VS Code, Cursor and SSH config

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Before you start

• An API key with the ssh action in BOAT_API_KEY. Read API keys.
• An SSH key pair at ~/.ssh/id_ed25519. Create one with ssh-keygen -t ed25519 if you have none.
• curl and jq.
• On Windows, run the script in Git Bash. VS Code reads the same C:\Users\<you>\.ssh\config.

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1. Save the script

#!/usr/bin/env bash
# Usage: bash boat-ssh-config.sh <sandbox-id>
# Authorizes ~/.ssh/id_ed25519 on the sandbox and writes ~/.ssh/boat/<id>.conf.
set -euo pipefail
id="$1"
key=~/.ssh/id_ed25519

resp="$(curl -fsS -X POST "https://boat.dev/api/v1/sandboxes/$id/sshkey" \
  -H "Authorization: Bearer $BOAT_API_KEY" \
  -H "Content-Type: application/json" \
  -d "{\"key\":\"$(cat "$key.pub")\"}")"

# sshEndpoint ("host:port") is set when the sandbox has no public IPv4 of its own
endpoint="$(echo "$resp" | jq -r '.sshEndpoint // empty')"
if [ -n "$endpoint" ]; then
  host="${endpoint%:*}"; port="${endpoint##*:}"
else
  host="$(echo "$resp" | jq -r .machineIp)"; port=22
fi

mkdir -p ~/.ssh/boat
echo "$id $(echo "$resp" | jq -r .hostKey)" > ~/.ssh/boat/"$id".known_hosts
cat > ~/.ssh/boat/"$id".conf <<EOF
Host $id
  HostName $host
  Port $port
  User user
  IdentityFile "$key"
  HostKeyAlias $id
  UserKnownHostsFile "$HOME/.ssh/boat/$id.known_hosts"
  StrictHostKeyChecking yes
EOF
echo "Wrote ~/.ssh/boat/$id.conf"

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2. Include the entries in your SSH config

Include ~/.ssh/boat/*.conf

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3. Write the entry and connect

bash boat-ssh-config.sh bx_f7k2q9hd
ssh bx_f7k2q9hd true    # test: prints nothing and exits 0

• VS Code: install the Remote - SSH extension. Run Remote-SSH: Connect to Host… and pick bx_f7k2q9hd.
• Cursor: run Remote-SSH: Connect to Host… and pick bx_f7k2q9hd.
• Other tools that read ~/.ssh/config work the same way.

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After a resume or a fork

1. Run bash boat-ssh-config.sh <id> again. It writes the new address and the new host key.
2. Reconnect the editor.

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Good to know

• An open editor does not delay auto-stop. To keep the sandbox up for a work day, run boat extend <id> --hours 8. Read Auto-stop.
• The editor installs its server in /home/user/.vscode-server or a similar folder. Snapshots keep it, so the next connection after a resume is faster.
• Your key stays authorized after a stop, a resume and a fork. The script authorizes it again anyway. This is safe.
• boat ssh <id> needs none of this. It finds the address and the host key itself.

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Related

• SSH
• Forward a port