Can't make use of cargo or rustup while container building.

[IamTheCarl]

Hello.
For my use case, I need to install a few extra toolchains for cross-compiling.

Trying to call rustup to install the target toochains fails during container build, wether I use rustup or /usr/local/cargo/bin/rustup.
I'm starting to suspect that rustup is not installed until after the image has completed building.
Is this correct?

Is there a recommended workaround?

[matschaffer]

I do toolchain installation as part of my docker file https://github.com/matschaffer/zero2prod/blob/main/.devcontainer/Dockerfile

So far it seems like cargo is best handled via postCreateCommand https://github.com/matschaffer/zero2prod/blob/main/.devcontainer/devcontainer.json#L49

I tried moving it into the docker file but ran these issues:

• Cargo space isn't writable by default, can chown around it but a little annoying
• VScode frame is unusable until a long cargo install completes, seems like caching could make this better but I haven't found a good way to cache data between container rebuilds