The skabus-rpc-daemon program
skabus-rpc-daemon is a RPC mapper daemon, i.e. a long-lived program. It listens on a Unix domain socket, then accepts client connections. It allows clients to register interfaces and methods; it transmits queries from a client Q to the appropriate client R that can handle them; it then transmits the answer back to client Q.
Interface
skabus-rpc-daemon [ -1 ] [ -v verbosity ] [ -D | -d ] [ -c maxconn ] [ -b backlog ] [ -G gidlist ] [ -g gid ] [ -u uid ] [ -U ] [ -t clienttimeout ] [ -T lameducktimeout ] [ -i rulesdir | -x rulesfile ] [ -S | -s ] [ -J | -j ] path
- skabus-rpc-daemon binds to the Unix domain socket at path.
- If applicable, it drops root privileges.
- It listens to its socket and accepts client connections.
- Clients are handled as described in the skabus-rpcd page.
skabus-rpc-daemon is just a wrapper that binds to its socket and drops privileges before executing into skabus-rpcd. For details of the daemon's operation, see the skabus-rpcd documentation.
Options
- -1 : write a newline to stdout, before closing it, right after binding and listening to the Unix socket. If stdout is suitably redirected, this can be used by monitoring programs to check when the server is ready to accept connections.
- -v verbosity : be quiet, normally verbose, or more verbose, depending on if verbosity is 0, 1, or more. The default is 1.
- -d : allow instant rebinding to the same path even if it has been used not long ago - this is the SO_REUSEADDR flag to setsockopt() and is generally used with server programs. This is the default. Note that path will be deleted if it already exists at program start time.
- -D : disallow instant rebinding to the same path.
- -c maxconn : accept at most maxconn concurrent client connections. Default is 40. It is impossible to set it higher than the value of the SKABUS_RPC_MAX macro, which is 1000. Client connections to this server are usually long-lived; make sure to correctly tune that number to your needs.
- -b backlog : set a maximum of backlog backlog connections on the socket. Extra connection attempts will rejected by the kernel.
- -G gidlist : change skabus-rpc-daemon's supplementary group list to gidlist after binding the socket. This is only valid when run as root. gidlist must be a comma-separated list of numerical group IDs.
- -g gid : change skabus-rpc-daemon's groupid to gid after binding the socket. This is only valid when run as root.
- -u uid : change skabus-rpc-daemon's userid to uid after binding the socket. This is only valid when run as root.
- -U : change skabus-rpc-daemon's user id, group id and supplementary group list according to the values of the UID, GID and GIDLIST environment variables after binding the socket. This is only valid when run as root. This can be used with the s6-envuidgid program to easily script a service that binds to a privileged socket then drops its privileges to those of a named non-root account.
- -t clienttimeout : disconnect a client if it's in the middle of an operation and it has not written or read any data in clienttimeout milliseconds. By default, clienttimeout is 0, which means infinite.
- -T lameducktimeout : give clients lameducktimeout milliseconds to finish their current operation before exiting after skabus-rpc-daemon has received a SIGTERM. By default, lameducktimeout is 0, which means infinite.
- -x rulesfile : read access rights configuration from CDB file rulesfile.
- -i rulesdir : read access rights configuration from the filesystem in directory rulesdir.
- -S : paranoid identification mode. Disallows unspecified clients from registering under any identifier. This is the default.
- -s : free registration. Allows unspecified clients to register with any identifier.
- -J : paranoid interface registration. Disallows unspecified clients from registering interfaces. This is the default.
- -j : free interface registration. Allows unspecified clients to register any interface name.
Notes
- skabus-rpc-daemon does not interpret its options itself. It just dispatches them to the appropriate program on the command line that it builds.
- From the user's point of view, skabus-rpc-daemon behaves like a long-lived process, even if the long-lived process itself is called skabus-rpcd. Every operational detail of skabus-rpcd applies to skabus-rpc-daemon as well; in particular, make sure to properly configure the clients' access rights.
- skabus-rpc-daemon is meant to be used in a s6 run script, as a supervised local service. It does not fork itself or write to syslog. However, it can be run under any infrastructure, including other supervision infrastructures, OpenRC, systemd, or SysV scripts.