Python: Add 'factory' support

src/nxt_conf_validation.c

@@ -841,6 +841,11 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_python_members[] = {
         .type       = NXT_CONF_VLDT_STRING,
         .validator  = nxt_conf_vldt_targets_exclusive,
         .u.string   = "callable",
+    }, {
+        .name       = nxt_string("factory"),
+        .type       = NXT_CONF_VLDT_BOOLEAN,
+        .validator  = nxt_conf_vldt_targets_exclusive,
+        .u.string   = "factory",
     }, {
         .name       = nxt_string("prefix"),
         .type       = NXT_CONF_VLDT_STRING,
@@ -865,6 +870,9 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_python_target_members[] = {
     }, {
         .name       = nxt_string("callable"),
         .type       = NXT_CONF_VLDT_STRING,
+    }, {
+        .name       = nxt_string("factory"),
+        .type       = NXT_CONF_VLDT_BOOLEAN,
     }, {
         .name       = nxt_string("prefix"),
         .type       = NXT_CONF_VLDT_STRING,
@@ -883,6 +891,9 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_python_notargets_members[] = {
     }, {
         .name       = nxt_string("callable"),
         .type       = NXT_CONF_VLDT_STRING,
+    }, {
+        .name       = nxt_string("factory"),
+        .type       = NXT_CONF_VLDT_BOOLEAN,
     }, {
         .name       = nxt_string("prefix"),
         .type       = NXT_CONF_VLDT_STRING,

src/python/nxt_python.c

@@ -403,11 +403,13 @@ nxt_python_set_target(nxt_task_t *task, nxt_python_target_t *target,
     char              *callable, *module_name;
     PyObject          *module, *obj;
     nxt_str_t         str;
+    nxt_bool_t        is_factory = 0;
     nxt_conf_value_t  *value;
 
     static nxt_str_t  module_str = nxt_string("module");
     static nxt_str_t  callable_str = nxt_string("callable");
     static nxt_str_t  prefix_str = nxt_string("prefix");
+    static nxt_str_t  factory_flag_str = nxt_string("factory");
 
     module = obj = NULL;
 
@@ -449,7 +451,30 @@ nxt_python_set_target(nxt_task_t *task, nxt_python_target_t *target,
         goto fail;
     }
 
-    if (nxt_slow_path(PyCallable_Check(obj) == 0)) {
+    value = nxt_conf_get_object_member(conf, &factory_flag_str, NULL);
+    if (value != NULL) {
+        is_factory = nxt_conf_get_boolean(value);
+    }
+
+    if (is_factory) {
+        if (nxt_slow_path(PyCallable_Check(obj) == 0)) {
+            nxt_alert(task,
+                      "factory \"%s\" in module \"%s\" "
+                      "can not be called to fetch callable",
+                      callable, module_name);
+            goto fail;
+        }
+
+        obj = PyObject_CallObject(obj, NULL);
+        if (nxt_slow_path(PyCallable_Check(obj) == 0)) {
+            nxt_alert(task,
+                      "factory \"%s\" in module \"%s\" "
+                      "did not return callable object",
+                      callable, module_name);
+            goto fail;
+        }
+
+    } else if (nxt_slow_path(PyCallable_Check(obj) == 0)) {
         nxt_alert(task, "\"%s\" in module \"%s\" is not a callable object",
                   callable, module_name);
         goto fail;

test/python/factory/wsgi.py

@@ -0,0 +1,23 @@
+def wsgi_a(env, start_response):
+    start_response("200", [("Content-Length", "1")])
+    return [b"1"]
+
+
+def wsgi_b(env, start_response):
+    start_response("200", [("Content-Length", "1")])
+    return [b"2"]
+
+
+def wsgi_a_factory():
+    return wsgi_a
+
+
+def wsgi_b_factory():
+    return wsgi_b
+
+
+wsgi_invalid_callable = None
+
+
+def wsgi_factory_returning_invalid_callable():
+    return wsgi_invalid_callable

test/test_python_factory.py

@@ -0,0 +1,140 @@
+from unit.applications.lang.python import ApplicationPython
+from unit.option import option
+
+prerequisites = {"modules": {"python": "all"}}
+
+client = ApplicationPython()
+
+
+def test_python_factory_targets():
+    python_dir = f"{option.test_dir}/python"
+
+    assert "success" in client.conf(
+        {
+            "listeners": {
+                "*:8080": {"pass": "applications/targets/1"},
+                "*:8081": {"pass": "applications/targets/2"},
+                "*:8082": {"pass": "applications/targets/factory-1"},
+                "*:8083": {"pass": "applications/targets/factory-2"},
+            },
+            "applications": {
+                "targets": {
+                    "type": client.get_application_type(),
+                    "working_directory": f"{python_dir}/factory/",
+                    "path": f"{python_dir}/factory/",
+                    "targets": {
+                        "1": {
+                            "module": "wsgi",
+                            "callable": "wsgi_a",
+                            "factory": False,
+                        },
+                        "2": {
+                            "module": "wsgi",
+                            "callable": "wsgi_b",
+                            "factory": False,
+                        },
+                        "factory-1": {
+                            "module": "wsgi",
+                            "callable": "wsgi_a_factory",
+                            "factory": True,
+                        },
+                        "factory-2": {
+                            "module": "wsgi",
+                            "callable": "wsgi_b_factory",
+                            "factory": True,
+                        },
+                    },
+                }
+            },
+        }
+    )
+
+    resp = client.get(port=8080)
+    assert resp["status"] == 200
+    assert resp["body"] == "1"
+
+    resp = client.get(port=8081)
+    assert resp["status"] == 200
+    assert resp["body"] == "2"
+
+    resp = client.get(port=8082)
+    assert resp["status"] == 200
+    assert resp["body"] == "1"
+
+    resp = client.get(port=8083)
+    assert resp["status"] == 200
+    assert resp["body"] == "2"
+
+
+def test_python_factory_without_targets():
+    python_dir = f"{option.test_dir}/python"
+
+    assert "success" in client.conf(
+        {
+            "listeners": {
+                "*:8080": {"pass": "applications/python-app-factory"},
+                "*:8081": {"pass": "applications/python-app"},
+            },
+            "applications": {
+                "python-app-factory": {
+                    "type": client.get_application_type(),
+                    "working_directory": f"{python_dir}/factory/",
+                    "path": f"{python_dir}/factory/",
+                    "module": "wsgi",
+                    "callable": "wsgi_a_factory",
+                    "factory": True,
+                },
+                "python-app": {
+                    "type": client.get_application_type(),
+                    "working_directory": f"{python_dir}/factory/",
+                    "path": f"{python_dir}/factory/",
+                    "module": "wsgi",
+                    "callable": "wsgi_b",
+                    "factory": False,
+                },
+            },
+        }
+    )
+
+    resp = client.get(port=8080)
+    assert resp["status"] == 200
+    assert resp["body"] == "1"
+
+    resp = client.get(port=8081)
+    assert resp["status"] == 200
+    assert resp["body"] == "2"
+
+
+def test_python_factory_invalid_callable_value(skip_alert):
+    skip_alert(
+        r"failed to apply new conf",
+        r"did not return callable object",
+        r"can not be called to fetch callable",
+    )
+    python_dir = f"{option.test_dir}/python"
+
+    invalid_callable_values = [
+        "wsgi_factory_returning_invalid_callable",
+        "wsgi_invalid_callable",
+    ]
+
+    for callable_value in invalid_callable_values:
+        assert "error" in client.conf(
+            {
+                "listeners": {"*:8080": {"pass": "applications/targets/1"}},
+                "applications": {
+                    "targets": {
+                        "type": client.get_application_type(),
+                        "working_directory": f"{python_dir}/factory/",
+                        "path": f"{python_dir}/factory/",
+                        "targets": {
+                            "1": {
+                                "module": "wsgi",
+                                "callable": callable_value,
+                                "factory": True,
+                            },
+                        },
+                    }
+                },
+            }
+        )