diff -urp dist/lib/cli/commands/install.js patched/lib/cli/commands/install.js
--- dist/lib/cli/commands/install.js	2017-02-01 00:36:23.000000000 +0000
+++ patched/lib/cli/commands/install.js	2017-02-01 01:25:41.000000000 +0000
@@ -226,6 +226,10 @@ function getUpdateCommand() {
     return 'choco upgrade yarn';
   }
 
+  if (YARN_INSTALL_METHOD === 'apk') {
+    return 'apk update && apk add -u yarn';
+  }
+
   return null;
 }
 
diff -urp dist/lib-legacy/cli/commands/install.js patched/lib-legacy/cli/commands/install.js
--- dist/lib-legacy/cli/commands/install.js	2017-01-30 14:13:43.000000000 +0000
+++ patched/lib-legacy/cli/commands/install.js	2017-02-01 01:32:32.000000000 +0000
@@ -238,6 +238,10 @@ function getUpdateCommand() {
     return 'choco upgrade yarn';
   }
 
+  if (YARN_INSTALL_METHOD === 'apk') {
+    return 'apk update && apk add -u yarn';
+  }
+
   return null;
 }
 
diff -urp dist/package.json patched/package.json
--- dist/package.json	2017-02-01 01:23:37.000000000 +0000
+++ patched/package.json	2017-02-01 01:23:50.000000000 +0000
@@ -1,6 +1,6 @@
 {
   "name": "yarn",
-  "installationMethod": "tar",
+  "installationMethod": "apk",
   "version": "0.20.3",
   "license": "BSD-2-Clause",
   "preferGlobal": true,