From c44015cee5277d69274375b1dad6ab264a2d8c7e Mon Sep 17 00:00:00 2001
From: Grant Slater <github@firefishy.com>
Date: Tue, 14 Oct 2025 23:17:38 +0100
Subject: [PATCH] imagery: extra headers and handle 204 responses

---
 cookbooks/imagery/files/default/transparent.png   | Bin 0 -> 102 bytes
 cookbooks/imagery/resources/site.rb               |   7 +++++++
 .../default/nginx_imagery_layer_fragment.conf.erb |  11 ++++++++++-
 3 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 cookbooks/imagery/files/default/transparent.png

diff --git a/cookbooks/imagery/files/default/transparent.png b/cookbooks/imagery/files/default/transparent.png
new file mode 100644
index 0000000000000000000000000000000000000000..26134c4c1ad21c2ecc90a5f5f3796d4f2377d833
GIT binary patch
literal 102
zcmeAS@N?(olHy`uVBq!ia0y~yU<5K5!6ZWo=hV|c9#ct>UoZnh+2pepK%Ts(i(^Q|
qt+xjmd4aq`3cr_|9XC$^GQpsbT@k2#$108IAg-sYpUXO@geCy`;})3!

literal 0
HcmV?d00001

diff --git a/cookbooks/imagery/resources/site.rb b/cookbooks/imagery/resources/site.rb
index d7c549587..498e02ab5 100644
--- a/cookbooks/imagery/resources/site.rb
+++ b/cookbooks/imagery/resources/site.rb
@@ -86,6 +86,13 @@ action :create do
     mode "644"
   end
 
+  cookbook_file "/srv/#{new_resource.site}/transparent.png" do
+    source "transparent.png"
+    user "root"
+    group "root"
+    mode "644"
+  end
+
   layers = Dir.glob("/srv/imagery/layers/#{new_resource.site}/*.yml").collect do |path|
     YAML.safe_load_file(path, :permitted_classes => [Symbol])
   end
diff --git a/cookbooks/imagery/templates/default/nginx_imagery_layer_fragment.conf.erb b/cookbooks/imagery/templates/default/nginx_imagery_layer_fragment.conf.erb
index 78b2532fa..a711f4659 100644
--- a/cookbooks/imagery/templates/default/nginx_imagery_layer_fragment.conf.erb
+++ b/cookbooks/imagery/templates/default/nginx_imagery_layer_fragment.conf.erb
@@ -10,7 +10,9 @@ location ~* "^/layer/<%= @layer %>/(\d+)/(\d+)/(\d+)\.(jpg|jpeg|png|webp)$" {
   # Serve local file if present; otherwise jump to proxy
   try_files /layer/<%= @layer %>/$z/$x/$y.jpg /layer/<%= @layer %>/$z/$x/$y.jpeg /layer/<%= @layer %>/$z/$x/$y.png /layer/<%= @layer %>/$z/$x/$y.webp @tile_backend;
 
-  # Response headers (apply to both static and proxied responses unless overridden)
+  # Return transparent PNG for HTTP 204 (no content) responses from backend
+  error_page 204 =200 /transparent.png;
+
   gzip off;
   expires 31d;
   add_header Cache-Control "stale-while-revalidate=2678400, stale-if-error=2678400";
@@ -52,6 +54,8 @@ location @tile_backend {
   proxy_hide_header "Cache-Control";
   proxy_hide_header "Expires";
   proxy_hide_header "Access-Control-Allow-Origin";
+  proxy_hide_header "Content-BBOX";
+  proxy_hide_header "Content-CRS";
 <% else -%>
   # Override QUERY_STRING to force mapserver query parameters
   fastcgi_param QUERY_STRING "map=/srv/imagery/mapserver/layer-<%= @layer %>.map&mode=tile&layers=<%= @layer %>&tilemode=gmap&tile=$x+$y+$z";
@@ -84,6 +88,11 @@ location @tile_backend {
   fastcgi_next_upstream error timeout invalid_header http_500 http_503;
   fastcgi_next_upstream_tries 8;
 <% end -%>
+  gzip off;
+  expires 31d;
+  add_header Cache-Control "stale-while-revalidate=2678400, stale-if-error=2678400";
+  add_header x-cache-status $upstream_cache_status;
+  add_header 'Access-Control-Allow-Origin' '*' always;
 }
 
 <% if @root_layer -%>
-- 
2.39.5