[Unit]
# step-ca, as the CA and its standby both install it (the standby keeps it disabled and stopped).
#
# The Debian package ships ONLY the binary: no user, no unit, no configuration. (Smallstep's
# own documentation says otherwise; it is wrong for the 0.30.x debs, measured 2026-08-08.)
# So this unit and the `step` user are configuration management's, on both machines.
Description=step-ca — the private certificate authority
Documentation=https://smallstep.com/docs/step-ca
After=network-online.target
Wants=network-online.target
StartLimitIntervalSec=30
StartLimitBurst=3
# Refuse to start rather than start empty: without this, a lost config silently becomes a CA
# that answers nothing while systemd reports the unit as running.
ConditionFileNotEmpty=/etc/step-ca/config/ca.json

[Service]
Type=simple
User=step
Group=step
Environment=STEPPATH=/etc/step-ca
WorkingDirectory=/etc/step-ca
ExecStart=/usr/bin/step-ca config/ca.json --password-file /etc/step-ca/password.txt
ExecReload=/bin/kill --signal HUP $MAINPID
Restart=on-failure
RestartSec=5
TimeoutStopSec=30

# This process holds the signing key in memory, which is unavoidable for ANY certificate authority. The sandbox below is not decoration: it
# is the whole difference between "a process on this box" and "the process that can sign".
AmbientCapabilities=CAP_NET_BIND_SERVICE
CapabilityBoundingSet=CAP_NET_BIND_SERVICE
SecureBits=keep-caps
NoNewPrivileges=yes
ProtectSystem=full
ProtectHome=true
PrivateTmp=true
RestrictNamespaces=true
RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6
ProtectClock=true
ProtectControlGroups=true
ProtectKernelTunables=true
ProtectKernelLogs=true
ProtectKernelModules=true
LockPersonality=true
RestrictSUIDSGID=true
RemoveIPC=true
RestrictRealtime=true
SystemCallFilter=@system-service
SystemCallArchitectures=native
MemoryDenyWriteExecute=true
# ProtectSystem=full makes /etc read-only; the badger DB underneath must still be writable.
ReadWritePaths=/etc/step-ca/db

[Install]
WantedBy=multi-user.target