AWS-Lambda-example-clj.notes

;; This simnle tutorial is using AWS CDK (Cloud Development Kit, JavaScript flavor), 
;; Clojure CLI (tools.deps), Cognitect Lab's aws-api, and Oracle's JDBC library.

;; deps.edn file looks like this:

{:deps {org.clojure/clojure {:mvn/version "1.10.1"} org.clojure/data.json {:mvn/version "1.0.0"}
        com.amazonaws/aws-lambda-java-core {:mvn/version "1.2.0"}
        com.cognitect.aws/api {:mvn/version "0.8.456"} com.cognitect.aws/endpoints {:mvn/version "1.1.11.753"} com.cognitect.aws/s3 {:mvn/version "784.2.593.0"} com.cognitect.aws/sqs {:mvn/version "770.2.568.0"} com.cognitect.aws/secretsmanager {:mvn/version "793.2.626.0"}
        com.oracle.database.jdbc/ojdbc10 {:mvn/version "19.3.0.0"} seancorfield/next.jdbc {:mvn/version "1.0.409"}}
 :paths ["src" "classes"]
 :aliases {:nrepl {:extra-deps {nrepl/nrepl {:mvn/version "0.6.0"} cider/cider-nrepl {:mvn/version "0.24.0"}} :main-opts ["--main" "nrepl.cmdline" "--middleware" "[cider.nrepl/cider-middleware]"]}
           :dev {:extra-paths ["dev"] :extra-deps {expound {:mvn/version "0.8.4"}}}
           :test {:extra-deps {lambdaisland/kaocha {:mvn/version "0.0-601"} lambdaisland/kaocha-junit-xml {:mvn/version "0.0-70"}} :extra-paths ["test"] :main-opts ["--main" "kaocha.runner" "--reporter" "documentation" "--plugin" "kaocha.plugin/junit-xml" "--junit-xml-file" "target/junit.xml"]}
           :uberjar {:deps {uberdeps {:mvn/version "0.1.8"}} :main-opts ["--main" "uberdeps.uberjar" "--target" "target/example.jar"]}}}
           
 
;; And here is what the hello.clj (the entry point) looks like in its simplest form:

(ns com.example.aws-lambda.handler
  (:require [clojure.data.json :as json]
            [clojure.java.io :as io])
  (:gen-class :implements [com.amazonaws.services.lambda.runtime.RequestStreamHandler]))

(defn handle-event [event context]
  (str "Hello, " (get event "firstName") (get event "lastName")))

(defn -handleRequest
  "Converts IO streams to data structures."
  [_ input-stream output-stream context]
  (with-open [reader (io/reader input-stream)
              writer (io/writer output-stream)]
    (-> reader
        (json/read)
        (handle-event context)
        (json/write writer))))        
 
;;Finally, here's how you would create the function and invoke it on the command line (for testing-purposes):

aws lambda create-function \
    --function-name hello \
    --handler com.example.aws_lambda.hello \
    --memory 512 \
    --role arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole \
    --runtime java11 \
    --timeout 10 \
    --zip-file fileb://target/hello.jar


;; how to invoke it:

aws lambda invoke \
    --function-name hello \
    --cli-binary-format raw-in-base64-out \
    --payload '{"firstName":"john","lastName":"doe"}' \
    response.json
    
;; create and invoke example, for testing purposes

aws lambda create-function \
  --function-name example \
  --handler com.example.aws_lambda.handler \
  --memory 512 \
  --role arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole \
  --runtime java11 \
  --timeout 10 \
  --zip-file fileb://./target/example.jar invoke it: aws lambda invoke \
  --function-name example \
  --cli-binary-format raw-in-base64-out \
  --payload '{"firstName":"john","lastName":"doe"}' \
  response.json