fix: docs: rent-a-human instructions for Caddy host SSH key setup (#748)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

formulas/rent-a-human-caddy-ssh.toml

@@ -0,0 +1,167 @@
+# formulas/rent-a-human-caddy-ssh.toml — Provision SSH key for Caddy log collection
+#
+# "Rent a Human" — walk the operator through provisioning a purpose-limited
+# SSH keypair so collect-engagement.sh can fetch Caddy access logs remotely.
+#
+# The key uses a `command=` restriction so it can ONLY cat the access log.
+# No interactive shell, no port forwarding, no agent forwarding.
+#
+# Parent vision issue: #426
+# Sprint: website-observability-wire-up (ops PR #10)
+# Consumed by: site/collect-engagement.sh (issue #745)
+
+name        = "rent-a-human-caddy-ssh"
+description = "Provision a purpose-limited SSH keypair for remote Caddy log collection"
+version     = 1
+
+# ── Step 1: Generate keypair ─────────────────────────────────────────────────
+
+[[steps]]
+id    = "generate-keypair"
+title = "Generate a dedicated ed25519 keypair"
+description = """
+Generate a purpose-limited SSH keypair for Caddy log collection.
+
+Run on your local machine (NOT the Caddy host):
+
+```
+ssh-keygen -t ed25519 -f caddy-collect -N '' -C 'disinto-collect-engagement'
+```
+
+This produces two files:
+  - caddy-collect      (private key — goes into the vault)
+  - caddy-collect.pub  (public key — goes onto the Caddy host)
+
+Do NOT set a passphrase (-N '') — the factory runs unattended.
+"""
+
+# ── Step 2: Install public key on Caddy host ─────────────────────────────────
+
+[[steps]]
+id    = "install-public-key"
+title = "Install the public key on the Caddy host with command= restriction"
+needs = ["generate-keypair"]
+description = """
+Install the public key on the Caddy host with a strict command= restriction
+so this key can ONLY read the access log.
+
+1. SSH into the Caddy host as the user who owns /var/log/caddy/access.log.
+
+2. Open (or create) ~/.ssh/authorized_keys:
+     mkdir -p ~/.ssh && chmod 700 ~/.ssh
+     nano ~/.ssh/authorized_keys
+
+3. Add this line (all on ONE line — do not wrap):
+
+     command="cat /var/log/caddy/access.log",no-port-forwarding,no-X11-forwarding,no-agent-forwarding ssh-ed25519 AAAA... disinto-collect-engagement
+
+   Replace "AAAA..." with the contents of caddy-collect.pub.
+
+   To build the line automatically:
+     echo "command=\"cat /var/log/caddy/access.log\",no-port-forwarding,no-X11-forwarding,no-agent-forwarding $(cat caddy-collect.pub)"
+
+4. Set permissions:
+     chmod 600 ~/.ssh/authorized_keys
+
+What the restrictions do:
+  - command="cat /var/log/caddy/access.log"
+      Forces this key to only execute `cat /var/log/caddy/access.log`,
+      regardless of what the client requests.
+  - no-port-forwarding    — blocks SSH tunnels
+  - no-X11-forwarding     — blocks X11
+  - no-agent-forwarding   — blocks agent forwarding
+
+If the access log is at a different path, update the command= restriction
+AND set CADDY_ACCESS_LOG in the factory environment to match.
+"""
+
+# ── Step 3: Add private key to vault secrets ─────────────────────────────────
+
+[[steps]]
+id    = "store-private-key"
+title = "Add the private key to .env.vault.enc as CADDY_SSH_KEY"
+needs = ["generate-keypair"]
+description = """
+Store the private key in the factory's encrypted vault secrets.
+
+1. Read the private key:
+     cat caddy-collect
+
+2. Add it to .env.vault.enc (or .env.vault for plaintext fallback) as
+   CADDY_SSH_KEY. The key is multi-line, so use the base64-encoded form:
+
+     echo "CADDY_SSH_KEY=$(base64 -w0 caddy-collect)" >> .env.vault.enc
+
+   Or, if using SOPS-encrypted vault, decrypt first, add the variable,
+   then re-encrypt.
+
+3. IMPORTANT: After storing, securely delete the local private key file:
+     shred -u caddy-collect 2>/dev/null || rm -f caddy-collect
+     rm -f caddy-collect.pub
+
+   The public key is already installed on the Caddy host; the private key
+   now lives only in the vault.
+
+Never commit the private key to any git repository.
+"""
+
+# ── Step 4: Configure Caddy host address ─────────────────────────────────────
+
+[[steps]]
+id    = "store-caddy-host"
+title = "Add the Caddy host address to .env.vault.enc as CADDY_HOST"
+needs = ["install-public-key"]
+description = """
+Store the Caddy host connection string so collect-engagement.sh knows
+where to SSH.
+
+1. Add to .env.vault.enc (or .env.vault for plaintext fallback):
+
+     echo "CADDY_HOST=user@caddy-host-ip-or-domain" >> .env.vault.enc
+
+   Replace user@caddy-host-ip-or-domain with the actual SSH user and host
+   (e.g. debian@203.0.113.42 or deploy@caddy.disinto.ai).
+
+2. If using SOPS, decrypt/add/re-encrypt as above.
+"""
+
+# ── Step 5: Test the connection ──────────────────────────────────────────────
+
+[[steps]]
+id    = "test-connection"
+title = "Verify the SSH key works and returns the access log"
+needs = ["install-public-key", "store-private-key", "store-caddy-host"]
+description = """
+Test the end-to-end connection before the factory tries to use it.
+
+1. From the factory host (or anywhere with the private key), run:
+
+     ssh -i caddy-collect -o StrictHostKeyChecking=accept-new user@caddy-host
+
+   Expected behavior:
+     - Outputs the contents of /var/log/caddy/access.log
+     - Disconnects immediately (command= restriction forces this)
+
+   If you already shredded the local key, decode it from the vault:
+     echo "$CADDY_SSH_KEY" | base64 -d > /tmp/caddy-collect-test
+     chmod 600 /tmp/caddy-collect-test
+     ssh -i /tmp/caddy-collect-test -o StrictHostKeyChecking=accept-new user@caddy-host
+     rm -f /tmp/caddy-collect-test
+
+2. Verify the output is Caddy structured JSON (one JSON object per line):
+     ssh -i /tmp/caddy-collect-test user@caddy-host | head -1 | jq .
+
+   You should see fields like: ts, request, status, duration.
+
+3. If the connection fails:
+     - Permission denied → check authorized_keys format (must be one line)
+     - Connection refused → check sshd is running on the Caddy host
+     - Empty output → check /var/log/caddy/access.log exists and is readable
+       by the SSH user
+     - "jq: error" → Caddy may be using Combined Log Format instead of
+       structured JSON; check Caddy's log configuration
+
+4. Once verified, the factory's collect-engagement.sh can use this key
+   to fetch logs remotely via:
+     ssh -i <decoded-key-path> $CADDY_HOST
+"""