Docker/Podman Multistage container with graceful shutdown

Dockerfile

FROM alpine:latest as build
RUN apk add build-base
WORKDIR /tmp
COPY . ./
RUN make

FROM alpine:latest
COPY --from=build /tmp/output /usr/local/bin/output

CMD ["output"]

makefile

output:
	gcc -Wall -Werror output.c -o output

container:
	podman build -t tmp:latest .

run:
	podman run --rm -ti --name foo tmp:latest

output.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>

void shutdown_now(int _) {
    fprintf(stderr, "SHUTDOWN!\n");
    exit(0);
}

int main(int argc, char **argv) {
    struct sigaction sa;

    sa.sa_handler = shutdown_now;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_RESTART;

    if (sigaction(SIGTERM, &sa, NULL) == -1) {
        fprintf(stderr, "failed to attach SIGTERM handler\n");
        return -1;
    }

    if (sigaction(SIGINT, &sa, NULL) == -1) {
        fprintf(stderr, "failed to attach SIGINT handler\n");
        return -1;
    }

    while(1) {
        printf("Hello World\n");
        sleep(1);
    }
    return 0;
}