GenerateWebhook.md

Breeze - GenerateWebook

The breeze package subcommand generate-webook provides the code to build a Serverless a GET/POST Webhook in Swift based on AWS Lambda and APIGateway.

Abstract

The generated template exposes a GET/POST webhook to the internet using the API Gateway. The lambdas implement the logic to retrieve data from GitHub using GET and POST.

The command line tool

swift run breeze generate-webhook --help

output:

USAGE: breeze generate-webhook --config-file <config-file> --target-path <target-path> [--force-overwrite] [-y]

OPTIONS:
  -c, --config-file <config-file>
                          YML configurarion file
  -t, --target-path <target-path>
                          Target path
  -f, --force-overwrite   Force target path overwrite
  -y
  -h, --help              Show help information.

Configuration file

Define a configuration file with the following format:

service: swift-breeze-webhook
awsRegion: us-east-1
swiftVersion: 5.10.1
swiftConfiguration: release
packageName: BreezeWebHook
buildPath: build
cors: false
breezeWebhook:
    targetName: WebHook
    httpPath: /webhook

Configuration parameters:

• awsRegion: AWS Region
• swiftVersion: Swift version
• swiftConfiguration: Swift configuration (debug or release)
• packageName: Swift Package name
• buildPath: Swift Package build path where the Lambda executable will be generated
• cors: Enable CORS (default: false)
• breezeGithubWebhook: Breeze GitHub Webhook configuration
  • targetName: The name of the target that will be generated by the Swift Package Manager
  • httpPath: The path of the API

Lambda customisation

Open the generated code, and implement your custom business logic by changing the default implementation of GetWebHook and PostWebHook.

GetWebHook default implementation

If the parameter github-user is present in the URL query string, the value is extracted and used to get the content from GitHub, the content is returned to the response payload.

class GetWebHook: BreezeLambdaWebHookHandler {
    
    let handlerContext: HandlerContext
    
    required init(handlerContext: HandlerContext) {
        self.handlerContext = handlerContext
    }
    
    func handle(context: AWSLambdaRuntimeCore.LambdaContext, event: AWSLambdaEvents.APIGatewayV2Request) async -> AWSLambdaEvents.APIGatewayV2Response {
        do {
            context.logger.info("event: \(event)")
            guard let params = event.queryStringParameters else {
                throw BreezeLambdaWebHookError.invalidRequest
            }
            if let user = params["github-user"] {
                let url = "https://github.com/\(user)"
                let request = HTTPClientRequest(url: url)
                let response = try await httpClient.execute(request, timeout: .seconds(3))
                let bytes = try await response.body.collect(upTo: 1024 * 1024) // 1 MB Buffer
                let body = String(buffer: bytes)
                return APIGatewayV2Response(with: body, statusCode: .ok)
            } else {
                return APIGatewayV2Response(with: params, statusCode: .ok)
            }
        } catch {
            return APIGatewayV2Response(with: error, statusCode: .badRequest)
        }
    }
}

PostWebHook default implementation

If the parameter github-user is present in the JSON payload, the value is extracted and used to get the content from GitHub, the content is returned to the response payload.

struct PostWebHookRequest: Codable {
    let githubUser: String
    
    enum CodingKeys: String, CodingKey {
        case githubUser = "github-user"
    }
}

class PostWebHook: BreezeLambdaWebHookHandler {
    
    let handlerContext: HandlerContext
    
    required init(handlerContext: HandlerContext) {
        self.handlerContext = handlerContext
    }
    
    func handle(context: AWSLambdaRuntimeCore.LambdaContext, event: AWSLambdaEvents.APIGatewayV2Request) async -> AWSLambdaEvents.APIGatewayV2Response {
        do {
            context.logger.info("event: \(event)")
            let incomingRequest: PostWebHookRequest = try event.bodyObject()
            let url = "https://github.com/\(incomingRequest.githubUser)"
            let request = HTTPClientRequest(url: url)
            let response = try await httpClient.execute(request, timeout: .seconds(3))
            let bytes = try await response.body.collect(upTo: 1024 * 1024) // 1 MB Buffer
            let body = String(buffer: bytes)
            return APIGatewayV2Response(with: body, statusCode: .ok)
        } catch {
            return APIGatewayV2Response(with: error, statusCode: .badRequest)
        }
    }
}