Use environment variables directly from lua rather than envsubst-ing then into nginx variables

Also gets rid of the need for a server_name variable

Dockerfile

 FROM uninett-docker-uninett.bintray.io/jessie/minbase
-RUN install_packages.sh nginx-extras gettext lua-cjson
+RUN install_packages.sh nginx-extras lua-cjson
 COPY lua /usr/local/share/lua/5.1/
-COPY nginx /etc/nginx/
+COPY nginx/nginx.conf /etc/nginx/
+COPY nginx/site.conf /etc/nginx/sites-enabled/default
 COPY entrypoint.sh /entrypoint.sh
 ENTRYPOINT ["/entrypoint.sh"]
 ENV memcache=memcache

entrypoint.sh

 #! /bin/sh
-export dollar='$'
 export namespace="$(cat /run/secrets/kubernetes.io/serviceaccount/namespace)"
-cat /etc/nginx/site.conf|envsubst>/etc/nginx/sites-enabled/default
 exec "$@"

lua/auth.lua

+local returnTo = ngx.req.get_uri_args().ReturnTo
+if not returnTo then
+   returnTo = ngx.var.scheme .. '://' .. ngx.var.host .. '/'
+end
+local authServer = os.getenv('auth_server')
+local action = ngx.var.action
+ngx.redirect('https://' .. authServer .. '/sp/' .. action .. '/?ReturnTo=' .. returnTo)

lua/feide.lua

@@ -72,8 +72,8 @@ function memcGetMultiple(hosta, hostb, port, key)
 end
 
 function memcache_server(index)
-   local domain = '.' .. ngx.var.namespace .. '.svc.cluster.local'
-   local memcache_service = ngx.var.memcache
+   local domain = '.' .. os.getenv('namespace') .. '.svc.cluster.local'
+   local memcache_service = os.getenv('memcache')
    return memcache_service .. '-' .. index .. '.' .. memcache_service .. domain
 end
 
@@ -122,7 +122,7 @@ clearHeaders()
 local feide_data = userData()
 
 if not feide_data then
-   if ngx.var.feide_mode == 'info' then
+   if os.getenv('feide_mode') == 'info' then
       return
    else
       local res = ngx.req.set_uri("/login", true)

nginx/site.conf

 server {
         listen 80 default_server;
-        server_name ${server_name};
         resolver 172.16.0.10;
+        set_by_lua $upstream_port 'return os.getenv("upstream_port")';
         location / {
                 proxy_pass http://localhost:${upstream_port};
-                set ${dollar}feide_mode '${feide_mode}';
-                set ${dollar}namespace '${namespace}';
-                set ${dollar}memcache '${memcache}';
                 rewrite_by_lua_file /usr/local/share/lua/5.1/feide.lua;
         }
 
@@ -15,10 +12,12 @@ server {
         }
 
         location /logout {
-                return 303  https://${auth_server}/sp/logout/?ReturnTo=https://${server_name}/;
+                set $action 'logout';
+                rewrite_by_lua_file /usr/local/share/lua/5.1/auth.lua;
         }
 
         location /login {
-                return 303  https://${auth_server}/sp/login/?ReturnTo=https://${server_name}/;
+                set $action 'login';
+                rewrite_by_lua_file /usr/local/share/lua/5.1/auth.lua;
         }
 }