refactor: define a default CMD handler as handler.main

Author: skunxicat

Dockerfile

@@ -58,6 +58,8 @@ ARG HTTP_CLI_VERSION
 
 COPY task/helpers.sh helpers.sh
 
+CMD ["handler.main"]
+
 LABEL org.opencontainers.image.title="lambda-shell-runtime:tiny"
 LABEL org.opencontainers.image.version="${VERSION}"
 LABEL org.opencontainers.image.http_cli_version="${HTTP_CLI_VERSION}"

README.md

@@ -23,7 +23,7 @@ Custom AWS Lambda runtime for executing Bash functions as serverless application
 
 ```bash
 # handler.sh
-hello() {
+main () {
     local event="$1"
     echo '{"message": "Hello from Bash Lambda!", "input": '"$event"'}'
 }
@@ -142,6 +142,7 @@ aws lambda create-function \
   --code ImageUri=123456789012.dkr.ecr.region.amazonaws.com/my-lambda:latest \
   --role arn:aws:iam::123456789012:role/lambda-execution-role \
   --package-type Image \
+  --architectures arm64 \
   --timeout 30
 ```
 
@@ -161,17 +162,14 @@ resource "aws_lambda_function" "bash_function" {
 
 ### Using Lambda Runtime Interface Emulator
 
-```bash
-# Download RIE (one time setup)
-mkdir -p ~/.aws-lambda-rie
-curl -Lo ~/.aws-lambda-rie/aws-lambda-rie \
-  https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie
-chmod +x ~/.aws-lambda-rie/aws-lambda-rie
+https://github.com/aws/aws-lambda-runtime-interface-emulator/
+
+The emulator is already available on the image, you just need to override the `entrypoint` to run test your lambda locally
 
+```
 # Run your function locally
 docker run --rm -p 9000:8080 \
-  -v ~/.aws-lambda-rie:/aws-lambda \
-  -e HANDLER="handler.hello" \
+  --env _HANDLER="handler.hello" \
   --entrypoint /aws-lambda/aws-lambda-rie \
   my-lambda:latest /var/runtime/bootstrap
 
@@ -180,15 +178,6 @@ curl -XPOST "http://localhost:9000/2015-03-31/functions/function/invocations" \
   -d '{"name": "World"}'
 ```
 
-### Debug Mode
-
-```bash
-# Run with debug output
-docker run --rm -p 9000:8080 \
-  -e HANDLER="handler.hello" \
-  -e _LAMBDA_RUNTIME_DEBUG=1 \
-  my-lambda:latest
-```
 
 ## Building from Source
 
@@ -239,8 +228,8 @@ The shell runtime is **highly competitive** with official runtimes while providi
 
 **Function not found:**
 ```bash
-# Ensure your function is defined and handler matches
-HANDLER="handler.my_function"  # filename.function_name
+# Ensure your function is defined and you override 
+# the CMD hander.my_function
 ```
 
 **Permission errors:**

task/handler.sh

@@ -1,8 +1,7 @@
 #!/bin/sh
 
-function f () {
+function main () {
   EVENT="$1"
   echo "$EVENT" | jq 
   echo "Default handler — override this in your runtime build context." >&2
-  # exit 1
 }

test/functions.sh

@@ -3,30 +3,28 @@
 VARIANT=${VARIANT:-"tiny"}
 HANDLER=${HANDLER:-"handler.f"}
 
-# Setup the AWS Lambda Runtime Interface Emulator
+TAG="lambda-shell-runtime-${VARIANT}"
+
+# The AWS Lambda Runtime Interface Emulator is already available
 # https://github.com/aws/aws-lambda-runtime-interface-emulator/
-em () {
-    mkdir -p ~/.aws-lambda-rie && curl -Lo ~/.aws-lambda-rie/aws-lambda-rie \
-    https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie-arm64 \
-    && chmod +x ~/.aws-lambda-rie/aws-lambda-rie
-}
+
 
 # Start the Lambda shell container
 # Optionally:
 # 
 # * add --detach flag to run the container in the background
 # * mount --volume ./task/handler.sh:/var/task/handler.sh
+# * set the _HANDLER environent variable 
+
 r () {
-    docker run --rm \
+    docker run \
+    --rm \
     --detach \
-    -p 9000:8080 \
-    --name lambda-shell-runtime \
     --platform linux/arm64 \
-    -v ~/.aws:/root/.aws:ro \
-    --volume ~/.aws-lambda-rie:/aws-lambda \
-    --entrypoint /aws-lambda/aws-lambda-rie \
-    --env HANDLER="$HANDLER" \
-    "lambda-shell-runtime:$VARIANT" \
+    --entrypoint /usr/local/bin/aws-lambda-rie \
+    -p 9000:8080 \
+    --name "$TAG" \
+    "$TAG" \
     /var/runtime/bootstrap
 }