API deployment and stages in AWS - Time & Space Complexity

Time Complexity: API deployment and stages

O(n)

Understanding Time Complexity

When deploying an API in AWS, we want to know how the time to deploy changes as we add more stages or APIs.

We ask: How does deployment time grow when we increase the number of stages or APIs?

Scenario Under Consideration

Analyze the time complexity of the following operation sequence.

# Create a new API
aws apigateway create-rest-api --name "MyAPI"

# For each stage, deploy the API
for stage in ["dev", "test", "prod"]:
  aws apigateway create-deployment --rest-api-id <api-id> --stage-name $stage

# Update stage settings if needed
aws apigateway update-stage --rest-api-id <api-id> --stage-name "prod" --patch-operations ...
    

This sequence creates an API, deploys it to multiple stages, and updates stage settings.

Identify Repeating Operations

Identify the API calls, resource provisioning, data transfers that repeat.

• Primary operation: The create-deployment call for each stage.
• How many times: Once per stage (e.g., 3 times for dev, test, prod).

How Execution Grows With Input

Each new stage requires a separate deployment call, so the total calls grow as the number of stages grows.

Input Size (n)	Approx. Api Calls/Operations
10 stages	10 deployment calls
100 stages	100 deployment calls
1000 stages	1000 deployment calls

Pattern observation: Deployment calls increase directly with the number of stages.

Final Time Complexity

Time Complexity: O(n)

This means deployment time grows in a straight line as you add more stages.

Common Mistake

[X] Wrong: "Deploying multiple stages happens all at once, so time stays the same."

[OK] Correct: Each stage requires its own deployment call, so time adds up with each stage.

Interview Connect

Understanding how deployment time scales helps you plan and explain API rollout strategies clearly and confidently.

Self-Check

"What if we deploy multiple APIs instead of stages? How would the time complexity change?"

Practice

1. What is the main purpose of an API stage in AWS API Gateway?

easy

A. To monitor network traffic outside AWS

B. To store API keys for users

C. To create backend Lambda functions

D. To manage different versions or environments of the API

Solution

1. Step 1: Understand API stages concept

   API stages in AWS API Gateway represent different versions or environments like development, testing, or production.

2. Step 2: Identify the role of stages

   Stages allow you to deploy and manage separate API versions independently.

3. Final Answer:

   To manage different versions or environments of the API -> Option D

4. Quick Check:

   API stages = version/environment management [OK]

Hint: Stages separate API versions or environments [OK]

Common Mistakes:

• Confusing stages with API keys
• Thinking stages create backend functions
• Assuming stages monitor external traffic

2. Which AWS CLI command is used to create a new deployment for an API Gateway REST API?

easy

A. aws apigateway create-deployment

B. aws apigateway create-stage

C. aws apigateway deploy-api

D. aws apigateway new-deployment

Solution

1. Step 1: Identify the correct AWS CLI command for deployment

   The command to create a deployment in API Gateway is create-deployment.

2. Step 2: Differentiate from other commands

   create-stage creates a stage, not a deployment. Other options are invalid commands.

3. Final Answer:

   aws apigateway create-deployment -> Option A

4. Quick Check:

   Deployment command = create-deployment [OK]

Hint: Deploy with 'create-deployment' command [OK]

Common Mistakes:

• Using create-stage instead of create-deployment
• Assuming deploy-api is a valid command
• Confusing deployment with stage creation

3. Given the following AWS CLI command:
aws apigateway create-stage --rest-api-id abc123 --stage-name prod --deployment-id dep456
What does this command do?

medium

A. Creates a new deployment named 'prod' for API 'abc123'

B. Creates a new stage 'prod' linked to deployment 'dep456' for API 'abc123'

C. Deletes the stage 'prod' from API 'abc123'

D. Updates the deployment 'dep456' with stage 'prod'

Solution

1. Step 1: Analyze the command parameters

   The command is create-stage with parameters for API ID, stage name, and deployment ID.

2. Step 2: Understand the effect of create-stage

   This creates a new stage named 'prod' that points to the deployment 'dep456' for the API 'abc123'.

3. Final Answer:

   Creates a new stage 'prod' linked to deployment 'dep456' for API 'abc123' -> Option B

4. Quick Check:

   create-stage + deployment-id = new stage linked to deployment [OK]

Hint: create-stage links stage to deployment by deployment-id [OK]

Common Mistakes:

• Confusing stage creation with deployment creation
• Thinking it deletes or updates instead
• Mixing up stage name and deployment ID

4. You ran this command to deploy your API stage:
aws apigateway create-stage --rest-api-id abc123 --stage-name test --deployment-id dep789
But you get an error saying the deployment ID does not exist. What is the likely cause?

medium

A. The deployment ID 'dep789' was not created before creating the stage

B. The stage name 'test' is invalid

C. The rest-api-id 'abc123' is incorrect format

D. You must create the stage before creating the deployment

Solution

1. Step 1: Understand the dependency between deployment and stage

   A stage must point to an existing deployment. If deployment ID does not exist, stage creation fails.

2. Step 2: Identify the error cause

   The error indicates deployment 'dep789' was not created or is invalid before stage creation.

3. Final Answer:

   The deployment ID 'dep789' was not created before creating the stage -> Option A

4. Quick Check:

   Stage needs existing deployment ID [OK]

Hint: Create deployment before stage with deployment ID [OK]

Common Mistakes:

• Assuming stage name format causes error
• Thinking API ID format is the issue
• Believing stage must be created before deployment

5. You want to deploy a new version of your API to a 'prod' stage without affecting the current live API. Which sequence of AWS CLI commands should you use?

hard

A. aws apigateway create-deployment -> aws apigateway create-stage with 'prod'

B. aws apigateway create-stage with 'prod' -> aws apigateway create-deployment

C. aws apigateway create-deployment -> aws apigateway update-stage with 'prod'

D. aws apigateway update-stage with 'prod' -> aws apigateway create-deployment

Solution

1. Step 1: Deploy new API version

   First, create a new deployment to capture the latest API changes.

2. Step 2: Update existing 'prod' stage to point to new deployment

   Use update-stage to switch the 'prod' stage to the new deployment without creating a new stage.

3. Final Answer:

   aws apigateway create-deployment -> aws apigateway update-stage with 'prod' -> Option C

4. Quick Check:

   Deploy then update stage to switch versions [OK]

Hint: Create deployment then update existing stage [OK]

Common Mistakes:

• Creating a new stage instead of updating existing
• Updating stage before deployment exists
• Assuming create-stage can update existing stage