NAME¶
Server::Starter - a superdaemon for hot-deploying server programs
SYNOPSIS¶
# from command line
% start_server --port=80 my_httpd
# in my_httpd
use Server::Starter qw(server_ports);
my $listen_sock = IO::Socket::INET->new(
Proto => 'tcp',
);
$listen_sock->fdopen((values %{server_ports()})[0], 'w')
or die "failed to bind to listening socket:$!";
while (1) {
if (my $conn = $listen_sock->accept) {
....
}
}
DESCRIPTION¶
It is often a pain to write a server program that supports graceful restarts,
with no resource leaks. Server::Starter solves the problem by splitting the
task into two. One is start_server, a script provided as a part of the module,
which works as a superdaemon that binds to zero or more TCP ports or unix
sockets, and repeatedly spawns the server program that actually handles the
necessary tasks (for example, responding to incoming commenctions). The
spawned server programs under Server::Starter call
accept(2) and handle
the requests.
To gracefully restart the server program, send SIGHUP to the superdaemon. The
superdaemon spawns a new server program, and if (and only if) it starts up
successfully, sends SIGTERM to the old server program.
By using Server::Starter it is much easier to write a hot-deployable server.
Following are the only requirements a server program to be run under
Server::Starter should conform to:
- receive file descriptors to listen to through an environment variable -
perform a graceful shutdown when receiving SIGTERM
A Net::Server personality that can be run under Server::Starter exists under the
name Net::Server::SS::PreFork.
METHODS¶
- server_ports
- Returns zero or more file descriptors on which the server program should
call accept(2) in a hashref. Each element of the hashref is:
(host:port|port|path_of_unix_socket) => file_descriptor.
- start_server(%options)
- Starts the superdaemon. Used by the "start_server" script.
Options are:
- envdir
- Defines a directory whose content is added into server's environment. Each
file name specifies an environment variable, the file's content specifies
a value of the environment variable. Files with names starting with a dot
are ignored.
The environment directory is scanned and read only on time-based autorestart
or SIGHUP signal. The first server instances have default environment. To
remove an environment variable added before, remove the file and send the
signal.
This option is not mandatory.
AUTHOR¶
Kazuho Oku
SEE ALSO¶
Net::Server::SS::PreFork
LICENSE¶
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.