Python: Added "prefix" to configuration.

This patch gives users the option to set a `"prefix"` attribute
for Python applications, either at the top level or for specific
`"target"`s. If the attribute is present, the value of `"prefix"`
must be a string beginning with `"/"`. If the value of the `"prefix"`
attribute is longer than 1 character and ends in `"/"`, the
trailing `"/"` is stripped.

The purpose of the `"prefix"` attribute is to set the `SCRIPT_NAME`
context value for WSGI applications and the `root_path` context
value for ASGI applications, allowing applications to properly route
requests regardless of the path that the server uses to expose the
application.

The context value is only set if the request's URL path begins with
the value of the `"prefix"` attribute. In all other cases, the
`SCRIPT_NAME` or `root_path` values are not set. In addition, for
WSGI applications, the value of `"prefix"` will be stripped from
the beginning of the request's URL path before it is sent to the
application.

Reviewed-by: Andrei Zeliankou <zelenkov@nginx.com>
Reviewed-by: Artem Konev <artem.konev@nginx.com>
Signed-off-by: Alejandro Colomar <alx@nginx.com>

17 files changed, 472 insertions, 23 deletions

diff --git a/docs/changes.xml b/docs/changes.xml
index 3a24f9ca..80febc54 100644
--- a/docs/changes.xml
+++ b/docs/changes.xml
@@ -111,6 +111,13 @@ report the regex status in configure summary.
 </para>
 </change>
 
+<change type="feature">
+<para>
+new "prefix" attribute in Python configurations to set WSGI SCRIPT_NAME
+and ASGI root-path variables.
+</para>
+</change>
+
 <change type="bugfix">
 <para>
 fix HTTP cookie parsing when the value contains an equals sign.
diff --git a/src/nxt_conf_validation.c b/src/nxt_conf_validation.c
index c6e63c25..bf8aa760 100644
--- a/src/nxt_conf_validation.c
+++ b/src/nxt_conf_validation.c
@@ -128,6 +128,8 @@ static nxt_int_t nxt_conf_vldt_python_path_element(nxt_conf_validation_t *vldt,
     nxt_conf_value_t *value);
 static nxt_int_t nxt_conf_vldt_python_protocol(nxt_conf_validation_t *vldt,
     nxt_conf_value_t *value, void *data);
+static nxt_int_t nxt_conf_vldt_python_prefix(nxt_conf_validation_t *vldt,
+    nxt_conf_value_t *value, void *data);
 static nxt_int_t nxt_conf_vldt_threads(nxt_conf_validation_t *vldt,
     nxt_conf_value_t *value, void *data);
 static nxt_int_t nxt_conf_vldt_thread_stack_size(nxt_conf_validation_t *vldt,
@@ -796,6 +798,11 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_python_members[] = {
         .validator  = nxt_conf_vldt_targets_exclusive,
         .u.string   = "callable",
     }, {
+        .name       = nxt_string("prefix"),
+        .type       = NXT_CONF_VLDT_STRING,
+        .validator  = nxt_conf_vldt_targets_exclusive,
+        .u.string   = "prefix",
+    }, {
         .name       = nxt_string("targets"),
         .type       = NXT_CONF_VLDT_OBJECT,
         .validator  = nxt_conf_vldt_targets,
@@ -814,6 +821,10 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_python_target_members[] = {
     }, {
         .name       = nxt_string("callable"),
         .type       = NXT_CONF_VLDT_STRING,
+    }, {
+        .name       = nxt_string("prefix"),
+        .type       = NXT_CONF_VLDT_STRING,
+        .validator  = nxt_conf_vldt_python_prefix,
     },
 
     NXT_CONF_VLDT_END
@@ -828,6 +839,10 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_python_notargets_members[] = {
     }, {
         .name       = nxt_string("callable"),
         .type       = NXT_CONF_VLDT_STRING,
+    }, {
+        .name       = nxt_string("prefix"),
+        .type       = NXT_CONF_VLDT_STRING,
+        .validator  = nxt_conf_vldt_python_prefix,
     },
 
     NXT_CONF_VLDT_NEXT(nxt_conf_vldt_python_common_members)
@@ -1871,6 +1886,28 @@ nxt_conf_vldt_python_protocol(nxt_conf_validation_t *vldt,
 
 
 static nxt_int_t
+nxt_conf_vldt_python_prefix(nxt_conf_validation_t *vldt,
+    nxt_conf_value_t *value, void *data)
+{
+    nxt_str_t  prefix;
+
+    if (nxt_conf_type(value) != NXT_CONF_STRING) {
+        return nxt_conf_vldt_error(vldt, "The \"prefix\" must be a string "
+                                   "beginning with \"/\".");
+    }
+
+    nxt_conf_get_string(value, &prefix);
+
+    if (!nxt_strchr_start(&prefix, '/')) {
+        return nxt_conf_vldt_error(vldt, "The \"prefix\" must be a string "
+                                   "beginning with \"/\".");
+    }
+
+    return NXT_OK;
+}
+
+
+static nxt_int_t
 nxt_conf_vldt_threads(nxt_conf_validation_t *vldt, nxt_conf_value_t *value,
     void *data)
 {
diff --git a/src/python/nxt_python.c b/src/python/nxt_python.c
index 8983815c..bdb04579 100644
--- a/src/python/nxt_python.c
+++ b/src/python/nxt_python.c
@@ -30,6 +30,8 @@ static nxt_int_t nxt_python_start(nxt_task_t *task,
     nxt_process_data_t *data);
 static nxt_int_t nxt_python_set_target(nxt_task_t *task,
     nxt_python_target_t *target, nxt_conf_value_t *conf);
+nxt_inline nxt_int_t nxt_python_set_prefix(nxt_task_t *task,
+    nxt_python_target_t *target, nxt_conf_value_t *value);
 static nxt_int_t nxt_python_set_path(nxt_task_t *task, nxt_conf_value_t *value);
 static int nxt_python_init_threads(nxt_python_app_conf_t *c);
 static int nxt_python_ready_handler(nxt_unit_ctx_t *ctx);
@@ -389,6 +391,7 @@ nxt_python_set_target(nxt_task_t *task, nxt_python_target_t *target,
 
     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");
 
     module = obj = NULL;
 
@@ -436,6 +439,11 @@ nxt_python_set_target(nxt_task_t *task, nxt_python_target_t *target,
         goto fail;
     }
 
+    value = nxt_conf_get_object_member(conf, &prefix_str, NULL);
+    if (nxt_slow_path(nxt_python_set_prefix(task, target, value) != NXT_OK)) {
+        goto fail;
+    }
+
     target->application = obj;
     obj = NULL;
 
@@ -453,6 +461,48 @@ fail:
 }
 
 
+nxt_inline nxt_int_t
+nxt_python_set_prefix(nxt_task_t *task, nxt_python_target_t *target,
+    nxt_conf_value_t *value)
+{
+    u_char            *prefix;
+    nxt_str_t         str;
+
+    if (value == NULL) {
+        return NXT_OK;
+    }
+
+    nxt_conf_get_string(value, &str);
+
+    if (str.length == 0) {
+        return NXT_OK;
+    }
+
+    if (str.start[str.length - 1] == '/') {
+        str.length--;
+    }
+    target->prefix.length = str.length;
+    prefix = nxt_malloc(str.length);
+    if (nxt_slow_path(prefix == NULL)) {
+        nxt_alert(task, "Failed to allocate target prefix string");
+        return NXT_ERROR;
+    }
+
+    target->py_prefix = PyString_FromStringAndSize((char *)str.start,
+                                                    str.length);
+    if (nxt_slow_path(target->py_prefix == NULL)) {
+        nxt_free(prefix);
+        nxt_alert(task, "Python failed to allocate target prefix "
+                        "string");
+        return NXT_ERROR;
+    }
+    nxt_memcpy(prefix, str.start, str.length);
+    target->prefix.start = prefix;
+
+    return NXT_OK;
+}
+
+
 static nxt_int_t
 nxt_python_set_path(nxt_task_t *task, nxt_conf_value_t *value)
 {
@@ -730,7 +780,8 @@ nxt_python_done_strings(nxt_python_string_t *pstr)
 static void
 nxt_python_atexit(void)
 {
-    nxt_int_t  i;
+    nxt_int_t            i;
+    nxt_python_target_t  *target;
 
     if (nxt_py_proto.done != NULL) {
         nxt_py_proto.done();
@@ -740,7 +791,12 @@ nxt_python_atexit(void)
 
     if (nxt_py_targets != NULL) {
         for (i = 0; i < nxt_py_targets->count; i++) {
-            Py_XDECREF(nxt_py_targets->target[i].application);
+            target = &nxt_py_targets->target[i];
+
+            Py_XDECREF(target->application);
+            Py_XDECREF(target->py_prefix);
+
+            nxt_free(target->prefix.start);
         }
 
         nxt_unit_free(NULL, nxt_py_targets);
diff --git a/src/python/nxt_python.h b/src/python/nxt_python.h
index eddb1cfc..37e6265e 100644
--- a/src/python/nxt_python.h
+++ b/src/python/nxt_python.h
@@ -40,6 +40,8 @@
 
 typedef struct {
     PyObject    *application;
+    PyObject    *py_prefix;
+    nxt_str_t   prefix;
     nxt_bool_t  asgi_legacy;
 } nxt_python_target_t;
 
diff --git a/src/python/nxt_python_asgi.c b/src/python/nxt_python_asgi.c
index 256bcdcc..587a17cf 100644
--- a/src/python/nxt_python_asgi.c
+++ b/src/python/nxt_python_asgi.c
@@ -27,7 +27,8 @@ static void nxt_py_asgi_remove_reader(nxt_unit_ctx_t *ctx,
 static void nxt_py_asgi_request_handler(nxt_unit_request_info_t *req);
 static void nxt_py_asgi_close_handler(nxt_unit_request_info_t *req);
 
-static PyObject *nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req);
+static PyObject *nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req,
+    nxt_python_target_t *app_target);
 static PyObject *nxt_py_asgi_create_address(nxt_unit_sptr_t *sptr, uint8_t len,
     uint16_t port);
 static PyObject *nxt_py_asgi_create_ip_address(nxt_unit_sptr_t *sptr,
@@ -455,16 +456,16 @@ nxt_py_asgi_request_handler(nxt_unit_request_info_t *req)
         goto release_send;
     }
 
-    scope = nxt_py_asgi_create_http_scope(req);
+    req->data = asgi;
+    target = &nxt_py_targets->target[req->request->app_target];
+
+    scope = nxt_py_asgi_create_http_scope(req, target);
     if (nxt_slow_path(scope == NULL)) {
         nxt_unit_request_done(req, NXT_UNIT_ERROR);
 
         goto release_done;
     }
 
-    req->data = asgi;
-    target = &nxt_py_targets->target[req->request->app_target];
-
     if (!target->asgi_legacy) {
         nxt_unit_req_debug(req, "Python call ASGI 3.0 application");
 
@@ -573,12 +574,14 @@ nxt_py_asgi_close_handler(nxt_unit_request_info_t *req)
 
 
 static PyObject *
-nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req)
+nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req,
+    nxt_python_target_t *app_target)
 {
     char                *p, *target, *query;
-    uint32_t            target_length, i;
+    uint32_t            target_length, i, path_length;
     PyObject            *scope, *v, *type, *scheme;
     PyObject            *headers, *header;
+    nxt_str_t           prefix;
     nxt_unit_field_t    *f;
     nxt_unit_request_t  *r;
 
@@ -612,6 +615,17 @@ nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req)
         return NULL;
     }
 
+    prefix = app_target->prefix;
+    path_length = r->path_length;
+    p = nxt_unit_sptr_get(&r->path);
+    if (prefix.length > 0
+        && ((path_length > prefix.length && p[prefix.length] == '/')
+            || path_length == prefix.length)
+        && memcmp(prefix.start, p, prefix.length) == 0)
+    {
+        SET_ITEM(scope, root_path, app_target->py_prefix);
+    }
+
     p = nxt_unit_sptr_get(&r->version);
     SET_ITEM(scope, http_version, p[7] == '1' ? nxt_py_1_1_str
                                               : nxt_py_1_0_str)
diff --git a/src/python/nxt_python_asgi_str.c b/src/python/nxt_python_asgi_str.c
index 34422973..7171d52b 100644
--- a/src/python/nxt_python_asgi_str.c
+++ b/src/python/nxt_python_asgi_str.c
@@ -99,7 +99,7 @@ static nxt_python_string_t nxt_py_asgi_strings[] = {
     { nxt_string("query_string"), &nxt_py_query_string_str },
     { nxt_string("raw_path"), &nxt_py_raw_path_str },
     { nxt_string("result"), &nxt_py_result_str },
-    { nxt_string("root_path"), &nxt_py_root_path_str }, // not used
+    { nxt_string("root_path"), &nxt_py_root_path_str },
     { nxt_string("scheme"), &nxt_py_scheme_str },
     { nxt_string("server"), &nxt_py_server_str },
     { nxt_string("set_exception"), &nxt_py_set_exception_str },
diff --git a/src/python/nxt_python_wsgi.c b/src/python/nxt_python_wsgi.c
index 34afd9a9..dfb31509 100644
--- a/src/python/nxt_python_wsgi.c
+++ b/src/python/nxt_python_wsgi.c
@@ -60,7 +60,8 @@ static void nxt_python_request_handler(nxt_unit_request_info_t *req);
 
 static PyObject *nxt_python_create_environ(nxt_python_app_conf_t *c);
 static PyObject *nxt_python_copy_environ(nxt_unit_request_info_t *req);
-static PyObject *nxt_python_get_environ(nxt_python_ctx_t *pctx);
+static PyObject *nxt_python_get_environ(nxt_python_ctx_t *pctx,
+    nxt_python_target_t *app_target);
 static int nxt_python_add_sptr(nxt_python_ctx_t *pctx, PyObject *name,
     nxt_unit_sptr_t *sptr, uint32_t size);
 static int nxt_python_add_char(nxt_python_ctx_t *pctx, PyObject *name,
@@ -141,6 +142,7 @@ static PyObject  *nxt_py_query_string_str;
 static PyObject  *nxt_py_remote_addr_str;
 static PyObject  *nxt_py_request_method_str;
 static PyObject  *nxt_py_request_uri_str;
+static PyObject  *nxt_py_script_name_str;
 static PyObject  *nxt_py_server_addr_str;
 static PyObject  *nxt_py_server_name_str;
 static PyObject  *nxt_py_server_port_str;
@@ -160,6 +162,7 @@ static nxt_python_string_t nxt_python_strings[] = {
     { nxt_string("REMOTE_ADDR"), &nxt_py_remote_addr_str },
     { nxt_string("REQUEST_METHOD"), &nxt_py_request_method_str },
     { nxt_string("REQUEST_URI"), &nxt_py_request_uri_str },
+    { nxt_string("SCRIPT_NAME"), &nxt_py_script_name_str },
     { nxt_string("SERVER_ADDR"), &nxt_py_server_addr_str },
     { nxt_string("SERVER_NAME"), &nxt_py_server_name_str },
     { nxt_string("SERVER_PORT"), &nxt_py_server_port_str },
@@ -304,11 +307,12 @@ nxt_python_wsgi_done(void)
 static void
 nxt_python_request_handler(nxt_unit_request_info_t *req)
 {
-    int               rc;
-    PyObject          *environ, *args, *response, *iterator, *item;
-    PyObject          *close, *result, *application;
-    nxt_bool_t        prepare_environ;
-    nxt_python_ctx_t  *pctx;
+    int                  rc;
+    PyObject             *environ, *args, *response, *iterator, *item;
+    PyObject             *close, *result;
+    nxt_bool_t           prepare_environ;
+    nxt_python_ctx_t     *pctx;
+    nxt_python_target_t  *target;
 
     pctx = req->ctx->data;
 
@@ -331,7 +335,9 @@ nxt_python_request_handler(nxt_unit_request_info_t *req)
 
     prepare_environ = 1;
 
-    environ = nxt_python_get_environ(pctx);
+    target = &nxt_py_targets->target[req->request->app_target];
+
+    environ = nxt_python_get_environ(pctx, target);
     if (nxt_slow_path(environ == NULL)) {
         rc = NXT_UNIT_ERROR;
         goto done;
@@ -352,8 +358,7 @@ nxt_python_request_handler(nxt_unit_request_info_t *req)
     Py_INCREF(pctx->start_resp);
     PyTuple_SET_ITEM(args, 1, pctx->start_resp);
 
-    application = nxt_py_targets->target[req->request->app_target].application;
-    response = PyObject_CallObject(application, args);
+    response = PyObject_CallObject(target->application, args);
 
     Py_DECREF(args);
 
@@ -584,11 +589,14 @@ nxt_python_copy_environ(nxt_unit_request_info_t *req)
 
 
 static PyObject *
-nxt_python_get_environ(nxt_python_ctx_t *pctx)
+nxt_python_get_environ(nxt_python_ctx_t *pctx,
+    nxt_python_target_t *app_target)
 {
     int                 rc;
-    uint32_t            i, j, vl;
+    char                *path;
+    uint32_t            i, j, vl, path_length;
     PyObject            *environ;
+    nxt_str_t           prefix;
     nxt_unit_field_t    *f, *f2;
     nxt_unit_request_t  *r;
 
@@ -608,8 +616,23 @@ nxt_python_get_environ(nxt_python_ctx_t *pctx)
                            r->target_length));
     RC(nxt_python_add_sptr(pctx, nxt_py_query_string_str, &r->query,
                            r->query_length));
-    RC(nxt_python_add_sptr(pctx, nxt_py_path_info_str, &r->path,
-                           r->path_length));
+
+    prefix = app_target->prefix;
+    path_length = r->path_length;
+    path = nxt_unit_sptr_get(&r->path);
+    if (prefix.length > 0
+        && ((path_length > prefix.length && path[prefix.length] == '/')
+            || path_length == prefix.length)
+        && memcmp(prefix.start, path, prefix.length) == 0)
+    {
+        RC(nxt_python_add_py_string(pctx, nxt_py_script_name_str,
+                                    app_target->py_prefix));
+
+        path += prefix.length;
+        path_length -= prefix.length;
+    }
+
+    RC(nxt_python_add_char(pctx, nxt_py_path_info_str, path, path_length));
 
     RC(nxt_python_add_sptr(pctx, nxt_py_remote_addr_str, &r->remote,
                            r->remote_length));
diff --git a/test/python/prefix/asgi.py b/test/python/prefix/asgi.py
new file mode 100644
index 00000000..234f084f
--- /dev/null
+++ b/test/python/prefix/asgi.py
@@ -0,0 +1,15 @@
+async def application(scope, receive, send):
+    assert scope['type'] == 'http'
+
+    await send(
+        {
+            'type': 'http.response.start',
+            'status': 200,
+            'headers': [
+                (b'content-length', b'0'),
+                (b'prefix', scope.get('root_path', 'NULL').encode()),
+            ],
+        }
+    )
+
+    await send({'type': 'http.response.body', 'body': b''})
diff --git a/test/python/prefix/wsgi.py b/test/python/prefix/wsgi.py
new file mode 100644
index 00000000..83b58c9a
--- /dev/null
+++ b/test/python/prefix/wsgi.py
@@ -0,0 +1,10 @@
+def application(environ, start_response):
+    start_response(
+        '200',
+        [
+            ('Content-Length', '0'),
+            ('Script-Name', environ.get('SCRIPT_NAME', 'NULL')),
+            ('Path-Info', environ['PATH_INFO']),
+        ],
+    )
+    return []
diff --git a/test/python/targets/asgi.py b/test/python/targets/asgi.py
index b51f3964..749ec5b1 100644
--- a/test/python/targets/asgi.py
+++ b/test/python/targets/asgi.py
@@ -22,6 +22,23 @@ async def application_200(scope, receive, send):
     )
 
 
+async def application_prefix(scope, receive, send):
+    assert scope['type'] == 'http'
+
+    await send(
+        {
+            'type': 'http.response.start',
+            'status': 200,
+            'headers': [
+                (b'content-length', b'0'),
+                (b'prefix', scope.get('root_path', 'NULL').encode()),
+            ],
+        }
+    )
+
+    await send({'type': 'http.response.body', 'body': b''})
+
+
 def legacy_application_200(scope):
     assert scope['type'] == 'http'
 
diff --git a/test/python/targets/wsgi.py b/test/python/targets/wsgi.py
index fa17ab87..3f3d4b27 100644
--- a/test/python/targets/wsgi.py
+++ b/test/python/targets/wsgi.py
@@ -6,3 +6,12 @@ def wsgi_target_a(env, start_response):
 def wsgi_target_b(env, start_response):
     start_response('200', [('Content-Length', '1')])
     return [b'2']
+
+
+def wsgi_target_prefix(env, start_response):
+    data = u'%s %s' % (
+        env.get('SCRIPT_NAME', 'No Script Name'),
+        env['PATH_INFO'],
+    )
+    start_response('200', [('Content-Length', '%d' % len(data))])
+    return [data.encode('utf-8')]
diff --git a/test/test_asgi_application.py b/test/test_asgi_application.py
index 7f5f1578..121a2fbc 100644
--- a/test/test_asgi_application.py
+++ b/test/test_asgi_application.py
@@ -79,6 +79,43 @@ custom-header: BLAH
             resp['headers']['query-string'] == 'var1=val1&var2=val2'
         ), 'query-string header'
 
+    def test_asgi_application_prefix(self):
+        self.load('prefix', prefix='/api/rest')
+
+        def set_prefix(prefix):
+            self.conf('"' + prefix + '"', 'applications/prefix/prefix')
+
+        def check_prefix(url, prefix):
+            resp = self.get(url=url)
+            assert resp['status'] == 200
+            assert resp['headers']['prefix'] == prefix
+
+        check_prefix('/ap', 'NULL')
+        check_prefix('/api', 'NULL')
+        check_prefix('/api/', 'NULL')
+        check_prefix('/api/res', 'NULL')
+        check_prefix('/api/restful', 'NULL')
+        check_prefix('/api/rest', '/api/rest')
+        check_prefix('/api/rest/', '/api/rest')
+        check_prefix('/api/rest/get', '/api/rest')
+        check_prefix('/api/rest/get/blah', '/api/rest')
+
+        set_prefix('/api/rest/')
+        check_prefix('/api/rest', '/api/rest')
+        check_prefix('/api/restful', 'NULL')
+        check_prefix('/api/rest/', '/api/rest')
+        check_prefix('/api/rest/blah', '/api/rest')
+
+        set_prefix('/app')
+        check_prefix('/ap', 'NULL')
+        check_prefix('/app', '/app')
+        check_prefix('/app/', '/app')
+        check_prefix('/application/', 'NULL')
+
+        set_prefix('/')
+        check_prefix('/', 'NULL')
+        check_prefix('/app', 'NULL')
+
     def test_asgi_application_query_string_space(self):
         self.load('query_string')
 
diff --git a/test/test_asgi_targets.py b/test/test_asgi_targets.py
index c1e345ef..84d7b3b0 100644
--- a/test/test_asgi_targets.py
+++ b/test/test_asgi_targets.py
@@ -90,3 +90,48 @@ class TestASGITargets(TestApplicationPython):
         )
 
         assert self.get(url='/1')['status'] != 200
+
+    def test_asgi_targets_prefix(self):
+        self.conf_targets(
+            {
+                "1": {
+                    "module": "asgi",
+                    "callable": "application_prefix",
+                    "prefix": "/1/",
+                },
+                "2": {
+                    "module": "asgi",
+                    "callable": "application_prefix",
+                    "prefix": "/api",
+                },
+            }
+        )
+        self.conf(
+            [
+                {
+                    "match": {"uri": "/1*"},
+                    "action": {"pass": "applications/targets/1"},
+                },
+                {
+                    "match": {"uri": "*"},
+                    "action": {"pass": "applications/targets/2"},
+                },
+            ],
+            "routes",
+        )
+
+        def check_prefix(url, prefix):
+            resp = self.get(url=url)
+            assert resp['status'] == 200
+            assert resp['headers']['prefix'] == prefix
+
+        check_prefix('/1', '/1')
+        check_prefix('/11', 'NULL')
+        check_prefix('/1/', '/1')
+        check_prefix('/', 'NULL')
+        check_prefix('/ap', 'NULL')
+        check_prefix('/api', '/api')
+        check_prefix('/api/', '/api')
+        check_prefix('/api/test/', '/api')
+        check_prefix('/apis', 'NULL')
+        check_prefix('/apis/', 'NULL')
diff --git a/test/test_configuration.py b/test/test_configuration.py
index 7c612db0..9c27222c 100644
--- a/test/test_configuration.py
+++ b/test/test_configuration.py
@@ -318,6 +318,92 @@ class TestConfiguration(TestControl):
 
         assert 'success' in self.conf(conf)
 
+    def test_json_application_python_prefix(self):
+        conf = {
+            "applications": {
+                "sub-app": {
+                    "type": "python",
+                    "processes": {"spare": 0},
+                    "path": "/app",
+                    "module": "wsgi",
+                    "prefix": "/app",
+                }
+            },
+            "listeners": {"*:7080": {"pass": "routes"}},
+            "routes": [
+                {
+                    "match": {"uri": "/app/*"},
+                    "action": {"pass": "applications/sub-app"},
+                }
+            ],
+        }
+
+        assert 'success' in self.conf(conf)
+
+    def test_json_application_prefix_target(self):
+        conf = {
+            "applications": {
+                "sub-app": {
+                    "type": "python",
+                    "processes": {"spare": 0},
+                    "path": "/app",
+                    "targets": {
+                        "foo": {"module": "foo.wsgi", "prefix": "/app"},
+                        "bar": {
+                            "module": "bar.wsgi",
+                            "callable": "bar",
+                            "prefix": "/api",
+                        },
+                    },
+                }
+            },
+            "listeners": {"*:7080": {"pass": "routes"}},
+            "routes": [
+                {
+                    "match": {"uri": "/app/*"},
+                    "action": {"pass": "applications/sub-app/foo"},
+                },
+                {
+                    "match": {"uri": "/api/*"},
+                    "action": {"pass": "applications/sub-app/bar"},
+                },
+            ],
+        }
+
+        assert 'success' in self.conf(conf)
+
+    def test_json_application_invalid_python_prefix(self):
+        conf = {
+            "applications": {
+                "sub-app": {
+                    "type": "python",
+                    "processes": {"spare": 0},
+                    "path": "/app",
+                    "module": "wsgi",
+                    "prefix": "app",
+                }
+            },
+            "listeners": {"*:7080": {"pass": "applications/sub-app"}},
+        }
+
+        assert 'error' in self.conf(conf)
+
+    def test_json_application_empty_python_prefix(self):
+        conf = {
+            "applications": {
+                "sub-app": {
+                    "type": "python",
+                    "processes": {"spare": 0},
+                    "path": "/app",
+                    "module": "wsgi",
+                    "prefix": "",
+                }
+            },
+            "listeners": {"*:7080": {"pass": "applications/sub-app"}},
+        }
+
+        assert 'error' in self.conf(conf)
+
     def test_json_application_many2(self):
         conf = {
             "applications": {
diff --git a/test/test_python_application.py b/test/test_python_application.py
index 946d2118..c9483b6a 100644
--- a/test/test_python_application.py
+++ b/test/test_python_application.py
@@ -94,6 +94,44 @@ custom-header: BLAH
             resp['headers']['Query-String'] == ' var1= val1 & var2=val2'
         ), 'Query-String space 4'
 
+    def test_python_application_prefix(self):
+        self.load('prefix', prefix='/api/rest')
+
+        def set_prefix(prefix):
+            self.conf('"' + prefix + '"', 'applications/prefix/prefix')
+
+        def check_prefix(url, script_name, path_info):
+            resp = self.get(url=url)
+            assert resp['status'] == 200
+            assert resp['headers']['Script-Name'] == script_name
+            assert resp['headers']['Path-Info'] == path_info
+
+        check_prefix('/ap', 'NULL', '/ap')
+        check_prefix('/api', 'NULL', '/api')
+        check_prefix('/api/', 'NULL', '/api/')
+        check_prefix('/api/res', 'NULL', '/api/res')
+        check_prefix('/api/restful', 'NULL', '/api/restful')
+        check_prefix('/api/rest', '/api/rest', '')
+        check_prefix('/api/rest/', '/api/rest', '/')
+        check_prefix('/api/rest/get', '/api/rest', '/get')
+        check_prefix('/api/rest/get/blah', '/api/rest', '/get/blah')
+
+        set_prefix('/api/rest/')
+        check_prefix('/api/rest', '/api/rest', '')
+        check_prefix('/api/restful', 'NULL', '/api/restful')
+        check_prefix('/api/rest/', '/api/rest', '/')
+        check_prefix('/api/rest/blah', '/api/rest', '/blah')
+
+        set_prefix('/app')
+        check_prefix('/ap', 'NULL', '/ap')
+        check_prefix('/app', '/app', '')
+        check_prefix('/app/', '/app', '/')
+        check_prefix('/application/', 'NULL', '/application/')
+
+        set_prefix('/')
+        check_prefix('/', 'NULL', '/')
+        check_prefix('/app', 'NULL', '/app')
+
     def test_python_application_query_string_empty(self):
         self.load('query_string')
 
diff --git a/test/test_python_targets.py b/test/test_python_targets.py
index 8e9ecb87..ae271b5f 100644
--- a/test/test_python_targets.py
+++ b/test/test_python_targets.py
@@ -47,3 +47,55 @@ class TestPythonTargets(TestApplicationPython):
         resp = self.get(url='/2')
         assert resp['status'] == 200
         assert resp['body'] == '2'
+
+    def test_python_targets_prefix(self):
+        assert 'success' in self.conf(
+            {
+                "listeners": {"*:7080": {"pass": "routes"}},
+                "routes": [
+                    {
+                        "match": {"uri": ["/app*"]},
+                        "action": {"pass": "applications/targets/app"},
+                    },
+                    {
+                        "match": {"uri": "*"},
+                        "action": {"pass": "applications/targets/catchall"},
+                    },
+                ],
+                "applications": {
+                    "targets": {
+                        "type": "python",
+                        "working_directory": option.test_dir
+                        + "/python/targets/",
+                        "path": option.test_dir + '/python/targets/',
+                        "protocol": "wsgi",
+                        "targets": {
+                            "app": {
+                                "module": "wsgi",
+                                "callable": "wsgi_target_prefix",
+                                "prefix": "/app/",
+                            },
+                            "catchall": {
+                                "module": "wsgi",
+                                "callable": "wsgi_target_prefix",
+                                "prefix": "/api",
+                            },
+                        },
+                    }
+                },
+            }
+        )
+
+        def check_prefix(url, body):
+            resp = self.get(url=url)
+            assert resp['status'] == 200
+            assert resp['body'] == body
+
+        check_prefix('/app', '/app ')
+        check_prefix('/app/', '/app /')
+        check_prefix('/app/rest/user/', '/app /rest/user/')
+        check_prefix('/catchall', 'No Script Name /catchall')
+        check_prefix('/api', '/api ')
+        check_prefix('/api/', '/api /')
+        check_prefix('/apis', 'No Script Name /apis')
+        check_prefix('/api/users/', '/api /users/')
diff --git a/test/unit/applications/lang/python.py b/test/unit/applications/lang/python.py
index 1e38f3fa..3768cf07 100644
--- a/test/unit/applications/lang/python.py
+++ b/test/unit/applications/lang/python.py
@@ -50,6 +50,7 @@ class TestApplicationPython(TestApplicationProto):
             'protocol',
             'targets',
             'threads',
+            'prefix',
         ):
             if attr in kwargs:
                 app[attr] = kwargs.pop(attr)