# Docs generator

This generator generates resource-level docs by utilizing the Pulumi schema.

## Crash course on templates

The templates use Go's built-in `html/template` package to process templates with data. The driver for this doc generator (e.g. tfbridge for TF-based providers) then persists each file from memory onto the disk as `.md` files.

Although we are using the `html/template` package, it has the same exact interface as the [`text/template`](https://golang.org/pkg/text/template) package, except for some HTML specific things. Therefore, all of the functions available in the `text/template` package are also available with the `html/template` package.

* Data can be injected using `{{.PropertyName}}`.
* Nested properties can be accessed using the dot notation, i.e. `{{.Property1.Property2}}`.
* Templates can inject other templates using the `{{template "template_name"}}` directive.
  * For this to work, you will need to first define the named template using `{{define "template_name"}}`.
* You can pass data to nested templates by simply passing an argument after the template's name.
* To remove whitespace from injected values, use the `-` in the template tags.
  * For example, `{{if .SomeBool}} some text {{- else}} some other text {{- end}}`. Note the use of `-` to eliminate whitespace from the enclosing text.
  * Read more [here](https://golang.org/pkg/text/template/#hdr-Text_and_spaces).
* To render un-encoded content use the custom global function `htmlSafe`.
  * **Note**: This should only be used if you know for sure you are not injecting any user-generated content, as it by-passes the HTML encoding.
* To print regular strings, that share the same syntax as the Go templating engine, use the built-in global function `print` [function](https://golang.org/pkg/text/template/#hdr-Functions).
  * For example, if you need to render `{{% md %}}`, you will instead need to do `{{print "{{% md %}}"}}`.

Learn more from here: https://curtisvermeeren.github.io/2017/09/14/Golang-Templates-Cheatsheet

## Modifying templates and updating tests

We run tests that validate our template-rendering output. If you need to make change that produces a set of Markdown files that differs from the set that we use in our tests (see `codegen/internal/test/testdata/**/*.md`), your pull-request checks will fail, and to get them to pass, you'll need to modify the test data to match the output produced by your change.

For minor diffs, you can just update the test files manually and include those updates with your PR. But for large diffs, you may want to regenerate the full set. To do that, from the root of the repo, run:

```
PULUMI_ACCEPT=true pushd pkg/codegen/docs && go test . && popd
```

## `bundler.go`

This file contains a `main` function and is part of the `main` package. We run it using the `go generate` command (see the `Makefile` and the starting comment in `pkg/codegen/gen.go`).

> This file is ignored using a `+build ignore` comment at the top of the file, so it is not ignored during a `go build ...`.

## `packaged.go`

A file generated by `bundler.go` that contains formatted byte strings, that represent the string templates from the `./templates/` folder. This file is also git-ignored as it is intended to only be generated by the `docs` repo and is not used during runtime of the main Pulumi CLI. In fact, this whole package is not used during the runtime of the CLI itself.

## `go:generate`

> Read more [here](https://blog.golang.org/generate).

`go:generate` is a special code comment that can be used to run custom commands by simply running `go generate <package>`, which then scans for `go:generate` comments in all sources in the package `<package>`. It also serves as a way to document, that a certain file relies on a command to have been executed before it can be used.