support for docker in docker feature ?

[KingBain]

looking to test this, but one of the issues I am experiencing is when there are multiple layers of abstraction. for example doing docker in docker.

"features": {
"ghcr.io/devcontainers/features/docker-in-docker:2": {}
}

will certsync work with docker in docker?

[ishwar170695]

Hi @KingBain,

Sorry for the delayed response, and thanks for raising this.

I just ran some Docker-in-Docker (DinD) tests to verify the behavior.

CertSync works for the inner Docker daemon (dockerd) itself. The daemon can use the certificates installed by CertSync and successfully pull images through a MITM/corporate proxy.
However, containers launched by that inner daemon do not automatically inherit those certificates, since they're separate filesystems. Those containers will need their own CA injection strategy (image bake, mount, or running CertSync inside them).

So currently:

• Inner dockerd is supported
• Automatic trust propagation into nested containers is not

I'll add this limitation to the documentation.

Thanks again for the question, it helped uncover and verify this edge case.