# [Docusaurus] How to enable showLastUpdate feature when deployed via Gitlab CI

# Context

I had trouble getting [showLastUpdateAuthor](https://docusaurus.io/docs/api/plugins/@docusaurus/plugin-content-docs#showLastUpdateAuthor) and [showLastUpdateTime](https://docusaurus.io/docs/api/plugins/@docusaurus/plugin-content-docs#showLastUpdateTime) to display in production build when deploying through `Gitlab CI`.

Before I show you how to fix it, let's see what this feature is about

![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1667634489223/PBjkzGB_B.png align="left")

As shown in the image (circled) above, at the bottom of each page, it will reflect when was the document last updated and by whom. While this feature is not absolutely necessary, it is useful to know this piece of information.

# Setup

The setup is pretty straight-forward if you are using the defaults for the most part. You can look at the [detailed instruction](https://docusaurus.io/docs/api/plugins/@docusaurus/plugin-content-docs) stated on the website.

Here's the TLDR version, in your `docusaurus.config.js`, navigate to `presets` config and configure like such

```json
presets: [
    [
      '@docusaurus/preset-classic',
      {
        docs: {
          sidebarPath: 'sidebars.js',
          editUrl: 'https://gitlab.com/bwgjoseph/etp-docs/-/edit/main/',
          showLastUpdateAuthor: true,
          showLastUpdateTime: true
        }
      }
    ]
  ],
```

That's actually all you have to do to get it working, but note that this does not (really) work in development mode. In development mode, it will be simulated.

![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1667635299347/hBs_w18Ki.png align="left")

If you wish to see the actual value, you have to build, and serve the content out locally.

```java
yarn build
yarn serve
```

# Problem

## What happened?

I'm deploying my docs using `Gitlab Pages` via `Gitlab CI`, and it wouldn't display the user and timestamp in the production build. There was no obvious error (the entire pipeline actually pass), until I look closer to my `Gitlab CI logs` which show this

```java
$ yarn build
yarn run v1.22.18
$ docusaurus build
[INFO] [en] Creating an optimized production build...
[WARNING] Sorry, the docs plugin last update options require Git.
Browserslist: caniuse-lite is outdated. Please run:
  npx browserslist@latest --update-db
  Why you should do it regularly: https://github.com/browserslist/browserslist#browsers-data-updating
[info] [webpackbar] Compiling Client
[info] [webpackbar] Compiling Server
[success] [webpackbar] Client: Compiled successfully in 57.72s
[success] [webpackbar] Server: Compiled successfully in 1.03m
[SUCCESS] Generated static files in "build".
[INFO] Use `npm run serve` command to test your build locally.
Done in 97.92s.
```

There was a warning message at Line 5, indicating `Sorry, the docs plugin last update options require Git` which I don't quite understand at first. Some thoughts that ran through my mind were, "Why wouldn't there be Git? If there isn't, then how did the pipeline clone the repository?"

## Understanding the cause

To explain this, let's zoom into the pipeline stage that is responsible to build the artifact.

```yaml
build:
  stage: build
  image: node:16.15.0-alpine
  script:
    - yarn install
    - yarn build
```

So in the `build` stage, the command `yarn build` will use `git` to generate the `lastUpdate` information. However, the image that I used is `node:16.15.0-alpine` which does not come with `git` installed.

## Resolution

> 15/2/2023 Update: Alternatively, switch to use non-alpine node image and it will work without manually installing git. If image size is a concern, then using the solution below might be better for you

Hence, to resolve it, all I had to do was to install `git` via the `before_script`

```yaml
build:
  stage: build
  image: node:16.15.0-alpine
  before_script:
    - apk update && apk --no-cache add git
    - git --version
  script:
    - yarn install
    - yarn build
```

Once I fixed this, and ran the pipeline again, we can see the following in the logs

```java
$ apk update && apk --no-cache add git
fetch https://dl-cdn.alpinelinux.org/alpine/v3.15/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/v3.15/community/x86_64/APKINDEX.tar.gz
// omitted
(7/7) Installing git (2.34.5-r0)
Executing busybox-1.34.1-r5.trigger
Executing ca-certificates-20220614-r0.trigger
OK: 21 MiB in 23 packages
$ git --version
git version 2.34.5
```

And viola! The production build will now display the last updated timestamp and author information.

# Conclusion

While the setup is straight-forward, to get it working in production which is deployed via `Gitlab CI`, you need some working knowledge of how the pipeline is configured and run.

Hope this helps someone else that face this issue when deploying via `Gitlab CI` as I was not able to find any information.

You will probably not face this issue if you deploy this manually.