installing cpp extension offline

[UrbanskiDawid]

hi,

I'm due to company proxy, in having problems
with "platform-specific binary dependencies"
for cpp extensions (pop-up errors and not working extension)
This is a know issue with this extension and workaround for it is to install binaries from local copy.
This seems easy but I cannot make it work.

This is my unsuccessful attempt:
download vscx and add it to dockerfile,
then in devcontainer.json add
$ code --instal-extension cpptools-linux.vscx
to onCreateCommand.

This command works in vscode terminal and installs binaries without any problem.

..but..

running it in "onCreateCommand" endeds up in:
"code or code-insiders is not installed".

could you please help me resolving this issue?