CI: build nightly on push.

Fixes #894.

.github/workflows/build_nightly.yml

@@ -0,0 +1,34 @@
+#https://github.com/marketplace/actions/android-emulator-runner
+name: Build nightly
+on: [ push ]
+
+jobs:
+  nightly-build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: checkout
+        uses: actions/checkout@v2.3.4
+
+      - uses: actions/setup-java@v2
+        with:
+          distribution: 'adopt'
+          java-version: '11'
+
+      - name: Assemble nighlty APK
+        shell: bash
+        run: |
+          echo ${NIGHTLY_STORE_FILE} | base64 -d > KEY_NIGHTLY.jks
+          ./gradlew assembleNightly -Dnightly_store_file=KEY_NIGHTLY.jks -Dnightly_store_password="${NIGHTLY_STORE_PASSWORD}" -Dnightly_key_alias="${NIGHTLY_KEY_ALIAS}" -Dnightly_key_password="${NIGHTLY_STORE_PASSWORD}"
+        env:
+          NIGHTLY_STORE_FILE: ${{ secrets.NIGHTLY_STORE_FILE }}
+          NIGHTLY_STORE_PASSWORD: ${{ secrets.NIGHTLY_STORE_PASSWORD }}
+          NIGHTLY_KEY_ALIAS: ${{ secrets.NIGHTLY_KEY_ALIAS }}
+
+      - name: Archive
+        if: always()
+        uses: actions/upload-artifact@v2
+        with:
+          name: OpenTracks-nightly.apk
+          path: ./build/outputs/apk/nightly/OpenTracks-nightly.apk
+          retention-days: 7
+

build.gradle

@@ -62,6 +62,16 @@ android {
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         testInstrumentationRunnerArguments clearPackageData: 'true'
     }
+    signingConfigs {
+        nightly {
+            if (System.getProperty("nightly_store_file") != null) {
+                storeFile file(System.getProperty("nightly_store_file"))
+                storePassword System.getProperty("nightly_store_password")
+                keyAlias System.getProperty("nightly_key_alias")
+                keyPassword System.getProperty("nightly_key_password")
+            }
+        }
+    }
 
     buildTypes {
         debug {
@@ -69,6 +79,12 @@ android {
             versionNameSuffix "-debug"
         }
 
+        nightly {
+            signingConfig signingConfigs.nightly
+            applicationIdSuffix ".nightly"
+            versionNameSuffix "-nightly"
+        }
+
         release {
             minifyEnabled false
         }