Docs: Re-add virtual host addressing (#7934)

* Docs: Re-add virtual host addressing

* CR Fixes

docs/howto/virtual-host-addressing.md

@@ -0,0 +1,71 @@
+---
+layout: default
+title: "S3 Virtual-host addressing (advanced)"
+description: Configure the lakeFS S3 API to use virtual host addressing
+parent: How-To
+---
+
+# Configuring lakeFS to use S3 Virtual-Host addressing
+
+## Understanding virtual-host addressing
+
+Some systems require S3 endpoints (such as lakeFS's [S3 Gateway](../understand/architecture.md#s3-gateway)) to support [virtual-host style addressing](https://docs.aws.amazon.com/AmazonS3/latest/userguide/VirtualHosting.html){: target="_blank" }.
+
+lakeFS supports this, but requires some configuration in order to extract the bucket name (used as the lakeFS repository ID) from the host address.
+
+For example:
+
+```text
+GET http://foo.example.com/some/location
+```
+
+There are two ways to interpret the URL above:
+- as a virtual-host URL where the endpoint URL is `example.com`, the bucket name is `foo`, and the path is `/some/location`
+- as a path-based URL where the endpoint is `foo.example.com`, the bucket name is `some` and the path is `location`
+
+By default, lakeFS reads URLs as path-based. To read the URL as a virtual-host request, lakeFS requires additional configuration which includes 
+defining an explicit set of DNS records for the lakeFS S3 gateway.
+
+## Adding an explicit S3 domain name to the S3 Gateway configuration
+
+The first step would be to tell the lakeFS installation which hostnames are used for the S3 Gateway. This should be a different DNS record from the one used for e.g. the UI or API.
+
+Typically, if the lakeFS installation is served under `lakefs.example.com`, a good choice would be `s3.lakefs.example.com`.
+
+This could be done using either an environment variable:
+
+```shell
+LAKEFS_GATEWAYS_S3_DOMAIN_NAME="s3.lakefs.example.com"
+```
+
+Or by adding the `gateways.s3.domain_name` setting to the lakeFS `config.yaml` file:
+
+```yaml
+---
+database:
+  connection_string: "..."
+
+...
+
+# This section defines an explict S3 gateway address that supports virtual-host addressing
+gateways:
+  s3:
+    domain_name: s3.lakefs.example.com
+```
+
+For more information on how to configure lakeFS, check out the [configuration reference](../reference/configuration.md)
+{: .note }
+
+## Setting up the appropriate DNS records
+
+Once our lakeFS installation is configured with an explicit S3 gateway endpoint address, we need to define 2 DNS records and have them point at our lakeFS installation.
+This requires 2 CNAME records:
+
+1. `s3.lakefs.example.com` - CNAME to `lakefs.example.com`. This would be used as the S3 endpoint when configuring clients and will serve as our bare domain.
+1. `*.s3.lakefs.example.com` - Also a CNAME to `lakefs.example.com`. This will resolve virtual-host requests such as `example-repo.s3.lakefs.example.com` that lakeFS would now know how to parse.
+
+
+<div class="note">
+   <p>For more information on how to configure these, see the official documentation of your DNS provider.</p>
+   <p>On AWS, This could also be done [using ALIAS records](https://aws.amazon.com/premiumsupport/knowledge-center/route-53-create-alias-records/) for a load balancer.</p> 
+</div>