From c2a24ae0c60f06328664273b15f58671ae373fed Mon Sep 17 00:00:00 2001
From: Bruce Martin <bruce@chanzuckerberg.com>
Date: Wed, 1 Apr 2020 16:43:43 -0600
Subject: [PATCH] add cache control headers (#1333)

* add cache control headers

* add config param check
---
 server/app/app.py               | 42 +++++++++++++++++++++++++++++++++
 server/common/app_config.py     |  2 ++
 server/common/default_config.py |  1 +
 3 files changed, 45 insertions(+)

diff --git a/server/app/app.py b/server/app/app.py
index fe7f1e1e..39d27a67 100644
--- a/server/app/app.py
+++ b/server/app/app.py
@@ -20,7 +20,39 @@ from functools import wraps
 webbp = Blueprint("webapp", "server.common.web", template_folder="templates")
 
 
+def _cache_control(always, **cache_kwargs):
+    """
+    Used to easily manage cache control headers on responses.
+    See Werkzeug for attributes that can be set, eg, no_cache, private, max_age, etc.
+    https://werkzeug.palletsprojects.com/en/1.0.x/datastructures/#werkzeug.datastructures.ResponseCacheControl
+    """
+    def inner_cache_control(f):
+        @wraps(f)
+        def wrapper(*args, **kwargs):
+            response = make_response(f(*args, **kwargs))
+            if not always and not current_app.app_config.server__generate_cache_control_headers:
+                return response
+            if response.status_code >= 400:
+                return response
+            for k, v in cache_kwargs.items():
+                setattr(response.cache_control, k, v)
+            return response
+        return wrapper
+    return inner_cache_control
+
+
+def cache_control(**cache_kwargs):
+    """ configu driven """
+    return _cache_control(False, **cache_kwargs)
+
+
+def cache_control_always(**cache_kwargs):
+    """ always generate headers, regardless of the config """
+    return _cache_control(True, **cache_kwargs)
+
+
 @webbp.route("/", methods=["GET"])
+@cache_control(public=True, max_age=3600)
 def dataset_index(dataset=None):
     config = current_app.app_config
     if dataset is None:
@@ -52,6 +84,7 @@ def favicon():
 
 
 @webbp.route("/health", methods=["GET"])
+@cache_control_always(no_cache=True)
 def health():
     config = current_app.app_config
     return health_check(config)
@@ -132,50 +165,59 @@ def dataroot_index():
 
 
 class SchemaAPI(Resource):
+    @cache_control(public=True, max_age=3600)
     @rest_get_data_adaptor
     def get(self, data_adaptor):
         return common_rest.schema_get(data_adaptor, current_app.annotations)
 
 
 class ConfigAPI(Resource):
+    @cache_control(public=True, max_age=3600)
     @rest_get_data_adaptor
     def get(self, data_adaptor):
         return common_rest.config_get(current_app.app_config, data_adaptor, current_app.annotations)
 
 
 class AnnotationsObsAPI(Resource):
+    @cache_control(public=True, max_age=3600)
     @rest_get_data_adaptor
     def get(self, data_adaptor):
         return common_rest.annotations_obs_get(request, data_adaptor, current_app.annotations)
 
+    @cache_control(no_cache=True)
     @rest_get_data_adaptor
     def put(self, data_adaptor):
         return common_rest.annotations_obs_put(request, data_adaptor, current_app.annotations)
 
 
 class AnnotationsVarAPI(Resource):
+    @cache_control(public=True, max_age=3600)
     @rest_get_data_adaptor
     def get(self, data_adaptor):
         return common_rest.annotations_var_get(request, data_adaptor, current_app.annotations)
 
 
 class DataVarAPI(Resource):
+    @cache_control(no_cache=True)
     @rest_get_data_adaptor
     def put(self, data_adaptor):
         return common_rest.data_var_put(request, data_adaptor)
 
 
 class DiffExpObsAPI(Resource):
+    @cache_control(no_cache=True)
     @rest_get_data_adaptor
     def post(self, data_adaptor):
         return common_rest.diffexp_obs_post(request, data_adaptor)
 
 
 class LayoutObsAPI(Resource):
+    @cache_control(public=True, max_age=3600)
     @rest_get_data_adaptor
     def get(self, data_adaptor):
         return common_rest.layout_obs_get(request, data_adaptor)
 
+    @cache_control(no_cache=True)
     @rest_get_data_adaptor
     def put(self, data_adaptor):
         return common_rest.layout_obs_put(request, data_adaptor)
diff --git a/server/common/app_config.py b/server/common/app_config.py
index cdd0d459..572932cc 100644
--- a/server/common/app_config.py
+++ b/server/common/app_config.py
@@ -66,6 +66,7 @@ class AppConfig(object):
             self.server__about_legal_privacy = dc["server"]["about_legal_privacy"]
             self.server__force_https = dc["server"]["force_https"]
             self.server__flask_secret_key = dc["server"]["flask_secret_key"]
+            self.server__generate_cache_control_headers = dc["server"]["generate_cache_control_headers"]
 
             self.multi_dataset__dataroot = dc["multi_dataset"]["dataroot"]
             self.multi_dataset__index = dc["multi_dataset"]["index"]
@@ -197,6 +198,7 @@ class AppConfig(object):
         self.__check_attr("server__open_browser", bool)
         self.__check_attr("server__force_https", bool)
         self.__check_attr("server__flask_secret_key", (type(None), str))
+        self.__check_attr("server__generate_cache_control_headers", bool)
 
         if self.server__port:
             if not is_port_available(self.server__host, self.server__port):
diff --git a/server/common/default_config.py b/server/common/default_config.py
index 0d4a08bb..32ecca33 100644
--- a/server/common/default_config.py
+++ b/server/common/default_config.py
@@ -14,6 +14,7 @@ server:
   about_legal_privacy: null
   force_https: false
   flask_secret_key: null
+  generate_cache_control_headers: false
 
 presentation:
   max_categories: 1000