add docker build ci

Author: chiplonton

Dockerfile

@@ -0,0 +1,16 @@
+FROM public.ecr.aws/lambda/provided:al2 as build
+# Install compiler
+RUN yum install -y golang
+
+ADD . .
+
+# Build binary
+RUN go build -o bin/fluentd-lambda-extension -v ./extensions
+RUN chmod +x bin/fluentd-lambda-extension
+
+# Move layerbinary to /opt
+RUN mkdir -pv /opt/extensions && mv bin/fluentd-lambda-extension /opt/extensions
+
+# Reduce image size
+FROM public.ecr.aws/lambda/provided:al2
+COPY --from=build /opt/extensions /opt/extensions