add ssh-agent systemd service

ssh-agent.service

@@ -0,0 +1,15 @@
+# Requires SSH_AUTH_SOCK="$XDG_RUNTIME_DIR/ssh-agent.socket"
+[Unit]
+ConditionEnvironment=!SSH_AGENT_PID
+Description=OpenSSH key agent
+Documentation=man:ssh-agent(1) man:ssh-add(1) man:ssh(1)
+
+[Service]
+Environment=SSH_AUTH_SOCK=%t/ssh-agent.socket
+ExecStart=/usr/bin/ssh-agent -a $SSH_AUTH_SOCK
+PassEnvironment=SSH_AGENT_PID
+SuccessExitStatus=2
+Type=forking
+
+[Install]
+WantedBy=default.target