CDN-Hosting-at-Google-Cloud-Storage.md

-*Note: these are notes about using Google Cloud Storage as a CDN service. We use GCS in combination with CloudFlare.*
+*Note: these are notes about using Google Cloud Storage to host a copy of MathJax. We use GCS in combination with CloudFlare which means these instructions are not always optimal if you are working in a pure GCS setup.*
 
 ### Preliminaries
 
@@ -6,6 +6,25 @@
 * The main tool is `gsutil`. 
 * Note: due to rapid development  a lot of information on the web uses outdated syntax (but is still useful, e.g., https://gist.github.com/mhulse/4362104).
 
+### Setting a default ACL (access control list) 
+
+Notes:
+* https://developers.google.com/storage/docs/gsutil/commands/defacl
+
+**This is a one-time task**
+
+The GCS default for access control is private. GCS does allow for ACLs to persist when files are overwritten.
+
+Since we update files in `\latest` with every releases and files in `beta` during beta runs,  we need to prevent GCS from marking those new files as private (breaking public access to the CDN).
+
+The solution is to set the default ACL for the bucket once following the instructions in the gsutil documentation. The XML file should contain 
+
+        <Entry>
+            <Scope type="AllUsers"/>
+            <Permission>READ</Permission>
+        </Entry>
+
+
 ### Copying
 
 Notes: