backend

EmergenSeek Backend

Trello Board: https://trello.com/b/O864ONXb/golang-backend

Setup

Note: AWS CLI tools may require you to have Python installed

1. Download, install, and setup Go 1.11+: http://howistart.org/posts/go/1/
2. Install dep: https://github.com/golang/dep (Requires GOBIN environment variable)
3. Within the src directory of $GOPATH, clone this repository using: git clone https://github.com/emergenseek
4. Change directories into this repository (cd backend) and install dependencies: dep ensure
5. Create an AWS account and enable billing
6. Create a new IAM user:
   • Configure the Access type
     • Enable Programmatic access and take note of the access key ID and secret access key
     • If you would like to create keys and accounts for multiple users, repeat step 4 and provide each account with a Console password
     • Configure user permissions; select Attach existing polices
   • For simplicity, give the new account the AdministratorAccess policy
     • Policies may be configured later on
7. Download the AWS CLI
   • Reference: https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-install.html
   • In a terminal, run aws --version to verify that the tool installed successfully
8. Configure the AWS CLI:
   • Run aws configure
   • Paste the Access Key ID that was generated for your user
   • Paste the Secret Access Key that was generated for your user
   • Set your default region name (recommended: us-east-2)
   • Set the output format (recommended: table)

Testing Locally

1. Install Docker (hub.docker.com account required)
   • On Windows, if you do not have access to Hyper-V (i.e. Windows 10 Pro), install Docker Toolbox
2. Install aws-sam-local using one of the methods listed at https://aws.amazon.com/serverless/sam/
3. For convenience, install make
   • Windows: choco install make

Every subdirectory within /functions will have:

• A Makefile with a sam rule, this will invoke the test. Docker must be running. To run the rule, change into the function directy install make and invoke make sam
• A main.go file containing the source code for each Lambda function handler (func Handler)
• If the function accepts non-idempotent HTTP methods, an event.json file used for locally testing using cURL, wget, or HTTPie. If the accepted method is anything other than POST, the JSON's filename will be prefixed with the request method.
• A template.yaml for the SAM CLI tool to provision resources, for local testing
• Optionally: a request.go file to encapsulate a Request struct, typcially used for validating the JSON request body

Example invocation of ESSendSMSNotification

curl -X POST http://127.0.0.1:3000/sms -d @event.json --header "Content-Type: application/json"
Successfully sent SMS to contacts of user: e78e0c86-f9ba-4375-9554-6dc1426f5605

Lambda Function Breakdown

Below is a table detailing the function and purpose of each of the Lambda functions contained within this repository. Function packages are prefixed with ES (EmergenSeek) followed by their operation/responsibility.

Project Structure

• /common
  • Common helper functions and packages which are shared by the Lambda functions in /functions
• /functions
  • Contains Lambda functions that are automatically built, tested, and deployed using AWS CodeBuild, CodeDeploy, and CodePipeline
• /githooks
  • Git hooks for ensuring goreportcard passes with a decent grade. Make sure to run git config core.hooksPath githooks to make sure Git can find these hooks. The default directory is .git/hooks/

Helpful References

• https://stackoverflow.com/questions/48619686/project-structure-for-go-program-to-run-on-aws-lambda
• https://outcrawl.com/go-url-shortener-lambda
• https://artem.krylysov.com/blog/2018/01/18/porting-go-web-applications-to-aws-lambda/
• https://www.alexedwards.net/blog/serverless-api-with-go-and-aws-lambda
• https://blog.rowanudell.com/aws-sam-local-error-with-golang/
• https://github.com/awslabs/aws-sam-cli/issues/437
• https://medium.com/a-man-with-no-server/running-go-aws-lambdas-locally-with-sls-framework-and-sam-af3d648d49cb

Acknowledgements

• Data source for ESGetEmergencyNumbers: https://github.com/Alex0x47/EmergencyNumbers