From 9f4958b5fde49e8c193d082068caa13712e974b8 Mon Sep 17 00:00:00 2001
From: Alexandru Ciobotaru <alcioa@amazon.com>
Date: Thu, 3 Nov 2022 13:54:59 +0200
Subject: [PATCH] kmstool-enclave: optimize the enclave image size

Use a scratch base image and copy only the mandatory
dependencies to run the KMS Decrypt demo.

This reduces the EIF image size from 147 MiB to 25 MiB.

Signed-off-by: Alexandru Ciobotaru <alcioa@amazon.com>
---
 containers/Dockerfile.al2 | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/containers/Dockerfile.al2 b/containers/Dockerfile.al2
index 37a1a0d..e166022 100644
--- a/containers/Dockerfile.al2
+++ b/containers/Dockerfile.al2
@@ -71,22 +71,35 @@ RUN cmake3 -DCMAKE_PREFIX_PATH=/usr -DCMAKE_INSTALL_PREFIX=/usr -GNinja \
 RUN cmake3 --build aws-nitro-enclaves-sdk-c/build --parallel $(nproc) --target install
 RUN cmake3 --build aws-nitro-enclaves-sdk-c/build --parallel $(nproc) --target docs
 
-# Test
-FROM builder as test
-RUN cmake3 --build aws-nitro-enclaves-sdk-c/build --target test
-
 # kmstool-enclave
-FROM amazonlinux:2 as kmstool-enclave
+RUN mkdir -p /rootfs
+WORKDIR /rootfs
+
+RUN BINS="\
+    /usr/lib64/libnsm.so \
+    /usr/bin/kmstool_enclave \
+    " && \
+    for bin in $BINS; do \
+        { echo "$bin"; ldd "$bin" | grep -Eo "/.*lib.*/[^ ]+"; } | \
+            while read path; do \
+                mkdir -p ".$(dirname $path)"; \
+                cp -fL "$path" ".$path"; \
+            done \
+    done
+
+RUN mkdir -p /rootfs/etc/pki/tls/certs/ \
+    && cp -f /etc/pki/tls/certs/* /rootfs/etc/pki/tls/certs/
+RUN find /rootfs
+
+FROM scratch as kmstool-enclave
+
+COPY --from=builder /rootfs /
 
-# TODO: building packages statically instead of cleaning up unwanted packages from amazonlinux
-RUN rpm -e python python-libs python-urlgrabber python2-rpm pygpgme pyliblzma python-iniparse pyxattr python-pycurl amazon-linux-extras yum yum-metadata-parser yum-plugin-ovl yum-plugin-priorities
-COPY --from=builder /usr/lib64/libnsm.so /usr/lib64/libnsm.so
-COPY --from=builder /usr/bin/kmstool_enclave /kmstool_enclave
 ARG REGION
 ARG ENDPOINT
 ENV REGION=${REGION}
 ENV ENDPOINT=${ENDPOINT}
-CMD ["/kmstool_enclave"]
+CMD ["/usr/bin/kmstool_enclave"]
 
 # kmstool-instance
 FROM amazonlinux:2 as kmstool-instance
@@ -104,3 +117,8 @@ FROM amazonlinux:2 as kmstool-enclave-cli
 RUN rpm -e python python-libs python-urlgrabber python2-rpm pygpgme pyliblzma python-iniparse pyxattr python-pycurl amazon-linux-extras yum yum-metadata-parser yum-plugin-ovl yum-plugin-priorities
 COPY --from=builder /usr/lib64/libnsm.so /usr/lib64/libnsm.so
 COPY --from=builder /usr/bin/kmstool_enclave_cli /kmstool_enclave_cli
+
+# Test
+FROM builder as test
+WORKDIR /tmp/crt-builder
+RUN cmake3 --build aws-nitro-enclaves-sdk-c/build --parallel $(nproc) --target test