Canary deployment in Microservices - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the percentage of traffic routed to the new version in a canary deployment.

Microservices

canary_traffic_percentage = [1]

Drag options to blanks, or click blank then click option'

A10

B100

C0

D50

Attempts:

3 left

💡 Hint

Common Mistakes

Setting traffic to 100% immediately defeats the purpose of canary.

Using 0% means no traffic reaches the new version.

In canary deployment, a small percentage like 10% of traffic is routed to the new version initially to test it safely.

2fill in blank

medium

Complete the code to check if the canary deployment is healthy before increasing traffic.

Microservices

if canary_health_status == [1]:
    increase_traffic()

Drag options to blanks, or click blank then click option'

A"healthy"

B"degraded"

C"failed"

D"unknown"

Attempts:

3 left

💡 Hint

Common Mistakes

Increasing traffic when status is 'failed' or 'degraded' causes errors.

Using 'unknown' status is unsafe.

Traffic should only be increased if the canary deployment is healthy.

3fill in blank

hard

Fix the error in the traffic routing rule to send 20% traffic to the canary version.

Microservices

route_traffic(canary_version, percentage=[1])

Drag options to blanks, or click blank then click option'

A200

B"20%"

C20

D0.2

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0.2 may be interpreted as 0.2%.

Using '20%' as a string may cause errors.

Using 200 exceeds 100%.

The percentage should be an integer representing 20%, not a decimal or string.

4fill in blank

hard

Fill both blanks to define a canary deployment function that routes traffic and monitors health.

Microservices

def canary_deploy(version, traffic_percentage):
    route_traffic(version, percentage=[1])
    status = check_health(version)
    if status == [2]:
        return "Canary is healthy"
    else:
        return "Canary failed"

Drag options to blanks, or click blank then click option'

Atraffic_percentage

B"healthy"

C"failed"

Dversion

Attempts:

3 left

💡 Hint

Common Mistakes

Hardcoding traffic percentage instead of using the argument.

Checking for 'failed' instead of 'healthy' to confirm success.

The function routes the given traffic percentage to the version and checks if the health status is 'healthy'.

5fill in blank

hard

Fill all three blanks to implement a canary deployment loop that gradually increases traffic.

Microservices

traffic = [1]
while traffic <= 100:
    route_traffic('canary', percentage=traffic)
    health = check_health('canary')
    if health != [2]:
        rollback('canary')
        break
    traffic += [3]

Drag options to blanks, or click blank then click option'

A10

B"healthy"

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Starting traffic at 5% but increasing by 10% causes uneven steps.

Checking for health not equal to 'healthy' incorrectly.

Increasing traffic by 5% instead of 10% may slow rollout.

The loop starts traffic at 10%, checks health, rolls back if unhealthy, and increases traffic by 10% each iteration.

Practice

1. What is the main purpose of a canary deployment in microservices?

easy

A. To permanently run two versions side by side

B. To deploy all users to a new version at once

C. To release a new version to a small group of users first to reduce risk

D. To test the new version only in a development environment

Solution

1. Step 1: Understand the goal of canary deployment

   Canary deployment aims to reduce risk by releasing new software versions to a small subset of users first.

2. Step 2: Compare options with this goal

   To release a new version to a small group of users first to reduce risk matches this goal exactly, while others describe different deployment strategies.

3. Final Answer:

   To release a new version to a small group of users first to reduce risk -> Option C

4. Quick Check:

   Canary deployment = gradual rollout [OK]

Hint: Canary means small test group first, not all users [OK]

Common Mistakes:

• Confusing canary with blue-green deployment
• Thinking canary deploys to all users at once
• Assuming canary is only for testing environments

2. Which of the following is the correct way to control traffic during a canary deployment?

easy

A. Send 100% of traffic to the new version immediately

B. Route a small percentage of traffic to the new version and the rest to the old

C. Stop all traffic during deployment

D. Send traffic randomly without control

Solution

1. Step 1: Understand traffic control in canary deployment

   Traffic is gradually shifted to the new version to monitor its behavior safely.

2. Step 2: Identify the correct traffic routing method

   Route a small percentage of traffic to the new version and the rest to the old describes routing a small percentage to the new version while keeping most on the old version, which is correct.

3. Final Answer:

   Route a small percentage of traffic to the new version and the rest to the old -> Option B

4. Quick Check:

   Traffic control = gradual routing [OK]

Hint: Gradually shift traffic, never 100% at once [OK]

Common Mistakes:

• Sending all traffic immediately to new version
• Stopping traffic completely during deployment
• Ignoring traffic routing control

3. Consider this simplified code snippet for traffic routing in a canary deployment:

def route_request(user_id):
    if user_id % 10 == 0:
        return "new_version"
    else:
        return "old_version"

print(route_request(20))
print(route_request(23))

What will be the output?

medium

A. "new_version" followed by "old_version"

B. "new_version" followed by "new_version"

C. "old_version" followed by "old_version"

D. "old_version" followed by "new_version"

Solution

1. Step 1: Evaluate route_request(20)

   20 % 10 equals 0, so it returns "new_version".

2. Step 2: Evaluate route_request(23)

   23 % 10 equals 3, not 0, so it returns "old_version".

3. Final Answer:

   "new_version" followed by "old_version" -> Option A

4. Quick Check:

   Modulo 10 == 0 routes to new version [OK]

Hint: Check modulo condition carefully for routing [OK]

Common Mistakes:

• Misunderstanding modulo operator
• Assuming all users go to new version
• Mixing output order

4. A team implemented a canary deployment but noticed that 100% of users are routed to the new version immediately. What is the most likely cause?

medium

A. Traffic routing logic sends all traffic to new version without percentage control

B. Monitoring tools are not enabled

C. Rollback was triggered accidentally

D. Old version servers are down

Solution

1. Step 1: Analyze the symptom

   All users routed to new version immediately means no gradual traffic control.

2. Step 2: Identify the cause

   Traffic routing logic sends all traffic to new version without percentage control explains that routing logic lacks percentage control, causing full traffic shift.

3. Final Answer:

   Traffic routing logic sends all traffic to new version without percentage control -> Option A

4. Quick Check:

   Immediate full traffic = missing gradual routing [OK]

Hint: Check traffic routing code for percentage control [OK]

Common Mistakes:

• Blaming monitoring tools for routing issues
• Assuming rollback causes full traffic shift
• Ignoring server status impact

5. You want to design a canary deployment system that automatically rolls back if error rates exceed 5% during rollout. Which combination of components is essential?

hard

A. Load balancer, static routing, manual rollback process

B. Manual deployment script, user feedback form, database backup

C. Continuous integration server, code linter, version control

D. Traffic router, monitoring system, automated rollback controller

Solution

1. Step 1: Identify components for traffic control and monitoring

   A traffic router directs user requests between old and new versions; monitoring system tracks error rates.

2. Step 2: Include automated rollback for quick response

   An automated rollback controller triggers rollback if error thresholds are exceeded.

3. Final Answer:

   Traffic router, monitoring system, automated rollback controller -> Option D

4. Quick Check:

   Canary needs routing + monitoring + rollback [OK]

Hint: Combine routing, monitoring, and rollback for safe canary [OK]

Common Mistakes:

• Ignoring automation in rollback
• Confusing deployment tools with monitoring
• Missing traffic routing component