fix(ubuntu): specify all avd-related environment variables

Allow for users to modify android install directories via standard
environment variables if desired by not clobbering env vars without
checking first

Define all the standard environment variables used in an emulator context

lib/sdk-installer.js

@@ -62,9 +62,25 @@ function installAndroidSdk(apiLevel, target, arch, channelId, emulatorBuild, ndk
             }
             // add paths for commandline-tools and platform-tools
             core.addPath(`${cmdlineToolsPath}/latest:${cmdlineToolsPath}/latest/bin:${process.env.ANDROID_HOME}/platform-tools`);
-            // set standard AVD path
-            yield io.mkdirP(`${process.env.HOME}/.android/avd`);
-            core.exportVariable('ANDROID_AVD_HOME', `${process.env.HOME}/.android/avd`);
+            // There are several environment variables that determine where AVD config and disk images go:
+            // https://developer.android.com/tools/variables#envar
+            // Users may set these for various reasons (self-hosted runners with specific disk space situations)
+            // so only set them if they are not already set.
+            // "user preferences directory for tools that are part of the Android SDK. Defaults to $HOME/.android/."
+            if (!process.env.ANDROID_USER_HOME) {
+                core.exportVariable('ANDROID_USER_HOME', `${process.env.HOME}/.android`);
+            }
+            yield io.mkdirP(`${process.env.ANDROID_USER_HOME}`);
+            // "user-specific emulator configuration directory. Defaults to $ANDROID_USER_HOME"
+            if (!process.env.ANDROID_EMULATOR_HOME) {
+                core.exportVariable('ANDROID_EMULATOR_HOME', process.env.ANDROID_USER_HOME);
+            }
+            yield io.mkdirP(`${process.env.ANDROID_EMULATOR_HOME}`);
+            // "all AVD-specific files, which mostly consist of very large disk images. Default is $ANDROID_EMULATOR_HOME/avd/"
+            if (!process.env.ANDROID_AVD_HOME) {
+                core.exportVariable('ANDROID_AVD_HOME', `${process.env.ANDROID_EMULATOR_HOME}/avd`);
+            }
+            yield io.mkdirP(`${process.env.ANDROID_AVD_HOME}`);
             // accept all Android SDK licenses
             yield exec.exec(`sh -c \\"yes | sdkmanager --licenses > /dev/null"`);
             console.log('Installing latest build tools, platform tools, and platform.');

src/sdk-installer.ts

@@ -31,9 +31,28 @@ export async function installAndroidSdk(apiLevel: string, target: string, arch:
     // add paths for commandline-tools and platform-tools
     core.addPath(`${cmdlineToolsPath}/latest:${cmdlineToolsPath}/latest/bin:${process.env.ANDROID_HOME}/platform-tools`);
 
-    // set standard AVD path
-    await io.mkdirP(`${process.env.HOME}/.android/avd`);
-    core.exportVariable('ANDROID_AVD_HOME', `${process.env.HOME}/.android/avd`);
+    // There are several environment variables that determine where AVD config and disk images go:
+    // https://developer.android.com/tools/variables#envar
+    // Users may set these for various reasons (self-hosted runners with specific disk space situations)
+    // so only set them if they are not already set.
+
+    // "user preferences directory for tools that are part of the Android SDK. Defaults to $HOME/.android/."
+    if (!process.env.ANDROID_USER_HOME) {
+      core.exportVariable('ANDROID_USER_HOME', `${process.env.HOME}/.android`);
+    }
+    await io.mkdirP(`${process.env.ANDROID_USER_HOME}`);
+
+    // "user-specific emulator configuration directory. Defaults to $ANDROID_USER_HOME"
+    if (!process.env.ANDROID_EMULATOR_HOME) {
+      core.exportVariable('ANDROID_EMULATOR_HOME', process.env.ANDROID_USER_HOME);
+    }
+    await io.mkdirP(`${process.env.ANDROID_EMULATOR_HOME}`);
+
+    // "all AVD-specific files, which mostly consist of very large disk images. Default is $ANDROID_EMULATOR_HOME/avd/"
+    if (!process.env.ANDROID_AVD_HOME) {
+      core.exportVariable('ANDROID_AVD_HOME', `${process.env.ANDROID_EMULATOR_HOME}/avd`);
+    }
+    await io.mkdirP(`${process.env.ANDROID_AVD_HOME}`);
 
     // accept all Android SDK licenses
     await exec.exec(`sh -c \\"yes | sdkmanager --licenses > /dev/null"`);