Add Redis cache backend

Dockerfile

@@ -3,6 +3,6 @@ FROM alpine:latest
 RUN apk add --no-cache python3 py3-lxml py3-pip py3-wheel git
 
 ADD . /app
-RUN pip3 install --no-cache-dir /app gunicorn
+RUN pip3 install --no-cache-dir /app[full] gunicorn
 
 CMD gunicorn --bind 0.0.0.0:8080 -w 4 --preload --access-logfile - morss

README.md

@@ -48,28 +48,25 @@ Some features of morss:
 
 ### Python package
 
+Simple install (without optional dependencies)
+
 ```shell
 pip install git+https://git.pictuga.com/pictuga/morss.git
 ```
 
+Full installation (including optional dependencies)
+
+```shell
+pip install git+https://git.pictuga.com/pictuga/morss.git#[full]
+```
+
+The full install includes mysql and redis (possible cache backends). Otherwise,
+only in-memory and sqlite3 caches are available.
+
 The dependency `lxml` is fairly long to install (especially on Raspberry Pi, as
 C code needs to be compiled). If possible on your distribution, try installing
 it with the system package manager.
 
-Dependencies:
-
-- [python](http://www.python.org/) >= 2.6 (python 3 is supported)
-- [lxml](http://lxml.de/) for xml parsing
-- [bs4](https://pypi.org/project/bs4/) for badly-formatted html pages
-- [dateutil](http://labix.org/python-dateutil) to parse feed dates
-- [chardet](https://pypi.python.org/pypi/chardet)
-- [six](https://pypi.python.org/pypi/six), a dependency of chardet
-- pymysql
-
-You may also need:
-- Apache, with python-cgi support, to run on a server
-- a fast internet connection
-
 ### Docker
 
 Build & run
@@ -375,6 +372,8 @@ will be cleared every time the program is run). Path can be defined with
 `SQLITE_PATH`.
 - `CACHE=mysql`: MySQL cache. Connection can be defined with the following
 environment variables: `MYSQL_USER`, `MYSQL_PWD`, `MYSQL_DB`, `MYSQL_HOST`
+- `CACHE=redis`: Redis cache. Connection can be defined with the following
+environment variables: `REDIS_HOST`, `REDIS_PORT`, `REDIS_DB`, `REDIS_PWD`
 
 To limit the size of the cache:
 

morss/cache.py

@@ -141,6 +141,23 @@ class CappedDict(OrderedDict, BaseCache):
         OrderedDict.__setitem__(self, key, data)
 
 
+try:
+    import redis # isort:skip
+except ImportError:
+    pass
+
+
+class RedisCacheHandler(BaseCache):
+    def __init__(self, host='localhost', port=6379, db=0, password=None):
+        self.r = redis.Redis(host=host, port=port, db=db, password=password)
+
+    def __getitem__(self, key):
+        return self.r.get(key)
+
+    def __setitem__(self, key, data):
+        self.r.set(key, data)
+
+
 if 'CACHE' in os.environ:
     if os.environ['CACHE'] == 'mysql':
         default_cache = MySQLCacheHandler(
@@ -159,5 +176,13 @@ if 'CACHE' in os.environ:
 
         default_cache = SQLiteCache(path)
 
+    elif os.environ['CACHE'] == 'redis':
+        default_cache = RedisCacheHandler(
+            host = os.getenv('REDIS_HOST', 'localhost'),
+            port = int(os.getenv('REDIS_PORT', 6379)),
+            db = int(os.getenv('REDIS_DB', 0)),
+            password = os.getenv('REDIS_PWD', None)
+        )
+
 else:
         default_cache = CappedDict()

setup.py

@@ -14,7 +14,7 @@ setup(
     license = 'AGPL v3',
     packages = [package_name],
     install_requires = ['lxml', 'bs4', 'python-dateutil', 'chardet'],
-    extras_require = {'full': ['pymysql']},
+    extras_require = {'full': ['pymysql', 'redis']},
     package_data = {package_name: ['feedify.ini']},
     data_files = [
         ('share/' + package_name, ['README.md', 'LICENSE']),