auto-detect NDKs installed in standard paths

'ndk_paths' will be automatically filled out from well known sources
like $ANDROID_HOME/ndk-bundle and $ANDROID_HOME/ndk/*.  If a required
version is missing in the buildserver VM, it will be automatically
downloaded and installed into the standard $ANDROID_HOME/ndk/
directory.  Manually setting it here will override the auto-detected
values.  The keys can either be the "release" (e.g. r21e) or the
"revision" (e.g. 21.4.7075529).

https://developer.android.com/studio/projects/configure-agp-ndk#agp_version_41
* sdkmanager installs "ndk;12.3.4567890" into $ANDROID_SDK_ROOT/ndk/
* sdkmanager installs "ndk-bundle" into $ANDROID_SDK_ROOT/ndk-bundle/

buildserver/config.buildserver.yml

@@ -1,8 +1,4 @@
 sdk_path: /opt/android-sdk
-ndk_paths:
-  r10e: /opt/android-sdk/ndk/r10e
-  r21e: /opt/android-sdk/ndk/21.4.7075529
-  r22b: /opt/android-sdk/ndk/22.0.7026061
 
 java_paths:
   8: /usr/lib/jvm/java-8-openjdk-amd64

examples/config.yml

@@ -5,24 +5,20 @@
 # Custom path to the Android SDK, defaults to $ANDROID_HOME
 # sdk_path: $ANDROID_HOME
 
-# Paths to various installed versions of the Android NDK.  If a
-# required version is missing in the buildserver VM, it will be
-# automatically downloaded and installed into a temporary dir.
+# Paths to installed versions of the Android NDK.  This will be
+# automatically filled out from well known sources like
+# $ANDROID_HOME/ndk-bundle and $ANDROID_HOME/ndk/*.  If a required
+# version is missing in the buildserver VM, it will be automatically
+# downloaded and installed into the standard $ANDROID_HOME/ndk/
+# directory.  Manually setting it here will override the auto-detected
+# values.  The keys can either be the "release" (e.g. r21e) or the
+# "revision" (e.g. 21.4.7075529).
 #
 # ndk_paths:
-#   r10e: None
-#   r11c: None
-#   r12b: None
-#   r13b: None
-#   r14b: None
-#   r15c: None
-#   r16b: None
-#   r17c: None
-#   r18b: None
-#   r19c: None
-#   r20b: None
-#   r21e: None
-#   r22b: None
+#   r10e: $ANDROID_HOME/android-ndk-r10e
+#   r17: ""
+#   21.4.7075529: ~/Android/Ndk
+#   r22b: null
 
 # Directory to store downloaded tools in (i.e. gradle versions)
 # By default, these are stored in ~/.cache/fdroidserver

fdroidserver/common.py

@@ -214,6 +214,14 @@ def _add_java_paths_to_config(pathlist, thisconfig):
 
 
 def fill_config_defaults(thisconfig):
+    """Fill in the global config dict with relevant defaults
+
+    For config values that have a path that can be expanded, e.g. an
+    env var or a ~/, this will store the original value using "_orig"
+    appended to the key name so that if the config gets written out,
+    it will preserve the original, unexpanded string.
+
+    """
     for k, v in default_config.items():
         if k not in thisconfig:
             thisconfig[k] = v
@@ -281,6 +289,28 @@ def fill_config_defaults(thisconfig):
                 thisconfig[k][k2] = exp
                 thisconfig[k][k2 + '_orig'] = v
 
+    ndk_paths = thisconfig.get('ndk_paths', {})
+
+    ndk_bundle = os.path.join(thisconfig['sdk_path'], 'ndk-bundle')
+    if os.path.exists(ndk_bundle):
+        version = get_ndk_version(ndk_bundle)
+        if version not in ndk_paths:
+            ndk_paths[version] = ndk_bundle
+
+    ndk_dir = os.path.join(thisconfig['sdk_path'], 'ndk')
+    if os.path.exists(ndk_dir):
+        for ndk in glob.glob(os.path.join(ndk_dir, '*')):
+            version = get_ndk_version(ndk)
+            if version not in ndk_paths:
+                ndk_paths[version] = ndk
+
+    for k in list(ndk_paths.keys()):
+        if not re.match(r'r[1-9][0-9]*[a-z]?', k):
+            for ndkdict in NDKS:
+                if k == ndkdict['revision']:
+                    ndk_paths[ndkdict['release']] = ndk_paths.pop(k)
+                    break
+
 
 def regsub_file(pattern, repl, path):
     with open(path, 'rb') as f:

tests/common.TestCase

@@ -1832,6 +1832,28 @@ class CommonTest(unittest.TestCase):
             fdroidserver.common.auto_install_ndk(build)
             list_entry.assert_has_calls(calls)
 
+    def test_fill_config_defaults(self):
+        """Test the auto-detection of NDKs installed in standard paths"""
+        sdk_path = tempfile.mkdtemp(
+            prefix=inspect.currentframe().f_code.co_name, dir=self.tmpdir
+        )
+
+        ndk_bundle = os.path.join(sdk_path, 'ndk-bundle')
+        os.makedirs(ndk_bundle)
+        with open(os.path.join(ndk_bundle, 'source.properties'), 'w') as fp:
+            fp.write('Pkg.Desc = Android NDK\nPkg.Revision = 17.2.4988734\n')
+        config = {'sdk_path': sdk_path}
+        fdroidserver.common.fill_config_defaults(config)
+        self.assertEqual({'r17c': ndk_bundle}, config['ndk_paths'])
+
+        r21e = os.path.join(sdk_path, 'ndk', '21.4.7075529')
+        os.makedirs(r21e)
+        with open(os.path.join(r21e, 'source.properties'), 'w') as fp:
+            fp.write('Pkg.Desc = Android NDK\nPkg.Revision = 21.4.7075529\n')
+        config = {'sdk_path': sdk_path}
+        fdroidserver.common.fill_config_defaults(config)
+        self.assertEqual({'r17c': ndk_bundle, 'r21e': r21e}, config['ndk_paths'])
+
 
 if __name__ == "__main__":
     os.chdir(os.path.dirname(__file__))