From bef536b035e57ff04557c83b53a2da64cb6d3590 Mon Sep 17 00:00:00 2001
From: David Backeus <duztdruid@gmail.com>
Date: Thu, 21 Sep 2023 09:23:24 +0200
Subject: [PATCH] Allow HOST to fall back to HEROKU_APP_DEFAULT_DOMAIN_NAME if
 available

---
 README.md             | 13 +++++++++++--
 app/models/server.rb  |  3 +--
 config/application.rb |  4 +++-
 3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index cd9c585..3d8b5f2 100644
--- a/README.md
+++ b/README.md
@@ -75,8 +75,17 @@ heroku config:set HETZNER_CLOUD_API_TOKEN=<hetzner-cloud-api-token>
 # If you're not planning to use dedicated servers you can skip this part.
 heroku config:set HETZNER_WEBSERVICE_USER=<username> HETZNER_WEBSERVICE_PASSWORD=<password>
 
-# Note: You may want to change this to your own domain via the Heroku application settings page
-heroku config:set HOST=<application-name>.herokuapp.com
+# For application host you have two options:
+
+# 1. Deploy to your own domain
+# Full documentation at https://devcenter.heroku.com/articles/custom-domains
+heroku domains:add <your-custom-url>
+heroku config:set HOST=<your-custom-url>
+
+# 2. Deploy to a Heroku subdomain
+# For this you'll want to enable the runtime-dyno-metadata lab feature which will provide us
+# with the HEROKU_APP_DEFAULT_DOMAIN_NAME environment variable.
+heroku labs:enable runtime-dyno-metadata
 
 # Assumes you created the SSH key for bootstrapping according to the instructions above
 heroku config:set SSH_PRIVATE_KEY="$(cat ~/.ssh/talos-manager.pem)"
diff --git a/app/models/server.rb b/app/models/server.rb
index e60ff84..f6ccb92 100644
--- a/app/models/server.rb
+++ b/app/models/server.rb
@@ -31,7 +31,6 @@ def bootstrap!
       raise "Invalid SMBIOS UUID, send this output to Hetzner support: #{system_data}"
     end
 
-    host = ENV.fetch("HOST")
     talos_image_url = architecture == "amd64" ? TALOS_AMD64_IMAGE_URL : TALOS_ARM64_IMAGE_URL
     nvme = session.exec!("ls /dev/nvme0n1 && echo 'has-nvme'").chomp.ends_with? "has-nvme"
 
@@ -45,7 +44,7 @@ def bootstrap!
 
     # assuming that p3 is the BOOT partition, can make sure with `gdisk /dev/nvme0n1` and `s` command
     ssh_exec_with_log! session, "mount #{bootstrap_disk}#{boot_partition} /mnt"
-    ssh_exec_with_log! session, "sed -i 's/vmlinuz/vmlinuz talos.config=https:\\/\\/#{host}\\/config?uuid=${uuid}/' "\
+    ssh_exec_with_log! session, "sed -i 's/vmlinuz/vmlinuz talos.config=https:\\/\\/#{HOST}\\/config?uuid=${uuid}/' "\
                                 "/mnt/grub/grub.cfg"
     ssh_exec_with_log! session, "umount /mnt"
 
diff --git a/config/application.rb b/config/application.rb
index cb28772..359cddc 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -35,7 +35,9 @@ class Application < Rails::Application
     config.generators.system_tests = nil
 
     # Allow requests from the host specified in the HOST environment variable
-    config.hosts << ENV["HOST"] if ENV["HOST"].present?
+    # (or HEROKU_APP_DEFAULT_DOMAIN_NAME if running on Heroku without a custom domain)
+    ::HOST = ENV["HOST"] || ENV["HEROKU_APP_DEFAULT_DOMAIN_NAME"]
+    config.hosts << HOST if HOST.present?
 
     # Configure ActiveRecord encryption via environment variables
     config.active_record.encryption.primary_key = ENV["AR_ENCRYPTION_PRIMARY_KEY"]