# Substituting local ac and GV
To build fenix with a local android-components or local GeckoView, we recommend the following methods:

|type|fenix -> local ac|fenix -> local GV|fenix -> local ac -> local GV|
|-|-|-|-|
|**method**|local.properties|local.properties|manual publish + local.properties|

For instructions with `local.properties`, see [the root README](https://github.com/mozilla-mobile/fenix/blob/main/README.md). For instructions on manual publish + local.properties, keep reading. See [ac#8386](https://github.com/mozilla-mobile/android-components/issues/8386) for why we can't use local properties for fenix -> local ac -> local GV publishing.

## fenix -> local ac -> local GV
We're going to manually publish our GeckoView to our local maven repository, modify ac locally to consume it, and use local.properties to build fenix -> local ac.

### 1. Synchronize checkouts
To avoid breaking changes causing our builds to fail, we should make sure each of the repositories is on a commit from around the same time frame. You can use the [`android-components/tools/list_compatible_dependency_versions.py` script](https://github.com/mozilla-mobile/android-components/blob/main/tools/list_compatible_dependency_versions.py) to trivially identify ac and GV builds from a given fenix commit. If you want to synchronize builds from a GV or ac commit, you'll likely need to try to align around the commit merge dates (use `git log --pretty=fuller`).

### 2. Manually publish GeckoView
With our builds synchronized, we can publish our local changes to GeckoView. To publish GeckoView, run:
```sh
./mach build && ./mach gradle \
    geckoview:publishWithGeckoBinariesDebugPublicationToMavenLocal \
    exoplayer2:publishDebugPublicationToMavenLocal
```

This **needs to be run every time you make changes.**

We also need to know what version of GeckoView we published. You can make this local change:
```diff
diff --git a/mobile/android/geckoview/build.gradle b/mobile/android/geckoview/build.gradle
--- a/mobile/android/geckoview/build.gradle
+++ b/mobile/android/geckoview/build.gradle
@@ -382,16 +382,17 @@ android.libraryVariants.all { variant ->
     // and we can simply extend its inputs.  See
     // https://android.googlesource.com/platform/tools/base/+/0cbe8846f7d02c0bb6f07156b9f4fde16d96d329/build-system/gradle-core/src/main/java/com/android/build/gradle/tasks/BundleAar.kt#94.
     variant.packageLibraryProvider.get().from("${topsrcdir}/toolkit/components/telemetry/geckoview/streaming/metrics.yaml")
 }

 apply plugin: 'maven-publish'

 version = getVersionNumber()
+println("version = " + version)
 group = 'org.mozilla.geckoview'

 def getArtifactId() {
     def id = "geckoview" + project.ext.artifactSuffix

     if (!mozconfig.substs.MOZ_ANDROID_GECKOVIEW_LITE) {
         id += "-omni"
     }
```

And execute `./mach build | grep version` to find a version number like `98.0.20211208151112-SNAPSHOT`.

### 3. Modify ac to consume local GV
See the diff below. Remember to update the GV version with the version you found in step 2!
```diff
diff --git a/build.gradle b/build.gradle
index fa8149781f..863df65a57 100644
--- a/build.gradle
+++ b/build.gradle
@@ -6,6 +6,7 @@ import static org.gradle.api.tasks.testing.TestResult.ResultType

 buildscript {
     repositories {
+        mavenLocal()
         if (project.hasProperty("googleRepo")) {
             maven {
                 name "Google"
@@ -40,6 +41,7 @@ plugins {

 allprojects {
     repositories {
+        mavenLocal()
         if (project.hasProperty("googleRepo")) {
             maven {
                 name "Google"
diff --git a/buildSrc/src/main/java/Gecko.kt b/buildSrc/src/main/java/Gecko.kt
index 331158bf50..f37a05791a 100644
--- a/buildSrc/src/main/java/Gecko.kt
+++ b/buildSrc/src/main/java/Gecko.kt
@@ -9,7 +9,10 @@ object Gecko {
     /**
      * GeckoView Version.
      */
-    const val version = "98.0.20220125100058"
+    const val version = "98.0.20211208151112-SNAPSHOT"

     /**
      * GeckoView channel
@@ -23,7 +26,7 @@ object Gecko {
 enum class GeckoChannel(
     val artifactName: String
 ) {
-    NIGHTLY("geckoview-nightly-omni"),
+    NIGHTLY("geckoview-default-omni"),
     BETA("geckoview-beta-omni"),
     RELEASE("geckoview-omni")
 }
```

### 4. Build fenix with local.properties change
Now build fenix as usual with [the `local.properties` change](https://github.com/mozilla-mobile/fenix#auto-publication-workflow-for-android-components-and-application-services) to build with your local ac. This build will automatically build ac each time it is run. You should have a fenix -> local ac -> local GV build now!