Let's create the same API that we created in the previous recipe, but do it by using a CloudFormation template, and then deploy it using the AWS CLI. Finally, we will invoke the API from a browser. The CLI commands corresponding to the CloudFormation template components were already discussed in the previous recipe:

1. Start by defining the template with AWSTemplateFormatVersion and a description, as follows:

---
AWSTemplateFormatVersion: '2010-09-09'
Description: Building API with AWS CloudFormation

2. Define our REST API with the resource type AWS::ApiGateway::RestApi, as follows:

Resources:
 MyFirstRestAPI:
 Type: AWS::ApiGateway::RestApi
 Properties:
 Name: Greeting API
      Description: API for greeting an user
      FailOnWarnings: true

3. Define the parent resource, greeting, under the root path, using the type AWS::ApiGateway::Resource:

GreetingResource:
  Type: AWS::ApiGateway::Resource
  Properties:
    RestApiId: !Ref MyFirstRestAPI
    ParentId: !GetAtt MyFirstRestAPI.RootResourceId
    PathPart: 'greeting'

4. Define a path parameter resource under greeting by using the type AWS::ApiGateway::Resource:

NamePathParamResource:
  Type: AWS::ApiGateway::Resource
  Properties:
    RestApiId: !Ref MyFirstRestAPI
    ParentId: !Ref GreetingResource
    PathPart: '{name}'

5. Create the method configuration with the resource type AWS::ApiGateway::Method, as follows:

MyMockMethod:
  Type: AWS::ApiGateway::Method
  Properties:
    AuthorizationType: NONE
    HttpMethod: GET
    Integration:
      Type: MOCK
      IntegrationHttpMethod: GET
      IntegrationResponses:
      - StatusCode: 200
        ResponseTemplates:
          application/json: "{"message": "Hello $input.params('name')" }"
      RequestTemplates:
        application/json: "{"statusCode": 200}"
    ResourceId: !Ref NamePathParamResource
    RestApiId: !Ref MyFirstRestAPI
    MethodResponses:
    - StatusCode: 200

The CloudFormation template combines multiple CLI commands (put-method, put-method-response, put-integration, and put-integration-response) into a single and simple configuration. 

6. Deploy our application using the resource type AWS::ApiGateway::Deployment, as follows:

MyFirstDeployment:
  DependsOn: MyMockMethod
  Type: AWS::ApiGateway::Deployment
  Properties:
    Description: 'First Deployment'
    RestApiId: !Ref MyFirstRestAPI
    StageDescription:
      Description: 'Dev Stage'
    StageName: 'dev'

We have to specify that our Deployment resource depends on our Method resource, by using DependsOn. Otherwise, the Deployment resource may be executed before the Method resource. 

7. Add an Outputs section to return the final URL for our REST API:

Outputs:
  SampleEndpoint:
    Description: 'Sample Endpoint'
    Value: !Sub
        - https://${API_ID}.execute-api.${AWS::Region}.amazonaws.com/dev/greeting/Heartin
        - API_ID: !Ref MyFirstRestAPI

Here, we use the intrinsic function Sub to create the final endpoint, using the pseudo-variable AWS::Region and the intrinsic function Ref.

8. Create a cloudformation stack with our template, as follows:

aws cloudformation create-stack 
    --stack-name myteststack 
    --template-body file://your-first-rest-api-with-api-gateway-cf.yml 
    --region us-east-1 
    --profile admin

Here, I have used the template-body option to read the template file from the local machine. You can use the template-url option to read the template file from an S3 bucket. 

The create-stack command will immediately return a stack-id, which we can use to check the stack creation status and delete the stack. We can also use the stack names for these operations:

9. Check the status of the stack creation by using the describe-stacks sub-command, until it shows CREATE_COMPLETE:

aws cloudformation describe-stacks 
    --stack-name myteststack 
    --region us-east-1 
    --profile admin

The describe-stacks command returns the current status of the stack (for example, CREATE_IN_PROGRESS, CREATE_COMPLETE, or DELETE_COMPLETE). If the stack creation completes successfully, it will return a status of <sphttps://packt-type-cloud.s3.amazonaws.com/uploads/sites/2819/2019/01/86d4cc9e-1a66-4aa3-ba42-f0d5dc363b52.pngan>CREATE_COMPLETE, along with the Outputs section with our sample URL:

You can verify the API by going to the URL in a browser. It should print the message Hello Heartin, as follows:

10. You can delete the stack, and all of the resources that it created will automatically be cleaned up:

aws cloudformation delete-stack 
    --stack-name myteststack 
    --region us-east-1 
    --profile admin