Chapter 9: Building the Frontend with S3

1. Implement a Lambda function that takes the movie category as input and returns a list of movies that corresponds to that category.Answer:

func filter(category string)(events.APIGatewayProxyResponse, error) {
    ...

    filter: = expression.Name("category").Equal(expression.Value(category))
    projection: = expression.NamesList(expression.Name("id"), expression.Name("name"), expression.Name("description"))
    expr, err: = expression.NewBuilder().WithFilter(filter).WithProjection(projection).Build()
    if err != nil {
        return events.APIGatewayProxyResponse {
            StatusCode: http.StatusInternalServerError,
            Body: "Error while building DynamoDB expression",
        }, nil
    }

    svc: = dynamodb.New(cfg)
    req: = svc.ScanRequest( & dynamodb.ScanInput {
        TableName: aws.String(os.Getenv("TABLE_NAME")),
        ExpressionAttributeNames: expr.Names(),
        ExpressionAttributeValues: expr.Values(),
        FilterExpression: expr.Filter(),
        ProjectionExpression: expr.Projection(),
    })

    ...
}

2. Implement a Lambda function that takes a movie's title as input and returns all movies that have the keyword in their title.Answer:

func filter(keyword string) (events.APIGatewayProxyResponse, error) {
  ...

  filter := expression.Name("name").Contains(keyword)
  projection := expression.NamesList(expression.Name("id"), expression.Name("name"), expression.Name("description"))
  expr, err := expression.NewBuilder().WithFilter(filter).WithProjection(projection).Build()
  if err != nil {
    return events.APIGatewayProxyResponse{
      StatusCode: http.StatusInternalServerError,
      Body: "Error while building DynamoDB expression",
    }, nil
  }

  svc := dynamodb.New(cfg)
  req := svc.ScanRequest(&dynamodb.ScanInput{
    TableName: aws.String(os.Getenv("TABLE_NAME")),
    ExpressionAttributeNames: expr.Names(),
    ExpressionAttributeValues: expr.Values(),
    FilterExpression: expr.Filter(),
    ProjectionExpression: expr.Projection(),
  })
  ... 
}

3. Implement a delete button on the web application to delete a movie by calling the DeleteMovie Lambda function from API Gateway.

Answer: Update the MoviesAPI service to include the following function:

delete(id: string){
    return this.http
      .delete(`${environment.api}/${id}`, {headers: this.getHeaders()})
      .map(res => {
        return res
      })
}

4. Implement an edit button on the web application to allow the user to update movie attributes.Answer:

update(movie: Movie){
    return this.http
      .put(environment.api, JSON.stringify(movie), {headers: this.getHeaders()})
      .map(res => {
        return res
      })
}

5. Implement a CI/CD workflow with either CircleCI, Jenkins, or CodePipeline to automate the generation and deployment of the API Gateway documentation.Answer:

def bucket = 'movies-api-documentation'
def api_id = ''

node('slaves'){
  stage('Generate'){
    if (env.BRANCH_NAME == 'master') {
      sh "aws apigateway get-export --rest-api-id ${api_id} \
        --stage-name production \
        --export-type swagger swagger.json"
    }
    else if (env.BRANCH_NAME == 'preprod') {
      sh "aws apigateway get-export --rest-api-id ${api_id} \
        --stage-name staging \
        --export-type swagger swagger.json"
    } else {
      sh "aws apigateway get-export --rest-api-id ${api_id} \
        --stage-name sandbox \
        --export-type swagger swagger.json"
    }
  }

  stage('Publish'){
    sh "aws s3 cp swagger.json s3://${bucket}"
  }
}