Fix unikernel deployment

[matthewjmarangoni]

This PR addresses an issue a user noticed where the instructions resulted in a broken deployment.

Issue

Instances based off the pushed image would do nothing but reboot as shown by the logs. Of note the uploaded image was 37MB.

Changes

• The primary fix is the addition of a flag specifying that the initrd filesystem is EROFS.
• The headless image memory allocation is increased from 1024MB as it was insufficient.
• Variables are added to run-unikernel.sh scripts that allow adjusting the volimport path prefix and the VCPUS parameter.
  • The volimport prefix environment variable might be unnecessary but was preferred as the original references onkernel. The official version seems to work and is the default.
• The README is improved.

Both headless and headful images were built and run. The headful image ran with WebRTC enabled.

---

Note

Package unikernels with EROFS, increase headless memory, add VCPUS and VOLIMPORT_PREFIX envs, and refine README unikernel instructions.

• Unikernel build
  • Add --rootfs-type erofs to images/chromium-headless/build-unikernel.sh and images/chromium-headful/build-unikernel.sh.
• Unikernel run
  • images/chromium-headless/run-unikernel.sh:
    • Memory: -M increased from 1024 to 3072.
    • vCPUs configurable via VCPUS (default 1).
  • images/chromium-headful/run-unikernel.sh:
    • vCPUs configurable via VCPUS (default 4).
    • Volume import image prefix configurable via VOLIMPORT_PREFIX (defaults to onkernel).
• Docs
  • README.md: Update Unikraft instructions—split secret exports, use explicit IMAGE=... images/.../{build,run}-unikernel.sh commands, add headful run alternative with VOLIMPORT_PREFIX, and note VCPUS tunable.

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[rgarcia]

thanks @matthewjmarangoni!