: [29]
     steps:
+      - name: Set env vars
+        run: |
+          echo "ANDROID_NDK_TOOLCHAIN_DIR=$ANDROID_NDK_HOME/toolchains" >> $GITHUB_ENV
+          export ANDROID_NDK_TOOLCHAIN_DIR=$ANDROID_NDK_HOME/toolchains
+          echo "Toolchain dir: $ANDROID_NDK_TOOLCHAIN_DIR."
+          echo "Contents:"
+          find $ANDROID_NDK_TOOLCHAIN_DIR -maxdepth 1
+
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
@@ -50,8 +58,6 @@ jobs:
 
       - name: Setup Gradle & Build test cases
         uses: gradle/gradle-build-action@v3
-        env:
-          ANDROID_NDK_TOOLCHAIN_DIR: ${{ env.ANDROID_NDK_HOME }}/toolchains
         with:
           build-root-directory: platforms/android
           cache-read-only: false

platforms/android/library/build.gradle

@@ -20,6 +20,7 @@ cargo {
     targets = ["arm", "x86", "x86_64", "arm64"]
     targetIncludes = ["libuniffi_wysiwyg_composer.so"]
     targetDirectory = '../../../target'
+    prebuiltToolchains = true
 }
 
 android {
@@ -69,12 +70,12 @@ android {
         jacocoVersion = "0.8.8"
     }
 
-    ndkVersion = "27.1.12297006"
-
     packagingOptions {
         resources.excludes += 'META-INF/LICENSE.md'
         resources.excludes += 'META-INF/LICENSE-notice.md'
     }
+
+    ndkVersion getNdkVersionAsWorkaround()
 }
 
 kotlin {
@@ -143,3 +144,10 @@ tasks.withType(Test) {
     jacoco.excludes = ['jdk.internal.*']
 }
 
+// Workaround for https://github.com/mozilla/rust-android-gradle/issues/46
+// This looks for the NDK path like: '/some/path/to/sdk/ndk/23.0.7599858'
+// and takes the last path component, which should be the version number
+def getNdkVersionAsWorkaround() {
+    def ndkDirectory = new File(android.sdkDirectory, "ndk")
+    return ndkDirectory.list().sort().last().split(PATH_SEPARATOR).last()
+}