Markdown Meta Action

07 May 2021 in Tech

Content containing some YAML frontmatter is very common nowadays (in fact, you're reading a post that uses it right now).

Today's action allows you to use that data in any way that you need in your workflows.

Fact Sheet
Authormheap
Contributors1
Stars0
Repohttps://github.com/mheap/markdown-meta-action
Marketplacehttps://github.com/marketplace/actions/markdown-meta

What does it do?

markdown-meta allows you to read that metadata and makes it available as an output in your GitHub Actions workflow.

The frontmatter for this file is as follows:

yaml
---
title: Markdown Meta Action
description: Read the frontmatter from your markdown files and use the values in your workflows
slug: markdown-meta-action
date: "2021-05-07T19:01:58+01:00"
category: "Tech"
tags:
- github-actions
---

Given that file we can run the following workflow that outputs the post title:

yaml
name: Get Post Meta
on: push
jobs:
post-meta:
name: Post Meta
runs-on: ubuntu-latest
steps:
- name: Checkout
uses: actions/checkout@v2
- name: Markdown Meta
uses: mheap/markdown-meta-action@v1
id: meta
with:
file: ./_posts/markdown-meta-action.md
- name: Output the post title
run: echo "${{ steps.meta.outputs.title }}"

We use the id parameter to name the markdown-meta step meta and then access the data returned by it using steps.meta.outputs. Each key in the frontmatter is available:

  • steps.meta.outputs.title
  • steps.meta.outputs.description
  • steps.meta.outputs.slug
  • steps.meta.outputs.date
  • steps.meta.outputs.category
  • steps.meta.outputs.tags

How does it work?

This is a really tiny action, just 7 lines long:

As it uses core.setOutput() any complex data types such as objects or arrays are JSON encoded before being output. This means that in the above example, tags will be ["github-actions"].

Common use cases

The best use case that I can think of for this action is automated blog post updates:

yaml
name: Get Post Meta
on: push
jobs:
post-meta:
name: Post Meta
runs-on: ubuntu-latest
steps:
- name: Checkout
uses: actions/checkout@v2
- name: Get latest post
run: |
cd _posts
echo "::set-output name=post_name::$(ls -rt | tail -n 1)"
id: latest_post
- name: Markdown Meta
uses: mheap/markdown-meta-action@v1
id: meta
with:
file: ./_posts/${{ steps.latest_post.outputs.post_name }}
- uses: ethomson/send-tweet-action@v1
with:
status: "I just published! ${{ steps.meta.outputs.title }} https://michaelheap.com/${{ steps.meta.outputs.slug }}"
consumer-key: ${{ secrets.TWITTER_CONSUMER_API_KEY }}
consumer-secret: ${{ secrets.TWITTER_CONSUMER_API_SECRET }}
access-token: ${{ secrets.TWITTER_ACCESS_TOKEN }}
access-token-secret: ${{ secrets.TWITTER_ACCESS_TOKEN_SECRET }}