fix(core): respect custom proxy_access_log (#12073)

* fix(core): respect custom proxy_access_log

Kong now has a fixed access log format `kong_log_format`
that prevents customization and error on `kong start`.
Related to #11663.

If the `proxy_access_log` is not a valid pathname, then
replace `kong_log_format` with the custom value.

* fix(config): cover log_format name with hyphen

* fix(config): early error when access log format is not defined

* fix(config): discard warning or return nil

* chore(config): style and comments

* chore(*): comments

changelog/unreleased/kong/respect-custom-proxy_access_log.yml

@@ -0,0 +1,3 @@
+message: "respect custom `proxy_access_log`"
+type: bugfix
+scope: Configuration

kong/cmd/utils/prefix_handler.lua

@@ -239,7 +239,6 @@ local function compile_conf(kong_config, conf_template)
   -- computed config properties for templating
   local compile_env = {
     _escape = ">",
-    proxy_access_log_enabled = kong_config.proxy_access_log ~= "off",
     pairs = pairs,
     ipairs = ipairs,
     tostring = tostring,
@@ -248,6 +247,18 @@ local function compile_conf(kong_config, conf_template)
     }
   }
 
+  local kong_proxy_access_log = kong_config.proxy_access_log
+  if kong_proxy_access_log ~= "off" then
+    compile_env.proxy_access_log_enabled = true
+  end
+  if kong_proxy_access_log then
+    -- example: proxy_access_log = 'logs/some-file.log apigw_json'
+    local _, custom_format_name = string.match(kong_proxy_access_log, "^(%S+)%s(%S+)")
+    if custom_format_name then
+      compile_env.custom_proxy_access_log = true
+    end
+  end
+
   do
     local worker_rlimit_nofile_auto
     if kong_config.nginx_main_directives then

kong/templates/nginx_kong.lua

@@ -82,7 +82,11 @@ server {
     lua_kong_error_log_request_id $kong_request_id;
 
 > if proxy_access_log_enabled then
+>   if custom_proxy_access_log then
+    access_log ${{PROXY_ACCESS_LOG}};
+>   else
     access_log ${{PROXY_ACCESS_LOG}} kong_log_format;
+>   end
 > else
     access_log off;
 > end

spec/01-unit/04-prefix_handler_spec.lua

@@ -486,34 +486,72 @@ describe("NGINX conf compiler", function()
 
     describe("injected NGINX directives", function()
       it("injects proxy_access_log directive", function()
-        local conf = assert(conf_loader(nil, {
+        local conf, nginx_conf
+        conf = assert(conf_loader(nil, {
           proxy_access_log = "/dev/stdout",
           stream_listen = "0.0.0.0:9100",
           nginx_stream_tcp_nodelay = "on",
         }))
-        local nginx_conf = prefix_handler.compile_kong_conf(conf)
+        nginx_conf = prefix_handler.compile_kong_conf(conf)
         assert.matches("access_log%s/dev/stdout%skong_log_format;", nginx_conf)
-        local nginx_conf = prefix_handler.compile_kong_stream_conf(conf)
+        nginx_conf = prefix_handler.compile_kong_stream_conf(conf)
         assert.matches("access_log%slogs/access.log%sbasic;", nginx_conf)
 
-        local conf = assert(conf_loader(nil, {
+        conf = assert(conf_loader(nil, {
           proxy_access_log = "off",
           stream_listen = "0.0.0.0:9100",
           nginx_stream_tcp_nodelay = "on",
         }))
-        local nginx_conf = prefix_handler.compile_kong_conf(conf)
+        nginx_conf = prefix_handler.compile_kong_conf(conf)
         assert.matches("access_log%soff;", nginx_conf)
-        local nginx_conf = prefix_handler.compile_kong_stream_conf(conf)
+        nginx_conf = prefix_handler.compile_kong_stream_conf(conf)
         assert.matches("access_log%slogs/access.log%sbasic;", nginx_conf)
 
-        local conf = assert(conf_loader(nil, {
+        conf = assert(conf_loader(nil, {
+          proxy_access_log = "/dev/stdout apigw-json",
+          nginx_http_log_format = 'apigw-json "$kong_request_id"',
+          stream_listen = "0.0.0.0:9100",
+          nginx_stream_tcp_nodelay = "on",
+        }))
+        nginx_conf = prefix_handler.compile_kong_conf(conf)
+        assert.matches("access_log%s/dev/stdout%sapigw%-json;", nginx_conf)
+        nginx_conf = prefix_handler.compile_kong_stream_conf(conf)
+        assert.matches("access_log%slogs/access.log%sbasic;", nginx_conf)
+
+        -- configure an undefined log format will error
+        -- on kong start. This is expected
+        conf = assert(conf_loader(nil, {
+          proxy_access_log = "/dev/stdout not-exist",
+          nginx_http_log_format = 'apigw-json "$kong_request_id"',
+          stream_listen = "0.0.0.0:9100",
+          nginx_stream_tcp_nodelay = "on",
+        }))
+        nginx_conf = prefix_handler.compile_kong_conf(conf)
+        assert.matches("access_log%s/dev/stdout%snot%-exist;", nginx_conf)
+        nginx_conf = prefix_handler.compile_kong_stream_conf(conf)
+        assert.matches("access_log%slogs/access.log%sbasic;", nginx_conf)
+
+        conf = assert(conf_loader(nil, {
+          proxy_access_log = "/tmp/not-exist.log",
+          stream_listen = "0.0.0.0:9100",
+          nginx_stream_tcp_nodelay = "on",
+        }))
+        nginx_conf = prefix_handler.compile_kong_conf(conf)
+        assert.matches("access_log%s/tmp/not%-exist.log%skong_log_format;", nginx_conf)
+        nginx_conf = prefix_handler.compile_kong_stream_conf(conf)
+        assert.matches("access_log%slogs/access.log%sbasic;", nginx_conf)
+
+        conf = assert(conf_loader(nil, {
+          prefix = "servroot_tmp",
+          nginx_stream_log_format = "custom '$protocol $status'",
           proxy_stream_access_log = "/dev/stdout custom",
           stream_listen = "0.0.0.0:9100",
           nginx_stream_tcp_nodelay = "on",
         }))
-        local nginx_conf = prefix_handler.compile_kong_conf(conf)
+        assert(prefix_handler.prepare_prefix(conf))
+        nginx_conf = prefix_handler.compile_kong_conf(conf)
         assert.matches("access_log%slogs/access.log%skong_log_format;", nginx_conf)
-        local nginx_conf = prefix_handler.compile_kong_stream_conf(conf)
+        nginx_conf = prefix_handler.compile_kong_stream_conf(conf)
         assert.matches("access_log%s/dev/stdout%scustom;", nginx_conf)
       end)