Architectural Decision Records (ADRs)

Index of architectural decisions made for the WebGrip infrastructure repository.

What are ADRs?

Architectural Decision Records (ADRs) document important architectural decisions along with their context and consequences. They help teams:

• Track decision history and understand why choices were made
• Share context with new team members and contributors
• Revisit decisions when circumstances change
• Learn from past decisions to improve future choices

ADR Format

We use the MADR (Markdown Architectural Decision Records) format for consistency and clarity.

Template Structure

# [short title of solved problem and solution]

* Status: [proposed | rejected | accepted | deprecated | superseded by [ADR-0005](0005-example.md)]
* Deciders: [list everyone involved in the decision]
* Date: [YYYY-MM-DD when the decision was last updated]

## Context and Problem Statement

[Describe the context and problem statement, e.g., in free form using two to three sentences. You may want to articulate the problem in form of a question.]

## Decision Drivers

* [driver 1, e.g., a force, facing concern, …]
* [driver 2, e.g., a force, facing concern, …]
* … <!-- numbers of drivers can vary -->

## Considered Options

* [option 1]
* [option 2]
* [option 3]
* … <!-- numbers of options can vary -->

## Decision Outcome

Chosen option: "[option 1]", because [justification. e.g., only option, which meets k.o. criterion decision driver | which resolves force force | … | comes out best (see below)].

### Positive Consequences

* [e.g., improvement of quality attribute satisfaction, follow-up decisions required, …]
* …

### Negative Consequences

* [e.g., compromising quality attribute, follow-up decisions required, …]
* …

## Links

* [Link type] [Link to ADR] <!-- example: Refines [ADR-0005](0005-example.md) -->
* … <!-- numbers of links can vary -->

Current ADRs

Infrastructure Architecture

ADR	Title	Status	Date
ADR-0001	Docker Image Architecture and Organization	Accepted	2024-01-15
ADR-0002	CI/CD Workflow Strategy with Reusable Components	Accepted	2024-01-20
ADR-0003	Documentation Platform Selection (TechDocs)	Accepted	2024-01-25

Image Design Decisions

ADR	Title	Status	Date
ADR-0004	Base Image Selection Strategy	Accepted	2024-02-01
ADR-0005	Multi-stage Build Pattern Adoption	Accepted	2024-02-05
ADR-0006	Container Security Hardening Standards	Accepted	2024-02-10

Operational Decisions

ADR	Title	Status	Date
ADR-0007	Docker Registry Strategy and Management	Accepted	2024-02-15
ADR-0008	Testing Strategy for Infrastructure Images	Accepted	2024-02-20
ADR-0009	Maintenance and Update Automation	Proposed	2024-02-25

Creating New ADRs

When to Create an ADR

Create an ADR when making decisions that:

• Affect system architecture or overall design
• Have long-term impact on the project
• Involve trade-offs between different approaches
• Change existing patterns or standards
• Require team consensus to move forward

Process

1. Identify the Decision: Recognize that an architectural decision needs to be made
2. Research Options: Investigate different approaches and their trade-offs
3. Draft ADR: Create a new ADR using the template
4. Gather Input: Share with team members and stakeholders for feedback
5. Make Decision: Finalize the decision and update the ADR status
6. Communicate: Share the decision with relevant teams

Naming Convention

ADRs are numbered sequentially and use descriptive titles:

NNNN-short-descriptive-title.md

Examples: - 0001-docker-image-architecture.md - 0010-monitoring-and-alerting-strategy.md - 0015-dependency-management-approach.md

File Location

ADRs are stored in the docs/adrs/ directory:

docs/adrs/
├── 0001-docker-image-architecture.md
├── 0002-ci-cd-workflow-strategy.md
├── 0003-documentation-platform.md
└── template.md

ADR Lifecycle

Status Transitions

flowchart TD
    DRAFT[Draft] --> PROPOSED[Proposed]
    PROPOSED --> ACCEPTED[Accepted]
    PROPOSED --> REJECTED[Rejected]
    ACCEPTED --> DEPRECATED[Deprecated]
    ACCEPTED --> SUPERSEDED[Superseded]

    PROPOSED --> DRAFT
    REJECTED --> DRAFT

Draft: Initial version being developed Proposed: Ready for review and decision Accepted: Decision has been made and is being implemented Rejected: Decision was considered but not adopted Deprecated: Decision is no longer recommended but not replaced Superseded: Decision has been replaced by a newer ADR

Reviewing ADRs

ADRs should be reviewed:

• Quarterly: Review all current ADRs for relevance and accuracy
• When circumstances change: Major technology shifts or requirement changes
• Before major decisions: Ensure new decisions align with existing ADRs
• During onboarding: Help new team members understand architectural context

Using ADRs in Development

Referencing ADRs

When making implementation decisions, reference relevant ADRs:

<!-- In pull request descriptions -->
This change implements the multi-stage build pattern as decided in [ADR-0005](docs/adrs/0005-multi-stage-builds.md).

<!-- In code comments -->
// Following the security hardening standards from ADR-0006
USER appuser

Updating Implementation

When ADR decisions affect implementation:

1. Review existing code for compliance with ADR decisions
2. Update implementation to align with architectural decisions
3. Document deviations if full compliance isn't immediately possible
4. Plan migration for systems that don't yet follow ADR guidelines

Tools and Automation

ADR Management

#!/bin/bash
# scripts/adr-tools.sh

# Create new ADR
create_adr() {
    local title="$1"
    local number=$(printf "%04d" $(($(ls docs/adrs/ | grep -E '^[0-9]{4}-' | wc -l) + 1)))
    local filename="docs/adrs/${number}-${title}.md"

    # Copy template and update
    cp docs/adrs/template.md "$filename"
    sed -i "s/\[short title of solved problem and solution\]/$title/" "$filename"
    sed -i "s/Date: \[YYYY-MM-DD when the decision was last updated\]/Date: $(date +%Y-%m-%d)/" "$filename"

    echo "Created ADR: $filename"
}

# List ADRs by status
list_adrs() {
    local status="$1"
    echo "ADRs with status: $status"
    grep -l "Status:.*$status" docs/adrs/*.md | sort
}

# Validate ADRs
validate_adrs() {
    echo "Validating ADR format..."

    for adr in docs/adrs/[0-9]*.md; do
        if ! grep -q "^# " "$adr"; then
            echo "❌ $adr: Missing title"
        fi

        if ! grep -q "Status:" "$adr"; then
            echo "❌ $adr: Missing status"
        fi

        if ! grep -q "Date:" "$adr"; then
            echo "❌ $adr: Missing date"
        fi
    done

    echo "ADR validation complete"
}

# Usage
case "$1" in
    "create")
        create_adr "$2"
        ;;
    "list")
        list_adrs "$2"
        ;;
    "validate")
        validate_adrs
        ;;
    *)
        echo "Usage: $0 {create|list|validate} [args]"
        ;;
esac

Integration with Documentation

ADRs are automatically included in the TechDocs site navigation and can be referenced from other documentation pages.

GitHub Integration

# .github/workflows/adr-validation.yml
name: ADR Validation
on:
  pull_request:
    paths:
      - 'docs/adrs/**'

jobs:
  validate:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Validate ADR format
        run: ./scripts/adr-tools.sh validate

      - name: Check for duplicate numbers
        run: |
          duplicates=$(ls docs/adrs/[0-9]*.md | sed 's/.*\/\([0-9]*\)-.*/\1/' | sort | uniq -d)
          if [[ -n "$duplicates" ]]; then
            echo "❌ Duplicate ADR numbers found: $duplicates"
            exit 1
          fi

      - name: Validate links
        run: |
          # Check that all ADR links are valid
          find docs/adrs -name "*.md" -exec markdown-link-check {} \;

Best Practices

Writing Effective ADRs

1. Be Specific: Focus on one architectural decision per ADR
2. Include Context: Explain the problem and constraints clearly
3. Compare Options: Show what alternatives were considered
4. Document Trade-offs: Explain both positive and negative consequences
5. Keep Updated: Update status and content as decisions evolve

Decision Process

1. Involve Stakeholders: Include relevant team members in decision-making
2. Time-box Decisions: Set deadlines to avoid endless discussion
3. Document Assumptions: Make implicit assumptions explicit
4. Plan Reviews: Schedule regular reviews of important decisions
5. Learn from Outcomes: Track how decisions work out in practice

Maintenance

1. Regular Reviews: Review ADRs quarterly for relevance
2. Update Status: Keep status information current
3. Link Maintenance: Ensure all links remain valid
4. Archive Old ADRs: Mark superseded ADRs clearly
5. Extract Patterns: Identify common decision patterns over time

Contributing to ADRs

Proposing New ADRs

1. Create Issue: Start with a GitHub issue to discuss the need for an ADR
2. Draft ADR: Create initial draft using the template
3. Seek Feedback: Share with team members for input
4. Iterate: Refine the ADR based on feedback
5. Finalize: Update status to "Accepted" after team agreement

Improving Existing ADRs

1. Identify Gaps: Notice missing information or outdated content
2. Propose Changes: Create pull request with improvements
3. Update Status: Change status if decision has evolved
4. Add Links: Connect related ADRs for better navigation
5. Enhance Context: Add more background information if helpful

Related Documentation

• Architecture Overview - High-level architectural context
• Contributing Images - How architectural decisions affect contributions
• Maintenance - How ADRs guide maintenance decisions

Templates and Examples

• ADR Template - Standard template for new ADRs
• Example ADRs - Real examples from this project
• MADR Documentation - Detailed format specification

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Note: ADRs are living documents that should evolve with the project. Regular review and updates ensure they remain valuable for decision-making and knowledge sharing.

Maintainer: WebGrip Ops Team
Location: docs/adrs/
Format: MADR (Markdown ADR)