Add more parametrizable variables + descriptions in README.md

Author: BJSS-JD

Makefile

@@ -1,8 +1,8 @@
 
 # Use this tag to build a customized local image
 
-SWIFT_VERSION=5.1
-LAYER_VERSION=5-1
+SWIFT_VERSION?=5.1
+LAYER_VERSION?=5-1
 # SWIFT_VERSION=5.0.3
 # LAYER_VERSION=5-0-3
 DOCKER_TAG=nio-swift:$(SWIFT_VERSION)

README.md

@@ -140,9 +140,48 @@ make package_lambda
 ```
 The output of this command is a ZIP file called `lambda.zip` under the folder `.build`.
 
-**Note:**
+# Lambda Configuration
+
+## Parametrized calls / Automation
+
+Can pass values to your `make` command either before or after the call like below. This will fit better in a script per example to setup continuous integration in your project.
+
+### Before `make`
 
-Edit the `Makefile` to build a different Example by commenting the following lines and uncommenting the line relateted to the example you want to build.
+```
+SWIFT_EXECUTABLE=HTTPSRequest \
+SWIFT_PROJECT_PATH=Examples/HTTPSRequest \
+LAMBDA_FUNCTION_NAME=HTTPSRequest \
+LAMBDA_HANDLER=${SWIFT_EXECUTABLE}.getHttps \
+    make invoke_lambda
+```
+
+### After `make`
+
+```
+make invoke_lambda \
+    SWIFT_EXECUTABLE=HTTPSRequest \
+    SWIFT_PROJECT_PATH=Examples/HTTPSRequest \
+    LAMBDA_FUNCTION_NAME=HTTPSRequest \
+    LAMBDA_HANDLER=${SWIFT_EXECUTABLE}.getHttps
+```
+
+### Parameters you can pass
+
+| Key | Usage | Default |
+| --- | --- | --- |
+| AWS_BUCKET | The AWS S3 bucket where your lambda artifacts get uploaded. | my-s3-bucket |
+| AWS_PROFILE | An AWS AIM profile you create to authenticate to your account. | default |
+| SWIFT_VERSION | Version of Swift used / Matches Dockerfile location too from `docker/` folder. | 5.1 |
+| LAYER_VERSION | Version of the Swift layer that will be created and uploaded for the Lambda to run on. | 5-1 |
+| SWIFT_EXECUTABLE | Name of the binary file. | HelloWorld |
+| SWIFT_PROJECT_PATH | Path to your Swift project. | Examples/HelloWorld |
+| LAMBDA_FUNCTION_NAME | Display name of your Lambda in AWS. | HelloWorld |
+| LAMBDA_HANDLER | Name of your lambda handler function. If you declare it using `sprinter.register(handler: "FUNCTION_NAME", lambda: syncLambda)` you should declare it as `<SWIFT_EXECUTABLE>.<FUNCTION_NAME>`. | $(SWIFT_EXECUTABLE).helloWorld |
+
+## Manual change
+
+You can also edit the `Makefile` to build a different Example by commenting the following lines and uncommenting the line relateted to the example you want to build.
 ```
 ...
 
@@ -154,16 +193,6 @@ LAMBDA_HANDLER?=$(SWIFT_EXECUTABLE).helloWorld
 ...
 ```
 
-You can also override these by passing values in the make command like below.
-
-```
-SWIFT_EXECUTABLE=HTTPSRequest \
-SWIFT_PROJECT_PATH=Examples/HTTPSRequest \
-LAMBDA_FUNCTION_NAME=HTTPSRequest \
-LAMBDA_HANDLER=${SWIFT_EXECUTABLE}.getHttps \
-  make invoke_lambda
-```
-
 # Lambda Deployment Workflow
 
 The folowing tutorial describes how to deploy the lambda in your AWS account from the command line using [AWS Command Line Interface](https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-welcome.html) through the `Makefile`.