diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c4c4ffc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.zip
diff --git a/Dockerfile b/Dockerfile
index 6a87915..aead3c4 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM lambci/lambda:build-python3.6
+FROM lambci/lambda:build-python3.7
 
 ENV \
   LANG=en_US.UTF-8 \
@@ -7,9 +7,13 @@ ENV \
 RUN yum makecache fast
 RUN yum install -y automake16 libpng-devel nasm
 
-ENV PREFIX /var/task
+# labda runtime: /var/task
+# labda layer: /opt
+ARG prefix=/var/task
+ENV PREFIX=${prefix}
 
-# versions of packages
+# versions of packages, see also rasterio test matrix at:
+# - https://github.com/mapbox/rasterio/blob/master/.travis.yml
 ENV \
   PKGCONFIG_VERSION=0.29.2 \
   PROJ_VERSION=5.2.0 \
@@ -179,5 +183,9 @@ ENV \
 
 ENV PATH=$PREFIX/bin:$PATH
 
-RUN pip3 install pip -U
-RUN pip3 install cython numpy --no-binary numpy
+# numpy 1.17 requires an explicit c99 compiler option
+# - https://github.com/numpy/numpy/pull/12783/files
+ENV CFLAGS='-std=c99'
+RUN pip3 install pip -U && \
+    pip3 install cython numpy "gdal==${GDAL_VERSION}" rasterio --no-binary :all:
+
diff --git a/Makefile b/Makefile
index eeb7f27..2f0eeeb 100644
--- a/Makefile
+++ b/Makefile
@@ -1,32 +1,59 @@
 SHELL = /bin/bash
-TAG = 2.4.2
-IMAGE := ${DOCKER_USERNAME}/amazonlinux-gdal:${TAG}
+PY_VERSION = 3.7
+GDAL_VERSION = 2.4.2
+TAG = gdal${GDAL_VERSION}-py${PY_VERSION}
+IMAGE := amazonlinux-gdal
+BUILD := ${IMAGE}:${TAG}
 
 all: build push
 
 build:
-	docker build -f Dockerfile -t amazonlinux-gdal:${TAG} .
+	docker build -f Dockerfile -t ${BUILD} .
 
-shell:
-	docker run --name amazonlinux --volume $(shell pwd)/:/data --rm  -it ${IMAGE} /bin/bash
+shell: build
+	docker run --name amazonlinux --volume $(shell pwd)/:/data --rm  -it ${BUILD} /bin/bash
 
 debug-gdal: build
-	docker run \
-		--name amazonlinux \
-		-itd amazonlinux-gdal:${TAG} /bin/bash
+	docker run --name amazonlinux \
+		-itd ${BUILD} /bin/bash
 	docker exec -it amazonlinux bash -c 'ldd /var/task/lib/libgdal.so'
 	docker exec -it amazonlinux bash -c 'readelf -d /var/task/lib/libgdal.so'
 	docker stop amazonlinux
 	docker rm amazonlinux
 
 test:
-	docker run amazonlinux-gdal:${TAG} bash -c "gdalinfo --version | grep '${TAG}'"
-	docker run amazonlinux-gdal:${TAG} bash -c "gdalinfo --formats | grep 'JP2OpenJPEG'"
+	docker run ${BUILD} bash -c "gdalinfo --version | grep '${GDAL_VERSION}'"
+	docker run ${BUILD} bash -c "gdalinfo --formats | grep 'JP2OpenJPEG'"
+	docker run ${BUILD} bash -c "python --version | grep '${PY_VERSION}'"
 
 push:
-	docker tag amazonlinux-gdal:${TAG} ${IMAGE}
-	docker push ${IMAGE}
+	docker push ${DOCKER_USERNAME}/${BUILD}
+
+container-clean:
+	docker stop amazonlinux > /dev/null 2>&1 || true
+	docker rm amazonlinux > /dev/null 2>&1 || true
+
+# ---
+# lambda layer build and package using /opt
+
+LAYER_BUILD = ${BUILD}-layer
+LAYER_PACKAGE := amazonlinux-${TAG}-layer.zip
+
+lambda-layer-build:
+	docker build -f Dockerfile -t ${LAYER_BUILD} --build-arg prefix=/opt .
+
+lambda-layer-shell: lambda-layer-build container-clean
+	docker run --name amazonlinux --volume $(shell pwd)/:/data --rm  -it ${LAYER_BUILD} /bin/bash
+
+lambda-layer-package: lambda-layer-build container-clean
+	docker run --name amazonlinux -itd ${LAYER_BUILD} /bin/bash
+	docker exec -it amazonlinux bash -c 'mkdir -p $${PREFIX}/python/lib/python${PY_VERSION}/site-packages'
+	docker exec -it amazonlinux bash -c 'rsync -a /var/lang/lib/python${PY_VERSION}/site-packages/ $${PREFIX}/python/lib/python${PY_VERSION}/site-packages/'
+	docker exec -it amazonlinux bash -c 'cd $${PREFIX} && zip -r9 --symlinks /tmp/package.zip python'
+	docker exec -it amazonlinux bash -c 'cd $${PREFIX} && zip -r9 --symlinks /tmp/package.zip lib/*.so*'
+	docker exec -it amazonlinux bash -c 'cd $${PREFIX} && zip -r9 --symlinks /tmp/package.zip lib64/*.so*'
+	docker exec -it amazonlinux bash -c 'cd $${PREFIX} && zip -r9 --symlinks /tmp/package.zip bin'
+	docker exec -it amazonlinux bash -c 'cd $${PREFIX} && zip -r9 /tmp/package.zip share'
+	docker cp amazonlinux:/tmp/package.zip ${LAYER_PACKAGE}
+	docker stop amazonlinux && docker rm amazonlinux
 
-clean:
-	docker stop amazonlinux
-	docker rm amazonlinux