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Building PAI in the Cloud

Building PAI on a laptop works, but it's slow (15–60 minutes) and disk-hungry (~30 GB for minimal, ~80 GB for full). If you're iterating on a custom flavor — extra packages, a different desktop, pre-bundled models, ARM64 cross-builds — a high-powered cloud VM pays for itself in saved time.

This guide focuses on Google Cloud, which gives new accounts $300 in free credits valid for 90 days. That's enough to run a 32-vCPU builder for roughly 190 hours — more ISO builds than any sane person needs.

Why cloud build?

Laptop (8 vCPU) GCP n2-standard-32
Minimal ISO build 15–25 min 3–4 min
Full ISO build 45–60 min 8–12 min
Disk I/O Thermal-throttled SSD pd-ssd, no throttling
Cost per build Your fan ~$0.10
Parallel flavors One at a time Spin up N VMs

The sweet spot is iterating on a custom flavor: edit a hook, kick off a build, have an ISO in 4 minutes, flash to a test USB, repeat.

1. Sign up and claim credits

  • Sign up at cloud.google.com/free
  • New accounts get $300 in credits valid for 90 days
  • A credit card is required for identity verification, but nothing is charged until you explicitly upgrade

2. Install the gcloud CLI

3. Create the build VM

gcloud compute instances create pai-builder \
  --machine-type=n2-standard-32 \
  --image-family=debian-12 --image-project=debian-cloud \
  --boot-disk-size=200GB --boot-disk-type=pd-ssd \
  --zone=us-central1-a

Machine type cheat sheet:

Type vCPUs RAM ~$/hr Best for
e2-standard-8 8 32 GB ~$0.27 Casual minimal builds
n2-standard-16 16 64 GB ~$0.77 Full builds, good balance
n2-standard-32 32 128 GB ~$1.55 Fastest iteration loop
c3-highcpu-44 44 88 GB ~$2.10 CPU-bound package installs

For one-off builds, e2-standard-8 is fine. For flavor development (many builds/day), pay for the bigger box — your time is worth more than the credits.

4. Build the ISO

gcloud compute ssh pai-builder --zone=us-central1-a

# Inside the VM:
sudo apt update && sudo apt install -y docker.io git
sudo usermod -aG docker $USER && newgrp docker

git clone https://github.com/nirholas/pai.git
cd pai

# Optional: edit hooks or package lists for your custom flavor
# vim config/package-lists/pai.list.chroot

docker build -f Dockerfile.build -t pai-builder .
docker run --privileged --rm -v "$PWD/output:/output" pai-builder

ls -lh output/*.iso

5. Pull the ISO back

# From your local machine:
gcloud compute scp pai-builder:~/pai/output/live-image-amd64.hybrid.iso . \
  --zone=us-central1-a

6. Delete the VM — don't forget this

gcloud compute instances delete pai-builder --zone=us-central1-a

A running n2-standard-32 burns ~$37/day. Even with $300 in credits, leaving one idle for a week eats most of it. Always delete when done.

Set a budget alert at console.cloud.google.com/billing/budgets for peace of mind.

Alternatives

AWS (EC2)

New accounts get a 12-month free tier, but it doesn't include build-grade machines. Expect to pay out-of-pocket. A c7i.8xlarge (32 vCPU, 64 GB) is ~$1.45/hr and performs similarly to n2-standard-32.

# Rough equivalent — assumes you already have an AWS CLI profile and a key pair
aws ec2 run-instances \
  --image-id ami-0fa1de1d60de6a97e \   # Debian 12 AMD64 us-east-1
  --instance-type c7i.8xlarge \
  --key-name YOUR_KEY \
  --block-device-mappings 'DeviceName=/dev/xvda,Ebs={VolumeSize=200,VolumeType=gp3}'

Azure

New accounts get $200 in credits for 30 days. A Standard_D32s_v5 (32 vCPU, 128 GB) is ~$1.54/hr.

Hetzner / OVH / self-hosted

Hetzner's CCX63 (48 dedicated vCPU, 192 GB) is €0.30/hr — dramatically cheaper than hyperscalers for throwaway build boxes. No free credits, but no egress fees either.

Tips for custom flavors

  1. Cache your Docker layers. The pai-builder image takes ~5 min to build the first time. Keep the VM alive across iterations and only rebuild the image when Dockerfile.build changes.
  2. Mount a persistent disk for /output and the git clone. Destroying the VM while keeping the disk means you can resume in seconds next session.
  3. Use docker run --rm with bind mounts so ISOs land on the host filesystem and survive container exits.
  4. Build both architectures in parallel. Spin up one VM for AMD64 and one for ARM64 (t2a-standard-32 on GCP) and let them run simultaneously.
  5. Stream the ISO straight to a machine for testing instead of downloading locally: 
    gcloud compute ssh pai-builder --zone=us-central1-a -- \
  'cat ~/pai/output/live-image-amd64.hybrid.iso' \
  | sudo dd of=/dev/sdX bs=4M status=progress && sync

Cost reality check

At current GCP pricing, one full ISO build on n2-standard-32 costs about $0.10. Even doing 10 builds a day while developing a custom flavor, you'll burn through maybe $5 of your $300 credit budget in a week. You would have to actively try to run out.

The real cost risk is leaving an idle VM running. Always gcloud compute instances delete when you're done, or use a preemptible/spot instance (--provisioning-model=SPOT) which is ~70% cheaper and auto-terminates within 24 hours.

See also