Python: app module callable name configuration.

Now it is possible to specify the name of the application callable using
optional parameter 'callable'.  Default value is 'application'.

This closes #290 issue on GitHub.

src/nxt_application.h

@@ -50,6 +50,7 @@ typedef struct {
     char       *home;
     nxt_str_t  path;
     nxt_str_t  module;
+    char       *callable;
 } nxt_python_app_conf_t;
 
 

src/nxt_conf_validation.c

@@ -773,6 +773,12 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_python_members[] = {
       NULL,
       NULL },
 
+    { nxt_string("callable"),
+      NXT_CONF_VLDT_STRING,
+      0,
+      NULL,
+      NULL },
+
     NXT_CONF_VLDT_NEXT(&nxt_conf_vldt_common_members)
 };
 

src/nxt_main_process.c

@@ -191,6 +191,12 @@ static nxt_conf_map_t  nxt_python_app_conf[] = {
         NXT_CONF_MAP_STR,
         offsetof(nxt_common_app_conf_t, u.python.module),
     },
+
+    {
+        nxt_string("callable"),
+        NXT_CONF_MAP_CSTRZ,
+        offsetof(nxt_common_app_conf_t, u.python.callable),
+    },
 };
 
 

src/python/nxt_python.c

@@ -60,6 +60,7 @@ nxt_python_start(nxt_task_t *task, nxt_process_data_t *data)
     char                   *nxt_py_module;
     size_t                 len;
     PyObject               *obj, *pypath, *module;
+    const char             *callable;
     nxt_unit_ctx_t         *unit_ctx;
     nxt_unit_init_t        python_init;
     nxt_common_app_conf_t  *app_conf;
@@ -199,16 +200,18 @@ nxt_python_start(nxt_task_t *task, nxt_process_data_t *data)
         goto fail;
     }
 
-    obj = PyDict_GetItemString(PyModule_GetDict(module), "application");
+    callable = (c->callable != NULL) ? c->callable : "application";
+
+    obj = PyDict_GetItemString(PyModule_GetDict(module), callable);
     if (nxt_slow_path(obj == NULL)) {
-        nxt_alert(task, "Python failed to get \"application\" "
-                  "from module \"%s\"", nxt_py_module);
+        nxt_alert(task, "Python failed to get \"%s\" "
+                  "from module \"%s\"", callable, nxt_py_module);
         goto fail;
     }
 
     if (nxt_slow_path(PyCallable_Check(obj) == 0)) {
-        nxt_alert(task, "\"application\" in module \"%s\" "
-                  "is not a callable object", nxt_py_module);
+        nxt_alert(task, "\"%s\" in module \"%s\" "
+                  "is not a callable object", callable, nxt_py_module);
         goto fail;
     }