Best/secure way to share data between sidecar and app containers

Thinking about building a sidecar container to act as an authentication client and retrieve access_tokens for a service. What’d be the best way to share the temporary access_token with the app container? will emptyDir fit the bill here? what you reckon are the main concerns?

Emptydir is great for this. If you don’t want it touching disk, you can set medium=Memory (aka tmpfs) or if you want to not even touch the VFS, you can use something like shared-memory.