FeedMixer is a tiny WSGI (Python3) micro service which takes a list of feed URLs and returns a new feed consisting of the most recent n entries from each given feed.
- v2.0.0 The JSON output now conforms to JSON Feed version 1. This breaks any client which depends on the previous ad-hoc JSON format. That legacy format will continue to be maintained in the v1 branch, so any clients which don't want to update to the JSON Feed format should depend on that branch.
- v1.0.0 Stable API. I'm using it in production for small personal "planet"-like feed aggregators.
FeedMixer exposes three endpoints:
- /atom
- /rss
- /json
When sent a GET request they return an Atom, an RSS 2.0, or a JSON feed, respectively. The query string of the GET request can contain these fields:
- f
- A url-encoded URL of a feed (any version of Atom or RSS). To include multiple feeds, simply include multiple f fields.
- n
- The number of entries to keep from each field (pass 0 to keep all entries, which is the default if no n field is provided).
- full
- If set, prefer the full entry content; otherwise prefer the shorter entry summary.
- Clone this repository:
$ git clone https://github.com/cristoper/feedmixer.git
$ cd feedmixer
- Recommended: use pipenv to create a virtualenv and install dependencies:
$ pipenv --three sync
The project consists of three modules:
feedmixer.py
- contains the core logicfeedmixer_api.py
- contains the Falcon-based API. Callwsgi_app()
to get a WSGI-compliant object to host.feedmixer_wsgi.py
- contains an actual WSGI application which can be used as-is or as a template to customize.
The feedmixer_wsgi module instantiates the feedmixer WSGI object (with sensible defaults and a rotating logfile) as both api and application (default names used by common WSGI servers). To start the service with gunicorn, for example, clone the repository and in the root directory run:
$ pipenv run pip3 install gunicorn $ pipenv run gunicorn feedmixer_wsgi
Note that the top-level install directory must be writable by the server running the app, because it creates the logfiles ('fm.log' and 'fm.log.1') and its cache database ('fmcache.db') there.
As an example, assuming an instance of the FeedMixer app is running on the localhost on port 8000, let's fetch the newest entry each from the following Atom and RSS feeds:
The constructed URL to GET is:
http://localhost:8000/atom?f=https://americancynic.net/shaarli/?do=atom&f=https://hnrss.org/newest&n=1
Entering it into a browser will return an Atom feed with two entries. To GET it from a client programatically, remember to URL-encode the f fields:
$ curl 'localhost:8000/atom?f=https%3A%2F%2Famericancynic.net%2Fshaarli%2F%3Fdo%3Datom&f=https%3A%2F%2Fhnrss.org%2Fnewest&n=1'
HTTPie is a nice command-line http client that makes testing RESTful services more pleasant:
$ pip3 install httpie $ http localhost:8000/json f==http://hnrss.org/newest f==http://americancynic.net/atom.xml n==1
HTTP/1.1 200 OK
Connection: close
Date: Mon, 24 Sep 2018 04:23:28 GMT
Server: gunicorn/19.9.0
content-length: 1323
content-type: application/json
{
"description": "json feed created by FeedMixer.",
"home_page_url": "http://localhost:8000/json?f=http%3A%2F%2Fhnrss.org%2Fnewest&f=http%3A%2F%2Famericancynic.net%2Fatom.xml&n=1",
"items": [
{
"author": {
"name": "jedwhite"
},
"content_html": "<p>Article URL: <a href=\"https://www.gsb.stanford.edu/insights/power-telling\">https://www.gsb.stanford.edu/insights/power-telling</a></p>\n<p>Comments URL: <a href=\"https://news.ycombinator.com/item?id=18054969\">https://news.ycombinator.com/item?id=18054969</a></p>\n<p>Points: 1</p>\n<p># Comments: 0</p>",
"date_modified": "2018-09-24T04:13:47Z",
"date_published": "2018-09-24T04:13:47Z",
"id": "https://news.ycombinator.com/item?id=18054969",
"title": "The Power of Telling It Like It Is",
"url": "https://www.gsb.stanford.edu/insights/power-telling"
},
{
"author": {
"name": "A. Cynic",
"url": "https://americancynic.net/about/"
},
"content_html": "A review of a friend's book and some thoughts on hell.",
"date_modified": "2018-09-12T15:03:22Z",
"date_published": "2018-08-29T18:07:24Z",
"id": "tag:americancynic.net,2018-08-29:/log/2018/8/29/thou_shalt_not_believe/",
"title": "Book Review: Thou Shalt Not Believe by John Ubhal",
"url": "https://americancynic.net/log/2018/8/29/thou_shalt_not_believe/"
}
],
"title": "FeedMixer feed",
"version": "https://jsonfeed.org/version/1"
}
Deploy FeedMixer using any WSGI-compliant server (uswgi, gunicorn, mod_wsgi, ...). Refer to the documentation of the server of your choice.
This is how I've deployed FeedMixer with Apache and mod_wsgi (on Debian):
- Create a directory outside of your Apache DocumentRoot in which to install:
$ sudo mkdir /usr/lib/wsgi-bin
- Install as above (so the cloned repo is at
/usr/lib/wsgi-bin/feedmixer
) - Give Apache write permissions:
$ sudo chown :www-data feedmixer; sudo chmod g+w feedmixer
- Configure Apache using something like the snippet below (either in apache2.conf or in a VirtualHost directive):
WSGIDaemonProcess feedmixer threads=10 \
python-home=/usr/lib/wsgi-bin/feedmixer/venv \
python-path=/usr/lib/wsgi-bin/feedmixer \
home=/usr/lib/wsgi-bin/feedmixer
WSGIProcessGroup feedmixer
WSGIApplicationGroup %{GLOBAL}
WSGIScriptAlias /feedmixer /usr/lib/wsgi-bin/fm/feedmixer_wsgi.py
<Directory "/usr/lib/wsgi-bin/fm">
Require all granted
Header set Access-Control-Allow-Origin "*"
</Directory>
The main things to note are the python-home
(set to the virtualenv directory), python-path
, and home
options to the WSGIDaemonProcess
.
As configured above, Apache will run the WSGI app in a single process, handling concurrent requests on up to 10 threads. It is also possible to pass the processes=N
directive to WSGIDaemonProcess
in order to run the app in N processes. If feedmixer_wsgi.py
detects that the WSGI server is running it in multiple processes, it will log to syslog instead of to a file.
Also note the CORS header in the Directory directive which allows the feed to
be fetched by JavaScript clients from any domain (this requires mod_headers
to be enabled). Restrict (or remove) as your application requires.
An alternative to using a virtualenv for both building and deploying is to run FeedMixer in a Docker container. The included Dockerfile will produce an image which runs FeedMixer using gunicorn.
Build the image from the feedmixer directory:
$ docker build . -t feedmixer
Run it in the foreground:
$ docker run -p 8000:8000 feedmixer
Now from another terminal you should be able to connect to FeedMixer on localhost port 8000 just as in the example above.
Using the provided feedmixer_wsgi.py application, information and errors are logged to the file fm.log in the directory the application is started from (auto rotated with a single old log called fm.1.log).
Any errors encountered in fetching and parsing remote feeds are reported in a custom HTTP header called X-fm-errors.
The included prune_expired.py
script can be used to prune old entries from
the database (for example by running it from cron):
>>> /path/to/venv/bin/python3 prune_expired.py 'dbname.db' 1200
The first argument is the path to the ShelfCache database file, and the second argument is the age threshold (in seconds), any entries older than which will be deleted.
FeedMixer does not (yet?) do these things itself, though finding or writing suitable WSGI middleware is one way to get them (running it behind a reverse proxy server like nginx is another way):
- Authentication
- Rate limiting
First install as per instructions above.
Other than this README, the documentation is in the docstrings. To build a pretty version (HTML) using Sphinx:
- Install Sphinx dependencies:
$ pipenv run pip install -r doc/requirements.txt
- Change to doc/ directory:
$ cd doc
- Build:
$ pipenv run make html
- View:
$ x-www-browser _build/html/index.html
Tests are in the test directory and Python will find and run them with:
$ pipenv run python3 -m unittest
To check types using mypy:
$ MYPYPATH=stub/ mypy --ignore-missing-imports -p feedmixer
Not everything is stubbed out, but can be useful for catching bugs after changing feedparser.py
Feel free to open an issue on Github for help: https://github.com/cristoper/feedmixer/issues
If this package was useful to you, please consider supporting my work on this and other open-source projects by making a small (like a tip) one-time donation: donate via PayPal
If you're looking to contract a Python developer, I might be able to help. Contact me at [email protected]
The project is licensed under the WTFPL license, without warranty of any kind.