SSH Agent as Systemd User-Service

Create a systemd user-level config directory:

   mdkir -p .config/systemd/user/

Create the service unit file:

.config/systemd/user/ssh-agent.service

[Unit]
Description=SSH key agent

[Service]
Type=simple
Environment=SSH_AUTH_SOCK=%t/ssh-agent.socket
ExecStart=/usr/bin/ssh-agent -D -a $SSH_AUTH_SOCK

[Install]
WantedBy=default.target

Enable the unit.

   systemctl --user enable --now ssh-agent

Add this to .bashrc so that the shell can find the socket:

   SSH_AUTH_SOCK="${XDG_RUNTIME_DIR}/ssh-agent.socket"

Then, add a key to the agent:

  ssh-add ~/.ssh/your-key.pem

From now until logout, keys will be stored in the agent.

Sensitive keys can be removed after use with ssh-add -D

References