Tweet a Random RSS Feed Item

Using AWS Lambda and Tweetinvi

This project is a slight modification of my last one, replacing reading posts via the Ghost API to a more general parsing of RSS feeds. I wanted to create something that would work for any blog... or anything else that generates an RSS feed.

My first experience with AWS Lambda was using Ephemeral to clean up my Twitter feed, but I wanted to try writing my own app for AWS Lambda, and I wanted to do it in C#. I've also had an idea for awhile now that it'd be nice to be able to randomly select and tweet my old blog posts.

Usage

So here it is, a C# console you can run from AWS Lambda. Schedule it to run as often as you like using Lambda's cron scheduling capabilities.

If you'd like to read more about it, I wrote a blog post about it too.

Getting the code

1. Clone the repo: git clone git@github.com:grantwinney/TweetRandomFeedItem.git
2. Open the project in Visual Studio.
3. Build the project (you may have to right-click the NuGet folder and choose 'restore' to download the dependencies, although VS usually takes care of that for you)
4. Find the bin directory on disk, and drill down until you get to the assemblies (dll files). Most likely: bin/Debug/netcoreapp2.0
5. Zip up the contents of the inner-most directory, but not the directory itself. (e.g. just select all the files inside netcoreapp2.0.)

Setting up AWS Lambda

Now you need to create a new AWS Lambda job. Check this out for a brief intro to setting up a job.

1. Create a new function and choose C# (.NET Core 2.0) for the runtime.
2. The name of the function, and the role it makes you create, don't matter.
3. Upload the zip file you created above.
4. Set the handler as TweetRandomFeedItem::TweetRandomFeedItem.Program::Main
5. Under "Basic settings", decrease the memory to 128MB and increase the timeout to a minute. For me, it generally takes about 15-20 seconds to run, and uses less than 100MB of memory. You may have to play with the settings a bit.
6. Set the following environment variables:

Environment Variables

I use quite a few environment variables, so credentials and other settings can easily be changed between runs, without having to recompile the code and upload it again.

Field	Required	Description
RSS_URI	Yes	The RSS feed to read in, like: https://grantwinney.com/rss/
RSS_ITEM_RETRIEVAL_LIMIT	No	Specify the number of posts you want to retrieve. If you omit this, or leave the value empty, the app will read the entire RSS feed.
TWITTER_CONSUMER_KEY TWITTER_CONSUMER_SECRET TWITTER_USER_ACCESS_TOKEN TWITTER_USER_ACCESS_TOKEN_SECRET	Yes	These values all come from your Twitter account. You need to create a new app to get these values, which allows you to post tweets.
TWITTER_MAX_TAG_COUNT	No	Although tag spamming is somewhat prevalent on Facebook, and even more-so on Instagram, I don't see a lot of it on Twitter. If you tend to use a lot of tags for posts on your blog, then you can limit how many of those transfer to your tweet. If you omit this, or leave the value empty, the app will use the first 3 tags.