diff --git a/.circleci/config.yml b/.circleci/config.yml
index c1ac780978..6801c3f37c 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -93,6 +93,15 @@ commands:
             rustup target add i686-linux-android
             rustup target add x86_64-linux-android
 
+  install-android-ndk:
+    steps:
+      - run:
+          name: Install missing Android SDK & NDK
+          command: |
+              sdkmanager \
+                "build-tools;28.0.3" \
+                "ndk;21.3.6528147"
+
   android-setup:
     steps:
       - checkout
@@ -100,10 +109,7 @@ commands:
       - setup-rust-toolchain:
           rust-version: stable
       - install-android-targets
-      - run:
-          name: Install missing Android SDK
-          command: |
-              sdkmanager 'build-tools;28.0.3'
+      - install-android-ndk
 
   test-python:
     steps:
@@ -436,16 +442,17 @@ jobs:
 
   Lint Android with ktlint and detekt:
     docker:
-      - image: circleci/android:api-28-ndk
+      - image: circleci/android:api-28
     steps:
       - checkout
+      - install-android-ndk
       - run: ./gradlew --no-daemon lint
       - run: ./gradlew --no-daemon ktlint
       - run: ./gradlew --no-daemon detekt
 
   Android tests:
     docker:
-      - image: circleci/android:api-28-ndk
+      - image: circleci/android:api-28
     steps:
       - android-setup
       - skip-if-doc-only
@@ -488,18 +495,13 @@ jobs:
           destination: coredumps
       - store_test_results:
           path: ~/test-results
-
-  Generate Kotlin documentation:
-    docker:
-      - image: circleci/android:api-28-ndk
-    steps:
-      - android-setup
       - run:
-          name: Build Kotlin documentation
-          command: ./gradlew --no-daemon docs
-      - persist_to_workspace:
-          root: build/
-          paths: docs/javadoc
+          name: Build Android Sample App
+          command: |
+              ./gradlew :glean-sample-app:assembleAndroidTest
+          environment:
+            GRADLE_OPTS: -Xmx2048m
+            TARGET_CFLAGS: -DNDEBUG
 
   ###########################################################################
   # Swift / iOS / macOS
@@ -1180,14 +1182,12 @@ workflows:
       - Generate Rust documentation:
           requires:
             - docs-spellcheck
-      - Generate Kotlin documentation
       - Generate Python documentation:
           requires:
             - Python 3_8 tests
       - docs-linkcheck:
           requires:
             - Generate Rust documentation
-            - Generate Kotlin documentation
             - Generate Python documentation
       - docs-spellcheck
       - docs-deploy:
diff --git a/Makefile b/Makefile
index 2c2169c868..7002948d4b 100644
--- a/Makefile
+++ b/Makefile
@@ -46,7 +46,7 @@ build-swift: ## Build all Swift code
 	bin/run-ios-build.sh
 
 build-apk: build-kotlin ## Build an apk of the Glean sample app
-	./gradlew glean-sample-app:build
+	./gradlew glean-sample-app:build glean-sample-app:assembleAndroidTest
 
 build-python: python-setup ## Build the Python bindings
 	$(GLEAN_PYENV)/bin/python3 glean-core/python/setup.py build install
@@ -72,6 +72,9 @@ test-kotlin: ## Run all Kotlin tests
 test-swift: ## Run all Swift tests
 	bin/run-ios-tests.sh
 
+test-android-sample: build-apk ## Run the Android UI tests on the sample app
+	./gradlew :glean-sample-app:connectedAndroidTest
+
 test-ios-sample: ## Run the iOS UI tests on the sample app
 	bin/run-ios-sample-app-test.sh
 
@@ -127,21 +130,18 @@ fmt-python: python-setup ## Run black to format Python code
 
 # Docs
 
-docs: rust-docs kotlin-docs ## Build the Rust and Kotlin API documentation
+docs: rust-docs ## Build the Rust API documentation
 
 rust-docs: ## Build the Rust documentation
 	bin/build-rust-docs.sh
 
-kotlin-docs: ## Build the Kotlin documentation
-	./gradlew docs
-
 swift-docs: ## Build the Swift documentation
 	bin/build-swift-docs.sh
 
 python-docs: build-python ## Build the Python documentation
 	$(GLEAN_PYENV)/bin/python3 -m pdoc --html glean --force -o build/docs/python --config show_type_annotations=True
 
-.PHONY: docs rust-docs kotlin-docs swift-docs
+.PHONY: docs rust-docs swift-docs
 
 metrics-docs: python-setup ## Build the internal metrics documentation
 	$(GLEAN_PYENV)/bin/pip install glean_parser==3.6.0
diff --git a/build.gradle b/build.gradle
index d9bdf37614..ac09184fb1 100644
--- a/build.gradle
+++ b/build.gradle
@@ -11,17 +11,16 @@ buildscript {
     // changing them. Please note that, for using in Android-Components, the
     // versions below must match the ones in that repository.
     ext.versions = [
-        android_gradle_plugin: '4.0.1',
+        android_gradle_plugin: '4.2.2',
         android_maven_publish_plugin: '3.6.2',
-        coroutines: '1.3.5',
-        dokka: '0.9.17',
+        coroutines: '1.5.0',
         jna: '5.6.0',
         junit: '4.12',
         mockito: '2.28.2',  // This is different than a-c, but we're fine, it's only tests.
         mockwebserver: '4.9.1', // This is different than a-c, but we're fine, it's only tests.
-        kotlin: '1.4.10',
+        kotlin: '1.5.20',
         robolectric: '4.5.1', // This is different than a-c, but we're fine, it's only tests.
-        rust_android_plugin: '0.8.3',
+        rust_android_plugin: '0.8.7',
 
         // Android X dependencies
         androidx_annotation: '1.1.0',
@@ -37,6 +36,7 @@ buildscript {
     ]
 
     ext.build = [
+        ndkVersion: "21.3.6528147", // Keep it in sync in TC Dockerfile.
         compileSdkVersion: 29,
         targetSdkVersion: 28,
         minSdkVersion: 21, // So that we can publish for aarch64.
@@ -56,15 +56,12 @@ buildscript {
         // Publish.
         classpath "digital.wup:android-maven-publish:$versions.android_maven_publish_plugin"
 
-        classpath "gradle.plugin.org.mozilla.rust-android-gradle:plugin:$versions.rust_android_plugin"
+        classpath "org.mozilla.rust-android-gradle:plugin:$versions.rust_android_plugin"
 
         // Yes, this is unusual.  We want to access some host-specific
         // computation at build time.
         classpath "net.java.dev.jna:jna:$versions.jna"
 
-        // Docs generation
-        classpath "org.jetbrains.dokka:dokka-android-gradle-plugin:$versions.dokka"
-
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
     }
diff --git a/docs/dev/api/index.md b/docs/dev/api/index.md
index a58862f842..f9e5049de9 100644
--- a/docs/dev/api/index.md
+++ b/docs/dev/api/index.md
@@ -1,6 +1,5 @@
 The following language-specific API docs are available:
 
-- [Kotlin API docs](../../javadoc/glean/index.html)
 - [Swift API docs](../../swift/index.html)
 - [Python API docs](../../python/glean/index.html)
 - [Rust core (internal) API docs](../../docs/index.html)
diff --git a/docs/dev/docs.md b/docs/dev/docs.md
index 33aaa9241b..dcb1868789 100644
--- a/docs/dev/docs.md
+++ b/docs/dev/docs.md
@@ -33,20 +33,7 @@ The built narrative documentation is saved in `build/docs/book`, and the Rust AP
 
 {{#include ../shared/tab_header.md}}
 
-<div data-lang="Kotlin" class="tab">
-
-Kotlin API documentation is generated using [dokka](https://github.com/Kotlin/dokka).
-It is automatically installed by Gradle.
-
-To build the Kotlin API documentation:
-
-```sh
-make kotlin-docs
-```
-
-The generated documentation is saved in `build/docs/javadoc`.
-
-</div>
+<div data-lang="Kotlin" class="tab" data-info="Kotlin API documentation was removed due to tooling issues."></div>
 
 <div data-lang="Swift" class="tab">
 
diff --git a/docs/user/reference/general/experiments-api.md b/docs/user/reference/general/experiments-api.md
index 00dac8fca2..6b6d4db7f2 100644
--- a/docs/user/reference/general/experiments-api.md
+++ b/docs/user/reference/general/experiments-api.md
@@ -177,5 +177,4 @@ Assert.Equal(
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean/-glean.html).
 * [Python API docs](../../../python/glean/glean.html)
diff --git a/docs/user/reference/metrics/boolean.md b/docs/user/reference/metrics/boolean.md
index 846b52eef1..0de9e6291c 100644
--- a/docs/user/reference/metrics/boolean.md
+++ b/docs/user/reference/metrics/boolean.md
@@ -270,7 +270,6 @@ N/A
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-boolean-metric-type/index.html)
 * [Swift API docs](../../../swift/Classes/BooleanMetricType.html)
 * [Python API docs](../../../python/glean/metrics/boolean.html)
 * [Rust API docs](../../../docs/glean/private/boolean/struct.BooleanMetric.html)
diff --git a/docs/user/reference/metrics/counter.md b/docs/user/reference/metrics/counter.md
index 0c69f48d2e..27fb029158 100644
--- a/docs/user/reference/metrics/counter.md
+++ b/docs/user/reference/metrics/counter.md
@@ -373,7 +373,6 @@ N/A
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-counter-metric-type/index.html)
 * [Swift API docs](../../../swift/Classes/CounterMetricType.html)
 * [Python API docs](../../../python/glean/metrics/counter.html)
 * [Rust API docs](../../../docs/glean/private/counter/struct.CounterMetric.html)
diff --git a/docs/user/reference/metrics/custom_distribution.md b/docs/user/reference/metrics/custom_distribution.md
index 5d64cf1997..1b0f7f5a3d 100644
--- a/docs/user/reference/metrics/custom_distribution.md
+++ b/docs/user/reference/metrics/custom_distribution.md
@@ -244,7 +244,6 @@ Custom distributions have the following optional parameters:
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-custom-distribution-metric-type/index.html)
 * [Rust API docs](../../../docs/glean/private/struct.CustomDistributionMetric.html)
 
 ## Simulator
diff --git a/docs/user/reference/metrics/datetime.md b/docs/user/reference/metrics/datetime.md
index 892169d739..ef116dabee 100644
--- a/docs/user/reference/metrics/datetime.md
+++ b/docs/user/reference/metrics/datetime.md
@@ -461,7 +461,6 @@ Carefully consider the required resolution for recording your metric, and choose
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-datetime-metric-type/index.html)
 * [Swift API docs](../../../swift/Classes/DatetimeMetricType.html)
 * [Python API docs](../../../python/glean/metrics/datetime.html)
 * [Rust API docs](../../../docs/glean/private/struct.DatetimeMetric.html)
diff --git a/docs/user/reference/metrics/event.md b/docs/user/reference/metrics/event.md
index 211cb15b45..d7216adb2e 100644
--- a/docs/user/reference/metrics/event.md
+++ b/docs/user/reference/metrics/event.md
@@ -506,7 +506,6 @@ Each extra key contains additional metadata:
   
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-event-metric-type/index.html)
 * [Swift API docs](../../../swift/Classes/EventMetricType.html)
 * [Python API docs](../../../python/glean/metrics/event.html)
 * [Rust API docs](../../../docs/glean/private/event/struct.EventMetric.html)
diff --git a/docs/user/reference/metrics/labeled_booleans.md b/docs/user/reference/metrics/labeled_booleans.md
index 6adbcaae74..eab90cda10 100644
--- a/docs/user/reference/metrics/labeled_booleans.md
+++ b/docs/user/reference/metrics/labeled_booleans.md
@@ -367,7 +367,6 @@ accessibility:
 
 ## Reference
 
-* Kotlin API docs [`LabeledMetricType`](../../../javadoc/glean/mozilla.telemetry.glean.private/-labeled-metric-type/index.html), [`BooleanMetricType`](../../../javadoc/glean/mozilla.telemetry.glean.private/-boolean-metric-type/index.html)
 * Swift API docs: [`LabeledMetricType`](../../../swift/Classes/LabeledMetricType.html), [`BooleanMetricType`](../../../swift/Classes/BooleanMetricType.html)
 * Python API docs: [`LabeledMetricBase`](../../../python/glean/metrics/labeled.html), [`BooleanMetricType`](../../../python/glean/metrics/boolean.html)
 * Rust API docs: [`LabeledMetric`](../../../docs/glean/private/struct.LabeledMetric.html), [`BooleanMetricType`](../../../docs/glean/private/struct.BooleanMetric.html)
diff --git a/docs/user/reference/metrics/labeled_counters.md b/docs/user/reference/metrics/labeled_counters.md
index e6cca21fad..64dcca1963 100644
--- a/docs/user/reference/metrics/labeled_counters.md
+++ b/docs/user/reference/metrics/labeled_counters.md
@@ -383,7 +383,6 @@ accessibility:
 
 ## Reference
 
-* Kotlin API docs [`LabeledMetricType`](../../../javadoc/glean/mozilla.telemetry.glean.private/-labeled-metric-type/index.html), [`CounterMetricType`](../../../javadoc/glean/mozilla.telemetry.glean.private/-counter-metric-type/index.html)
 * Swift API docs: [`LabeledMetricType`](../../../swift/Classes/LabeledMetricType.html), [`CounterMetricType`](../../../swift/Classes/CounterMetricType.html)
 * Python API docs: [`LabeledMetricBase`](../../../python/glean/metrics/labeled.html), [`CounterMetricType`](../../../python/glean/metrics/counter.html)
 * Rust API docs: [`LabeledMetric`](../../../docs/glean/private/struct.LabeledMetric.html), [`CounterMetricType`](../../../docs/glean/private/struct.CounterMetric.html)
diff --git a/docs/user/reference/metrics/labeled_strings.md b/docs/user/reference/metrics/labeled_strings.md
index 7a8db8c4d7..202513c566 100644
--- a/docs/user/reference/metrics/labeled_strings.md
+++ b/docs/user/reference/metrics/labeled_strings.md
@@ -352,7 +352,6 @@ login:
 
 ## Reference
 
-* Kotlin API docs: [`LabeledMetricType`](../../../javadoc/glean/mozilla.telemetry.glean.private/-labeled-metric-type/index.html), [`StringMetricType`](../../../javadoc/glean/mozilla.telemetry.glean.private/-string-metric-type/index.html)
 * Swift API docs: [`LabeledMetricType`](../../../swift/Classes/LabeledMetricType.html), [`StringMetricType`](../../../swift/Classes/StringMetricType.html)
 * Python API docs: [`LabeledMetricBase`](../../../python/glean/metrics/labeled.html), [`StringMetricType`](../../../python/glean/metrics/string.html)
 * Rust API docs: [`LabeledMetric`](../../../docs/glean/private/struct.LabeledMetric.html), [`StringMetricType`](../../../docs/glean/private/struct.StringMetric.html)
diff --git a/docs/user/reference/metrics/memory_distribution.md b/docs/user/reference/metrics/memory_distribution.md
index 889872a7d6..18500ecd01 100644
--- a/docs/user/reference/metrics/memory_distribution.md
+++ b/docs/user/reference/metrics/memory_distribution.md
@@ -275,7 +275,6 @@ Assert.equal(1, Object.entries(data.values).reduce(([bucket, count], sum) => cou
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-memory-distribution-metric-type/index.html)
 * [Swift API docs](../../../swift/Classes/MemoryDistributionMetricType.html)
 * [Python API docs](../../../python/glean/metrics/timing_distribution.html)
 * [Rust API docs](../../../docs/glean/private/struct.MemoryDistributionMetric.html)
diff --git a/docs/user/reference/metrics/quantity.md b/docs/user/reference/metrics/quantity.md
index cf93e37157..19b75fe5a3 100644
--- a/docs/user/reference/metrics/quantity.md
+++ b/docs/user/reference/metrics/quantity.md
@@ -371,7 +371,6 @@ Quantities have the required `unit` parameter, which is a free-form string for d
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-quantity-metric-type/index.html)
 * [Swift API docs](../../../swift/Classes/QuantityMetricType.html)
 * [Python API docs](../../../python/glean/metrics/quantity.html)
 * [Rust API docs](../../../docs/glean/private/quantity/struct.QuantityMetric.html)
diff --git a/docs/user/reference/metrics/string.md b/docs/user/reference/metrics/string.md
index 1d6d131951..03616ef9c4 100644
--- a/docs/user/reference/metrics/string.md
+++ b/docs/user/reference/metrics/string.md
@@ -410,7 +410,6 @@ N/A
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-string-metric-type/index.html)
 * [Swift API docs](../../../swift/Classes/StringMetricType.html)
 * [Python API docs](../../../python/glean/metrics/string.html)
 * [Rust API docs](../../../docs/glean/private/struct.StringMetric.html)
diff --git a/docs/user/reference/metrics/string_list.md b/docs/user/reference/metrics/string_list.md
index 01232c6d40..387581e477 100644
--- a/docs/user/reference/metrics/string_list.md
+++ b/docs/user/reference/metrics/string_list.md
@@ -403,7 +403,6 @@ N/A
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-string-list-metric-type/index.html)
 * [Swift API docs](../../../swift/Classes/StringListMetricType.html)
 * [Python API docs](../../../python/glean/metrics/string_list.html)
 * [Rust API docs](../../../docs/glean/private/struct.StringListMetric.html)
diff --git a/docs/user/reference/metrics/timespan.md b/docs/user/reference/metrics/timespan.md
index bf481ddc84..eae20176fc 100644
--- a/docs/user/reference/metrics/timespan.md
+++ b/docs/user/reference/metrics/timespan.md
@@ -727,7 +727,6 @@ and use the largest possible value that will provide useful information so as to
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-timespan-metric-type/index.html)
 * [Swift API docs](../../../swift/Classes/TimespanMetricType.html)
 * [Python API docs](../../../python/glean/metrics/timespan.html)
 * [Rust API docs](../../../docs/glean/private/struct.TimespanMetric.html)
diff --git a/docs/user/reference/metrics/timing_distribution.md b/docs/user/reference/metrics/timing_distribution.md
index 727360ca08..0a026b82f5 100644
--- a/docs/user/reference/metrics/timing_distribution.md
+++ b/docs/user/reference/metrics/timing_distribution.md
@@ -394,7 +394,6 @@ Assert.ok(Glean.pages.pageLoad.testGetValue().sum > 0);
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-timing-distribution-metric-type/index.html)
 * [Swift API docs](../../../swift/Classes/TimingDistributionMetricType.html)
 * [Python API docs](../../../python/glean/metrics/timing_distribution.html)
 
diff --git a/docs/user/reference/metrics/uuid.md b/docs/user/reference/metrics/uuid.md
index 8633025a45..f1f59abe4b 100644
--- a/docs/user/reference/metrics/uuid.md
+++ b/docs/user/reference/metrics/uuid.md
@@ -475,7 +475,6 @@ N/A
 
 ## Reference
 
-* [Kotlin API docs](../../../javadoc/glean/mozilla.telemetry.glean.private/-uuid-metric-type/index.html).
 * [Swift API docs](../../../swift/Classes/UuidMetricType.html)
 * [Python API docs](../../../python/glean/metrics/uuid.html)
 * [Rust API docs](../../../docs/glean/private/uuid/struct.UuidMetric.html)
diff --git a/glean-core/android-native/build.gradle b/glean-core/android-native/build.gradle
index 6839aaf276..1992133d9b 100644
--- a/glean-core/android-native/build.gradle
+++ b/glean-core/android-native/build.gradle
@@ -11,6 +11,7 @@ apply plugin: 'com.android.library'
 apply plugin: 'org.mozilla.rust-android-gradle.rust-android'
 
 android {
+    ndkVersion rootProject.ext.build.ndkVersion
     compileSdkVersion rootProject.ext.build.compileSdkVersion
 
     defaultConfig {
diff --git a/glean-core/android/build.gradle b/glean-core/android/build.gradle
index de0c122fc6..a719509c58 100644
--- a/glean-core/android/build.gradle
+++ b/glean-core/android/build.gradle
@@ -14,7 +14,6 @@ plugins {
 apply plugin: 'com.android.library'
 apply plugin: 'kotlin-android'
 apply plugin: 'kotlin-android-extensions'
-apply plugin: 'org.jetbrains.dokka-android'
 apply plugin: 'jacoco'
 
 /*
@@ -101,7 +100,7 @@ android {
 
 afterEvaluate {
     jacoco {
-      toolVersion = "0.8.4"
+      toolVersion = "0.8.7"
     }
 
     task jacocoTestReport(type: JacocoReport) {
@@ -156,7 +155,7 @@ dependencies {
     implementation project(":glean-native")
 
     // Note: the following version must be kept in sync
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$versions.kotlin"
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$versions.kotlin"
     implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$versions.coroutines"
 
     implementation "androidx.annotation:annotation:$versions.androidx_annotation"
@@ -211,14 +210,6 @@ afterEvaluate {
 apply from: "$projectDir/publish.gradle"
 ext.configurePublish()
 
-tasks.register("docs", org.jetbrains.dokka.gradle.DokkaAndroidTask) {
-    moduleName = "glean"
-    outputDirectory = "$buildDir/../../../build/docs/javadoc"
-    outputFormat = "html"
-    jdkVersion = 7
-    reportUndocumented = true
-}
-
 // Generate markdown docs for the collected metrics.
 ext.gleanGenerateMarkdownDocs = true
 ext.gleanDocsDirectory = "$rootDir/docs/user/user/collected-metrics"
diff --git a/glean-core/android/src/test/java/mozilla/telemetry/glean/TestUtil.kt b/glean-core/android/src/test/java/mozilla/telemetry/glean/TestUtil.kt
index dcf4f80bf2..7c55e072e8 100644
--- a/glean-core/android/src/test/java/mozilla/telemetry/glean/TestUtil.kt
+++ b/glean-core/android/src/test/java/mozilla/telemetry/glean/TestUtil.kt
@@ -62,7 +62,7 @@ object GleanBuildInfo {
  * @throws AssertionError If the JSON content is not valid
  */
 internal fun checkPingSchema(content: JSONObject) {
-    val os = System.getProperty("os.name")?.toLowerCase()
+    val os = System.getProperty("os.name")?.lowercase()
     val pythonExecutable =
         if (os?.indexOf("win")?.compareTo(0) == 0)
             "${BuildConfig.GLEAN_MINICONDA_DIR}/python"
diff --git a/glean-core/android/src/test/java/mozilla/telemetry/glean/scheduler/MetricsPingSchedulerTest.kt b/glean-core/android/src/test/java/mozilla/telemetry/glean/scheduler/MetricsPingSchedulerTest.kt
index 3f6dc5b459..ae4fc99d6a 100644
--- a/glean-core/android/src/test/java/mozilla/telemetry/glean/scheduler/MetricsPingSchedulerTest.kt
+++ b/glean-core/android/src/test/java/mozilla/telemetry/glean/scheduler/MetricsPingSchedulerTest.kt
@@ -81,7 +81,7 @@ class MetricsPingSchedulerTest {
         fakeNow.set(2015, 6, 11, 3, 0, 0)
 
         // We expect the function to return 1 hour, in milliseconds.
-        assertEquals(60 * 60 * 1000,
+        assertEquals(60 * 60 * 1000L,
             metricsPingScheduler.getMillisecondsUntilDueTime(
                 sendTheNextCalendarDay = false, now = fakeNow, dueHourOfTheDay = 4)
         )
@@ -104,7 +104,7 @@ class MetricsPingSchedulerTest {
 
         // With `sendTheNextCalendarDay` true, we expect the function to return 23 hours
         // and 55 minutes, in milliseconds.
-        assertEquals(23 * 60 * 60 * 1000 + 55 * 60 * 1000,
+        assertEquals(23 * 60 * 60 * 1000L + 55 * 60 * 1000L,
             metricsPingScheduler.getMillisecondsUntilDueTime(
                 sendTheNextCalendarDay = true, now = fakeNow, dueHourOfTheDay = 4)
         )
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index bb8b2fc26b..4d9ca16491 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.5.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.7.1-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/samples/android/app/build.gradle b/samples/android/app/build.gradle
index 17ddf511ad..d56fc55162 100644
--- a/samples/android/app/build.gradle
+++ b/samples/android/app/build.gradle
@@ -39,7 +39,7 @@ android {
 dependencies {
     implementation project(':glean')
 
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$rootProject.versions.kotlin"
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$rootProject.versions.kotlin"
 
     implementation "androidx.appcompat:appcompat:$rootProject.versions.androidx_appcompat"
     implementation "androidx.browser:browser:$rootProject.versions.androidx_browser"
diff --git a/samples/android/app/src/androidTest/java/org/mozilla/samples/gleancore/MainActivityTest.kt b/samples/android/app/src/androidTest/java/org/mozilla/samples/gleancore/MainActivityTest.kt
index 0a22fc3169..9bcd1a8269 100644
--- a/samples/android/app/src/androidTest/java/org/mozilla/samples/gleancore/MainActivityTest.kt
+++ b/samples/android/app/src/androidTest/java/org/mozilla/samples/gleancore/MainActivityTest.kt
@@ -4,6 +4,8 @@
 
 package org.mozilla.samples.gleancore
 
+import android.content.Context
+import androidx.test.core.app.ApplicationProvider
 import androidx.test.espresso.Espresso.onView
 import androidx.test.espresso.action.ViewActions.click
 import androidx.test.espresso.matcher.ViewMatchers.withId
@@ -12,6 +14,7 @@ import androidx.test.ext.junit.rules.ActivityScenarioRule
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertTrue
 import org.mozilla.samples.gleancore.GleanMetrics.Test as GleanTestMetrics
+import mozilla.telemetry.glean.testing.GleanTestLocalServer
 
 import org.junit.Rule
 import org.junit.Test
@@ -22,6 +25,12 @@ class MainActivityTest {
     @get:Rule
     val activityRule: ActivityScenarioRule<MainActivity> = ActivityScenarioRule(MainActivity::class.java)
 
+    @get:Rule
+    val gleanRule = GleanTestLocalServer(context, 0)
+
+    private val context: Context
+        get() = ApplicationProvider.getApplicationContext()
+
     @Test
     fun checkGleanClickData() {
         // We don't reset the storage in this test as the GleanTestRule does not
diff --git a/samples/android/app/src/androidTest/java/org/mozilla/samples/gleancore/pings/SharedTestUtils.kt b/samples/android/app/src/androidTest/java/org/mozilla/samples/gleancore/pings/SharedTestUtils.kt
index aecd4f6442..32ed79e092 100644
--- a/samples/android/app/src/androidTest/java/org/mozilla/samples/gleancore/pings/SharedTestUtils.kt
+++ b/samples/android/app/src/androidTest/java/org/mozilla/samples/gleancore/pings/SharedTestUtils.kt
@@ -21,7 +21,7 @@ import java.util.zip.GZIPInputStream
  */
 internal fun createMockWebServer(): MockWebServer {
     val server = MockWebServer()
-    server.setDispatcher(object : Dispatcher() {
+    server.dispatcher = (object : Dispatcher() {
         override fun dispatch(request: RecordedRequest): MockResponse {
             return MockResponse().setBody("OK")
         }
@@ -72,7 +72,7 @@ fun waitForPingContent(
     var parsedPayload: JSONObject? = null
     for (attempts in 1..maxAttempts) {
         val request = server.takeRequest(20L, TimeUnit.SECONDS) ?: break
-        val docType = request.path.split("/")[3]
+        val docType = request.path!!.split("/")[3]
         if (pingName == docType) {
             parsedPayload = JSONObject(request.getPlainBody())
             if (pingReason == null) {
diff --git a/taskcluster/docker/linux/Dockerfile b/taskcluster/docker/linux/Dockerfile
index 7624567efc..aca112d680 100644
--- a/taskcluster/docker/linux/Dockerfile
+++ b/taskcluster/docker/linux/Dockerfile
@@ -141,26 +141,11 @@ RUN curl -sfSL --retry 5 --retry-delay 10 https://dl.google.com/android/reposito
         "platforms;android-${ANDROID_PLATFORM_VERSION}" \
         "build-tools;${ANDROID_BUILD_TOOLS}" \
         "extras;android;m2repository" \
-        "extras;google;m2repository"
+        "extras;google;m2repository" \
+        "ndk;21.3.6528147"
 
 RUN chown -R worker:worker /builds/worker/android-sdk
 
-# Android NDK
-
-ENV ANDROID_NDK_VERSION "r21"
-
-# $ANDROID_NDK_ROOT is the preferred name, but the android gradle plugin uses $ANDROID_NDK_HOME.
-ENV ANDROID_NDK_ROOT /builds/worker/android-ndk
-ENV ANDROID_NDK_HOME /builds/worker/android-ndk
-
-RUN curl -sfSL --retry 5 --retry-delay 10 https://dl.google.com/android/repository/android-ndk-${ANDROID_NDK_VERSION}-linux-x86_64.zip > ndk.zip \
-    && unzip -q ndk.zip -d /builds/worker \
-    && rm ndk.zip \
-    && mv /builds/worker/android-ndk-${ANDROID_NDK_VERSION} ${ANDROID_NDK_ROOT}
-
-ENV ANDROID_NDK_TOOLCHAIN_DIR /builds/worker/.android-ndk-r21-toolchain
-ENV ANDROID_NDK_API_VERSION 21
-
 # sccache
 RUN \
     curl -sfSL --retry 5 --retry-delay 10 \