Compile and run a simple C Hello World app using Docker scratch & Distroless

build-distroless.sh

#!/bin/bash -e

docker build -t myapp -f Dockerfile.distroless .
docker run --rm -t myapp

build-scratch.sh

#!/bin/bash -e

docker run --rm -v $PWD:/build ubuntu:latest /bin/bash -c \
  "apt-get update && apt-get -y install build-essential && \
   cd /build && \
   gcc -o hello -static -nostartfiles hello.c"
docker build --tag hello -f Dockerfile.scratch .
docker run --rm -t hello

Dockerfile.distroless

FROM ubuntu:latest as builder

WORKDIR /build
ADD . /build

RUN apt-get update && apt-get -y install build-essential
RUN gcc -o hello -static -nostartfiles hello.c

# Now copy it into our base image.
FROM gcr.io/distroless/static-debian10
COPY --from=builder /build/hello /
CMD ["/hello"]

Dockerfile.scratch

FROM scratch
ADD hello /
CMD ["/hello"]

hello.c

#include <sys/syscall.h>
#include <unistd.h>

#ifndef DOCKER_IMAGE
	#define DOCKER_IMAGE "hello-world"
#endif

#ifndef DOCKER_GREETING
	#define DOCKER_GREETING "Hello from Docker!"
#endif

#ifndef DOCKER_ARCH
	#define DOCKER_ARCH "amd64"
#endif

const char message[] =
	"\n"
	DOCKER_GREETING "\n"
	"This message shows that your installation appears to be working correctly.\n"
	"\n"
	"To generate this message, Docker took the following steps:\n"
	" 1. The Docker client contacted the Docker daemon.\n"
	" 2. The Docker daemon pulled the \"" DOCKER_IMAGE "\" image from the Docker Hub.\n"
	"    (" DOCKER_ARCH ")\n"
	" 3. The Docker daemon created a new container from that image which runs the\n"
	"    executable that produces the output you are currently reading.\n"
	" 4. The Docker daemon streamed that output to the Docker client, which sent it\n"
	"    to your terminal.\n"
	"\n"
	"To try something more ambitious, you can run an Ubuntu container with:\n"
	" $ docker run -it ubuntu bash\n"
	"\n"
	"Share images, automate workflows, and more with a free Docker ID:\n"
	" https://hub.docker.com/\n"
	"\n"
	"For more examples and ideas, visit:\n"
	" https://docs.docker.com/get-started/\n"
	"\n";

int main() {
	//write(1, message, sizeof(message) - 1);
	syscall(SYS_write, STDOUT_FILENO, message, sizeof(message) - 1);

	//_exit(0);
	//syscall(SYS_exit, 0);
	return 0;
}

The docker image sizes are:

$ docker image ls
REPOSITORY           TAG        IMAGE ID       CREATED          SIZE
hello                latest     82cbe50a3059   3 minutes ago    10.4kB
myapp                latest     b778045f2958   7 minutes ago    1.83MB