Using TechDocs

Published on January 30th, 2022

Introduction

The TechDocs feature of Roadie Backstage allows markdown files written alongside the code of your components to appear in Backstage as styled HTML documentation. Because this documentation is centralized in Backstage, it is more likely to be found and used by other people in your organization.

a page of basic documentation for a service in the Backstage service catalog

Adding documentation to a component

Under the hood, Backstage uses the popular MkDocs library to render documentation.

Prerequisites

In order to write and view changes to docs you will need to install:

Step 1: Add the mkdocs configuration file

Create a file called mkdocs.yml in the root of a component you want to document in Backstage. Inside that YAML file, add the following content, replacing {component-name} with the human name of your component.

site_name: '{component-name}'

plugins:
  - techdocs-core

# Uncomment to add extensions if desired
#markdown_extensions:
#  - markdown_inline_mermaid

Step 2: Add markdown documentation

Create a directory called docs in the root of your component. Inside that directory, create a file called index.md with some markdown content inside. No frontmatter is required.

This is the documentation.

Your component’s directory structure should now look something like this:

├── README.md
├── catalog-info.yaml
├── docs
│   └── index.md
├── mkdocs.yml
└── src
    └── // The code of your component

Ensure you publish this new content to GitHub.

Step 3: Update the YAML metadata

We can use the catalog-info.yaml file of our component to tell Backstage where to find the documentation.

To do this, add the backstage.io/techdocs-ref annotation to the list of annotations.

If your docs are in the root of the repo, as described above, you can set the techdocs annotation to this:

annotations:
  backstage.io/techdocs-ref: dir:.

If your docs are located elsewhere, you must explicitly point to them like this:

apiVersion: backstage.io/v1alpha1
kind: Component
metadata:
  name: sample-service
  description: # ...
  annotations:
    backstage.io/techdocs-ref: url:https://github.com/your-org/your-repo/tree/main
spec:
  type: service
  owner: engineering
  lifecycle: experimental

⚠️ The GitHub URL must be prefixed with url: or the documentation will not render in Backstage.

Step 4: Test your documentation

You can generate / serve your docs locally to view what they would look like when they are deployed to Roadie.

To generate the docs to the site directory of the project you can run the following command:

npx @techdocs/[email protected] generate --docker-image roadiehq/techdocs

To start a local server at port 3000 containing the generated docs, you can run the following command:

npx @techdocs/[email protected] serve --docker-image roadiehq/techdocs

NB: We have seen some issues generating and serving plantuml and mermaid diagrams sometimes on M1 Macbooks due to unresolved bugs in open source dependencies. Please reach out to us anyway if you run into any difficulties. NB: We need to pin to an earlier version until this bug in @techdocs/[email protected] is fixed in the Open Source project.

Step 5: Publish your documentation

Commit the changes made in steps 1 through 3 to your repository. Roadie Backstage will pick up the changes shortly after they are merged to the default branch.

Viewing documentation in Backstage

To view your documentation in Backstage, first find the service in your service catalog and click it to open the Overview page.

On the Overview page, click Docs in the tab bar. You should now see your documentation.

a page of basic documentation for a service in the Backstage service catalog

Customize graphs in TechDocs

In order to customize the look of the graphs you will need to use the Graphviz attributes. Setting different values for specific set of attributes will result in graph being rendered that way. For example, let’s say we want to change background color from white to lightblue in following graph:

white graph background

which could be defined in TechDocs with following code:

{% dot attack_plan.svg
    digraph G {
        rankdir=LR
        Earth [peripheries=2]
        Mars
        Earth -> Mars
    }
%}

Adding ‘bgcolor’ attribute in the Graphviz code above (so its final form is):

{% dot attack_plan.svg
    digraph G {
        bgcolor="lightblue"
        rankdir=LR
        Earth [peripheries=2]
        Mars
        Earth -> Mars
    }
%}

will result in graph being rendered in lightblue color.

lightblue graph in techdocs

This way you can customize the graph adding or removing any attribute you want.

Using Mermaid Diagrams

Roadie supports using Mermaid JS to render diagrams. It must first be enabled in your mkdocs.yaml:

markdown_extensions:
  - markdown_inline_mermaid

Then you can add mermaid diagrams as follows:

```mermaid
%%{init: {'theme': 'forest'}}%%
graph LR
  A[Start] --> B{Error?};
  B -->|Yes| C[Hmm...];
  C --> D[Debug];
  D --> B;
  B ---->|No| E[Yay!];
```

Adding more docs

Let’s add a page called Local Development to our docs.

All that is required is to create a markdown file called local-development.md inside the docs directory of our component.

Add some content to it.

Commit and merge these changes to the default branch of your repo on GitHub and Backstage will pick up the changes after a short period of time.

a new page called local development with a code block and some navigation

By default, the structure of the docs pages will mirror that of the file system. You can also explicitly describe your page structure using the nav object in your mkdocs.yaml. Both approaches are described here.

Similarly, mkdocs will determine a title for your document according to these rules.

Handling Documentation Monorepos

If you need to have a place to store docs that are not related to a specific codebase or component, you may want to use a single repository to collect that meta documentation.

Nested file structures and sub-directories can be modeled using the Monorepo plugin for techdocs.

  1. Add to your root mkdocs.yaml file.
plugins:
  - monorepo
  1. Reference other mkdocs.yaml files in sub-directories using the !include syntax like so:
nav:
  - Intro: 'index.md'
  - Authentication: 'authentication.md'
  - API:
    - v1: '!include ./v1/mkdocs.yml'
    - v2: '!include ./v2/mkdocs.yml'

Standalone repos for documentation not related to a codebase or component should still be modeled in Roadie Backstage with a catalog-info.yaml file. The docs repo entity can be described with the following kind and spec type:

---
apiVersion: backstage.io/v1alpha1
kind: Component
...
spec: 
  type: documentation
...

Including existing markdown files

Mkdocs only processes markdown files in the mkdocs directory (defaults to docs/). If you’ve existing docs which live closer to the code e.g. a README.md in the root or at some other level they can’t be referenced in the mkdocs.yaml.

It is possible to use the PyMdown snippets extension to include markdown files from outside the mkdocs docs directory in markdown files within it.

To enable this extension update your mkdocs.yaml:

markdown_extensions:
  # ... other extensions 
  - pymdownx.snippets:
      check_paths: true

Then you can include snippets in your markdown files. If a snippet is the only content in a file then the content is replaced by the referenced file. For example, to include a file TEST.md at the root of our repo we could do the following:

  • Create a file under the docs directory e.g. docs/test.md
  • Add a snippet to test.md (the snippet path is relative to the mkdocs.yaml file)
    --8<-- "TEST.md"

Further reading

  1. Backstage TechDocs uses MkDocs under the hood and the MkDocs configuration and user guide will broadly apply to your Backstage documentation setup. In particular, the “Writing your docs” page is a good place to start
  2. The official Backstage TechDocs guide.

Next steps

If you use OpenAPI specs in your organization you can learn how to associate them with your components.