docs: OEP-67 automated bundle size checking.

oeps/best-practices/oep-0067-bp-tools-and-technology.rst

@@ -235,6 +235,13 @@ Frontend Technology Selection
    There is much desire to replace Mako within edx-platform so this
    exception may eventually be removed.
 
+#. **BundleWatch should be used to automatically monitor JavaScript bundle sizes**
+
+   **Rationale**: It is important for users of the Open edX platform that we deliver
+   reasonably sized JavaScript bundles. This provides faster load times to all users,
+   and is vital for users with low bandwidth and/or metered connections. To ensure we 
+   don't unintentionally increase the size of our JavaScript bundles, we utilize BundleWatch
+   for automated bundle size monitoring.
 
 Backend Technology Selection
 ============================

oeps/best-practices/oep-0067/decisions/frontend/0007-bundle-size.rst

@@ -0,0 +1,63 @@
+Use BundleWatch to automate bundle size checking
+################################################
+
+Status
+******
+
+Accepted
+
+Context
+*******
+
+It is important for users of the Open edX platform that we deliver reasonably sized JavaScript bundles. This provides
+faster load times to all users, and is vital for users with low bandwidth and/or metered connections.  
+
+It is currently possible to manually monitor bundle size information by utilizing webpack configurations provided by
+frontend-build, but this functionality is not very discoverable. Given the "hidden" nature of this functionality, it is
+very possible for changes that increase bundle size to be missed in the PR review process. 
+
+The increased visibility provided by automated bundle size monitoring will ensure we don't unintentionally increase
+the size of our JavaScript bundles, as well as encourage maintainers to adopt best practices such as `code splitting`_.
+
+Decision
+********
+
+`BundleWatch`_ will be adopted by the Open edX community for automatic JavaScript bundle size monitoring. Repository maintainers will
+decide if this CI check will be blocking or informative on a repo-by-repo basis.
+
+BundleWatch
+===========
+
+`BundleWatch`_ is solely focused on ensuring bundle sizes stay under control. It is actively maintained and used by popular projects such as `bootstrap`_. 
+
+Consequence
+***********
+
+Implementing BundleWatch will require very few changes to our existing CI workflows. The BundleWatch GitHub app
+will be added to the Open edX GitHub organization, and bundle size checking will be added to the CI process for
+JavaScript based repositories.
+
+Rejected Alternatives
+*********************
+
+1. **Code Checks**
+
+   `Code Checks`_ is a pluggable framework for automated code review. It provides more
+   than just bundle size monitoring, presenting us with an opportunity to rethink our
+   current CI workflows. For example, Code Checks provides test coverage monitoring,
+   which would allow us to re-evaluate the choice to use CodeCov as documented in
+   :doc:`0006-codecov`.
+
+   While this additional functionality is potentially desirable, moving forward with a
+   single purpose tool (`BundleWatch`_) provides us the functionality we need with
+   minimal changes to our current CI workflows.
+
+2. **Bundlesize**
+
+   `Bundlesize`_ is no longer actively maintained.
+
+.. _Bundlesize: https://github.com/siddharthkp/bundlesize
+.. _BundleWatch: https://bundlewatch.io/
+.. _bootstrap: https://github.com/twbs/bootstrap/blob/main/.github/workflows/bundlewatch.yml
+.. _Code Checks: https://www.codechecks.io/
+.. _code splitting: https://webpack.js.org/guides/code-splitting/