Dockerfile from scratch using dynamic build

Question

The following post it too long , please be patient while going through

Hi , i'm quite new to docker and dds .

i am creating a simple code using rti-dds and docker . The code will provide me two exes one for publishing the data and other for subscribing the data.

I want to use FROM scratch in my Dockerfile as i don't need bash nor any os.

Now if i use FROM scratch do i need to have my exes statically build with the g++ -static flag or can it be done dynamically , that is without the static flag.

Which one is preferred or is there a rule to it?

Docker Verion

Client: Docker Engine - Community
Version: 19.03.2
API version: 1.40
Go version: go1.12.8
Git commit: 6a30dfc
Built: Thu Aug 29 05:29:11 2019
OS/Arch: linux/amd64
Experimental: false

Dockerfile when exe files are build with -static flag

FROM scratch

COPY rti_license.dat /
COPY USER_QOS_PROFILES.xml /
COPY /objs/x64Linux3gcc4.8.2/DynamicTest_publisher /
COPY /objs/x64Linux3gcc4.8.2/DynamicTest_subscriber /

CMD ["/DynamicTest_publisher"]

The docker image gets successfully build and runs without any error

BUT

Dockerfile when exe files are build dynamically (without static flag)

figuring all the dependencies were to be copied as well checked the dependencies using

ldd on the exe

FROM scratch

COPY rti_license.dat /
COPY USER_QOS_PROFILES.xml /
COPY /lib/x86_64-linux-gnu/libdl.so.2 /
COPY /lib/x86_64-linux-gnu/libnsl.so.1 /
COPY /lib/x86_64-linux-gnu/libpthread.so.0 /
COPY /lib/x86_64-linux-gnu/librt.so.1 /
COPY /usr/lib/x86_64-linux-gnu/libstdc++.so.6 /
COPY /lib/x86_64-linux-gnu/libc.so.6 /
COPY /lib/x86_64-linux-gnu/libgcc_s.so.1 /
COPY /objs/x64Linux3gcc4.8.2/DynamicTest_publisher /
COPY /objs/x64Linux3gcc4.8.2/DynamicTest_subscriber /
COPY /lib64/ld-linux-x86-64.so.2 /

CMD ["/DynamicTest_publisher"]

Build the docker image

docker build --tag dynamictest .

But when i try to run this i get the following error

docker run --rm -it dynamictest

Error
standard_init_linux.go:211: exec user process caused "no such file or directory

So , am i missing something here or is it that "FROM scratch only works with static builds"

Answer 1

THIS WORKED OUT BEST FOR ME - Dynamic Build

The very first thing was to find out all the dependencies for your exe file

    $ldd dytest_publisher

    linux-vdso.so.1 =>  (0x00007ffec3df9000)
    libdl.so.2 => /usr/lib64/libdl.so.2 (0x00007ffb0e740000)
    libnsl.so.1 => /usr/lib64/libnsl.so.1 (0x00007ffb0e526000)
    libpthread.so.0 => /usr/lib64/libpthread.so.0 (0x00007ffb0e30a000)
    librt.so.1 => /usr/lib64/librt.so.1 (0x00007ffb0e102000)
    libstdc++.so.6 => /usr/local/lib64/libstdc++.so.6 (0x00007ffb0dd28000)
    libm.so.6 => /usr/lib64/libm.so.6 (0x00007ffb0da26000)
    libc.so.6 => /usr/lib64/libc.so.6 (0x00007ffb0d665000)
    /lib64/ld-linux-x86-64.so.2 (0x00007ffb0e945000)
    libgcc_s.so.1 => /usr/local/lib64/libgcc_s.so.1 (0x00007ffb0d44c000)

Copy the above libraries along with the folder structure in your project folder and create a docker file with name Dockerfile

Dockerfile

FROM scratch

COPY rti_license.dat / 
COPY USER_QOS_PROFILES.xml /     
COPY /objs/x64Linux3gcc4.8.2/DynamicTest_publisher /     
COPY /objs/x64Linux3gcc4.8.2/DynamicTest_subscriber /     
COPY /lib64/* /lib64/     
COPY /usr/lib64/* /usr/lib64/      

ENV LD_LIBRARY_PATH=/usr/lib64/:/lib64/     

CMD ["/dytest_publisher"]   

Note: project folder must have the directory: /usr/lib64/ and /lib64/ along with all the depended libraries. Depended libraries can be checked by the following command :

$ldd "your exe file" 

Build the docker image

docker build --tag dynamictest .

Running the created image

docker run --rm -it dynamictest

To see the running container

docker container ls

PS : thanks to everyone for their help on this