A genuinely free remote computer

The local provider is free and shares your machine. The container providers isolate properly and need Docker. The ssh provider is the third option: a Linux box you own, somewhere else, for zero dollars.

Oracle Cloud's Always Free tier is the only mainstream cloud that gives you a persistent ARM VM indefinitely rather than for a trial period. This guide gets one running and points Husk at it.

What you will have at the end: husk doctor reporting ✓ ssh, and husk up remote --provider ssh giving your agent a machine that is not your laptop.

Time: about 30 minutes, most of it Oracle's console.

What Oracle actually gives you

Verified against Oracle's own documentation. Cloud free tiers change; check Always Free Resources before you plan around any of these numbers.

Two things that will bite you

Capacity. Oracle documents an "out of host capacity" error for Always Free shapes and tells you to try a different availability domain or wait. A1 capacity in popular regions is reported by users as intermittently unavailable for days at a time. Oracle publishes no capacity data and makes no availability promise, so treat a successful launch as luck rather than as a plan. Upgrading to Pay As You Go unlocks more shape types; Oracle does not state that it improves A1 host capacity.

Idle reclamation. Oracle "may reclaim" an Always Free compute instance when, over a 7-day period, all of these are true:

• CPU utilisation at the 95th percentile is below 20%
• network utilisation is below 20%
• memory utilisation is below 20% (A1 shapes only)

An agent box that sits idle most of the week qualifies. Oracle does not document what reclamation does — stop or terminate — or whether you are notified. Keep anything you care about in git, not on the boot volume.

Step 1: Create the instance

1. Sign up at oracle.com/cloud/free. A card is required for identity verification; the Always Free resources are not charged. Note your home region — you cannot change it, and Always Free compute must live there.

2. In the console: Compute → Instances → Create instance.

3. Image and shape → Change shape → Ampere, pick VM.Standard.A1.Flex, and set 2 OCPUs / 12 GB.

4. Image: Ubuntu 24.04 (the plain Ubuntu image, not Minimal Ubuntu — Oracle documents Minimal as unsupported on Arm shapes).

5. Add SSH keys: paste your public key. Generate one first if you need to:

   copy

   ssh-keygen -t ed25519 -C husk -f ~/.ssh/husk_oracle
   cat ~/.ssh/husk_oracle.pub

6. Leave networking at the defaults — a new VCN with a public subnet and a public IPv4 address.

7. Create. If you get Out of host capacity, change the availability domain and try again, or come back later.

Step 2: Get in

The default username depends on the image: ubuntu for Ubuntu, opc for Oracle Linux.

ssh -i ~/.ssh/husk_oracle ubuntu@<public-ip>

The VCN's default security list already allows inbound TCP 22, so SSH works out of the box. Nothing else does — see step 5 if you plan to use expose_port.

Give the box the handful of tools an agent expects:

sudo apt-get update
sudo apt-get install -y git curl jq ripgrep fd-find python3-venv build-essential

Step 3: Make the connection non-interactive

Husk runs every ssh invocation with BatchMode=yes, so it never prompts — which means a passphrase-protected key must already be in an agent, and an unknown host key must already be accepted. Husk passes StrictHostKeyChecking=accept-new, so the first connection records the key rather than failing, but doing it by hand once is clearer:

ssh -i ~/.ssh/husk_oracle ubuntu@<public-ip> 'echo ok'      # accept the host key
ssh-add ~/.ssh/husk_oracle                                   # if the key has a passphrase

A ~/.ssh/config entry keeps the rest tidy:

Host husk-oracle
  HostName 203.0.113.10
  User ubuntu
  IdentityFile ~/.ssh/husk_oracle
  ServerAliveInterval 30

Step 4: Point Husk at it

export HUSK_SSH_TARGET=ubuntu@203.0.113.10        # or ubuntu@host:2222
export HUSK_SSH_KEY=~/.ssh/husk_oracle            # optional; the agent is used otherwise
husk doctor

The probe is a real command, not a TCP connect: Husk runs echo husk-ssh-ok; uname -sm and reports the remote uname back to you. If the architecture line says aarch64, you are on the ARM instance.

husk up remote --provider ssh
husk exec remote -- 'uname -sm; nproc; free -h | head -2'
husk exec remote -- 'git clone https://github.com/org/repo /work/repo && ls /work/repo'

Per-husk, the same two settings live in the spec's labels rather than the environment — but note that husk.yaml has no labels field, so this is reachable only through POST /v1/computers:

{ "provider": "ssh",
  "labels": { "husk.ssh": "ubuntu@203.0.113.10", "husk.ssh.key": "/home/me/.ssh/husk_oracle" } }

How it works, briefly

• One SSH ControlMaster is opened per computer and reused, so forty tool calls cost one handshake instead of forty. The socket outlives suspends and network changes; if it dies, every exec falls back to ControlMaster=auto and simply opens a new connection.
• Workspaces live at $HOME/.husk-work/<id>/, with work and tmp subdirectories, both chmod 700. $HOME is resolved on the remote rather than assumed.
• File transfers use scp.
• The path jail is compiled into the remote command itself: readlink -f resolves the target and the guard exits 77 if it lands outside the workspace. A local realpath would cost a round trip per operation.

Step 5: If you want to reach a port

expose_port publishes a port from the machine. On a cloud VM two firewalls stand in the way and both must be opened.

1. The VCN security list. Console → the instance's subnet → its security list → add an ingress rule for the TCP port. Oracle's default list allows only SSH and a couple of ICMP types.

2. The host firewall. Oracle's platform images ship their own rules; opening a port in the console is not enough. Oracle's documentation is explicit that you must check the network security groups, the subnet's security lists and the instance's own firewall rules.

   copy

   # Ubuntu on OCI — Oracle warns not to use ufw here, it can leave the box unbootable.
   sudo iptables -I INPUT 6 -m state --state NEW -p tcp --dport 8000 -j ACCEPT
   sudo netfilter-persistent save

   copy

   # Oracle Linux
   sudo firewall-cmd --zone=public --permanent --add-port=8000/tcp
   sudo firewall-cmd --reload

An honest simpler option: if you only need to reach a dev server, forward the port over SSH instead of opening it to the internet.

ssh -N -L 8000:127.0.0.1:8000 husk-oracle

Step 6: Keep it cheap and keep it alive

• Stay inside Always Free. One A1 instance at 2 OCPU / 12 GB, one boot volume under 200 GB, in your home region. Anything beyond that bills.
• Set a budget alert anyway. Console → Billing → Budgets, at $1. It costs nothing and it catches the mistake.
• Do not fight the idle reclamation with a busy-loop. Burning CPU to look busy is against the spirit of the thing and costs you the CPU. Keep the box's state in git and accept that you may have to rebuild it.

What this does and does not protect

✓ ssh      isolated from this machine
    commands run as your user on that box -- isolated from this machine, not from itself

Husk reports isolationKind: 'machine' rather than a plain green isolated, and the distinction is the whole point.

It does protect your laptop. A prompt-injected agent on the Oracle box cannot touch your home directory, your SSH keys, or your other machines. For "an agent will read a scraped page and I do not want it near my laptop", this is a real boundary and it is free.

It does not protect the Oracle box. The agent runs as ubuntu, with ubuntu's reach: every file that user owns, sudo if it is passwordless (it is, by default, on OCI images), and the box's network position inside your VCN.

Next

• Self-hosting — run husk serve on that same box.
• Isolation — the full provider comparison.
• Providers — every ssh setting.