Create a Docker image FROM SCRATCH

The C Program

#include <stdio.h>
#include <unistd.h>
#include <sys/utsname.h>

int main() {
   printf("This program runs in (or as?) a container\n");
   printf("The processid (PID) is %d\n", getpid());

   struct utsname unam;
   if (uname(&unam) != -1) {
       printf("Kernel version and release:\n  %s\n  %s\n", unam.version, unam.release);
   } else {
       printf("Failed to retrieve kernel information.\n");
   }
}

Compiling the program

gcc -static prog.c -o prog

Building the image from the executable and a dockerfile

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

docker build -t prog-img .

Run the image

docker run prog-img

See also