Evaluate Markdown

This is a tool to evaluate or export code from Markdown files.

Why? Because I like writing Markdown files with code snippets (it's good with Obsidian too).

With smaller code snippets and documentation in a markdown file, the file will be easily consumed by the reader, yet it can be executed without copy-paste. If the file has more than one code block with given language, eval-md will combine them and evaluate as one script.

Install

cargo install eval-md

Supported languages

• JavaScript (node, deno)
• Lua
• Python3
• Ruby
• Shell (bash, zsh)

Export

With the --export flag, target language can be anything, it will not evaluate the final code. It will print out the content to stdout. Ideal to generate content from a Markdown file, for example configuration files. In the example we have a JSON configuration file for a service, and we can add extra comments about sections of the configuration file.

In the output, a header will be added, for example Python scripts get #!/usr/bin/env python3 on --export.

Custom Tag

Custom tag and executor can be defined with :. The first part will be the string tag to extract code blocks, and the second part will be the language that will evaluate the extracted code.

• py:python => will parse py and run as python
• js => will parse js and run as js (js is an alias to javascript)
• js:deno => will parse js and run with deno

Examples

The following examples will use example/test.md:

❯ eval-md zsh example/test.md -- --random-flag
nice in zsh
Arguments: --random-flag

❯ eval-md bash example/test.md
nice in bash
Arguments:

❯ eval-md python example/test.md -- --hype-level=awesomeness
awesome
Arguments: ['-', '--hype-level=awesomeness']

❯ eval-md ruby example/test.md -- --debug
it works :)
Arguments: ["--debug"]

❯ eval-md --debug python example/test.md -- --hype-level=awesomeness
 -- Target Language: python
 -- Source file: example/test.md
 -- Arguments: ["--hype-level=awesomeness"]
awesome
Arguments: ['-', '--hype-level=awesomeness']

❯ eval-md json example/test.md --export
{
  "enable_registration": true,
  "debug": false,
  "hostname": "efertone.me",
  "port": 9999
}

❯ eval-md lua example/test.md
Value:  15

❯ eval-md something:javascript example/test.md
Fancy

Install and Bootstrap Flux

Obviously the whole documentation can live in a shell script as comment. In case you want to add images and links to other pages, you can still "execute" the documentation about how to install Flux. Of course this example installs and bootstraps only one specific way.

❯ eval-md bash example/install-flux.md
 !! git repository is not defined.
 --help            This help message
 --repo <repo>     Git repository. (example: git@github.com/org/repo)
 --branch <branch> Git branch. [default: main]
 --path <path>     Path to the cluster. [default: ./clusters/management]

❯ eval-md bash example/install-flux.md -- --repo git@github.com/yitsushi/cluster-conf --branch production
...

Deploy Helm Release with Flux

The example/flux-helm-repo.md example shows a simple scenario where we describe how to deploy helm charts on a cluster. Usually that comes with a lot of copy-paste, but we can be smart with eval-md.

This simple command will evaluate all bash in the markdown file. The only bash snippet is the one that exports yaml blocks and pass it to kubectl. At the end, we have a nice documentation (not this one, it's mostly just filler text, did not really spend much time on it).

❯ eval-md bash example/flux-helm-repo.md
helmrepository.source.toolkit.fluxcd.io/podinfo created
helmrelease.helm.toolkit.fluxcd.io/podinfo created