scratch-bash

This is note to myself on how to use bin/bash with scratch image.

1. Check bin/bash dependencies

   $ ldd /bin/bash
           linux-vdso.so.1 (0x00007ffff87c1000)
           libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007f37b09a9000)
           libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f37b0780000)
           /lib64/ld-linux-x86-64.so.2 (0x00007f37b0b44000)
   

2. Copy bin/bash and dependent files to work directory.

   $ cp /lib/x86_64-linux-gnu/libtinfo.so.6 ./
   $ cp /lib/x86_64-linux-gnu/libc.so.6 ./
   $ cp /lib64/ld-linux-x86-64.so.2 ./
   $ cp /bin/bash ./
   

3. Write a Dockerfile that copies /bin/bash and the dependency files to the container.

   FROM scratch
   COPY ./libtinfo.so.6 /lib/x86_64-linux-gnu/libtinfo.so.6
   COPY ./libc.so.6 /lib/x86_64-linux-gnu/libc.so.6
   COPY ./ld-linux-x86-64.so.2 /lib64/ld-linux-x86-64.so.2
   COPY ./bash /bin/bash
   CMD ["/bin/bash"]
   

4. Build

   $ docker build -t scrach ./
   [+] Building 0.1s (8/8) FINISHED                                                                 docker:default
   => [internal] load build definition from Dockerfile                                                       0.0s
   => => transferring dockerfile: 254B                                                                       0.0s
   => [internal] load .dockerignore                                                                          0.0s
   => => transferring context: 2B                                                                            0.0s
   => [internal] load build context                                                                          0.0s
   => => transferring context: 4.06MB                                                                        0.0s
   => CACHED [1/4] COPY ./libtinfo.so.6 /lib/x86_64-linux-gnu/libtinfo.so.6                                  0.0s
   => CACHED [2/4] COPY ./libc.so.6 /lib/x86_64-linux-gnu/libc.so.6                                          0.0s
   => CACHED [3/4] COPY ./ld-linux-x86-64.so.2 /lib64/ld-linux-x86-64.so.2                                   0.0s
   => CACHED [4/4] COPY ./bash /bin/bash                                                                     0.0s
   => exporting to image                                                                                     0.0s
   => => exporting layers                                                                                    0.0s
   => => writing image sha256:80733217972cae75a51053bc6e20269ca75df7357f3473055b51dd1d0b621fc3               0.0s
   => => naming to docker.io/library/scrach
   

5. Run

   $ docker run -it scrach
   bash-5.1# echo *
   bin dev etc lib lib64 proc sys
   bash-5.1#