Category: Virtualisation

Started looking into a service to auto-post from this blog onto my Mastodon feed. Feed2Toot fit the bill perfectly.

I wanted to run the whole thing from a Docker container, though, so I’ll quickly write a how-to.

This whole thing runs from a Raspberry Pi, as root. No k8s or k3s for me. The path I use is /root/git/feed2toot/, so be sure to modify that to whatever you’re using.

First off, get your credentials for the app. You can either install the Feed2Toot package on a system (i.e. throwaway VM, to keep it clean), or use the Docker container below, but add RUN apk add bash and change the last line to CMD ["bash"] and then chroot into it via docker exec -it feed2toot bash.

This will generate two files (feed2toot_clientcred.txt and feed2toot_usercred.txt). Be sure to save these.

You can also try to run Feed2Toot at least once to make sure it’s working and to fine-tune your ini file. This is mine:

[mastodon]
instance_url=https://mastodon.yeri.be
; Here you need the two files created by register_feed2toot_app
user_credentials=/etc/feed2toot/feed2toot_usercred.txt
client_credentials=/etc/feed2toot/feed2toot_clientcred.txt
; Default visibility is public, but you can override it:
; toot_visibility=unlisted

[cache]
cachefile=/feed2toot/feed2toot.db
cache_limit=10000

[lock]
lock_file=/var/lock/feed2toot.lock
lock_timeout=3600

[rss]
uri=https://yeri.be/feed
; uri_list=/feed2toot/rsslist.txt
toot={title} {link}
; toot_max_len=500
title_pattern=Open Source
title_pattern_case_sensitive=true
no_uri_pattern_no_global_pattern=true
; ignore_ssl=false

[hashtaglist]
; several_words_hashtags_list=/feed2toot/hashtags.txt
; no_tags_in_toot=false

[feedparser]
; accept_bozo_exceptions=true

[media]
; custom=/var/lib/feed2toot/media/logo.png

I have three other files to make this work, first off Dockerfile:

FROM python:3.6-alpine
RUN pip3 install feed2toot && mkdir -p /etc/feed2toot/
COPY feed2toot.ini feed2toot_clientcred.txt feed2toot_usercred.txt /etc/feed2toot/
VOLUME /feed2toot/
CMD ["feed2toot", "-c", "/etc/feed2toot/feed2toot.ini"]

The script I run to build the container (start.sh):

#!/bin/bash
git pull

BASEIMAGE=`cat Dockerfile | grep FROM | awk '{print $2}'`
docker pull $BASEIMAGE
docker stop feed2toot
docker rm feed2toot
docker build -t feed2toot .
./run.sh

And finally, the script to run the container every so often (run.sh):

#!/bin/bash
docker run -d --rm -v /srv/mastodon/feed2toot/:/feed2toot/ --name feed2toot feed2toot

This will save the database file under /srv/mastodon/, to preserve states across rebuilds.

Note that once Feed2Toot runs, it’ll exit, and the container will be stopped. So it does not automatically run all the time.

So, you’ll want to run this every so often. You can add a file to /etc/cron.d/ to run it, for example, every six hours:

#
# cron-jobs for feed2toot
#

MAILTO=root

0 */6 * * *		root	if [ -x /root/git/feed2toot/run.sh ]; then /root/git/feed2toot/run.sh >/dev/null; fi

That’s it. Should do the trick. It’ll now post stuff from your RSS feed onto your timeline.

Oh, and Jeroen has a good post about Mastodon.