systemd-socket-proxyd(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | EXAMPLES | SEE ALSO | COLOPHON

SYSTEMD-SOCKET-PROXYD(8)  systemd-socket-proxyd SYSTEMD-SOCKET-PROXYD(8)

NAME         top

       systemd-socket-proxyd - Bidirectionally proxy local sockets to
       another (possibly remote) socket

SYNOPSIS         top

       systemd-socket-proxyd [OPTIONS...] HOST:PORT

       systemd-socket-proxyd [OPTIONS...] UNIX-DOMAIN-SOCKET-PATH

DESCRIPTION         top

       systemd-socket-proxyd is a generic socket-activated network
       socket forwarder proxy daemon for IPv4, IPv6 and UNIX stream
       sockets. It may be used to bi-directionally forward traffic from
       a local listening socket to a local or remote destination socket.

       One use of this tool is to provide socket activation support for
       services that do not natively support socket activation. On
       behalf of the service to activate, the proxy inherits the socket
       from systemd, accepts each client connection, opens a connection
       to a configured server for each client, and then bidirectionally
       forwards data between the two.

       This utility's behavior is similar to socat(1). The main
       differences for systemd-socket-proxyd are support for socket
       activation with "Accept=no" and an event-driven design that
       scales better with the number of connections.

OPTIONS         top

       The following options are understood:

       -h, --help
           Print a short help text and exit.

       --version
           Print a short version string and exit.

       --connections-max=, -c
           Sets the maximum number of simultaneous connections, defaults
           to 256. If the limit of concurrent connections is reached
           further connections will be refused.

       --exit-idle-time=
           Sets the time before exiting when there are no connections,
           defaults to infinity. Takes a unit-less value in seconds, or
           a time span value such as "5min 20s".

EXIT STATUS         top

       On success, 0 is returned, a non-zero failure code otherwise.

EXAMPLES         top

   Simple Example
       Use two services with a dependency and no namespace isolation.

       Example 1. proxy-to-nginx.socket

           [Socket]
           ListenStream=80

           [Install]
           WantedBy=sockets.target

       Example 2. proxy-to-nginx.service

           [Unit]
           Requires=nginx.service
           After=nginx.service
           Requires=proxy-to-nginx.socket
           After=proxy-to-nginx.socket

           [Service]
           ExecStart=/usr/lib/systemd/systemd-socket-proxyd /run/nginx/socket
           PrivateTmp=yes
           PrivateNetwork=yes

       Example 3. nginx.conf

           [...]
           server {
               listen       unix:/run/nginx/socket;
               [...]

       Example 4. Enabling the proxy

           # systemctl enable --now proxy-to-nginx.socket
           $ curl http://localhost:80/

       If nginx.service has StopWhenUnneeded= set, then passing
       --exit-idle-time= to systemd-socket-proxyd allows both services
       to stop during idle periods.

   Namespace Example
       Similar as above, but runs the socket proxy and the main service
       in the same private namespace, assuming that nginx.service has
       PrivateTmp= and PrivateNetwork= set, too.

       Example 5. proxy-to-nginx.socket

           [Socket]
           ListenStream=80

           [Install]
           WantedBy=sockets.target

       Example 6. proxy-to-nginx.service

           [Unit]
           Requires=nginx.service
           After=nginx.service
           Requires=proxy-to-nginx.socket
           After=proxy-to-nginx.socket
           JoinsNamespaceOf=nginx.service

           [Service]
           ExecStart=/usr/lib/systemd/systemd-socket-proxyd 127.0.0.1:8080
           PrivateTmp=yes
           PrivateNetwork=yes

       Example 7. nginx.conf

           [...]
           server {
               listen       8080;
               [...]

       Example 8. Enabling the proxy

           # systemctl enable --now proxy-to-nginx.socket
           $ curl http://localhost:80/

SEE ALSO         top

       systemd(1), systemd.socket(5), systemd.service(5), systemctl(1),
       socat(1), nginx(1), curl(1)

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have
       a bug report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-08-27.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 249                                     SYSTEMD-SOCKET-PROXYD(8)