---
title: "How to update a released site"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{How to update a released site}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
```

## Checklist

If you're already up-to-speed, here's the checklist:

* Make sure your dev site looks the way you want before embarking on an update
  of your released site. Here are good instructions for updating an existing
  site for pkgdown 2.0.0, Bootstrap 5, and "tidyverse/tidytemplate" (only
  applies to certain packages):  
  <https://tidytemplate.tidyverse.org>
* Make sure you are using automatic development mode. In `_pkgdown.yml`:

  ``` yaml
  development:
    mode: auto
  ```
* Push/pull to sync your default branch.
* Create and checkout a branch based on the tag of your most recent GitHub/CRAN
  release.
  
  Example for readr, whose latest release is 2.1.1:  
  `git checkout -b update-pkgdown-2-1-1 v2.1.1`
  
  General pattern:  
  `git checkout -b NEW-BRANCH-NAME NAME-OF-RELEASE-TAG`
* Backport innovations from the future. Example of a useful opening move:  
  `git checkout main -- _pkgdown.yml .github/workflows/pkgdown.yaml`

  Most likely candidates:
  - `_pkgdown.yml`
  - `.github/workflows/pkgdown.yaml`
  - `Config/Needs/website: tidyverse/tidytemplate` in DESCRIPTION
  - Any fixes to `README.Rmd` / `README.md` or released roxygen comments. Don't
    forget to `devtools::build_readme()` or `devtools::document()`, in that
    case.
  
  These are the two main Git commands you'll need:
  ```
  git checkout REF -- path/to/a/specific/file
  git cherry-pick SHA
  ```
* Monitor your progress locally with `pkgdown::build_site()`.
* Push this branch, maybe using `usethis::pr_push()`. Don't bother opening
  a pull request (the branch will still be created and pushed).
* Go to your package's GHA page, maybe using `usethis::browse_github_actions()`.
  Select the pkgdown workflow. Click *Run workflow* and select the branch you
  just pushed. If there's no dropdown menu for this, that means your pkgdown
  workflow config is not current.
* Scrutinize your newly published **released** site and make sure things look
  right.
* You can let this branch sit around for a while, in case you need to iterate
  on this or if you'd like to backport more niceties before your next CRAN
  release. Or you can delete immediately, if you're happy with the released
  site.

## Context

Before we talk about **how** to update a released site, we first establish **why** you might need to do this.
What is a released site? What other kind of pkgdown site could you have?
Why does updating a released site take special effort?

### Automatic development mode

Every pkgdown site has a so-called [*development mode*](https://pkgdown.r-lib.org/reference/build_site.html#development-mode), which can be specified via the `development` field in `_pkgdown.yml`.
If unspecified, the default is `mode: release`, which results in a single pkgdown site.
Despite the name, this single site reflects "the current package state", which could be either a released state or a development state.

For packages with a substantial user base, it is recommended instead to specify `mode: auto` like so:

``` yaml
development:
  mode: auto
```

This directs pkgdown to "generate different sites for the development and released versions of your package."

The readr package demonstrates what happens in automatic development mode:

[readr.tidyverse.org](https://readr.tidyverse.org) documents the released version, i.e. what `install.packages()` would deliver.  
[readr.tidyverse.org/dev/](https://readr.tidyverse.org/dev/) documents the dev version, i.e. what you'd get by installing from GitHub.

In this mode, `pkgdown::build_site()`, consults DESCRIPTION to learn the package's version number.
For a development version number, the rendered site is written to `docs/dev/`.
For a released version number, the site is written to `docs/`.
(There are also other signals to alert users that they are reading documentation for a dev version vs. a released version.)

Automatic development mode is recommended for packages with a broad user base, because it maximizes the chance that a user will read web-based documentation that reflects the package version that is locally installed.

### Publishing

Now that we've established the meaning of a released (vs dev) site, we have to consider how the site gets rendered and deployed.

Many people use `usethis::use_pkgdown_github_pages()` to do basic pkgdown setup and configure a GitHub Actions (GHA) workflow to automatically render and publish the site to GitHub Pages.
Here's an overview of what this function does:

```
usethis::use_pkgdown_github_pages() =
  use_pkgdown() +
  use_github_pages() + 
  use_github_action("pkgdown") +
  add the pkgdown site's URL to _pkgdown.yml, URL field of DESCRIPTION,
    and to the GitHub repo +
  (if owning org is one of: tidyverse, r-lib, tidymodels, rstudio) 
  add "tidyverse/tidytemplate" to Config/Needs/website in DESCRIPTION
```

As a result, the publishing cadence of many pkgdown sites is governed by the workflow maintained at [`r-lib/actions/examples/pkgdown.yaml`](https://github.com/r-lib/actions/blob/v2/examples/pkgdown.yaml).
(Do not confuse `_pkgdown.yml`, which gives instructions to the pkgdown package, with `.github/workflows/pkgdown.yaml`, which gives instructions to GHA.)

Here are some of the most important bits of the GHA workflow config:

*NOTE: this is from v2 of `r-lib/actions`, which is important! If you use usethis to add/update workflow config, make sure you're using the dev version of usethis, which will pull from the `v2` tag.*

``` yaml
on:
  push:
    branches: [main, master]
  pull_request:
    branches: [main, master]
  release:
    types: [published]
  workflow_dispatch:
  
<snip, snip>

      - name: Build site
        run: Rscript -e 'pkgdown::build_site_github_pages(...)'
        
      - name: Deploy to GitHub pages 🚀
        if: github.event_name != 'pull_request'
        uses: JamesIves/github-pages-deploy-action@4.1.4
        
        <snip, snip>
```

We build and deploy for pushes to `main` (or `master`).    
We build for pull requests against `main` (or `master`).  
But we don't deploy for pull requests.

We build and deploy when we publish a GitHub release.  
By convention, we assume that a GitHub release coincides with a CRAN release.  
**This is the primary mechanism for building the released pkgdown site.**  

`pkgdown::build_site_github_pages()` consults the version in DESCRIPTION to detect whether it's building from a released version or a dev version.
That determines the `dest_dir`, e.g. `docs/` for released and `docs/dev/` for dev.
For a package in automatic development mode, this means that almost all of your pushes trigger an update to the dev site. 
The released site is only updated when you push a state with a non-development version number or when you publish a GitHub release.

So how do you tweak things about the released site *in between* releases?

That brings us to `workflow_dispatch:`. (Yes that dangling colon is correct.)

The inclusion of `workflow_dispatch` as a trigger means the pkgdown workflow can be run on demand, either manually from the browser or via the GitHub REST API.
We're going to show how to update a released site from a GitHub branch or tag, using the browser method.
In the future, we might build some tooling around the API method.

Places to learn more about triggering GHA workflows:

* <https://docs.github.com/en/actions/learn-github-actions/events-that-trigger-workflows#workflow_dispatch>
* <https://docs.github.com/en/actions/managing-workflow-runs/manually-running-a-workflow>
* <https://docs.github.com/en/rest/reference/actions/#create-a-workflow-dispatch-event>

Before we move on, I repeat:  
It is important that your `main` branch have the latest pkgdown workflow.
(Or whatever your default branch is called.)
At the time of writing, this means the `v2` tag in `r-lib/actions`.
The easiest way to get this is to install dev usethis and run `usethis::use_github_action("pkgdown")`.

## Construct a branch for the update

The overall goal is to create a package state from which to update the released site that corresponds to (HEAD of) a Git branch.
This package state should:

* Be based on the most recent GitHub and CRAN release.
* Incorporate all desired updates to your documentation, such as pkgdown config.

Create and checkout a branch based on the tag of the most recent CRAN release.
For example, if readr's latest release is 2.1.1:

```
git checkout -b update-pkgdown-2-1-1 v2.1.1
```

And here is the general pattern:

```
git checkout -b NEW-BRANCH-NAME NAME-OF-RELEASE-TAG
```

Now you should backport innovations from the future that you would like to retroactively apply to your released site.

Files you must update:

* `.github/workflows/pkgdown.yaml`
* `_pkgdown.yml`
* `Config/Needs/website` field of DESCRIPTION (And, probably, only this field!
  In particular, do not mess with the version number.)

Other likely candidates:  

* `README.Rmd` + `README.md`, e.g., if you've updated badges.
* Any documentation fixes that **apply to the released version**. This is the
  only reason to touch anything below `R/` and even then it should only affect
  roxygen comments. Don't forget to `document()` if you do this!
* Any new vignettes or articles that apply to the released version.

Here are some tips on backporting specific changes into this branch.
If you are lucky, there are specific commits in your default branch that contain all the necessary changes.
In that case, we can cherry pick such a commit by its SHA:

```
git cherry-pick SHA
```

If that doesn't cover everything, for each file you want to update, identify a Git reference (meaning: a SHA, tag, or branch) where the file is in the desired state.
Checkout that specific file path from that specific ref:

```
git checkout REF -- path/to/the/file
```
  
For example, readr recently gained a new vignette that applies to the released version of readr, i.e. it does not document any dev-only features or functions.
Here's how to introduce the new vignette from HEAD of `main` into the current branch:

```
git checkout main -- vignettes/column-types.Rmd
```

Commit and push this new branch to GitHub.
`usethis::pr_push()` can be handy for this.
Just don't bother opening a pull request (the branch will still be pushed).

Now we will use the `workflow_dispatch` GHA trigger.
Go to the Actions page of your repo, maybe via `usethis::browse_github_actions()`.
Click on the `pkgdown` workflow.

You should see "This workflow has a workflow_dispatch event trigger."  
(If you don't, that means you didn't do one of the pre-requisites, which is to update to `v2` of the pkgdown workflow.)
  
See the "Run workflow" button?
CLICK IT.
In the "Use workflow from" dropdown menu, select the branch you've just made and pushed.
This should kick off a pkgdown build-and-deploy and, specifically, it should cause updates to the **released** site.
  
You can keep this branch around for a while, in case you didn't get everything right the first time or if more things crop up that you'd like backport to the released site, before your next CRAN release.

## Problem-solving

Remember GitHub search is a great way to get other people's `_pkgdown.yml` files in front of your eyeballs:

Example query: [`filename:_pkgdown.yml org:tidyverse org:r-lib`](https://github.com/search?q=filename%3A_pkgdown.yml+org%3Atidyverse+org%3Ar-lib)

For any given `_pkgdown.yml` file on GitHub, remember that its History and Blame can be helpful for seeing how another package's config has evolved over time.