android build: persist debug keystore

so that we can upgrade debug installations on the phone and keep the datadir

.gitignore

@@ -30,3 +30,4 @@ contrib/build-wine/tmp/
 contrib/build-wine/fresh_clone/
 contrib/build-linux/appimage/build/
 contrib/build-linux/appimage/.cache/
+contrib/android_debug.keystore

contrib/make_apk

@@ -30,6 +30,17 @@ if [[ -n "$1"  && "$1" == "release" ]] ; then
     export P4A_RELEASE_KEYALIAS=electrum
     make release
 else
+    export P4A_DEBUG_KEYSTORE="$CONTRIB"/android_debug.keystore
+    export P4A_DEBUG_KEYSTORE_PASSWD=unsafepassword
+    export P4A_DEBUG_KEYALIAS_PASSWD=unsafepassword
+    export P4A_DEBUG_KEYALIAS=electrum
+    if [ ! -f "$P4A_DEBUG_KEYSTORE" ]; then
+        keytool -genkey -v -keystore "$CONTRIB"/android_debug.keystore \
+            -alias "$P4A_DEBUG_KEYALIAS" -keyalg RSA -keysize 2048 -validity 10000 \
+            -dname "CN=mqttserver.ibm.com, OU=ID, O=IBM, L=Hursley, S=Hants, C=GB" \
+            -storepass "$P4A_DEBUG_KEYSTORE_PASSWD" \
+            -keypass "$P4A_DEBUG_KEYALIAS_PASSWD"
+    fi
     make apk
 fi
 

electrum/gui/kivy/Readme.md

@@ -81,13 +81,34 @@ $ sudo docker run -it --rm \
 ```
 
 
-### How do I get more verbose logs?
+### How do I get more verbose logs for the build?
 See `log_level` in `buildozer.spec`
 
 
+### How can I see logs at runtime?
+This should work OK for most scenarios:
+```
+adb logcat | grep python
+```
+Better `grep` but fragile because of `cut`:
+```
+adb logcat | grep -F "`adb shell ps | grep org.electrum.electrum | cut -c14-19`"
+```
+
+
 ### Kivy can be run directly on Linux Desktop. How?
 Install Kivy.
 
 Build atlas: `(cd electrum/gui/kivy/; make theming)`
 
 Run electrum with the `-g` switch: `electrum -g kivy`
+
+### debug vs release build
+If you just follow the instructions above, you will build the apk
+in debug mode. The most notable difference is that the apk will be
+signed using a debug keystore. If you are planning to upload
+what you build to e.g. the Play Store, you should create your own
+keystore, back it up safely, and run `./contrib/make_apk release`.
+
+See e.g. [kivy wiki](https://github.com/kivy/kivy/wiki/Creating-a-Release-APK)
+and [android dev docs](https://developer.android.com/studio/build/building-cmdline#sign_cmdline).

electrum/gui/kivy/tools/Dockerfile

@@ -152,6 +152,8 @@ RUN cd /opt \
     && git cherry-pick d7f722e4e5d4b3e6f5b1733c95e6a433f78ee570 \
        # fix gradle "versionCode" overflow:
     && git cherry-pick ed20e196fbcdce718a180f88f23bb2d165c4c5d8 \
+       # gradle: persist debug keystore:
+    && git cherry-pick aaa0d5d0e7a334631df71e0a9bf127817e0ab9ab \
     && python3 -m pip install --user -e .
 
 # build env vars