Reorganize documentation for new website (#213)

This PR should be merged after the new website is deployed.

- [x] Rename files
- [x] Add front matter section to all `.md` files in the book (necessary for Zola)
- [x] Change all internal links to use Zola's linking system that checks broken links
- [x] Some updates to documentation contents and organization

Co-authored-by: Alex Auvolat <alex@adnab.me>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/213
Co-authored-by: Alex <alex@adnab.me>
Co-committed-by: Alex <alex@adnab.me>

1 files changed, 69 insertions, 0 deletions

diff --git a/doc/book/cookbook/exposing-websites.md b/doc/book/cookbook/exposing-websites.md
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+title = "Exposing buckets as websites"
+weight = 25
++++
+
+## Configuring a bucket for website access
+
+There are two methods to expose buckets as website:
+
+1. using the PutBucketWebsite S3 API call, which is allowed for access keys that have the owner permission bit set
+
+2. from the Garage CLI, by an adminstrator of the cluster
+
+The `PutBucketWebsite` API endpoint [is documented](https://docs.aws.amazon.com/AmazonS3/latest/API/API_PutBucketWebsite.html) in the official AWS docs.
+This endpoint can also be called [using `aws s3api`](https://docs.aws.amazon.com/cli/latest/reference/s3api/put-bucket-website.html) on the command line.
+The website configuration supported by Garage is only a subset of the possibilities on Amazon S3: redirections are not supported, only the index document and error document can be specified.
+
+If you want to expose your bucket as a website from the CLI, use this simple command:
+
+```bash
+garage bucket website --allow my-website
+```
+
+Now it will be **publicly** exposed on the web endpoint (by default listening on port 3902).
+
+## How exposed websites work
+
+Our website serving logic is as follow:
+
+  - Supports only static websites (no support for PHP or other languages)
+  - Does not support directory listing
+  - The index file is defined per-bucket and can be specified in the `PutBucketWebsite` call
+     or on the CLI using the `--index-document` parameter (default: `index.html`)
+  - A custom error document for 404 errors can be specified in the `PutBucketWebsite` call
+    or on the CLI using the `--error-document` parameter
+
+Now we need to infer the URL of your website through your bucket name.
+Let assume:
+  - we set `root_domain = ".web.example.com"` in `garage.toml` ([ref](@/documentation/reference-manual/configuration.md#root_domain))
+  - our bucket name is `garagehq.deuxfleurs.fr`.
+
+Our bucket will be served if the Host field matches one of these 2 values (the port is ignored):
+
+  - `garagehq.deuxfleurs.fr.web.example.com`: you can dedicate a subdomain to your users (here `web.example.com`).
+
+  - `garagehq.deuxfleurs.fr`: your users can bring their own domain name, they just need to point them to your Garage cluster.
+
+You can try this logic locally, without configuring any DNS, thanks to `curl`:
+
+```bash
+# prepare your test
+echo hello world > /tmp/index.html
+mc cp /tmp/index.html garage/garagehq.deuxfleurs.fr
+
+curl -H 'Host: garagehq.deuxfleurs.fr' http://localhost:3902
+# should print "hello world"
+
+curl -H 'Host: garagehq.deuxfleurs.fr.web.example.com' http://localhost:3902
+# should also print "hello world"
+```
+
+Now that you understand how website logic works on Garage, you can:
+
+ - make the website endpoint listens on port 80 (instead of 3902)
+ - use iptables to redirect the port 80 to the port 3902:  
+   `iptables -t nat -A PREROUTING -p tcp -dport 80 -j REDIRECT -to-port 3902`
+ - or configure a [reverse proxy](@/documentation/cookbook/reverse-proxy.md) in front of Garage to add TLS (HTTPS), CORS support, etc.
+
+You can also take a look at [Website Integration](@/documentation/connect/websites.md) to see how you can add Garage to your workflow.