added use cert and key from secret manager (#39)

SSG-API-Testing-Application-v2/lambda/README.md

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+# Introduction
+This directory is still **WIP**
+
+It will contain POC of obtaining secrets from AWS Systems Manager Parameter Store.
+
+This POC is meant to showcase how you can put your authentication secrets in AWS Systems Manager Parameter Store and retrieve them to use when calling our APIs
+
+There are also samples in the `secrets-manager-samples` folder if you wish to use AWS Secrets Manager instead.
+
+# Description of files
+
+`lambda_function.py` contains the lambda function POC
+
+- Permissions given to the lambda function:
+    - AWSLambdaBasicExecutionRole (AWS managed)
+    - KmsDecrypt 
+    ```
+    {
+        "Version": "2012-10-17",
+        "Statement": [
+            {
+                "Sid": "VisualEditor0",
+                "Effect": "Allow",
+                "Action": "kms:Decrypt",
+                "Resource": "*"
+            }
+        ]
+    }
+    ```
+    - SecretsPolicy  
+    ```
+    {
+        "Version": "2012-10-17",
+        "Statement": [
+            {
+                "Sid": "VisualEditor0",
+                "Effect": "Allow",
+                "Action": [
+                    "secretsmanager:GetSecretValue"
+                ],
+                "Resource": "*"
+            }
+        ]
+    }
+    ```
+
+To import dependencies into AWS Lambda, you can add them via custom layers. The steps to do so are described [here](https://stackoverflow.com/questions/65975883/aws-lambda-python-error-runtime-importmoduleerror)
+
+The minimum dependancy required to run the lambda function provided is:
+- requests 

SSG-API-Testing-Application-v2/lambda/lambda_function.py

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+# Use this code snippet in your app.
+# If you need more information about configurations
+# or implementing the sample code, visit the AWS docs:
+# https://aws.amazon.com/developer/language/python/
+
+import certifi
+import requests
+import json
+from tempfile import NamedTemporaryFile  # noqa: E402
+
+import boto3
+from botocore.exceptions import ClientError
+
+course_run_id = "35423"
+endpoint = f"https://uat-api.ssg-wsg.sg/courses/courseRuns/id/{course_run_id}"
+params = {"includeExpiredCourses": "true"}
+header = {
+    "accept": "application/json",
+    "Content-Type": "application/json"}
+
+
+def lambda_handler(event, context):
+    secrets = json.loads(get_secret())
+    cert_pem = create_temp_file(secrets["cert"])
+    key_pem = create_temp_file(secrets["key"])
+    response = view_course_run(cert_pem, key_pem)
+    print(response)
+
+
+def get_secret():
+
+    secret_name = "SampleApp/testing"
+    region_name = "ap-southeast-1"
+
+    # Create a Secrets Manager client
+    retrieve_secrets_session = assume_role()
+    session = boto3.session.Session()
+    client = retrieve_secrets_session.client(
+        service_name='secretsmanager',
+        region_name=region_name
+    )
+
+    try:
+        get_secret_value_response = client.get_secret_value(
+            SecretId=secret_name
+        )
+    except ClientError as e:
+        # For a list of exceptions thrown, see
+        # https://docs.aws.amazon.com/secretsmanager/latest/apireference/API_GetSecretValue.html
+        raise e
+
+    secret = get_secret_value_response['SecretString']
+
+    # Your code goes here.
+    return secret
+
+
+def assume_role():
+    sts_client = boto3.client('sts')
+    response = sts_client.assume_role(
+        RoleArn="arn:aws:iam::767397936445:role/SampleAppRetrieveSecret",
+        RoleSessionName="retrieve-secret-session"
+    )
+
+    new_session = boto3.Session(aws_access_key_id=response['Credentials']['AccessKeyId'],
+                                aws_secret_access_key=response['Credentials']['SecretAccessKey'],
+                                aws_session_token=response['Credentials']['SessionToken'])
+
+    return new_session
+
+
+def create_temp_file(inputStuff):
+    ''' save input into temporary file and return file name '''
+    temp_file = NamedTemporaryFile(
+        delete=False, delete_on_close=False, suffix=".pem")
+    with open(temp_file.name, 'w') as f:
+        f.write(inputStuff)
+    return temp_file.name
+
+
+def view_course_run(cert_pem, key_pem):
+    return requests.get(endpoint,
+                        params=params,
+                        headers=header,
+                        verify=certifi.where(),
+                        cert=(cert_pem, key_pem))

SSG-API-Testing-Application-v2/lambda/secrets-manager-samples/README.md

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+This directory contains files specific to using AWS Secrets Manager instead of parameter store.
+
+`deploy-secrets.yml` is the workflow file for github actions to deploy the secret to AWS Secret Manager
+
+The lambda function is given the role `SampleAppLambda` with the policies below:
+- AWSLambdaBasicExecutionRole (AWS managed)
+- StsAssumeRole (Customer inline)
+
+```
+{
+"Version": "2012-10-17",
+    "Statement": [
+        {
+            "Sid": "VisualEditor0",
+            "Effect": "Allow",
+            "Action": "sts:AssumeRole",
+            "Resource": "arn:aws:iam::YourAccountNumber:role/SampleAppRetrieveSecret"
+        }
+    ]
+}
+```
+
+The role that the lambda function will assume when retrieving the secret from AWS Secrets Manager `SampleAppRetrieveSecret` with the policies below:
+- AWSLambdaBasicExecutionRole (AWS managed) 
+- KmsDecrypt 
+```
+{
+    "Version": "2012-10-17",
+    "Statement": [
+        {
+            "Sid": "VisualEditor0",
+            "Effect": "Allow",
+            "Action": "kms:Decrypt",
+            "Resource": "*"
+        }
+    ]
+}
+```
+- SecretsPolicy  
+```
+{
+    "Version": "2012-10-17",
+    "Statement": [
+        {
+            "Sid": "VisualEditor0",
+            "Effect": "Allow",
+            "Action": [
+                "secretsmanager:GetSecretValue"
+            ],
+            "Resource": "*"
+        }
+    ]
+}
+```
+
+> [!NOTE]
+> You can choose to remove the `AWSLambdaBasicExecutionRole` policy from the `SampleAppRetrieveSecret` role if logging to CloudWatch is not required. This ensures the role adheres to the principle of least privilege by only granting the permissions necessary for its task.

SSG-API-Testing-Application-v2/lambda/secrets-manager-samples/deploy-secrets.yml

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+name: "Deploy Secrets to AWS Secrets Manager"
+
+on: workflow_dispatch
+
+jobs:
+  deploy-secrets:
+    name: "Deploy to AWS Secrets Manager"
+    runs-on: ubuntu-latest
+    environment: dev
+
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v4
+
+      - name: Set up Terraform
+        uses: hashicorp/setup-terraform@v3
+
+      - name: Verify Terraform Script
+        id: create-backend-verify
+        working-directory: ./SSG-API-Testing-Application-v2/lambda/deploy/
+        run: |
+          terraform fmt
+          terraform fmt -check
+      
+      - name: Initialise Backend
+        id: init-backend
+        working-directory: ./SSG-API-Testing-Application-v2/lambda/deploy/
+        run: terraform init
+
+      - name: Validate Terraform Script
+        id: create-backend-validate
+        working-directory: ./SSG-API-Testing-Application-v2/lambda/deploy/
+        run: terraform validate
+
+      # Generates an execution plan for Terraform
+      - name: Terraform Plan
+        id: plan
+        working-directory: ./SSG-API-Testing-Application-v2/lambda/deploy/
+        env: 
+          AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+          AWS_REGION: ${{ env.AWS_REGION }}
+          # this is the secret value that will be placed in aws secret manager
+          TF_VAR_secret_value: ${{ secrets.AWS_SECRET }} 
+        run: terraform plan
+
+      # On push to "main", build or change infrastructure according to Terraform configuration files
+      - name: Terraform Apply
+        working-directory: ./SSG-API-Testing-Application-v2/lambda/deploy/
+        id: apply
+        env: 
+          AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+          AWS_REGION: ${{ env.AWS_REGION }}
+          # this is the secret value that will be placed in aws secret manager
+          TF_VAR_secret_value: ${{ secrets.AWS_SECRET }}
+        run: terraform apply -auto-approve
+        continue-on-error: true

SSG-API-Testing-Application-v2/lambda/secrets-manager-samples/deploy/secretsmanager.tf

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+# Define input variable for the secret value
+variable "secret_value" {
+  description = "The value of the secret to be stored"
+  type        = string
+  sensitive   = true
+}
+
+provider "aws" {
+  region = "ap-southeast-1"
+}
+
+resource "aws_secretsmanager_secret" "example_secret" {
+  name = "SampleApp/test" # Name of the secret
+}
+
+resource "aws_secretsmanager_secret_version" "example_secret_version" {
+  secret_id = aws_secretsmanager_secret.example_secret.id
+  secret_string = jsonencode({
+    test_secret = var.secret_value
+  })
+}
+