pg_createcluster

#!/usr/bin/perl -w

# Create new PostgreSQL cluster or integrate an existing data directory into
# the postgresql-common infrastructure.
#
# (C) 2005-2013 Martin Pitt <mpitt@debian.org>
# (C) 2012-2017 Christoph Berg <myon@debian.org>
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.

use PgCommon;
use Getopt::Long;
use POSIX qw/lchown setlocale LC_ALL LC_CTYPE/;

$ENV{'PATH'} = '/bin:/usr/bin'; # untaint

my @postgres_user = getpwuid $<;
my %defaultconf;
my $explicit_auth_config = 0;

chdir '/';

# replace placeholders
# Arguments: <string> <version> <cluster>
sub replace_v_c ($$$) {
    my ($str, $version, $cluster) = @_;
    $str =~ s/%([vc%])/$1 eq 'v' ? $version :
		       $1 eq 'c' ? $cluster : '%'/eg;
    return $str;
}

# call initdb 
# Arguments: <version> <data directory> <owner uid> <owner gid> <initdb options>
sub init_db {
    my ($version, $datadir, $owneruid, $ownergid, $initdb_opts_from_cli) = @_;
    $datadir = readlink $datadir if (-l $datadir);
    if ($version >= '8.4') {
	$ident_method = 'ident';
    } else {
	$ident_method = 'ident sameuser';
    }
    if ($version >= '9.1') {
	$peer_method = 'peer';
    } else {
	$peer_method = $ident_method;
    }

    if (system 'install', '-d', '-o', $owneruid, '-g', $ownergid, $datadir) {
        error 'could not create data directory; you might need to run this program with root privileges';
    }

    # disable copy-on-write semantics for PostgreSQL data on btrfs and similar;
    # this fails on file systems which don't support it, so ignore errors
    system "chattr +C '$datadir' 2>/dev/null";

    my @initdb = (get_program_path 'initdb', $version);
    die 'Internal error: could not determine initdb path' unless $initdb[0];
    if (my $options = $defaultconf{'initdb_options'}) {
	push @initdb, split (/\s+/, replace_v_c ($options, $version, $cluster));
    }
    push @initdb, ('-D', $datadir);
    if (my $waldir = $defaultconf{'waldir'} || $defaultconf{'xlogdir'}) {
        my $wal = $version >= 10 ? 'wal' : 'xlog'; # renamed in PG 10
	push @initdb, ("--${wal}dir", replace_v_c ($waldir, $version, $cluster));
    }
    if ($explicit_auth_config) {
	# do nothing
    } elsif ($version >= '9.2') {
	push @initdb, ('--auth-local', $peer_method);
	push @initdb, ('--auth-host', 'md5');
    } else {
	push @initdb, ('-A', $ident_method);
    }
    push @initdb, ('--encoding', $encoding) if $encoding;
    push @initdb, ('--locale', $locale) if $locale;
    push @initdb, ('--lc-collate', $lc_collate) if $lc_collate;
    push @initdb, ('--lc-ctype', $lc_ctype) if $lc_ctype;
    push @initdb, ('--lc-messages', $lc_messages) if $lc_messages;
    push @initdb, ('--lc-monetary', $lc_monetary) if $lc_monetary;
    push @initdb, ('--lc-numeric', $lc_numeric) if $lc_numeric;
    push @initdb, ('--lc-time', $lc_time) if $lc_time;
    push @initdb, @$initdb_opts_from_cli;

    if (fork) {
        wait;
        error 'initdb failed' if $?;
    } else{
        change_ugid $owneruid, $ownergid;
        print "@initdb\n";
        exec @initdb;
    }
}

# move a file to a directory with defined permissions; set <postgresql.conf option> in
# postgresql.conf.
# Arguments: <source file> <target dir> <uid> <gid> <perms> <postgresql.conf option>
sub move_conffile {
    ($file, $target, $uid, $gid, $perms, $confopt) = @_;
    $realfile = $file;
    while (-l $realfile) {
        $realfile = readlink $realfile;
    }
    if (-e $file) {
	install_file $realfile, $target, $uid, $gid, $perms;
        unlink $file, $realfile;

	@pathcomps = split ('/', $file);
	$target .= '/' . $pathcomps[-1];
	PgCommon::set_conf_value $version, $cluster, 'postgresql.conf', $confopt, $target if $confopt;
    } else {
        error "move_conffile: required configuration file $realfile does not exist";
    }
}

# Set up the default pg_hba.conf file:
# - Add a "local all" entry to pg_hba.conf for the db superuser before all
# other entries. 
# - Change default authentication for host entries to md5.
sub setup_pg_hba {
    my ($version) = @_;
    $user = (getpwuid $owneruid)[0];
    $fname = "$confdir/pg_hba.conf";
    $su_comment = "
# DO NOT DISABLE!
# If you change this first entry you will need to make sure that the
# database superuser can access the database using some other method.
# Noninteractive access to all databases is required during automatic
# maintenance (custom daily cronjobs, replication, and similar tasks).
#
# Database administrative login by Unix domain socket
";
    
    open (F, $fname) or error "could not open $fname for reading";
    $search = 1;
    while (<F>) {
	$line = $_;
	# add superuser entry before column description line
	if ($search && /#.*TYPE\s+DATABASE/) {
	    push @lines, $su_comment;
	    $s = sprintf "%-7s %-15s %-39s %s\n", 'local', 'all', $user, $peer_method;
	    push @lines, $s;
	    push @lines, "\n";
	    $search = 0;
	}

	if (not $explicit_auth_config and $version lt '9.2') {
	    # default authentication for Unix socket connections
	    if ($line =~ /^#?local/) {
		$line =~ s/trust/$peer_method/;
	    }

	    # default authentication for TCP connections
	    if ($line =~ /^#?host/) {
		$line =~ s/($ident_method|trust)/md5/;
	    }
	}

	push @lines, $line;
    }
    close F;

    error "setup_pg_hba: did not find insert position" if $search;

    open (F, ">$fname") or error "could not open $fname for writing";
    foreach (@lines) {
	print F $_;
    }
    close F;
}

#
# Execution starts here
#

# this flag gets set when we started creating the cluster, and thus we need to
# clean up on errors
my $cleanup_cruft = 0;

# command line arguments

my $startconf = '';
my $pgoptions = [];
my $createclusterconf = "$PgCommon::common_confdir/createcluster.conf";
my $environmentfile = "$PgCommon::common_confdir/environment";

exit 1 unless GetOptions ('u|user=s' => \$owneruid, 'g|group=s' => \$ownergid,
    's|socketdir=s' => \$socketdir, 'd|datadir=s' => \$datadir, 
    'start' => \$start, 'e|encoding=s' => \$encoding, 
    'l|logfile=s' => \$custom_logfile, 'start-conf=s' => \$startconf,
    'o|pgoption=s' => sub { $_[1] =~ /(.*?)=(.*)/ or error ("No '=' in pgoption '$_[1]'");
	push @pgoptions, [$1, $2];
    },
    'createclusterconf=s' => \$createclusterconf,
    'environment=s' => \$environmentfile,
    'p|port=i' => \$port, 'locale=s' => \$locale,
    'lc-collate=s' => \$lc_collate, 'lc-ctype=s' => \$lc_ctype,
    'lc-messages=s' => \$lc_messages, 'lc-monetary=s' => \$lc_monetary,
    'lc-numeric=s' => \$lc_numeric, 'lc-time=s' => \$lc_time);

# read defaults from /etc/postgresql-common/createcluster.conf
%defaultconf = PgCommon::read_conf_file ($createclusterconf);

# check validity of locale
unless (setlocale (LC_ALL, "")) {
    my $env = join "\n",
        map { "  $_: $ENV{$_}" }
        grep { /^(LC_|LANG)/ } sort keys %ENV;
    error ("The locale requested by the environment is invalid:\n$env")
}

if (@ARGV < 2) {
    print "Usage: $0 [options] <version> <cluster name> [-- <initdb options>]

Options:
  -u <uid>      cluster owner and superuser (default: 'postgres')
  -g <gid>      group for data files (default: primary group of owner)
  -d <dir>      data directory (default: 
                /var/lib/postgresql/<version>/<cluster name>)
  -s <dir>      socket directory (default: /tmp)
  -l <dir>      path to desired log file (default:
                /var/log/postgresql/postgresql-<version>-<cluster>.log)
  --locale <encoding>
                set cluster locale (default: inherit from environment)
  --lc-collate/ctype/messages/monetary/numeric/time <locale>
                like --locale, but only set for a particular category
  -e <encoding> Default encoding (default: derived from locale)
  -p <port>     port number (default: next free port starting from 5432)
  --start       start the cluster after creating it
  --start-conf auto|manual|disabled
                Set automatic startup behaviour in start.conf (default: 'auto')
  --createclusterconf=file alternative createcluster.conf to use
  --environment=file alternative environment file to use
  <initdb options> other options to pass to initdb
";
    exit 1;
}

$startconf ||= $defaultconf{'start_conf'} || 'auto';
error "Invalid --start-conf value: $startconf" if $startconf ne 'auto' &&
    $startconf ne 'manual' && $startconf ne 'disabled';

if ($owneruid) {
    $owneruid = (getpwnam $owneruid)[2] unless $owneruid =~ /^\d+$/;
} elsif ($> == 0) {
    $owneruid = getpwnam 'postgres';
    error 'User postgres does not exist' unless $owneruid;
} else
{
    $owneruid = $>;
}

if ($ownergid) {
    $ownergid = (getgrnam $ownergid)[2] unless $ownergid =~ /^\d+$/;
} else {
    $ownergid = (getpwuid $owneruid)[3];
}

error 'clusters must not be owned by root' unless $owneruid && $ownergid;

($version) = $ARGV[0] =~ /^(\d+\.?\d+)$/;
error "invalid version '$ARGV[0]'" unless defined $version;
($cluster) = $ARGV[1] =~ /^([-.\w]+)$/;
error "invalid cluster name '$ARGV[1]'" unless defined $cluster;
if ($cluster =~ /-/ and -t 1) {
    print "Warning: cluster names containing dashes (-) will cause problems when running from systemd. Continuing anyway\n";
}
splice @ARGV, 0, 2;

# initdb options passed after --
my @initdb_opts_from_cli = ();
foreach my $argv (@ARGV) {
    # the user passed an authentication method, don't mess with initdb and pg_hba.conf
    if ($argv =~ /^(-\w*A|--auth\b)/) { # -A --auth --auth-host --auth-local
	$explicit_auth_config = 1;
    }
    push @initdb_opts_from_cli, $argv =~ /(.*)/; # untaint
}

my $datadirp_created;
if (!defined $datadir) {
    $datadir = replace_v_c ($defaultconf{'data_directory'} || "/var/lib/postgresql/%v/%c", $version, $cluster);
    $datadir =~ s!/+$!!;
    my $pd = $datadir;
    $pd =~ s!/[^/]*$!!;

    # ensure that the version data dir is owned by postgres as well, so that
    # it can be administrated without root permissions
    if (!stat $pd) {
        my @install = qw(install -d);
        push @install, '-o', $postgres_user[2], '-g', $postgres_user[3] if ($> == 0);
        system @install, $pd;
        $datadirp_created = $pd; # clean up in case of error
    }
}
$confdirp = "$PgCommon::confroot/$version";
$confdir = "$confdirp/$cluster";

# some sanity checks
error "no initdb program for version $version found" unless get_program_path 'initdb', $version;
error 'cluster configuration already exists' 
    if -e "$confdir/postgresql.conf" || -e "$confdir/pg_hba.conf";

if (defined $port) {
    error 'port must be a positive integer between 1024 and 65535' 
	unless $port =~ /^\d+/ && $port >= 1024 && $port <= 65535;

    foreach $v (get_versions) {
	foreach $c (get_version_clusters $v) {
	    error "port $port is already used by cluster $v/$c"
		if (get_cluster_port $v, $c) == $port;
	}
    }
} else {
    $port = next_free_port;
}

# create configuration directory
if (!stat $confdirp) {
    my @install = qw(install -d);
    push @install, '-o', $postgres_user[2], '-g', $postgres_user[3] if ($> == 0);
    system @install, $confdirp;
}
# now we created the first new directory for this cluster and start to rollback
# on error
$cleanup_cruft = 1;

error 'could not create configuration directory; you might ' .
    'need to run this program with root privileges' if system ('install', '-d', $confdir);

# check whether we have an already existing cluster; check version and
# determine owner in this case
$newcluster = 0;

if (-f "$datadir/PG_VERSION") {
    if (open F, "$datadir/PG_VERSION") {
        $existingver = <F>;
        close F;
    } else {
        error "could not open $datadir/PG_VERSION";
    }
    ($owneruid, $ownergid) = (stat "$datadir/PG_VERSION")[4,5];
    if ($existingver = $version) {
        print "Configuring already existing cluster (configuration: $confdir, data: $datadir, owner: $owneruid:$ownergid)\n";
    } else {
        error "$datadir already contains a version $existingver cluster";
    }
} else {
    print "Creating new PostgreSQL cluster $version/$cluster ...\n";
    init_db $version, $datadir, $owneruid, $ownergid, \@initdb_opts_from_cli;
    $newcluster = 1;
}

# create default "start" file
set_cluster_start_conf $version, $cluster, $startconf;

# create default pg_ctl.conf file
set_cluster_pg_ctl_conf $version, $cluster, '';

# move conffiles, setup permissions
move_conffile "$datadir/postgresql.conf", $confdir, $owneruid, $ownergid, '644';
move_conffile "$datadir/pg_hba.conf", $confdir, $owneruid, $ownergid, '640', 'hba_file';
move_conffile "$datadir/pg_ident.conf", $confdir, $owneruid, $ownergid, '640', 'ident_file';
foreach my $f ($datadir, $confdir, "$confdir/start.conf", "$confdir/pg_ctl.conf") {
    lchown $owneruid, $ownergid, $f or error "lchown $f: $!";
}

PgCommon::set_conf_value $version, $cluster, 'postgresql.conf', 'data_directory', $datadir;

# add access for database superuser
setup_pg_hba $version if $newcluster and not $explicit_auth_config;

# configure socket directory
if (! $socketdir && ! -e '/var/run/postgresql') {
    system 'install', '-d', '-o', $postgres_user[2], '-g', $postgres_user[3], '/var/run/postgresql';
}
if ($socketdir && ! -e $socketdir) {
    if (system 'install', '-d', '-m', '0755', '-o', $owneruid, '-g', $ownergid, $socketdir) {
        error "could not create socket directory $socketdir";
    }
}
$orig_euid = $>;
$orig_egid = $);
$) = $ownergid;
$> = $owneruid;
unless ($socketdir) {
    if (1) {
        $socketdir = '/tmp'; # RedHat defaults to /tmp in libpq et al.
    } elsif (-w '/var/run/postgresql') {
	$socketdir = '/var/run/postgresql';
    } else {
        $socketdir='/tmp';
    }
}
set_cluster_socketdir $version, $cluster, $socketdir;
$> = $orig_euid;
$) = $orig_egid;

set_cluster_port $version, $cluster, $port;

# create log file
if (! -d '/var/log/postgresql') {
    mkdir '/var/log/postgresql' or
	error "could not create log directory; you might need to run this program with root privileges";
    chmod 01775, '/var/log/postgresql';
    lchown 0, $postgres_user[3], '/var/log/postgresql';
}
$real_logfile = $custom_logfile || "/var/log/postgresql/postgresql-$version-$cluster.log";
error "logfile $real_logfile is a directory, not a file" if (-d $real_logfile);
if (! -e $real_logfile) {
    open L, ">>$real_logfile" or error "could not create log file $real_logfile";
    close L;
}
chmod 0640, $real_logfile;
my $g;
if ($owneruid < 500) {
    $g = (getgrnam 'adm')[2];
} else {
    $g = $ownergid;
}
lchown $owneruid, $g, $real_logfile;
# if we are using a non-default log file, create a log symlink
if ($custom_logfile) {
    symlink $real_logfile, "$confdir/log";
    lchown $owneruid, $ownergid, "$confdir/log";
}

# SSL configuration
my $want_ssl = PgCommon::config_bool($defaultconf{ssl} || 'on');

# Check whether we can access the SSL private key as the cluster owner
my $ssl_key_file = '/etc/ssl/private/ssl-cert-snakeoil.key';
my $ssl_cert_file = '/etc/ssl/certs/ssl-cert-snakeoil.pem';
my $ssl_ca_file = "$PgCommon::common_confdir/root.crt";
my $ssl_key_access;
my ($uid, $euid, $gid, $egid) = ($<, $>, $(, $));
change_ugid $owneruid, $ownergid;
$ssl_key_access = -r $ssl_key_file;

# check for stats_temp_directory access
delete $defaultconf{stats_temp_directory} if ($version < 8.4);
if ($defaultconf{stats_temp_directory}) {
    my $stats_temp_directory = replace_v_c ($defaultconf{stats_temp_directory}, $version, $cluster);
    $stats_temp_directory =~ s!/$!!; # strip trailing slash
    my $stats_temp_parent = $stats_temp_directory;
    $stats_temp_parent =~ s!/[^/]+$!!;
    if (-d $stats_temp_directory) {
        if (! -w $stats_temp_directory) {
            print "Warning: The selected stats_temp_directory $stats_temp_directory
is not writable for the cluster owner. Not adding this setting in
postgresql.conf.\n";
            delete $defaultconf{stats_temp_directory};
        }
    } elsif (! -d $stats_temp_parent) {
        print "Warning: The parent $stats_temp_parent of the selected
stats_temp_directory does not exist. Not adding this setting in
postgresql.conf.\n";
        delete $defaultconf{stats_temp_directory};
    } elsif (! -w $stats_temp_parent) {
        print "Warning: The parent $stats_temp_parent of the selected
stats_temp_directory is not writable for the cluster owner. Not adding this
setting in postgresql.conf.\n";
        delete $defaultconf{stats_temp_directory};
    }
}

$> = $euid;
$< = $uid; 
$( = $gid;
$) = $egid;
die "changing euid back: $!" if $> != $euid;
die "changing egid back: $!" if $) != $egid;

# enable SSL if we have the snakeoil default certificate
if ($want_ssl && $newcluster && -e $ssl_cert_file && $ssl_key_access) {
    if ($version >= '9.2') {
        PgCommon::set_conf_value $version, $cluster, 'postgresql.conf',
            'ssl_cert_file', $ssl_cert_file;
        PgCommon::set_conf_value $version, $cluster, 'postgresql.conf',
            'ssl_key_file', $ssl_key_file;
    } else {
        symlink $ssl_cert_file, "$datadir/server.crt";
        symlink $ssl_key_file, "$datadir/server.key";
    }

    PgCommon::set_conf_value $version, $cluster, 'postgresql.conf', 'ssl', 'on';
}

# SSL client certificate CA
if ($want_ssl && $newcluster && -e $ssl_ca_file) {
    # check if we have a cert in there or just the boilerplate installed by our postinst
    open F, $ssl_ca_file;
    my $val;
    read F, $val, 4096;
    if ($val =~ /^-----BEGIN CERTIFICATE-----/m) {
        if ($version >= '9.2') {
            PgCommon::set_conf_value $version, $cluster, 'postgresql.conf',
                'ssl_ca_file', $ssl_ca_file;
        } else {
            symlink $ssl_ca_file, $datadir.'/root.crt';
        }
    }
}

# SSL client certificate revocation list
if ($want_ssl && $newcluster && -e "$PgCommon::common_confdir/root.crl") {
    if ($version >= '9.2') {
        PgCommon::set_conf_value $version, $cluster, 'postgresql.conf',
            'ssl_crl_file', "$PgCommon::common_confdir/root.crl";
    } else {
        symlink "$PgCommon::common_confdir/root.crl", $datadir.'/root.crl';
    }
}

# create default (empty) environment file
my $defaultenv = "# environment variables for postgres processes
# This file has the same syntax as postgresql.conf:
#  VARIABLE = simple_value
#  VARIABLE2 = 'any value!'
# I. e. you need to enclose any value which does not only consist of letters,
# numbers, and '-', '_', '.' in single quotes. Shell commands are not
# evaluated.
";
if (-e $environmentfile) {
    open ENV, '<', $environmentfile or error "could not read environment file $environmentfile";
    local $/; # slurp mode
    $defaultenv = <ENV>;
    close ENV;
}
$defaultenv = replace_v_c ($defaultenv, $version, $cluster);
open ENV, ">$confdir/environment" or error "could not create environment file $confdir/environment";
print ENV $defaultenv;
close ENV;
chmod 0644, "$confdir/environment";
lchown $owneruid, $ownergid, "$confdir/environment";

$cleanup_cruft = 0;

# configure to create external PID file
if ($socketdir eq '/var/run/postgresql') {
    PgCommon::set_conf_value $version, $cluster, 'postgresql.conf', 'external_pid_file', "/var/run/postgresql/$version-$cluster.pid";
}

# handle other createcluster.conf parameters
foreach my $guc (sort keys %defaultconf) {
    next if $guc =~ /^(create_main_cluster|start_conf|data_directory|waldir|xlogdir|initdb_options|ssl)$/;
    next if $guc eq 'logging_collector' and $version < 8.3;
    next if $guc eq 'cluster_name' and $version < 9.5;
    my $val = replace_v_c ($defaultconf{$guc}, $version, $cluster);
    $guc =~ s/^add_include/include/; # remove harness from include directives in createcluster.conf
    if ($guc eq 'include_dir') {
        next if ($version < 9.3);
        if ($val =~ /^[\w.]+$/ and not -e "$confdir/$val") { # create directory relative to new config directory
            mkdir "$confdir/$val", 0755;
            lchown $owneruid, $ownergid, "$confdir/$val";
        }
    }
    PgCommon::set_conf_value $version, $cluster, 'postgresql.conf', $guc, $val;
}

# process --pgoption parameters
foreach my $guc (@pgoptions) {
    PgCommon::set_conf_value $version, $cluster, 'postgresql.conf', $guc->[0], $guc->[1];
}

# notify systemd about the new cluster
if (not exists $ENV{'PG_CLUSTER_CONF_ROOT'} and $startconf eq 'auto' and -d '/run/systemd/system') {
    if ($> == 0) {
        system 'systemctl daemon-reload';
    } elsif (-t 1) {
        print "Warning: systemd does not know about the new cluster yet. Operations like \"service postgresql start\" will not handle it. To fix, run:\n";
        print "  sudo systemctl daemon-reload\n";
    }
}

# start it if requested
if ($start) {
    system 'pg_ctlcluster', $version, $cluster, 'start';
    die "Could not start cluster\n" if ($?);
}

# finally, show the cluster we created
system 'pg_lsclusters', $version, $cluster;

END {
    # clean up cruft if something went wrong
    if ($cleanup_cruft && defined $version && defined $cluster) {
	system "pg_dropcluster $version $cluster 2>/dev/null";
        rmdir $datadirp_created if ($datadirp_created); # clean up after early errors which pg_dropcluster doesn't handle
	exit 1;
    }
}

__END__

=head1 NAME

pg_createcluster - create a new PostgreSQL cluster

=head1 SYNOPSIS

B<pg_createcluster> [I<options>] I<version> I<name> [B<--> I<initdb options>]

=head1 DESCRIPTION

B<pg_createcluster> creates a new PostgreSQL server cluster (i. e. a
collection of databases served by a L<postgres(1)> instance) and
integrates it into the multi-version/multi-cluster architecture of the
B<postgresql-common> package. 

Every cluster is uniquely identified by its version and name. The name can be
arbitrary. The default cluster that is created on installation of a server
package is C<main>. However, you might wish to create other clusters for
testing, with other superusers, a cluster for each user on a shared server,
etc. C<pg_createcluster> will abort with an error if you try to create a
cluster with a name that already exists for that version.

For compatibility with B<systemd> service units, the cluster name should not
contain any dashes (B<->). B<pg_ctlcluster> will warn about the problem, but
succeed with the operation.

Given a major PostgreSQL I<version> (like "8.2" or "8.3") and a cluster
I<name>, it creates the necessary configuration files in
C</etc/postgresql/>I<version>C</>I<name>C</>; in particular these are
C<postgresql.conf>, C<pg_ident.conf>, C<pg_hba.conf>, a postgresql-common
specific configuration file C<start.conf> (see B<STARTUP CONTROL> below),
C<pg_ctl.conf>, and a symbolic link C<log> which points to the log file (by
default, C</var/log/postgresql/postgresql->I<version>C<->I<name>C<.log>).

C<postgresql.conf> is automatically adapted to use the next available port, i.
e. the first port (starting from 5432) which is not yet used by an already
existing cluster.

If the data directory does not yet exist, PostgreSQL's L<initdb(1)> command is
used to generate a new cluster structure. If the data directory already exists,
it is integrated into the B<postgresql-common> structure by moving the
configuration file and setting the data_directory option. Please note that this
I<only> works for data directories which were created directly with B<initdb>, i.
e. all the configuration files (C<postgresql.conf> etc.) must be present in the
data directory.

If a custom socket directory is given and it does not exist, it is created.

If the log file does not exist, it is created. In any case the permissions are
adjusted to allow write access to the cluster owner. Please note that
C<postgresql.conf> can be customized to specify C<log_directory> and/or
C<log_filename>; if at least one of these options is present, then the symbolic
link C<log> in the cluster configuration directory is ignored.

If the default snakeoil SSL certificate exists
(C</etc/ssl/certs/ssl-cert-snakeoil.pem> and
C</etc/ssl/private/ssl-cert-snakeoil.key>), and the C<postgres> user is in the
C<ssl-cert> Unix group, B<pg_createcluster> configures the cluster to use this
certificate, and enables SSL. Therefore all clusters will use the same SSL
certificate by default. For versions up to 9.1, symlinks in the data directory
will be created (C<server.crt> and C<server.key>); for 9.2 and later, the
appropriate C<postgresql.conf> options will be set (C<ssl_cert_file> and
C<ssl_key_file>). Of course you can replace this with a cluster specific
certificate. Similarly for C</etc/postgresql-common/root.crt> and
C</etc/postgresql-common/root.crl>, these files will be configured as client
certificate CA and revocation list, when present. (C<root.crt> is initially a
placeholder that will only be used if real certificates are added to the file.)

=head1 OPTIONS

=over 4

=item B<-u> I<user>, B<--user=>I<user>

Set the user who owns the cluster and becomes the database superuser to the
given name or uid.  By default, this is the user B<postgres>.  A cluster must
not be owned by root.

=item B<-g> I<group>, B<--group=>I<group>

Change the group of the cluster related data files. By default this will be the
primary group of the database owner.

=item B<-d> I<dir>, B<--datadir=>I<dir>

Explicitly set the data directory path, which is used to store all the actual
databases and tables. This will become quite big (easily in the order of five
times the amount of actual data stored in the cluster). Defaults to
C</var/lib/postgresql/>I<version>C</>I<cluster>.

=item B<-s> I<dir>, B<--socketdir=>I<dir>

Explicitly set the directory where the L<postgres(1)> server stores the Unix
socket for local connections. Defaults to C</var/run/postgresql/> for clusters
owned by the user B<postgres>, and C</tmp> for clusters owned by other users.
Please be aware that C</tmp> is an unsafe directory since everybody can create
a socket there and impersonate the database server. If the given directory does
not exist, it is created with appropriate permissions.

=item B<-l> I<path>, B<--logfile=>I<path>

Explicitly set the path for the L<postgres(1)> server log file. Defaults to
C</var/log/postgresql/postgresql->I<version>C<->I<cluster>C<.log>.

=item B<--locale=>I<locale>

Set the default locale for the database cluster. If this option is not
specified, the locale is inherited from the environment that
B<pg_createcluster> runs in.

=item B<--lc-collate=>I<locale>

=item B<--lc-ctype=>I<locale>

=item B<--lc-messages=>I<locale>

=item B<--lc-monetary=>I<locale>

=item B<--lc-numeric=>I<locale>

=item B<--lc-time=>I<locale>

Like B<--locale>, but only sets the locale in the specified category.

=item B<-e> I<encoding>, B<--encoding=>I<encoding>

Select the encoding of the template database. This will also be the default
encoding of any database you create later, unless you override it there. The
default is derived from the locale, or SQL_ASCII if that does not work.  The
character sets supported by the PostgreSQL server are described in the
documentation. 

B<Note>: It is not recommended to set this option directly! Set the locale
instead.

=item B<-p> I<port>, B<--port=>I<port>

Select the port the new cluster listens on (for the Unix socket and the TCP
port); this must be a number between 1024 and 65535, since PostgreSQL does not
run as root and thus needs an unprivileged port number. By default the next
free port starting from 5432 is assigned.

=item B<--start>

Immediately start a server for the cluster after creating it (i. e. call
C<pg_ctlcluster> I<version cluster> C<start> on it). By default, the cluster is
not started.

=item B<--start-conf=>B<auto>|B<manual>|B<disabled>

Set the initial value in the C<start.conf> configuration file. See B<STARTUP
CONTROL> below. By default, B<auto> is used, which means that the cluster is
handled by C</etc/init.d/postgresql>, i. e. starts and stops
automatically on system boot.

=item B<-o> I<guc>B<=>I<value>, B<--pgoption> I<guc>B<=>I<value>

Configuration option to set in the new C<postgresql.conf> file.

=item B<--createclusterconf=>I<file>

Alternative B<createcluster.conf> file to use. Default is
C</etc/postgresql-common/createcluster.conf> (or
C<$PGSYSCONFDIR/createcluster.conf>).

=item B<--environment=>I<file>

Alternative default B<environment> file to use. Default is
C</etc/postgresql-common/environment> (or C<$PGSYSCONFDIR/environment>).
If the file is missing, a placeholder string is used.
%v and %c are replaced; see DEFAULT VALUES below.

=item B<--> I<initdb options>

Options passed directly to L<initdb(1)>.

Per default, B<pg_createcluster> will update the C<pg_hba.conf> file generated
by initdb to use peer authentication on local (unix) connections, and md5 on
TCP (host) connections. If explicit authentication config is included here
(B<-A>, B<--auth>, B<--auth-host>, B<--auth-local>), the C<pg_hba.conf> file
will be left untouched.

=back

=head1 STARTUP CONTROL

The C<start.conf> file in the cluster configuration directory controls the
start/stop behavior of that cluster's postgres process. The file can contain
comment lines (started with '#'), empty lines, and must have exactly one
line with one of the following keywords:

=over 4

=item B<auto>

The postgres process is started/stopped automatically in the init script.

When running from B<systemd>, the cluster is started/stopped when
B<postgresql.service> is started/stopped.
This is also the default if the file is missing.

=item B<manual>

The postgres process is not handled by the init script, but manually
controlling the cluster with L<pg_ctlcluster(1)> is permitted.

When running from B<systemd>, the cluster is not started automatically when
B<postgresql.service> is started. However, stopping/restarting
B<postgresql.service> will stop/restart the cluster. The cluster can be started
using B<systemctl start postgresql@>I<version>B<->I<cluster>.

=item B<disabled>

Neither the init script, L<pg_ctlcluster(1)>, nor B<postgresql@.service> are permitted to start/stop the
cluster. Please be aware that this will not stop the cluster owner from calling
lower level tools to control the postgres process; this option is only meant
to prevent accidents during maintenance, not more.

=back

When running from B<systemd>, invoke B<systemctl daemon-reload> after editing
C<start.conf>.

The C<pg_ctl.conf> file in the cluster configuration directory can contain
additional options passed to B<pg_ctl> of that cluster.

=head1 DEFAULT VALUES

Some default values used by B<pg_createcluster> can be modified in
C</etc/postgresql-common/createcluster.conf>. Occurrences of B<%v> are replaced
by the major version number, and B<%c> by the cluster name. Use B<%%> for a
literal B<%>.

=over 4

=item B<create_main_cluster> (Default: B<true>)

Create a B<main> cluster when a new postgresql-x.y server package is installed.

=item B<start_conf> (Default: B<auto>)

Default C<start.conf> value to use.

=back

=over 4

=item B<data_directory> (Default: B</var/lib/postgresql/%v/%c>)

Default data directory.

=item B<waldir|xlogdir> (Default: unset)

Default directory for transaction logs. When used, B<initdb> will create a
symlink from C<pg_wal> (PostgreSQL 9.6 and earlier: C<pg_xlog>) in the data
directory to this location. Unset by default, i.e. transaction logs remain in
the data directory. Both spellings of this option are accepted, and translated
to the correct initdb invocation depending on the cluster version.

=item B<initdb_options> (Default: unset)

Other options to pass to B<initdb>.

=item Other options

All other options listed are copied into the new cluster's postgresql.conf, e.g.:

    listen_addresses = '*'
    log_line_prefix = '%%t '

Some postgresql.conf options are treated specially:

=over 4

=item B<ssl>

Only added to postgresql.conf if the default snakeoil certificates exist and
are readable for the cluster owner as detailed above.

=item B<stats_temp_directory>

Only added to postgresql.conf if existing, and writable for the cluster owner,
or else if the parent directory is writable.

=back

=item Include files

=over 4

=item B<include>

=item B<include_if_exists>

=item B<include_dir>

B<createcluster.conf> supports the same include directives as
B<postgresql.conf>.

=item B<add_include>

=item B<add_include_if_exists>

=item B<add_include_dir>

To add include directives to the new postgresql.conf file, use the B<add_*>
directives. The B<add_> prefix is removed.

=back

=back

=head1 SEE ALSO

L<initdb(1)>, L<pg_ctlcluster(8)>, L<pg_lsclusters(1)>, L<pg_wrapper(1)>

=head1 AUTHORS

Martin Pitt L<E<lt>mpitt@debian.orgE<gt>>, Christoph Berg L<E<lt>myon@debian.orgE<gt>>