Architecture decision records (ADR) in Microservices - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an Architecture Decision Record (ADR)?

An ADR is a document that captures important architectural decisions made during a project. It explains the decision, the reasons behind it, and its consequences.

beginner

Why are ADRs important in microservices architecture?

ADRs help teams keep track of why certain design choices were made, making it easier to understand, maintain, and evolve microservices over time.

intermediate

What key elements should an ADR contain?

An ADR should include: the decision title, context, the decision itself, alternatives considered, and the consequences of the decision.

beginner

How does an ADR help new team members?

It provides clear explanations of past decisions, helping new members understand the system design without needing lengthy meetings or guesswork.

intermediate

When should an ADR be created?

An ADR should be created whenever a significant architectural decision is made that affects the system's design or behavior.

What does an ADR primarily document?

A User interface designs

B Architectural decisions and their reasons

C Code implementation details

D Testing procedures

ADRs focus on documenting architectural decisions and why they were made.

Which of the following is NOT typically part of an ADR?

A Decision title

B Context and background

C Consequences of the decision

D Code snippets

Code snippets are usually not included in ADRs; ADRs focus on decisions and reasoning.

When is the best time to write an ADR?

A At the end of the project

B Only when problems occur

C After a major architectural decision is made

D Before starting any work

ADRs should be written right after important architectural decisions to capture context and reasoning.

How do ADRs benefit microservices teams?

A By tracking architectural decisions for clarity and future reference

B By replacing all documentation

C By automating deployment

D By managing user accounts

ADRs help teams understand past decisions, improving clarity and maintenance.

Which is a common consequence documented in an ADR?

A Impact on system scalability

B User feedback scores

C Marketing strategies

D Employee schedules

ADRs document consequences like how a decision affects scalability, performance, or maintainability.

Explain what an Architecture Decision Record (ADR) is and why it is useful in microservices.

Think about how teams remember important design choices.

Describe the typical structure of an ADR and what each part contains.

Consider the story an ADR tells about a decision.

Practice

1. What is the main purpose of an Architecture Decision Record (ADR) in microservices projects?

easy

A. To document important architecture decisions and their reasons

B. To write detailed code for each microservice

C. To track bugs and issues in the system

D. To monitor server performance metrics

Solution

1. Step 1: Understand the role of ADRs

   ADRs are used to record key architecture decisions and why they were made.

2. Step 2: Differentiate ADRs from other documents

   ADRs are not for code, bugs, or performance monitoring but for decision documentation.

3. Final Answer:

   To document important architecture decisions and their reasons -> Option A

4. Quick Check:

   Purpose of ADR = Document decisions [OK]

Hint: ADRs capture decisions, not code or bugs [OK]

Common Mistakes:

• Confusing ADRs with bug tracking
• Thinking ADRs are code documentation
• Assuming ADRs monitor system metrics

2. Which of the following is the correct basic structure of an ADR document?

easy

A. Title, Status, Context, Decision, Consequences

B. Title, Code, Tests, Deployment, Logs

C. Summary, Bugs, Fixes, Performance, Metrics

D. Introduction, User Stories, UI Design, API Endpoints

Solution

1. Step 1: Recall ADR standard sections

   ADRs typically include Title, Status, Context, Decision, and Consequences.

2. Step 2: Eliminate unrelated structures

   Options with code, bugs, or UI design are unrelated to ADR format.

3. Final Answer:

   Title, Status, Context, Decision, Consequences -> Option A

4. Quick Check:

   ADR structure = Title, Status, Context, Decision, Consequences [OK]

Hint: Look for Context and Consequences in ADR structure [OK]

Common Mistakes:

• Mixing ADR with test or deployment docs
• Confusing ADR with bug reports
• Including UI design in ADR

3. Given this ADR excerpt:

Title: Use REST for service communication
Status: Accepted
Context: Need simple, stateless communication
Decision: Use REST over HTTP
Consequences: Easier integration but higher latency

What is the main consequence documented here?

medium

A. REST requires stateful connections for speed

B. REST causes stateless communication to fail

C. REST reduces integration complexity and latency

D. REST leads to easier integration but higher latency

Solution

1. Step 1: Read the Consequences section carefully

   The consequence states "Easier integration but higher latency".

2. Step 2: Match the consequence with options

   REST leads to easier integration but higher latency matches exactly; others contradict the text.

3. Final Answer:

   REST leads to easier integration but higher latency -> Option D

4. Quick Check:

   Consequence = Easier integration, higher latency [OK]

Hint: Focus on Consequences section for effects [OK]

Common Mistakes:

• Ignoring the 'higher latency' part
• Assuming REST reduces latency
• Confusing stateless with stateful

4. You find an ADR with this status:

Status: Deprecated

What does this status indicate about the decision?

medium

A. The decision is newly proposed and under review

B. The decision is no longer recommended or used

C. The decision is currently active and enforced

D. The decision has been accepted but not implemented yet

Solution

1. Step 1: Understand ADR status meanings

   "Deprecated" means the decision is outdated and should not be used.

2. Step 2: Compare with other statuses

   New proposals are "Proposed", active ones "Accepted", so deprecated means no longer recommended.

3. Final Answer:

   The decision is no longer recommended or used -> Option B

4. Quick Check:

   Status 'Deprecated' = Not recommended [OK]

Hint: Deprecated means outdated, avoid using [OK]

Common Mistakes:

• Confusing deprecated with accepted
• Thinking deprecated means new proposal
• Assuming deprecated means pending

5. Your team must decide between using REST or gRPC for microservice communication. You want to document this choice clearly for future reference. Which is the best way to use an ADR in this situation?

hard

A. Write code samples for both REST and gRPC without explanation

B. Skip documentation and decide by majority vote only

C. Write an ADR with Context explaining needs, Decision stating REST or gRPC, and Consequences of each choice

D. Create a bug report to track this decision

Solution

1. Step 1: Identify ADR purpose for decision documentation

   ADRs should explain context, decision, and consequences clearly.

2. Step 2: Evaluate options for documenting architecture choices

   Only Write an ADR with Context explaining needs, Decision stating REST or gRPC, and Consequences of each choice uses ADR properly; others ignore documentation or misuse formats.

3. Final Answer:

   Write an ADR with Context explaining needs, Decision stating REST or gRPC, and Consequences of each choice -> Option C

4. Quick Check:

   Use ADR to document decision and consequences [OK]

Hint: Use ADR to record context, decision, and consequences [OK]

Common Mistakes:

• Skipping documentation
• Confusing ADR with bug reports
• Only writing code without explanation