Log4brains

Log4brains is a docs-as-code knowledge base for your development and infrastructure projects. It enables you to log Architecture Decision Records (ADR) right from your IDE and to publish them automatically as a static website.

By logging your decisions chronologically, you will be able to:

• Understand past technical decisions and their context
• Take new decisions with confidence
• Always have a up-to-date technical documentation and training material available
• Onboard new developers quicker
• Set up a collaborative decision process thanks to pull requests

• Docs-as-code: ADRs are written in markdown, stored in your git repository, close to your code
• Local preview with Hot Reload
• Interactive ADR creation from the CLI
• Static site generation to publish to GitHub/GitLab Pages or S3
• Timeline menu
• Searchable
• ADR metadata automatically guessed from its raw text and git logs
• No enforced markdown structure: you are free to write however you want
• No required file numbering schema (i.e., adr-0001.md, adr-0002.md...): avoids git merge issues
• Customizable template (default: MADR)
• Multi-package projects support (mono or multi repo): notion of global and package-specific ADRs

Coming soon:

• Local images and diagrams support
• RSS feed to be notified of new ADRs
• Decision backlog
• @adr annotation to include code references in ADRs
• ADR creation/edition from the UI
• Create a new GitHub/GitLab issue from the UI
• ... let's suggest a new feature if you have other needs!

Table of contents

• 🚀 Getting started
• 🤔 What is an ADR and why should you use them
• 📨 CI/CD configuration examples
• ❓ FAQ
  • What are the prerequisites?
  • Is Log4brains only for JS projects?
  • What about multi-package projects?
  • How to configure .log4brains.yml?
  • Is Log4brains also available as a Docker image?
• 📣 Your feedback is welcome!
• Contributing
• Acknowledgments
• License

🚀 Getting started

We recommend storing your Architecture Decision Records (ADR) next to the source code of your project, in the same git repository, to keep them in sync.

To get started, run these commands inside your project root folder:

npm install -g log4brains # if you want to install the latest beta version, run `npm install -g log4brains@beta` instead
log4brains init

It will ask you several questions to get Log4brains properly configured. It will also create the required template files and your first ADR as well. Then, you can start the web UI to preview your knowledge base locally:

log4brains preview

In this mode, the Hot Reload feature is enabled: any change you make to a markdown file from your IDE is applied live.

To create a new ADR from your template, run this command:

log4brains adr new

Get all the available commands and options by running log4brains --help.

Finally, do not forget to set up your CI/CD pipeline to automatically publish your knowledge base on a static website service like GitHub/GitLab Pages or S3.

🤔 What is an ADR and why should you use them

The term ADR became popular in 2011 with Michael Nygard's article: documenting architecture decisions. He aimed to reconcile Agile methods with software documentation by creating a very concise template to record functional or non-functional "architecturally significant" decisions in a lightweight format like markdown. The original template had only a few parts:

• Title: Which sums up the solved problem and its solution
• Context: Probably the essential part, which describes "the forces at play, including technological, political, social, and project local"
• Decision
• Status: Proposed, accepted, deprecated, superseded...
• Consequences: The positive and negative ones for the future of the project

There are other ADR templates like Y-Statements or MADR, which is the default one that is shipped with Log4brains.

As you can guess from the template above, an ADR is immutable. Only its status can change. Thanks to this, your documentation is never out-of-date! Yes, an ADR can be deprecated or superseded by another one, but it was at least true one day! And even if it's not the case anymore, it is still a precious piece of information.

This leads us to the main goals of this methodology:

• Avoid blind acceptance and blind reversal when you face past decisions
• Speed up the onboarding of new developers on a project
• Formalize a collaborative decision-making process

To learn more on this topic, I recommend you to read these great resources:

• Documenting architecture decisions, by Michael Nygard
• ADR GitHub organization, home of the MADR template, by Oliver Kopp and Olaf Zimmermann
• Collection of ADR templates and examples by Joel Parker Henderson

📨 CI/CD configuration examples

Log4brains lets you publish automatically your knowledge base on the static hosting service of your choice, thanks to the log4brains-web build command. Here are some configuration examples for the most common hosting services / CI runners.

First, create .github/workflows/publish-log4brains.yml and adapt it to your case:

name: Publish Log4brains
on:
  push:
    branches:
      - main
jobs:
  build-and-publish:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          persist-credentials: false # required by JamesIves/github-pages-deploy-action
          fetch-depth: 0 # required by Log4brains to work correctly (needs the whole Git history)
      - uses: actions/setup-node@v4
        with:
          node-version: lts/*
      - name: Install and Build Log4brains
        run: |
          npm install -g log4brains
          log4brains build --basePath /${GITHUB_REPOSITORY#*/}/log4brains
      - name: Deploy
        uses: JamesIves/[email protected]
        with:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          BRANCH: gh-pages
          FOLDER: .log4brains/out
          TARGET_FOLDER: log4brains

After the first run, this workflow will create a gh-pages branch in your repository containing the generated static files to serve. Then, we have to tell GitHub that we don't want to use Jekyll, otherwise, you will get a 404 error:

git checkout gh-pages
touch .nojekyll
git add .nojekyll
git commit -m "Add .nojekyll for Log4brains"
git push

Finally, you can enable your GitHub page:

• On GitHub, go to Settings > GitHub Pages
• Select the gh-pages branch as the "Source"
• Then, select the / (root) folder

You should now be able to see your knowledge base at https://<username>.github.io/<repository>/log4brains/. It will be re-built and published every time you push on main.

Create your .gitlab-ci.yml and adapt it to your case:

image: node:lts-alpine
pages:
  stage: deploy
  variables:
    GIT_DEPTH: 0 # required by Log4brains to work correctly (needs the whole Git history)
  script:
    - mkdir -p public
    - npm install -g --unsafe-perm log4brains
    - log4brains build --basePath /$CI_PROJECT_NAME/log4brains --out public/log4brains
  artifacts:
    paths:
      - public
  rules:
    - if: "$CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH"

You should now be able to see your knowledge base at https://<username>.gitlab.io/<repository>/log4brains/. It will be re-built and published every time you push on main.

First, create a bucket with the "Static website hosting" feature enabled:

# This is an example: replace with the bucket name of your choice
export BUCKET_NAME=yourcompany-yourproject-log4brains

aws s3api create-bucket --acl public-read --bucket ${BUCKET_NAME}
read -r -d '' BUCKET_POLICY << EOP
{
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": "*",
      "Action": "s3:GetObject",
      "Resource": "arn:aws:s3:::${BUCKET_NAME}/*"
    }
  ]
}
EOP
aws s3api put-bucket-policy --bucket ${BUCKET_NAME} --policy "$BUCKET_POLICY"
aws s3 website s3://${BUCKET_NAME} --index-document index.html

Then, configure your CI to run these commands:

• Install Node and the AWS CLI
• Checkout your Git repository with the full history. Otherwise, Log4brains won't work correctly (see previous examples)
• npm install -g log4brains
• log4brains build
• aws s3 sync .log4brains/out s3://<YOUR BUCKET> --delete

Your knowledge base will be available on http://<YOUR BUCKET>.s3-website-<YOUR REGION>.amazonaws.com/. You can get some inspiration on implementing this workflow for GitHub Actions or GitLab CI by looking at the previous examples.

Finally, you can add the ADR badge to your README.md!

❓ FAQ

What are the prerequisites?

• Node.js: active or maintenance LTS version (see Node.js release schedule; versions outside of this range are not guaranteed to work; "current" version is supported in a best effort mode)
• NPM or Yarn
• Git

Is Log4brains only for JS projects?

Of course not! Log4brains is developed with TypeScript and use NPM as a package manager. You need Node and NPM to be installed globally to run Log4brains, but it is designed to work for all kind of projects.

What about multi-package projects?

Log4brains supports both mono and multi packages projects. The log4brains init command will prompt you regarding this.

In the case of a multi-package project, you have two options:

• Mono-repository: in this case, just install Log4brains in the root folder. It will manage "global ADRs", for example in docs/adr and "package-specific ADRs", for example in packages/<package name>/docs/adr.
• One repository per package: in the future, Log4brains will handle this case with a central repository for the "global ADRs" while fetching "package-specifics ADRs" directly from each package repository. For the moment, all the ADRs have to be stored in a central repository.

Here is an example of a typical file structure for each case:

project-root
├── docs
|   └── adr
|       ├── 20200101-your-first-adr.md
|       ├── 20200115-your-second-adr.md
|       ├── [...]
|       ├── index.md
|       └── template.md
[...]

project-root
├── docs
|   └── adr
|       ├── 20200101-your-first-global-adr.md
|       ├── 20200115-your-second-global-adr.md
|       ├── [...]
|       ├── index.md
|       └── template.md
├── packages
|   ├── package1
|   |   ├── docs
|   |   |   └── adr
|   |   |       ├── 20200102-your-first-package-specific-adr.md
|   |   |       ├── 20200116-your-second-package-specific-adr.md
|   |   |       [...]
|   |   [...]
|   ├── package2
|   |   ├── docs
|   |   |   └── adr
|   |   |       ├── [...]
|   |   |       [...]
|   |   [...]
|   [...]
[...]

For the moment in one central repository (specific for the docs, or not):

project-docs
├── adr
|   ├── global
|   |   ├── 20200101-your-first-global-adr.md
|   |   ├── 20200115-your-second-global-adr.md
|   |   ├── [...]
|   |   ├── index.md
|   |   └── template.md
|   ├── package1
|   |   ├── 20200102-your-first-package-specific-adr.md
|   |   ├── 20200116-your-second-package-specific-adr.md
|   |   [...]
|   ├── package2
|   |   ├── [...]
|   |   [...]
|   [...]
[...]

In the future:

project-docs
├── adr
|   ├── 20200101-your-first-global-adr.md
|   ├── 20200115-your-second-global-adr.md
|   ├── [...]
|   ├── index.md
|   └── template.md
[...]

repo1
├── docs
|   └── adr
|       ├── 20200102-your-first-package-specific-adr.md
|       ├── 20200116-your-second-package-specific-adr.md
|       [...]
[...]

repo2
├── docs
|   └── adr
|       ├── [...]
|       [...]
[...]

How to configure .log4brains.yml?

This file is automatically created when you run log4brains init (cf getting started), but you may need to configure it manually.

Here is an example with just the required fields:

project:
  name: Foo Bar # The name that should be displayed in the UI
  tz: Europe/Paris # The timezone that you use for the dates in your ADR files
  adrFolder: ./docs/adr # The location of your ADR files

If you have multiple packages in your project, you may want to support package-specific ADRs by setting the optional project.packages field:

project:
  # [...]
  packages:
    - name: backend # The name (unique identifier) of the package
      path: ./packages/backend # The location of its codebase
      adrFolder: ./packages/backend/docs/adr # The location of its ADR files
#   - ...

Another optional field is project.repository, which is normally automatically guessed by Log4brains to create links to GitHub, GitLab, etc. But in some cases, like for GitHub or GitLab enterprise, you have to configure it manually:

project:
  #  [...]
  repository:
    url: https://github.com/foo/bar # Absolute URL of your repository
    provider: github # Supported providers: github, gitlab, bitbucket. Use `generic` if yours is not supported
    viewFileUriPattern: /blob/%branch/%path # Only required for `generic` providers

Is Log4brains also available as a Docker image?

Yes! https://hub.docker.com/r/thomvaill/log4brains

📣 Your feedback is welcome!

I had the idea of Log4brains based on my needs and my past experiences with ADRs, but it is now constantly evolving with your precious feedback. You are very welcome to create a new feedback in the Discussions or to reach out to me at [email protected]. Thanks a lot 🙏

Contributing

Pull Requests are more than welcome! Please read CONTRIBUTING.md for more details. You can also create a new issue or give your feedback.

Acknowledgments

• Next.js, which is used under the hood to provide the web UI and the static site generation capability (look for #NEXTJS-HACK in the code to see the custom adaptations we had to make)
• Michael Nygard for all his work on Architecture Decision Records
• Oliver Kopp and Olaf Zimmermann for the MADR template
• Joel Parker Henderson for his Collection of ADR templates and examples repository
• Tippawan Sookruay for the Log4brains logo
• @npryce, who inspired me for the CLI part with his adr-tools bash CLI
• @mrwilson, who inspired me for the static site generation part with his adr-viewer

License

This project is licensed under the Apache 2.0 license, Copyright (c) 2020 Thomas Vaillant. See the LICENSE file for more information.