Serverless - Deploying Applications with AWS SAM > Config APIs And Lambda Function

Config APIs And Lambda Function

Add the following code to template.yaml file in sam project. This code block describe a DynamoDB table with a Partition key - user id and a Sort key - file name.

  # Create a table to storage document informations
  DocsTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: Documents
      BillingMode: PAY_PER_REQUEST
      AttributeDefinitions:
        - AttributeName: user_id
          AttributeType: S
        - AttributeName: file
          AttributeType: S
      KeySchema:
        - AttributeName: user_id
          KeyType: HASH
        - AttributeName: file
          KeyType: RANGE
      StreamSpecification:
        StreamViewType: NEW_IMAGE

  # Create a table to storage general informations
  GeneralTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: General
      BillingMode: PAY_PER_REQUEST
      AttributeDefinitions:
        - AttributeName: id
          AttributeType: S
      KeySchema:
        - AttributeName: id
          KeyType: HASH

CreateLambda

Add the following code to template.yaml file to config 5 lambda functions:
- upload_doc
- list_docs
- delete_doc
- upload_general_infor
- get_general_infor

  # Lambda function to scan all document by user id
  DocsList:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: lambda/list_docs
      Handler: list_docs.lambda_handler
      Runtime: python3.9
      FunctionName: list_docs
      Architectures:
        - x86_64
      Policies:
        - Statement:
            - Sid: ReadDynamoDB
              Effect: Allow
              Action:
                - dynamodb:Scan
                - dynamodb:Query
              Resource:
                - !GetAtt DocsTable.Arn
      Events:
        ListDocs:
          Type: Api
          Properties:
            Path: /docs/{id}
            Method: get
            RestApiId: !Ref DocApi
      Environment:
        Variables:
          TABLE_NAME: !Ref DocsTable

  # Lambda function to upload documents
  DocsUpload:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: lambda/upload_doc
      Handler: upload_doc.lambda_handler
      Runtime: python3.9
      FunctionName: upload_doc
      Architectures:
        - x86_64
      Policies:
        - Statement:
            - Sid: WriteToDynamoDB
              Effect: Allow
              Action:
                - dynamodb:PutItem
              Resource:
                - !GetAtt DocsTable.Arn
      Events:
        UpoadDocs:
          Type: Api
          Properties:
            Path: /docs
            Method: post
            RestApiId: !Ref DocApi
      Environment:
        Variables:
          TZ: Asia/Jakarta
          TABLE_NAME: !Ref DocsTable

  # Lambda function to delete documents by user id
  DocsDelete:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: lambda/delete_doc
      Handler: delete_doc.lambda_handler
      Runtime: python3.9
      FunctionName: delete_doc
      Architectures:
        - x86_64
      Policies:
        - Statement:
          - Sid: DeleteItems
            Effect: Allow
            Action:
              - dynamodb:DeleteItem
              - dynamodb:GetItem
              - dynamodb:Query
            Resource:
              - !GetAtt DocsTable.Arn
      Events:
        DeleteDoc:
          Type: Api
          Properties:
            Path: /docs/{id}
            Method: delete
            RestApiId: !Ref DocApi
      Environment:
        Variables:
          TABLE_NAME: !Ref DocsTable

  GeneralInforUpload:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: lambda/upload_general_infor
      Handler: upload_general_infor.lambda_handler
      Runtime: python3.9
      FunctionName: upload_general_infor
      Architectures:
        - x86_64
      Policies:
        - Statement:
          - Sid: DeleteItems
            Effect: Allow
            Action:
              - dynamodb:PutItem
            Resource:
              - !GetAtt GeneralTable.Arn
      Events:
        DeleteDoc:
          Type: Api
          Properties:
            Path: /docs/{id}/gen/
            Method: post
            RestApiId: !Ref DocApi
      Environment:
        Variables:
          TABLE_NAME: !Ref GeneralTable

  GeneralInforGet:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: lambda/get_general_infor
      Handler: get_general_infor.lambda_handler
      Runtime: python3.9
      FunctionName: get_general_infor
      Architectures:
        - x86_64
      Policies:
        - Statement:
          - Sid: DeleteItems
            Effect: Allow
            Action:
              - dynamodb:GetItem
              - dynamodb:Query
            Resource:
              - !GetAtt GeneralTable.Arn
      Events:
        DeleteDoc:
          Type: Api
          Properties:
            Path: /docs/{id}/gen/
            Method: get
            RestApiId: !Ref DocApi
      Environment:
        Variables:
          TABLE_NAME: !Ref GeneralTable

CreateLambda

Download the following file and add it to the root directory of the sam project. This file describes the APIs that we need.

Swagger

swagger.yaml (6 ko)

CreateLambda

Add the following code block to the bottom of template.yaml file to import swagger.yaml file.

  # Create REST Api
  DocApi:
    Type: AWS::Serverless::Api
    Properties:
      StageName: dev
      DefinitionBody:
        'Fn::Transform':
          Name: 'AWS::Include'
          Parameters:
            Location: "./swagger.yaml"

CreateLambda

Create folder and file: lambda/list_docs/list_docs.py
Add the following code block to list_docs.py file

import json
import boto3
import os
from decimal import *
from boto3.dynamodb.types import TypeDeserializer

dynamodb = boto3.client('dynamodb') 
serializer = TypeDeserializer()

class DecimalEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, Decimal):
            return str(obj)
        return json.JSONEncoder.default(self, obj)

def deserialize(data):
    if isinstance(data, list):
        return [deserialize(v) for v in data]

    if isinstance(data, dict):
        try:
            return serializer.deserialize(data)
        except TypeError:
            return {k: deserialize(v) for k, v in data.items()}
    else:
        return data
        
def lambda_handler(event, context):
    table_name = os.environ['TABLE_NAME']
    user_id = event['pathParameters']['id']
    print(user_id)
    docs = dynamodb.query(
        TableName=table_name,
        KeyConditionExpression="user_id = :id",
        ExpressionAttributeValues={ ":id": { 'S': user_id } }
    )
    
    format_data_docs = deserialize(docs["Items"])
    # TODO implement
    return {
        "statusCode": 200,
        "headers": {
            "Content-Type": "application/json",
            "Access-Control-Allow-Origin": "*",
            "Access-Control-Allow-Methods": "GET,PUT,POST,DELETE, OPTIONS",
            "Access-Control-Allow-Headers": "Access-Control-Allow-Headers, Origin,Accept, X-Requested-With, Content-Type, Access-Control-Request-Method,X-Access-Token,XKey,Authorization"
        },
        "body": json.dumps(format_data_docs, cls=DecimalEncoder)
    }

CreateLambda

Similarly, create upload_doc/upload_doc.py folder and file in lambda folder. Next copy the code below for the created file.

import json
import boto3
import os
from datetime import datetime, timezone

dynamodb = boto3.resource('dynamodb')
client_cloudwatch = boto3.client('cloudwatch')

def lambda_handler(event, context):
    table_name = os.environ['TABLE_NAME']
    now = datetime.now(tz=timezone.utc)
    dt_string = now.strftime("%d/%m/%Y %H:%M:%S")
    doc_data = json.loads(event["body"])

    path = "protected/{}/{}".format(doc_data['identityId'], doc_data['file'])
    doc_data.update({"path": path, "modified": dt_string})
    table = dynamodb.Table(table_name)
    table.put_item(Item = doc_data)
        
    # TODO implement
    return {
        'statusCode': 200,
        'body': 'successfully upload!',
        'headers': {
            'Content-Type': 'application/json',
            "Access-Control-Allow-Headers": "Access-Control-Allow-Headers, Origin, Accept, X-Requested-With, Content-Type, Access-Control-Request-Method,X-Access-Token, XKey, Authorization",
            "Access-Control-Allow-Origin": "*",
            "Access-Control-Allow-Methods": "GET,PUT,POST,DELETE,OPTIONS"
        }
    }

CreateLambda

Similar with lambda/delete_doc/delete_doc.py file.

import json
import boto3
import os

client = boto3.resource('dynamodb')

def lambda_handler(event, context):
    # TODO implement
    table_name = os.environ['TABLE_NAME']
    error = None
    doc_pk = event['pathParameters']['id']
    print("doc_pk ", doc_pk)
    doc_sk = event['queryStringParameters']['file']
    print("doc_sk ", doc_sk)
    table = client.Table(table_name)
    key = {
        'user_id':doc_pk,
        'file':  doc_sk
    }
    
    try:
        table.delete_item(Key = key)
    except Exception as e:
        error = e
        
        
    except Exception as e:
        error = e
        
    if error is None:
        message = 'successfully document item!'
    else:
        print(error)
        message = 'delete document fail'
    
    return {
            'statusCode': 200,
            'body': message,
            'headers': {
                'Content-Type': 'application/json',
                'Access-Control-Allow-Origin': '*'
            },
        }

CreateLambda

Similar with lambda/upload_general_infor/upload_general_infor.py file.

import json
import boto3
import os

dynamodb = boto3.resource('dynamodb')

def lambda_handler(event, context):
    table_name = os.environ['TABLE_NAME']
    data = json.loads(event["body"])
    table = dynamodb.Table(table_name)
    data.update({"id": event['pathParameters']['id']})
    table.put_item(Item = data)

    # TODO implement
    return {
        'statusCode': 200,
        'body': 'successfully upload!',
        'headers': {
            'Content-Type': 'application/json',
            "Access-Control-Allow-Headers": "Access-Control-Allow-Headers, Origin, Accept, X-Requested-With, Content-Type, Access-Control-Request-Method,X-Access-Token, XKey, Authorization",
            "Access-Control-Allow-Origin": "*",
            "Access-Control-Allow-Methods": "GET,PUT,POST,DELETE,OPTIONS"
        }
    }

CreateLambda

Similar with lambda/get_general_infor/get_general_infor.py file.

import json
import boto3
import os
from decimal import *
from boto3.dynamodb.types import TypeDeserializer

dynamodb = boto3.client('dynamodb') 
serializer = TypeDeserializer()
    
class DecimalEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, Decimal):
            return str(obj)
        return json.JSONEncoder.default(self, obj)
        
def deserialize(data):
    if isinstance(data, list):
        return [deserialize(v) for v in data]

    if isinstance(data, dict):
        try:
            return serializer.deserialize(data)
        except TypeError:
            return {k: deserialize(v) for k, v in data.items()}
    else:
        return data
        
def lambda_handler(event, context):
    # TODO implement
    table_name = os.environ['TABLE_NAME']
    user_id = event['pathParameters']['id']
    print(user_id)
    data = dynamodb.query(
        TableName=table_name,
        KeyConditionExpression="id = :id",
        ExpressionAttributeValues={ ":id": { 'S': user_id } }
    )
    
    format_data = deserialize(data["Items"])

    return {
        "statusCode": 200,
        "headers": {
            "Content-Type": "application/json",
            "Access-Control-Allow-Origin": "*",
            "Access-Control-Allow-Methods": "GET,PUT,POST,DELETE, OPTIONS",
            "Access-Control-Allow-Headers": "Access-Control-Allow-Headers, Origin,Accept, X-Requested-With, Content-Type, Access-Control-Request-Method,X-Access-Token,XKey,Authorization"
        },
        "body": json.dumps(format_data, cls=DecimalEncoder)
        #"body": format_data
    }

CreateLambda

Run the following command to build and deploy the sam project after updating:

sam build
sam deploy

While you wait for CloudFormation to complete, you can learn about the swagger.yaml file. The next part we will perform operations on the Front-end to test the operation of the APIs.