Repack apk files into zip format to generate stable size measurements.

apk-size/apk-size.gradle

@@ -24,6 +24,10 @@ buildscript {
     }
 }
 
+plugins {
+    id "com.dorongold.task-tree" version "1.5"
+}
+
 apply from: '../sdkProperties.gradle'
 
 task clean(type: Delete) {

apk-size/app/configure.gradle

@@ -48,3 +48,41 @@ if (project.hasProperty('sdks')) {
         }
     }
 }
+
+
+// Configures two new tasks `unpack` and `repack` for each `assemble` task created for all
+// configured application build variants.
+//
+// `unpack` task takes the apk file and unpacks it into a folder `archive`. `repack` task compresses
+// the folder back into a zip file. The size of the generated zip file will then be collected as the
+// stable version of the size for its corresponding apk file.
+project.afterEvaluate {
+    def unpack = project.tasks.create("unpack")
+    def repack = project.tasks.create("repack")
+
+    android.applicationVariants.all {
+        def assemble = it.assembleProvider.get()
+        def packageApplication = it.packageApplicationProvider.get()
+        def apk = packageApplication.apkNames[0]
+        def dir = packageApplication.outputDirectory
+        def unpackTaskName = "unpack" + it.name.capitalize()
+        def repackTaskName = "repack" + it.name.capitalize()
+
+        def unpackVariant = project.tasks.create(unpackTaskName, Copy.class) {
+            dependsOn assemble
+
+            from zipTree(file("$dir/$apk"))
+            into file("$dir/archive")
+        }
+        unpack.dependsOn unpackVariant
+
+        def repackVariant = project.tasks.create(repackTaskName, Zip.class) {
+            dependsOn unpackTaskName
+
+            archiveFileName = apk.replace(".apk", ".zip")
+            destinationDirectory = file(dir)
+            from "$dir/archive"
+        }
+        repack.dependsOn repackVariant
+    }
+}

ci/fireci/fireciplugins/binary_size.py

@@ -57,7 +57,7 @@ def binary_size(pull_request, log, metrics_service_url, access_token):
   artifacts = affected_artifacts if pull_request else all_artifacts
   sdks = ','.join(artifacts)
 
-  gradle.run('assemble', '-p', 'apk-size', '--continue', gradle.P('sdks', sdks), check=False)
+  gradle.run('repack', '-p', 'apk-size', '--continue', gradle.P('sdks', sdks), check=False)
 
   test_results = _measure_aar_sizes(artifacts) + _measure_apk_sizes(artifacts)
   test_report = {'metric': 'BinarySize', 'results': test_results, 'log': log}
@@ -84,11 +84,11 @@ def _measure_apk_sizes(artifacts):
 
   for artifact in artifacts:
     group_id, artifact_id, version = artifact.split(':')
-    apk_files = glob.glob(f'./apk-size/**/{artifact_id}/**/*.apk', recursive=True)
+    apk_zip_files = glob.glob(f'./apk-size/**/{artifact_id}/**/*.zip', recursive=True)
 
-    for apk_file in apk_files:
-      build_type = re.search(fr'{artifact_id}/([^/]*)/', apk_file).group(1)
-      apk_size = os.path.getsize(apk_file)
+    for zip_file in apk_zip_files:
+      build_type = re.search(fr'{artifact_id}/([^/]*)/', zip_file).group(1)
+      apk_size = os.path.getsize(zip_file)
       test_results.append({'sdk': artifact_id, 'type': f'apk ({build_type})', 'value': apk_size})
 
   return test_results