Giters

drewdresser / barcode-demo

Geek Repo:Geek Repo

Github PK Tool:Github PK Tool

Barcode Reader Lambda Function

This project demonstrates how you can create a Lambda function to detect barcodes within images using the pyzbar and zbar libraries. Within the project, you will find:

  • hello_world - Code for the application's Lambda function and Project Dockerfile.
  • events - Invocation events that you can use to invoke the function plus a sample barcode image.
  • tests - Unit tests for the application code.
  • template.yaml - A template that defines the application's AWS resources.

The application uses several AWS resources, including Lambda functions and two Amazon S3 buckets. These resources are defined in the template.yaml file in this project. You can update the template to add AWS resources through the same deployment process that updates your application code.

Deploy the sample application

The Serverless Application Model Command Line Interface (SAM CLI) is an extension of the AWS CLI that adds functionality for building and testing Lambda applications. It uses Docker to run your functions in an Amazon Linux environment that matches Lambda. It can also emulate your application's build environment and API.

To use the SAM CLI, you need the following tools.

You also must create an ECR Repository to store the docker image that your Lambda function will use.

To build and deploy your application for the first time, run the following in your shell:

sam build
sam deploy --guided

The first command will build a docker image from a Dockerfile and then copy the source of your application inside the Docker image. The second command will package and deploy your application to AWS, with a series of prompts:

  • Stack Name: The name of the stack to deploy to CloudFormation. This should be unique to your account and region, and a good starting point would be something matching your project name.
  • AWS Region: The AWS region you want to deploy your app to.
  • Confirm changes before deploy: If set to yes, any change sets will be shown to you before execution for manual review. If set to no, the AWS SAM CLI will automatically deploy application changes.
  • Allow SAM CLI IAM role creation: Many AWS SAM templates, including this example, create AWS IAM roles required for the AWS Lambda function(s) included to access AWS services. By default, these are scoped down to minimum required permissions. To deploy an AWS CloudFormation stack which creates or modifies IAM roles, the CAPABILITY_IAM value for capabilities must be provided. If permission isn't provided through this prompt, to deploy this example you must explicitly pass --capabilities CAPABILITY_IAM to the sam deploy command.
  • Save arguments to samconfig.toml: If set to yes, your choices will be saved to a configuration file inside the project, so that in the future you can just re-run sam deploy without parameters to deploy changes to your application.

You can find your S3 buckets in the output values displayed after deployment.

Use the SAM CLI to build and test locally

Build your application with the sam build command.

barcode-demo$ sam build

The SAM CLI builds a docker image from a Dockerfile and then installs dependencies defined in hello_world/requirements.txt inside the docker image. The processed template file is saved in the .aws-sam/build folder.

Test a single function by invoking it directly with a test event. An event is a JSON document that represents the input that the function receives from the event source. Test events are included in the events folder in this project.

Run functions locally and invoke them with the sam local invoke command.

  1. First, go replace the bucket name and key name of the mock event in events/event.json with a bucket a file that actually exists. You can use the bucket that you created as part of this stack on the first deploy.
  2. Open env.json and replace the destination bucket with the destination bucket you created during the deploy.
  3. Run:
barcode-demo$ sam local invoke BarcodeDetectorFn --event events/event.json --env-vars env.json

Fetch, tail, and filter Lambda function logs

To simplify troubleshooting, SAM CLI has a command called sam logs. sam logs lets you fetch logs generated by your deployed Lambda function from the command line. In addition to printing the logs on the terminal, this command has several nifty features to help you quickly find the bug.

NOTE: This command works for all AWS Lambda functions; not just the ones you deploy using SAM.

barcode-demo$ sam logs -n BarcodeDetectorFn --stack-name barcode-demo --tail

You can find more information and examples about filtering Lambda function logs in the SAM CLI Documentation.

Cleanup

To delete the sample application that you created, use the AWS CLI. Assuming you used your project name for the stack name, you can run the following:

aws cloudformation delete-stack --stack-name barcode-demo

Resources

About

Languages

Language:Python 82.9%Language:Dockerfile 16.7%Language:Shell 0.4%