Exporting build files from docker container - docker

Question

I have a docker image that builds a c/c++ embedded project and creates build artifacts.
I wrote a shell script which builds the code by using the docker image. It is intended be launched by the user on his machine to do debugging.
The build process work just fine and the files are created, but I'm not able to export them to the host machine for debugging.
I'm getting the error:
Error: No such container:path: builder:/usr/src/myCppProject/build/*.elf
This is my script:
#!/bin/bash
echo "Building docker image"
docker build --tag my-gcc:1.0 .
echo "Running docker container"
docker run -t -d --name builder --privileged my-gcc:1.0
echo "extracting artifacts"
docker cp builder:/usr/src/myCppProject/build/*.elf .
echo "Removing container"
docker stop builder
docker rm builder
echo "Cleaning up"
docker rmi $(docker images -f "dangling=true" -q)
the detailed output is:
...
/usr/src/myCppProject/LIBS/Shell/shell.h:80:76: warning: missing braces around initializer [-Wmissing-braces]
80 | sConsoleCMD_td s##name __attribute__ ((section(".shell_cmds"))) = {"MAGIC", (uint8_t*)#name, (uint8_t*)basic_desciption, (uint8_t*)detailed_description, (uint32_t)param_count, false, 0, CallBack, {0,0}}
| ^
/usr/src/myCppProject/APPS/main.c:32:1: note: in expansion of macro 'CON_CREATE_CMD'
32 | CON_CREATE_CMD(test, "test", "", 1, NULL);
| ^~~~~~~~~~~~~~
[100%] Linking C executable Testbench.elf
text data bss dec hex filename
25536 2044 7680 35260 89bc Testbench.elf
[100%] Built target Testbench.elf
Removing intermediate container 3d4a78e05b33
---> 8f2bfcfd19d7
Step 16/17 : WORKDIR /usr/src/myCppProject/build
---> Running in fd30a67e6d93
Removing intermediate container fd30a67e6d93
---> 5f0104d0b1e7
Step 17/17 : RUN ls
---> Running in 6096737dd094
CMakeCache.txt
CMakeFiles
Makefile
Testbench.bin
Testbench.elf
Testbench.hex
Testbench.map
cmake_install.cmake
Removing intermediate container 6096737dd094
---> 3624660a131b
Successfully built 3624660a131b
Successfully tagged my-gcc:1.0
Running docker container
4a31aee944118084602841f51b317df21b49d831345d78e652e36a3b2dfd1801
extracting artifacts
Error: No such container:path: builder:/usr/src/myCppProject/build/*.elf
Removing container
builder
...
Trying to use volumes is even worse, when calling:
mkdir build
docker run --name builder --privileged -v /build:/usr/src/myCppProject/build my-gcc:1.0
The script finishes successfully but the folder build on the host is empty :-( In my understanding whatever is but into build folder in the container should be also present in the just created build folder on the Host.
Thanks in advance e for your help.
Martin

Answer 1

OK finally I found it:
docker cp builder:/usr/src/myCppProject/build/*.elf does not work. It seems you need to specify the exact name.