# Tutorial: Deploy a Hello World application with AWS SAM In this tutorial, you use the AWS Serverless Application Model Command Line Interface (AWS SAM CLI) to complete the following: + Initialize, build, and deploy a sample **Hello World** application. + Make local changes and sync to AWS CloudFormation. + Perform local testing on your development host. + Delete the sample application from the AWS Cloud. The sample **Hello World** application implements a basic API backend. It consists of the following resources: + **Amazon API Gateway** – API endpoint that you will use to invoke your function. + **AWS Lambda** – Function that processes the HTTP API GET request and returns a `hello world` message. + **AWS Identity and Access Management (IAM) role** – Provisions permissions for the services to securely interact. The following diagram shows the components of this application: ![\[A diagram of a Lambda function that's invoked when you send a GET request to the API Gateway endpoint.\]](http://docs.aws.amazon.com/serverless-application-model/latest/developerguide/images/gs-01.png) **Topics** + [ ## Prerequisites ](#serverless-getting-started-hello-world-prerequisites) + [ ## Step 1: Initialize the sample Hello World application ](#serverless-getting-started-hello-world-init) + [ ## Step 2: Build your application ](#serverless-getting-started-hello-world-build) + [ ## Step 3: Deploy your application to the AWS Cloud ](#serverless-getting-started-hello-world-deploy) + [ ## Step 4: Run your application ](#serverless-getting-started-hello-world-run) + [ ## Step 5: Interact with your function in the AWS Cloud ](#serverless-getting-started-hello-world-remote-invoke) + [ ## Step 6: Modify and sync your application to the AWS Cloud ](#serverless-getting-started-hello-world-sync) + [ ## Step 7: (Optional) Test your application locally ](#serverless-getting-started-hello-world-test) + [ ## Step 8: Delete your application from the AWS Cloud ](#serverless-getting-started-hello-world-delete) + [ ## Troubleshooting ](#serverless-getting-started-hello-world-troubleshoot) + [ ## Learn more ](#serverless-getting-started-hello-world-learn) ## Prerequisites Verify that you have completed the following: + [AWS SAM prerequisites](prerequisites.md) + [Install the AWS SAM CLI](install-sam-cli.md) **Note** If you prefer using Visual Studio Code for serverless development, see [Creating serverless applications](https://docs.aws.amazon.com/toolkit-for-vscode/latest/userguide/sam-get-started.html#serverless-apps-create) in the AWS Toolkit for VS Code User Guide for step-by-step instructions using the VS Code interface. ## Step 1: Initialize the sample Hello World application In this step, you will use the AWS SAM CLI to create a sample **Hello World** application project on your local machine. **To initialize the sample Hello World application** 1. In your command line, run the following from a starting directory of your choice: ``` $ sam init ``` **Note** This command initializes your serverless application and creates a project directory. The directory contains several files and folders, including the `template.yaml` file, which is your AWS SAM template. The installed Python version must match the `Runtime` property specified in `template.yaml`. For production workloads, we recommend using Python 3.12 or earlier versions that are fully supported in AWS environments. If the Python versions don't match, you'll encounter build errors. To resolve version compatibility issues: Specify a compatible [runtime](sam-cli-command-reference-sam-init.md#sam-cli-command-reference-sam-init-options-runtime) during initialization: `sam init --runtime python3.9` Modify the `Runtime` property in `template.yaml` after initialization 1. The AWS SAM CLI will guide you through initializing a new application. Configure the following: 1. Select **AWS Quick Start Templates** to choose a starting template. 1. Choose the **Hello World Example** template and download it. 1. Use the Python runtime and `zip` package type. 1. For this tutorial, opt out of AWS X-Ray tracing. To learn more, see [What is AWS X-Ray?](https://docs.aws.amazon.com/xray/latest/devguide/aws-xray.html) in the *AWS X-Ray Developer Guide*. 1. For this tutorial, opt out of monitoring with Amazon CloudWatch Application Insights. To learn more, see [ Amazon CloudWatch Application Insights](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/cloudwatch-application-insights.html) in the *Amazon CloudWatch User Guide*. 1. For this tutorial, opt out of setting Structured Logging in JSON format on your Lambda functions. 1. Name your application as **sam-app**. To use the AWS SAM CLI interactive flow: + Brackets (`[ ]`) indicate default values. Leave your answer blank to select the default value. + Enter **`y`** for **yes**, and **`n`** for **no**. The following is an example of the `sam init` interactive flow: ``` $ sam init ... Which template source would you like to use? 1 - AWS Quick Start Templates 2 - Custom Template Location Choice: 1 Choose an AWS Quick Start application template 1 - Hello World Example 2 - Data processing 3 - Hello World Example with Powertools for AWS Lambda 4 - Multi-step workflow 5 - Scheduled task 6 - Standalone function 7 - Serverless API 8 - Infrastructure event management 9 - Lambda Response Streaming 10 - GraphQLApi Hello World Example 11 - Full Stack 12 - Lambda EFS example 13 - Serverless Connector Hello World Example 14 - Multi-step workflow with Connectors 15 - DynamoDB Example 16 - Machine Learning Template: 1 Use the most popular runtime and package type? (Python and zip) [y/N]: y Would you like to enable X-Ray tracing on the function(s) in your application? [y/N]: ENTER Would you like to enable monitoring using CloudWatch Application Insights? For more info, please view https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/cloudwatch-application-insights.html [y/N]: ENTER Would you like to set Structured Logging in JSON format on your Lambda functions? [y/N]: ENTER Project name [sam-app]: ENTER ``` 1. The AWS SAM CLI downloads your starting template and creates the application project directory structure on your local machine. The following is an example of the AWS SAM CLI output: ``` Cloning from https://github.com/aws/aws-sam-cli-app-templates (process may take a moment) ----------------------- Generating application: ----------------------- Name: sam-app Runtime: python3.9 Architectures: x86_64 Dependency Manager: pip Application Template: hello-world Output Directory: . Configuration file: sam-app/samconfig.toml Next steps can be found in the README file at sam-app/README.md Commands you can use next ========================= [*] Create pipeline: cd sam-app && sam pipeline init --bootstrap [*] Validate SAM template: cd sam-app && sam validate [*] Test Function in the Cloud: cd sam-app && sam sync --stack-name {stack-name} --watch ``` 1. From your command line, move to the newly created `sam-app` directory. The following is an example of what the AWS SAM CLI has created: **Note** If `tree` command is not auto installed run this command: `brew install tree` ``` $ cd sam-app $ tree ├── README.md ├── __init__.py ├── events │ └── event.json ├── hello_world │ ├── __init__.py │ ├── app.py │ └── requirements.txt ├── samconfig.toml ├── template.yaml └── tests ├── __init__.py ├── integration │ ├── __init__.py │ └── test_api_gateway.py ├── requirements.txt └── unit ├── __init__.py └── test_handler.py 6 directories, 14 files ``` Some important files to highlight: + `hello_world/app.py` – Contains your Lambda function code. + `hello_world/requirements.txt` – Contains any Python dependencies that your Lambda function requires. + `samconfig.toml` – Configuration file for your application that stores default parameters used by the AWS SAM CLI. + `template.yaml` – The AWS SAM template that contains your application infrastructure code. You now have a completely authored serverless application on your local machine\$1 ## Step 2: Build your application In this step, you use the AWS SAM CLI to build your application and prepare for deployment. When you build, the AWS SAM CLI creates a `.aws-sam` directory and organizes your function dependencies, project code, and project files there. **To build your application** + In your command line, from the `sam-app` project directory, run the following: ``` $ sam build ``` **Note** If you don't have Python on your local machine, use the **sam build --use-container ** command instead. The AWS SAM CLI will create a Docker container that includes your function's runtime and dependencies. This command requires Docker on your local machine. To install Docker, see [Installing Docker](install-docker.md). The following is an example of the AWS SAM CLI output: ``` $ sam build Starting Build use cache Manifest file is changed (new hash: 3298f1304...d4d421) or dependency folder (.aws-sam/deps/4d3dfad6-a267-47a6-a6cd-e07d6fae318c) is missing for (HelloWorldFunction), downloading dependencies and copying/building source Building codeuri: /Users/.../Demo/sam-tutorial1/sam-app/hello_world runtime: python3.9 metadata: {} architecture: x86_64 functions: HelloWorldFunction Running PythonPipBuilder:CleanUp Running PythonPipBuilder:ResolveDependencies Running PythonPipBuilder:CopySource Running PythonPipBuilder:CopySource Build Succeeded Built Artifacts : .aws-sam/build Built Template : .aws-sam/build/template.yaml Commands you can use next ========================= [*] Validate SAM template: sam validate [*] Invoke Function: sam local invoke [*] Test Function in the Cloud: sam sync --stack-name {{stack-name}} --watch [*] Deploy: sam deploy --guided ``` The following is a shortened example of the `.aws-sam` directory created by the AWS SAM CLI: ``` .aws-sam ├── build │ ├── HelloWorldFunction │ │ ├── __init__.py │ │ ├── app.py │ │ └── requirements.txt │ └── template.yaml └── build.toml ``` Some important files to highlight: + `build/HelloWorldFunction` – Contains your Lambda function code and dependencies. The AWS SAM CLI creates a directory for each function in your application. + `build/template.yaml` – Contains a copy of your AWS SAM template that is referenced by CloudFormation at deployment. + `build.toml` – Configuration file that stores default parameter values referenced by the AWS SAM CLI when building and deploying your application. You are now ready to deploy your application to the AWS Cloud. ## Step 3: Deploy your application to the AWS Cloud **Note** This step requires AWS credentials configuration. For more information, see [Step 5: Use the AWS CLI to configure AWS credentials](prerequisites.md#prerequisites-configure-credentials) in [AWS SAM prerequisites](prerequisites.md). In this step, you use the AWS SAM CLI to deploy your application to the AWS Cloud. The AWS SAM CLI will do the following: + Guide you through configuring your application settings for deployment. + Upload your application files to Amazon Simple Storage Service (Amazon S3). + Transform your AWS SAM template into an CloudFormation template. It then uploads your template to the CloudFormation service to provision your AWS resources. **To deploy your application** 1. In your command line, from the `sam-app` project directory, run the following: ``` $ sam deploy --guided ``` 1. Follow the AWS SAM CLI interactive flow to configure your application settings. Configure the following: 1. The **CloudFormation stack name** – A stack is a collection of AWS resources that you can manage as a single unit. To learn more, see [Working with stacks](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/stacks.html) in the *AWS CloudFormation User Guide*. 1. The **AWS Region** to deploy your CloudFormation stack to. For more information, see [CloudFormation endpoints](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-endpoints.html) in the *AWS CloudFormation User Guide*. 1. For this tutorial, opt out of **confirming changes before deploy**. 1. Allow **IAM role creation** – This lets AWS SAM create the IAM role necessary for your API Gateway resource and Lambda function resource to interact. 1. For this tutorial, opt out of **disabling rollback**. 1. Allow **HelloWorldFunction without authorization defined** – This message displays because your API Gateway endpoint is configured to be publicly accessible, without authorization. Since this is the intended configuration for your Hello World application, allow the AWS SAM CLI to continue. For more information about configuring authorization, see [Control API access with your AWS SAM template](serverless-controlling-access-to-apis.md). 1. **Save arguments to configuration file** – This will update your application’s `samconfig.toml` file with your deployment preferences. 1. Select the default **configuration file name**. 1. Select the default **configuration environment**. The following is an example output of the `sam deploy --guided` interactive flow: ``` $ sam deploy --guided Configuring SAM deploy ====================== Looking for config file [samconfig.toml] : Found Reading default arguments : Success Setting default arguments for 'sam deploy' ========================================= Stack Name [sam-app]: ENTER AWS Region [us-west-2]: ENTER #Shows you resources changes to be deployed and require a 'Y' to initiate deploy Confirm changes before deploy [Y/n]: n #SAM needs permission to be able to create roles to connect to the resources in your template Allow SAM CLI IAM role creation [Y/n]: ENTER #Preserves the state of previously provisioned resources when an operation fails Disable rollback [y/N]: ENTER HelloWorldFunction may not have authorization defined, Is this okay? [y/N]: y Save arguments to configuration file [Y/n]: ENTER SAM configuration file [samconfig.toml]: ENTER SAM configuration environment [default]: ENTER ``` 1. The AWS SAM CLI deploys your application by doing the following: + The AWS SAM CLI creates an Amazon S3 bucket and uploads your `.aws-sam` directory. + The AWS SAM CLI transforms your AWS SAM template into CloudFormation and uploads it to the CloudFormation service. + CloudFormation provisions your resources. During deployment, the AWS SAM CLI displays your progress. The following is an example output: ``` Looking for resources needed for deployment: Managed S3 bucket: aws-sam-cli-managed-default-samclisam-s3-demo-bucket-1a4x26zbcdkqr A different default S3 bucket can be set in samconfig.toml Parameter "stack_name=sam-app" in [default.deploy.parameters] is defined as a global parameter [default.global.parameters]. This parameter will be only saved under [default.global.parameters] in /Users/.../Demo/sam-tutorial1/sam-app/samconfig.toml. Saved arguments to config file Running 'sam deploy' for future deployments will use the parameters saved above. The above parameters can be changed by modifying samconfig.toml Learn more about samconfig.toml syntax at https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-config.html File with same data already exists at sam-app/da3c598813f1c2151579b73ad788cac8, skipping upload Deploying with following values =============================== Stack name : sam-app Region : us-west-2 Confirm changeset : False Disable rollback : False Deployment s3 bucket : aws-sam-cli-managed-default-samclisam-s3-demo-bucket-1a4x26zbcdkqr Capabilities : ["CAPABILITY_IAM"] Parameter overrides : {} Signing Profiles : {} Initiating deployment ===================== File with same data already exists at sam-app/2bebf67c79f6a743cc5312f6dfc1efee.template, skipping upload Waiting for changeset to be created.. CloudFormation stack changeset --------------------------------------------------------------------------------------------------------------------------------------------- Operation LogicalResourceId ResourceType Replacement --------------------------------------------------------------------------------------------------------------------------------------------- * Modify HelloWorldFunction AWS::Lambda::Function False * Modify ServerlessRestApi AWS::ApiGateway::RestApi False - Delete AwsSamAutoDependencyLayerNestedSt AWS::CloudFormation::Stack N/A ack --------------------------------------------------------------------------------------------------------------------------------------------- Changeset created successfully. arn:aws:cloudformation:us-west-2:012345678910:changeSet/samcli-deploy1678917603/22e05525-08f9-4c52-a2c4-f7f1fd055072 2023-03-15 12:00:16 - Waiting for stack create/update to complete CloudFormation events from stack operations (refresh every 0.5 seconds) --------------------------------------------------------------------------------------------------------------------------------------------- ResourceStatus ResourceType LogicalResourceId ResourceStatusReason --------------------------------------------------------------------------------------------------------------------------------------------- UPDATE_IN_PROGRESS AWS::Lambda::Function HelloWorldFunction - UPDATE_COMPLETE AWS::Lambda::Function HelloWorldFunction - UPDATE_COMPLETE_CLEANUP_IN_PROGRE AWS::CloudFormation::Stack sam-app - SS DELETE_IN_PROGRESS AWS::CloudFormation::Stack AwsSamAutoDependencyLayerNestedSt - ack DELETE_COMPLETE AWS::CloudFormation::Stack AwsSamAutoDependencyLayerNestedSt - ack UPDATE_COMPLETE AWS::CloudFormation::Stack sam-app - --------------------------------------------------------------------------------------------------------------------------------------------- CloudFormation outputs from deployed stack ---------------------------------------------------------------------------------------------------------------------------------------------- Outputs ---------------------------------------------------------------------------------------------------------------------------------------------- Key HelloWorldFunctionIamRole Description Implicit IAM Role created for Hello World function Value arn:aws:iam::012345678910:role/sam-app-HelloWorldFunctionRole-15GLOUR9LMT1W Key HelloWorldApi Description API Gateway endpoint URL for Prod stage for Hello World function Value https://.execute-api.us-west-2.amazonaws.com/Prod/hello/ Key HelloWorldFunction Description Hello World Lambda Function ARN Value arn:aws:lambda:us-west-2:012345678910:function:sam-app-HelloWorldFunction-yQDNe17r9maD ---------------------------------------------------------------------------------------------------------------------------------------------- Successfully created/updated stack - sam-app in us-west-2 ``` Your application is now deployed and running in the AWS Cloud\$1 ## Step 4: Run your application In this step, you will send a GET request to your API endpoint and see your Lambda function output. **To get your API endpoint value** 1. From the information displayed by the AWS SAM CLI in the previous step, locate the `Outputs` section. In this section, locate your `HelloWorldApi` resource to find your HTTP endpoint value. The following is an example output: ``` ---------------------------------------------------------------------------------------------------------------------------------------------- Outputs ---------------------------------------------------------------------------------------------------------------------------------------------- ... Key HelloWorldApi Description API Gateway endpoint URL for Prod stage for Hello World function Value https://ets1gv8lxi.execute-api.us-west-2.amazonaws.com/Prod/hello/ ... ---------------------------------------------------------------------------------------------------------------------------------------------- ``` 1. Alternatively, you can use the **sam list endpoints --output json** command to get this information. The following is an example output: ``` $ sam list endpoints --output json 2023-03-15 12:39:19 Loading policies from IAM... 2023-03-15 12:39:25 Finished loading policies from IAM. [ { "LogicalResourceId": "HelloWorldFunction", "PhysicalResourceId": "sam-app-HelloWorldFunction-yQDNe17r9maD", "CloudEndpoint": "-", "Methods": "-" }, { "LogicalResourceId": "ServerlessRestApi", "PhysicalResourceId": "ets1gv8lxi", "CloudEndpoint": [ "https://ets1gv8lxi.execute-api.us-west-2.amazonaws.com/Prod", "https://ets1gv8lxi.execute-api.us-west-2.amazonaws.com/Stage" ], "Methods": [ "/hello['get']" ] } ] ``` **To invoke your function** + Using your browser or the command line, send a GET request to your API endpoint. The following is an example using the curl command: ``` $ curl https://ets1gv8lxi.execute-api.us-west-2.amazonaws.com/Prod/hello/ {"message": "hello world"} ``` ## Step 5: Interact with your function in the AWS Cloud In this step, you use the AWS SAM CLI to invoke your Lambda function in the AWS Cloud. **To invoke your Lambda function in the cloud** 1. Take note of your function’s `LogicalResourceId` from the previous step. It should be `HelloWorldFunction`. 1. In your command line, from the `sam-app` project directory, run the following: ``` $ sam remote invoke HelloWorldFunction --stack-name sam-app ``` 1. The AWS SAM CLI invokes your function in the cloud and returns a response. The following is an example output: ``` $ sam remote invoke HelloWorldFunction --stack-name sam-app Invoking Lambda Function HelloWorldFunction START RequestId: d5ef494b-5f45-4086-86fd-d7322fa1a1f9 Version: $LATEST END RequestId: d5ef494b-5f45-4086-86fd-d7322fa1a1f9 REPORT RequestId: d5ef494b-5f45-4086-86fd-d7322fa1a1f9 Duration: 6.62 ms Billed Duration: 7 ms Memory Size: 128 MB Max Memory Used: 67 MB Init Duration: 164.06 ms {"statusCode":200,"body":"{\"message\":\"hello world\"}"}% ``` ## Step 6: Modify and sync your application to the AWS Cloud In this step, you use the AWS SAM CLI **sam sync --watch** command to sync local changes to the AWS Cloud. **To use sam sync** 1. In your command line, from the `sam-app` project directory, run the following: ``` $ sam sync --watch ``` 1. The AWS SAM CLI prompts you to confirm that you are syncing a development stack. Since the **sam sync --watch** command automatically deploys local changes to the AWS Cloud in real time, we recommend it for development environments only. The AWS SAM CLI performs an initial deployment before it begins monitoring for local changes. The following is an example output: ``` $ sam sync --watch The SAM CLI will use the AWS Lambda, Amazon API Gateway, and AWS StepFunctions APIs to upload your code without performing a CloudFormation deployment. This will cause drift in your CloudFormation stack. **The sync command should only be used against a development stack**. Confirm that you are synchronizing a development stack. Enter Y to proceed with the command, or enter N to cancel: [Y/n]: y Queued infra sync. Waiting for in progress code syncs to complete... Starting infra sync. Manifest is not changed for (HelloWorldFunction), running incremental build Building codeuri: /Users/.../Demo/sam-tutorial1/sam-app/hello_world runtime: python3.9 metadata: {} architecture: x86_64 functions: HelloWorldFunction Running PythonPipBuilder:CopySource Build Succeeded Successfully packaged artifacts and wrote output template to file /var/folders/45/5ct135bx3fn2551_ptl5g6_80000gr/T/tmpq3x9vh63. Execute the following command to deploy the packaged template sam deploy --template-file /var/folders/45/5ct135bx3fn2551_ptl5g6_80000gr/T/tmpq3x9vh63 --stack-name Deploying with following values =============================== Stack name : sam-app Region : us-west-2 Disable rollback : False Deployment s3 bucket : aws-sam-cli-managed-default-samclisam-s3-demo-bucket-1a4x26zbcdkqr Capabilities : ["CAPABILITY_NAMED_IAM", "CAPABILITY_AUTO_EXPAND"] Parameter overrides : {} Signing Profiles : null Initiating deployment ===================== 2023-03-15 13:10:05 - Waiting for stack create/update to complete CloudFormation events from stack operations (refresh every 0.5 seconds) --------------------------------------------------------------------------------------------------------------------------------------------- ResourceStatus ResourceType LogicalResourceId ResourceStatusReason --------------------------------------------------------------------------------------------------------------------------------------------- UPDATE_IN_PROGRESS AWS::CloudFormation::Stack sam-app Transformation succeeded CREATE_IN_PROGRESS AWS::CloudFormation::Stack AwsSamAutoDependencyLayerNestedSt - ack CREATE_IN_PROGRESS AWS::CloudFormation::Stack AwsSamAutoDependencyLayerNestedSt Resource creation Initiated ack CREATE_COMPLETE AWS::CloudFormation::Stack AwsSamAutoDependencyLayerNestedSt - ack UPDATE_IN_PROGRESS AWS::Lambda::Function HelloWorldFunction - UPDATE_COMPLETE AWS::Lambda::Function HelloWorldFunction - UPDATE_COMPLETE_CLEANUP_IN_PROGRE AWS::CloudFormation::Stack sam-app - SS UPDATE_COMPLETE AWS::CloudFormation::Stack sam-app - --------------------------------------------------------------------------------------------------------------------------------------------- CloudFormation outputs from deployed stack ---------------------------------------------------------------------------------------------------------------------------------------------- Outputs ---------------------------------------------------------------------------------------------------------------------------------------------- Key HelloWorldFunctionIamRole Description Implicit IAM Role created for Hello World function Value arn:aws:iam::012345678910:role/sam-app-HelloWorldFunctionRole-15GLOUR9LMT1W Key HelloWorldApi Description API Gateway endpoint URL for Prod stage for Hello World function Value https://ets1gv8lxi.execute-api.us-west-2.amazonaws.com/Prod/hello/ Key HelloWorldFunction Description Hello World Lambda Function ARN Value arn:aws:lambda:us-west-2:012345678910:function:sam-app-HelloWorldFunction-yQDNe17r9maD ---------------------------------------------------------------------------------------------------------------------------------------------- Stack update succeeded. Sync infra completed. Infra sync completed. CodeTrigger not created as CodeUri or DefinitionUri is missing for ServerlessRestApi. ``` Next, you will modify your Lambda function code. The AWS SAM CLI will automatically detect this change and sync your application to the AWS Cloud. **To modify and sync your application** 1. In your IDE of choice, open the `sam-app/hello_world/app.py` file. 1. Change the `message` and save your file. The following is an example: ``` import json ... def lambda_handler(event, context): ... return { "statusCode": 200, "body": json.dumps({ "message": "hello everyone!", ... }), } ``` 1. The AWS SAM CLI detects your change and syncs your application to the AWS Cloud. The following is an example output: ``` Syncing Lambda Function HelloWorldFunction... Manifest is not changed for (HelloWorldFunction), running incremental build Building codeuri: /Users/.../Demo/sam-tutorial1/sam-app/hello_world runtime: python3.9 metadata: {} architecture: x86_64 functions: HelloWorldFunction Running PythonPipBuilder:CopySource Finished syncing Lambda Function HelloWorldFunction. ``` 1. To verify your change, send a GET request to your API endpoint again. ``` $ curl https://ets1gv8lxi.execute-api.us-west-2.amazonaws.com/Prod/hello/ {"message": "hello everyone!"} ``` ## Step 7: (Optional) Test your application locally **Note** This step is optional. **Important** This step requires Docker on your local machine. You must have Docker installed and configured to use the AWS SAM CLI for local testing. For more information, see [Installing Docker](install-docker.md). In this step, you use the AWS SAM CLI **sam local** command to test your application locally. To accomplish this, the AWS SAM CLI creates a local environment using Docker. This local environment emulates the cloud-based execution environment of your Lambda function. You will do the following: 1. Create a local environment for your Lambda function and invoke it. 1. Host your HTTP API endpoint locally and use it to invoke your Lambda function. **To invoke your Lambda function locally** 1. In your command line, from the `sam-app` project directory, run the following: ``` $ sam local invoke ``` 1. The AWS SAM CLI creates a local Docker container and invokes your function. The following is an example output: ``` $ sam local invoke Invoking app.lambda_handler (python3.9) Local image was not found. Removing rapid images for repo public.ecr.aws/sam/emulation-python3.9 Building image..................... Using local image: public.ecr.aws/lambda/python:3.9-rapid-x86_64. Mounting /Users/.../Demo/sam-tutorial1/sam-app/.aws-sam/build/HelloWorldFunction as /var/task:ro,delegated inside runtime container START RequestId: b046db01-2a00-415d-af97-35f3a02e9eb6 Version: $LATEST END RequestId: b046db01-2a00-415d-af97-35f3a02e9eb6 REPORT RequestId: b046db01-2a00-415d-af97-35f3a02e9eb6 Init Duration: 1.01 ms Duration: 633.45 ms Billed Duration: 634 ms Memory Size: 128 MB Max Memory Used: 128 MB {"statusCode": 200, "body": "{\"message\": \"hello world\"}"} ``` **To host your API locally** 1. In your command line, from the `sam-app` project directory, run the following: ``` $ sam local start-api ``` 1. The AWS SAM CLI creates a local Docker container for your Lambda function and creates a local HTTP server to simulate your API endpoint. The following is an example output: ``` $ sam local start-api Initializing the lambda functions containers. Local image is up-to-date Using local image: public.ecr.aws/lambda/python:3.9-rapid-x86_64. Mounting /Users/.../Demo/sam-tutorial1/sam-app/.aws-sam/build/HelloWorldFunction as /var/task:ro,delegated inside runtime container Containers Initialization is done. Mounting HelloWorldFunction at http://127.0.0.1:3000/hello [GET] You can now browse to the above endpoints to invoke your functions. You do not need to restart/reload SAM CLI while working on your functions, changes will be reflected instantly/automatically. If you used sam build before running local commands, you will need to re-run sam build for the changes to be picked up. You only need to restart AWS SAM CLI if you update your AWS SAM template 2023-03-15 14:25:21 WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead. * Running on http://127.0.0.1:3000 2023-03-15 14:25:21 Press CTRL+C to quit ``` 1. Using your browser or the command line, send a GET request to your local API endpoint. The following is an example using the curl command: ``` $ curl http://127.0.0.1:3000/hello {"message": "hello world"} ``` ## Step 8: Delete your application from the AWS Cloud In this step, you use the AWS SAM CLI **sam delete** command to delete your application from the AWS Cloud. **To delete your application from the AWS Cloud** 1. In your command line, from the `sam-app` project directory, run the following: ``` $ sam delete ``` 1. The AWS SAM CLI will ask you to confirm. Then, it will delete your application’s Amazon S3 bucket and CloudFormation stack. The following is an example output: ``` $ sam delete Are you sure you want to delete the stack sam-app in the region us-west-2 ? [y/N]: y Are you sure you want to delete the folder sam-app in S3 which contains the artifacts? [y/N]: y - Deleting S3 object with key c6ce8fa8b5a97dd022ecd006536eb5a4 - Deleting S3 object with key 5d513a459d062d644f3b7dd0c8b56a2a.template - Deleting S3 object with key sam-app/2bebf67c79f6a743cc5312f6dfc1efee.template - Deleting S3 object with key sam-app/6b208d0e42ad15d1cee77d967834784b.template - Deleting S3 object with key sam-app/da3c598813f1c2151579b73ad788cac8 - Deleting S3 object with key sam-app/f798cdd93cee188a71d120f14a035b11 - Deleting Cloudformation stack sam-app Deleted successfully ``` ## Troubleshooting To troubleshoot the AWS SAM CLI, see [AWS SAM CLI troubleshooting](sam-cli-troubleshooting.md). ## Learn more To continue learning about AWS SAM, see the following resources: + **[The Complete AWS SAM Workshop](https://s12d.com/sam-ws-en-intro)** – A workshop designed to teach you many of the major features that AWS SAM provides. + **[ Sessions with SAM](https://www.youtube.com/playlist?list=PLJo-rJlep0ED198FJnTzhIB5Aut_1vDAd)** – Video series created by our AWS Serverless Developer Advocate team on using AWS SAM. + **[Serverless Land](https://serverlessland.com/)** – Site that brings together the latest information, blogs, videos, code, and learning resources for AWS serverless.