Markdown with PlantUML

README.md

How to use PlantUML with Markdown

PlantUML is a really awesome way to create diagrams by writing code instead of drawing and dragging visual elements. Markdown is a really nice documentation tool.

Here's how I combine the two, to create docs with embedded diagrams.

Step 0: Setup

Get the command-line PlantUML from the download page or your relevant package manager.

Step 1: Create a Markdown file

Use your favorite markdown or text editor. Most (if not all) developer-oriented text editors have some kind of markdown support.

Remember that md files can contain html, and that html is passed-through to the generated html as-is.

When you want to embed a diagram, create a hidden div: <div hidden>.

Now start a code block by indenting or typing 3 backticks. The first line of the code block must be @startuml followed by a file name (with no extension). The following lines should be the actual diagram code, ending with @enduml. End the code block and close the div.

Finally, to actually show the diagram in the document, add an image in markdown: ![](firstDiagram.svg). The name must be the same name as in the @startuml command, with a .svg extension.

All together now

Regular **Markdown** here.

<div hidden>
```
@startuml firstDiagram

Alice -> Bob: Hello
Bob -> Alice: Hi!
		
@enduml
```
</div>

![](firstDiagram.svg)

Some more markdown.

Step 2: Run PlantUML on the Markdown file

On the command line:

plantuml -tsvg FILENAME

Where FILENAME is the name of the markdown file.

For every PlantUML block in the file, one svg diagram is generated. When the markdown to html converter is running, the html will contain image links to the generated images.

Step 3: Convert locally to HTML or upload to GitHub

If you host the files in GitHub (or other services that convert md to html on the fly), the last step is uploading or pushing the files. Make sure to include everything: the markdown and the generated diagrams.

Otherwise, use your favorite tool for converting markdown to html - a markdown editor or a command line tool.

firstDiagram.svg

sample.md

Regular Markdown here.

@startuml firstDiagram

Alice -> Bob: Hello
Bob -> Alice: Hi!

@enduml

Some more markdown.

I created this GitHub Action to processes .src.md files, converts them to .md files, and embeds PlantUML diagrams using an external PlantUML server. It is designed to be an out-of-the-box solution, requiring minimal configuration.

Another alternative officially supported by GitHub is mermaid

I just wanted to give an update on my previous comment, which was three years old. I have developed Jamal, and now you can edit a Markdown file with the Jamal preprocessor in IntelliJ WYSIWYG, so you immediately see the rendered document, including the diagrams. You can also use KROKI with it, which means you can use not only PlamtUML but also more than 10 different text-based diagramming tools.

Using just Mermaid is simpler, though it is GitHub specific. To use Jamal you need some setup (just unzip a file into a directory and restart IntelliJ), and you will have your edited XXX.md.jam and the generated XXX.md file.

URL to this tool is still https://github.com/verhas/jamal