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README.md

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-# issilksongoutyet.com
+# issilksongoutyet.com
+
+A website that tracks the release date of [Hollow Knight: Silksong](https://store.steampowered.com/app/1030300/Hollow_Knight_Silksong/).
+
+To get the site to update dynamically, I looked into options for how to fetch data from Steam.
+Steam's website hits an underlying API that can be queried directly:
+```sh
+$ curl 'https://store.steampowered.com/api/appdetails?appids=1030300' | jq '.["1030300"].data.release_date'
+{
+  "coming_soon": true,
+  "date": "To be announced"
+}
+```
+
+My first thought was to fetch this data client-side in the browser, but this didn't work due to CORS (the API doesn't return an `Access-Control-Allow-Origin` header).
+
+Next, I tried to fetch the data in a Cloudflare Worker, still processing it client-side. When I started making the request in the Worker, I began getting 403 responses back.
+I suspected the Steam API was blocking Cloudflare Workers, and confirmed this by making a test request with one of the headers that Cloudflare injects into outbound requests from Workers:
+```sh
+$ curl -I 'https://store.steampowered.com/api/appdetails?appids=1030300'
+HTTP/1.1 200 OK
+...
+
+$ curl -I -H 'cf-worker: blah' 'https://store.steampowered.com/api/appdetails?appids=1030300'
+HTTP/1.1 403 Forbidden
+...
+```
+
+OK, looks like Steam doesn't want Cloudflare Workers to scrape their API. Fair enough. Not wanting to give up so easily, I rewrote the Worker script in an AWS Lambda function.
+This worked, but still had a couple of undesirable characteristics:
+* Data fetching on page load takes time, and there is a noticable lag when the page loads before the content appears.
+* The Lambda function is public, so I can rack up costs from bots hitting it, etc. It's just not very elegant.
+
+To overcome these issues, I changed the site to build hourly, producing a static site with the data from the Steam API injected at build time.
+The finished site is built with Jekyll on GitHub Pages and updates via a scheduled GitHub Actions workflow.