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README.md

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+# NYTimes Tech Guild Library
+
+This repository is responsible for the configuration and deployment
+of the [Library](https://github.com/nytimes/library.git) instance
+for the NYTimes Tech Guild. As of 12/23/2022, this repository actually
+deploys the
+[newsguildny/library](https://github.com/newsguildny/library.git)
+fork of Library in order to support hosting Library at a subpath of
+[https://nytimesguild.org/](nytimesguild.org). Once
+[the PR](https://github.com/nytimes/library/pull/334) to add this
+support upstream is merged, the .github/workflows/deploy.yml
+configuration can be updated to use the upstream repo.
+
+## How it works
+
+### Customizing Library
+
+The docs for how customization works in Library can be found
+[here](https://github.com/nytimes/library/blob/master/custom/README.md).
+
+The `styles/` directory and `strings.yaml` file are the standard
+UI customization entrypoints. Changes to these files will change the
+styles and markup rendered by the Library backend.
+
+### User authentication
+
+By default, Library uses Google OAuth and passport to authenticate users.
+For our NYTimes Guild Library sites, we prefer to use Google's
+[Identity-Aware Proxy](https://cloud.google.com/iap/docs/concepts-overview)
+(IAP), which allows us to give arbitrary principals (in the form of
+individual users and Google groups) access to each Library instance as
+needed, through the Google Cloud Console.
+
+IAP executes its own OAuth flow, so we implement our own custom
+`userAuth.js` that simply validates the JWT authentication tokens it
+receives from IAP.
+
+### Deployment
+
+This repo also contains a GitHub Action for deploying the Library instance
+to Google App Engine. The load balancer and IAP are configured separately
+in GCP; this repo is only concerned with deploying this App Engine service.
+
+The actual application code for Library doesn't live in this repository;
+instead, the Action clones the Library repo and configures this repo as the
+customization repo.
+
+The Action configures the deployed environment via a `.env` file. The values
+are all either hard coded or stored in GitHub Repository Secrets. It then uses
+the GCloud CLI to deploy the app.