From 77ab65ef4a8da28a0a48979a1f35c7d1e5ead067 Mon Sep 17 00:00:00 2001
From: Steve Mao <maochenyan@gmail.com>
Date: Wed, 16 Mar 2022 00:07:16 +1100
Subject: [PATCH] update dockerfile template

- Use Amazon Linux 2
- cache dependencies by separating it to a different step and utilising docker layer caching
- add comments on where we can install native dependencies
---
 stack-template.hsfiles | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/stack-template.hsfiles b/stack-template.hsfiles
index d45ec6f..06221d6 100644
--- a/stack-template.hsfiles
+++ b/stack-template.hsfiles
@@ -67,12 +67,11 @@ handler person context =
     return (Left "A person's age must be positive")
 
 {-# START_FILE Dockerfile #-}
+# Loosely based on https://timwspence.github.io/blog/posts/2019-08-02-optimized-docker-builds-for-haskell-stack.html
 ARG OUTPUT_DIR=/root/output
 ARG EXECUTABLE_NAME=bootstrap
 
-FROM lambci/lambda:build-provided as build
-
-COPY . .
+FROM lambci/lambda:build-provided.al2 as build
 
 SHELL ["/bin/bash", "--rcfile", "~/.profile", "-c"]
 
@@ -83,17 +82,18 @@ RUN yum update -y ca-certificates
 # Installing Haskell Stack
 RUN curl -sSL https://get.haskellstack.org/ | sh
 
-# Build the lambda
-COPY . /root/lambda-function/
+WORKDIR /root/lambda-function/
 
-RUN pwd
+# Build the deps
+RUN stack clean --full
+RUN yum install -y gmp-devel ncurses-devel # Add more build time dependencies here if needed. EG: postgresql-devel
 
-RUN cd /root/lambda-function
-WORKDIR /root/lambda-function/
+COPY stack.yaml package.yaml stack.yaml.lock /root/lambda-function/
+RUN stack build --dependencies-only
 
-RUN ls
+# Build the lambda
+COPY . /root/lambda-function/
 
-RUN stack clean --full
 RUN stack build
 
 ARG OUTPUT_DIR
@@ -103,12 +103,15 @@ RUN mkdir -p ${OUTPUT_DIR} && \
 
 ARG EXECUTABLE_NAME
 
-RUN cp $(stack path --local-install-root)/bin/${EXECUTABLE_NAME} ${OUTPUT_DIR}/${EXECUTABLE_NAME}
+RUN mv $(stack path --local-install-root)/bin/${EXECUTABLE_NAME} ${OUTPUT_DIR}/${EXECUTABLE_NAME}
 
 ENTRYPOINT sh
 
 FROM public.ecr.aws/lambda/provided:al2 as deploy
 
+# Install any runtime dependencies. EG:
+# RUN yum install -y postgresql
+
 ARG EXECUTABLE_NAME
 
 WORKDIR ${LAMBDA_RUNTIME_DIR}
@@ -117,9 +120,7 @@ ARG OUTPUT_DIR
 
 COPY --from=build ${OUTPUT_DIR} .
 
-RUN ls
 RUN mv ${EXECUTABLE_NAME} bootstrap || true
-RUN ls
 
 CMD [ "handler" ]