Fix tunnel script overwriting credentials for existing tunnels

When an existing Cloudflare tunnel was found, the script would overwrite
the credentials file with an empty TunnelSecret, breaking the service.
Now validates existing credentials and only recreates the tunnel if the
credentials file is missing or invalid.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

phantom/playbooks/common/templates/setup-tunnel.sh.j2

@@ -92,9 +92,44 @@ try:
 except: pass
 " 2>/dev/null || true)
 
+CREATED_NEW_TUNNEL=false
 if [ -n "${TUNNEL_ID}" ]; then
     echo "[+] Tunnel '${TUNNEL_NAME}' already exists: ${TUNNEL_ID}"
-else
+    # Check if we have valid credentials on disk
+    CRED_FILE="/etc/cloudflared/${TUNNEL_ID}.json"
+    if [ -f "${CRED_FILE}" ]; then
+        EXISTING_SECRET=$(python3 -c "
+import json, sys
+try:
+    with open('${CRED_FILE}') as f:
+        d = json.load(f)
+    s = d.get('TunnelSecret', '')
+    if s: print(s)
+except: pass
+" 2>/dev/null || true)
+        if [ -n "${EXISTING_SECRET}" ]; then
+            echo "[+] Existing credentials file is valid"
+        else
+            echo "[-] Credentials file exists but has empty secret — tunnel must be recreated"
+            echo "[*] Deleting tunnel '${TUNNEL_NAME}' to recreate with new credentials..."
+            curl -sf -X DELETE \
+                "https://api.cloudflare.com/client/v4/accounts/${ACCOUNT_ID}/cfd_tunnel/${TUNNEL_ID}" \
+                -H "Authorization: Bearer ${CF_TOKEN}" \
+                -H "Content-Type: application/json" >/dev/null 2>&1 || true
+            TUNNEL_ID=""
+        fi
+    else
+        echo "[-] No credentials file found — tunnel must be recreated"
+        echo "[*] Deleting tunnel '${TUNNEL_NAME}' to recreate with new credentials..."
+        curl -sf -X DELETE \
+            "https://api.cloudflare.com/client/v4/accounts/${ACCOUNT_ID}/cfd_tunnel/${TUNNEL_ID}" \
+            -H "Authorization: Bearer ${CF_TOKEN}" \
+            -H "Content-Type: application/json" >/dev/null 2>&1 || true
+        TUNNEL_ID=""
+    fi
+fi
+
+if [ -z "${TUNNEL_ID}" ]; then
     echo "[*] Creating tunnel '${TUNNEL_NAME}'..."
     TUNNEL_SECRET=$(python3 -c "import secrets, base64; print(base64.b64encode(secrets.token_bytes(32)).decode())")
 
@@ -124,20 +159,24 @@ except: pass
         exit 1
     fi
     echo "[+] Tunnel created: ${TUNNEL_ID}"
+    CREATED_NEW_TUNNEL=true
 fi
 
 # ── Write credentials + config ────────────────────────────────────────
 echo "[*] Writing tunnel configuration..."
 mkdir -p /etc/cloudflared
 
-# Write credentials file — required by cloudflared service install
-python3 -c "
+# Write credentials file only for newly created tunnels
+if [ "${CREATED_NEW_TUNNEL}" = true ]; then
+    python3 -c "
 import json
-creds = {'AccountTag': '${ACCOUNT_ID}', 'TunnelID': '${TUNNEL_ID}', 'TunnelSecret': '${TUNNEL_SECRET:-}'}
+creds = {'AccountTag': '${ACCOUNT_ID}', 'TunnelID': '${TUNNEL_ID}', 'TunnelSecret': '${TUNNEL_SECRET}'}
 with open('/etc/cloudflared/${TUNNEL_ID}.json', 'w') as f:
     json.dump(creds, f)
 "
-chmod 600 "/etc/cloudflared/${TUNNEL_ID}.json"
+    chmod 600 "/etc/cloudflared/${TUNNEL_ID}.json"
+    echo "[+] Credentials file written"
+fi
 
 cat > /etc/cloudflared/config.yml << CFEOF
 tunnel: ${TUNNEL_ID}