SME10 serviceControl
Previous version boot process and service control
Basically we use SysVinit, with initscripts built to handle a specific run level rc7.d. On top of that we use Runit to handle services indexed in /services / and /var/services.
A cli wrapper for the command service /sbin/e-smith/service has been created so that only initscripts which exist in run-level 7 can be run. This ensures that the supervised service is run, if one exists, and protects against running "service httpd restart". The wrapper will also choose between a sv command for runit processes or regular call to /etc/rc.d/init.d/ scripts.
- /sbin/e-smith/service
#! /bin/sh
runlevel=$(runlevel | cut -d" " -f2)
if [ "$runlevel" = "4" ]
then
if ls /etc/rc7.d/S??$1 >/dev/null 2>/dev/null
then
script=$(ls /etc/rc7.d/S??$1 | head -1)
exec $script $2
fi
echo "'$1' is not a valid service name" 1>&2
exit 1
else
exec /sbin/service "$@"
fi
Current SME10 alpha boot process and service control
Systemd has been designed as the way to handle services upstream. Systemd will override all /etc/rc.d/init.d/ scripts and call to /usr/sbin/service.
We have added a first systemd unit for bootstrap console and make it a drop in replacement of Sysvinit to boot all processes linked in /etc/rc.d/rc7.d/.
From there we could keep this way, or try to move as many process as we can to systemd. This way works, but is even more complex than it was on previous SME version. Plus we can not guarantee without further scripts that one will not be able to do a systemctl start httpd.
- new startup with consol see /usr/share/perl5/vendor_perl/esmith/console/startup.pm
package esmith::console::startup;
use Locale::gettext;
use esmith::console;
use esmith::ConfigDB;
use strict;
use warnings;
sub new
{
my $class = shift;
my $self = {
@_,
};
bless $self, $class;
return $self;
}
sub startup_callback {
my $fd = shift;
my @out = ();
my $done = 0;
use DirHandle;
my $d = DirHandle->new("/etc/rc7.d");
my @services = sort
{
$a =~ /^S(\d+)/; my $A = $1;
$b =~ /^S(\d+)/; my $B = $1;
$A <=> $B
} grep { /^S/ } $d->read;
my $rows = 12;
my $status_col = 65;
my $db = esmith::ConfigDB->open_ro;
my $rec = $db->get('smb');
my $i=0;
foreach (@services) {
$i=$i+1;
next unless /^S(\d+)([^\.][\.\w\-]+)$/;
next unless $2 eq "smb";
splice @services,$i-1 , 1, "S${1}4smbd", "S${1}5nmbd" unless ($rec and $rec->prop('status') eq 'disabled');
last;
}
open(STDOUT, ">&STDERR");
foreach (@services)
{
sleep 1;
my $percent = int(($done * 100) / ($#services + 1));
$done += 1;
my $link = $_;
#warn "Looking at symlink $_\n";
next unless /^S\d+([^\.][\.\w\-]+)$/; # Untaint service name
my $service = $1;
#my $db = esmith::ConfigDB->open_ro;
$rec = $db->get($service);
do
{
warn "not starting disabled service $service\n";
next;
} unless ($rec and $rec->prop('status') eq 'enabled');
my $prompt = "starting ";
my $supervised = -x "/service/$service/run";
my @cmd;
if (-x "/service/$service/run")
{
$prompt .= " supervised service $service";
warn "starting supervised service $service\n";
@cmd = ("sv", "up", "/service/$service");
}
elsif (-x "/etc/init.d/$service")
{
$prompt .= " unsupervised service $service";
warn "starting unsupervised service $service\n";
@cmd = ("/etc/init.d/$service", "start");
}
else
{
warn "ignoring unknown service $service: bogus start symlink $link\n";
next;
}
push @out, "$prompt\n";
print $fd "XXX\n";
print $fd "$percent\n";
my @show = $#out > $rows ? @out[$#out - $rows .. $#out] : @out;
do { print $fd $_ } foreach @show;
print $fd "XXX\n";
$prompt .= " " x ($status_col - length($prompt));
$prompt .= system(@cmd) ? "\\Z1FAILED\\Zn" : "\\Z2OK\\Zn";
$out[-1] = "$prompt\n";
@show = $#out > $rows ? @out[$#out - $rows .. $#out] : @out;
print $fd "XXX\n";
print $fd "$percent\n";
do { print $fd $_ } foreach @show;
print $fd "XXX\n";
}
print $fd "100\n";
sleep 2;
return undef;
};
my $console = esmith::console->new;
sub doit
{
my ($self, $console, $db) = @_;
$console->infobox
(
title => gettext("Starting system services"),
text => "\n" .
gettext("Please standby while system services are started ..."
),
);
system(qw(touch /var/lock/subsys/backup-running));
system(qw(chown admin /var/lock/subsys/backup-running));
sleep(6); # Wait to be certain that all runsv services have been started.
$console->gauge(\&startup_callback,
text => '',
title => 'Starting system services',
colors => 1,
no_collapse => 1);
}
#use esmith::console;
#use esmith::ConfigDB;
#esmith::console::startup->new->doit(esmith::console->new(),
# esmith::ConfigDB->open);
1;
- a new /sbin/e-smith/service
1#! /bin/sh
2# prevent initscript to use systemctl
3export SYSTEMCTL_SKIP_REDIRECT=1
4. /etc/rc.d/init.d/functions
5
6# what is our current runlevel
7runlevel=$(systemctl get-default)
8SERVICE=$1
9USAGE="Usage: service SERVICENAME [ACTION]"
10
11#if no servicename is provided return usage
12if [[ "${SERVICE}" == "" ]]
13then
14 echo ${USAGE} >&2
15 exit
16fi
17
18if [ "$runlevel" = "multi-user.target" ]
19then
20 if ls /etc/rc7.d/S??$1 >/dev/null 2>/dev/null
21 then
22 script=$(ls /etc/rc7.d/S??$1 | head -1)
23 exec $script $2
24
25 elif ls /usr/lib/systemd/system/${SERVICE}.service >/dev/null 2>/dev/null || ls /etc/systemd/system/${SERVICE}.service >/dev/null 2>/dev/null
26 then
27 if [[ "$2" == "" ]] ; then
28 echo "'$1' requires an action" 1>&2
29 echo ${USAGE} >&2
30 exit
31 elif [[ $2 == "status" ]] ; then
32 exec /bin/systemctl status -n0 ${SERVICE}
33 exit
34 elif [[ $2 == "start" ]] ; then
35 echo -n "Starting ${SERVICE}" 2>/dev/null
36 elif [[ $2 == "stop" ]] ; then
37 echo -n "Stopping ${SERVICE}" 2>/dev/null
38 elif [[ $2 == "restart" ]] ; then
39 echo -n "Restarting ${SERVICE}" 2>/dev/null
40 else
41 echo -n "Sending $2 signal to ${SERVICE}" 2>/dev/null
42 fi
43 /bin/systemctl $2 ${SERVICE}.service> /dev/null
44 if [ $? -ne 0 ]; then
45 echo_failure
46 else
47 echo_success
48 fi
49 echo
50 exit
51 fi
52
53 echo "'$1' is not a valid service name" 1>&2
54 exit 1
55else
56 exec /sbin/service "$@"
57fi
- And the current controlService perl function from /usr/share/perl5/vendor_perl/esmith/util.pm
1=pod
2
3=head1 SERVICE MANAGEMENT UTILITIES
4
5=head2 serviceControl()
6
7Manage services - stop/start/restart/reload/graceful
8
9Returns 1 for success, 0 if something went wrong, fatal exception on bad
10arguments.
11
12 serviceControl(
13 NAME=>serviceName,
14 ACTION=>start|stop|restart|reload|graceful
15 [ BACKGROUND=>true|false (default is false) ]
16 );
17
18EXAMPLE:
19
20 serviceControl( NAME=>'httpd-e-smith', ACTION=>'reload' );
21
22NOTES:
23
24The BACKGROUND parameter is optional and can be set to true if
25start/stop/restart/etc. is to be done in the background (with
26backgroundCommand()) rather than synchronously.
27
28CONVENTIONS:
29
30This command is the supported method for action scripts, blade handlers, etc.,
31to start/stop/restart their services. Currently this is done via the rc7
32symlinks, but this may change one day. Using this function gives us one
33location to change this behaviour if desired, instead of hunting all over
34every scrap of code. Please use it.
35
36=cut
37
38sub serviceControl
39{
40 my %params = @_;
41
42 my $serviceName = $params{NAME};
43 unless ( defined $serviceName )
44 {
45 die "serviceControl: NAME must be specified";
46 }
47
48 my $serviceAction = $params{ACTION};
49 unless (defined $serviceAction)
50 {
51 die "serviceControl: ACTION must be specified";
52 }
53
54 if ( $serviceAction =~ /^(start|stop|restart|reload|graceful|adjust|svdisable)$/ )
55 {
56 my ($startScript) = glob("/etc/rc.d/rc7.d/S*$serviceName") ||'' ;
57 my ($systemdScript) = "/usr/lib/systemd/system/$serviceName.service" ||'';
58
59 unless ( -e $startScript or -e $systemdScript)
60 {
61 warn "serviceControl: startScript not found "
62 . "for service $serviceName\n";
63 return 0;
64 }
65
66 if (-e $systemdScript and ! -e $startScript){
67 if ($serviceAction =~/^(start|stop|restart|reload)$/) {
68 system('/usr/bin/systemctl',"$serviceAction","$serviceName.service") == '0'
69 || warn "serviceControl: Couldn't " .
70 "system( /usr/bin/systemctl $serviceAction $serviceName.service): $!\n";
71 }
72 else {
73 die "serviceControl: systemd doesn't know : systemctl $serviceAction $serviceName.service";
74 }
75 }
76
77 elsif (-e $startScript) {
78 my $background = $params{'BACKGROUND'} || 'false';
79
80 if ( $background eq 'true' )
81 {
82 backgroundCommand( 0, $startScript, $serviceAction );
83 }
84 elsif ( $background eq 'false' )
85 {
86 unless ( system( $startScript, $serviceAction ) == 0 )
87 {
88 warn "serviceControl: "
89 . "Couldn't system($startScript, $serviceAction): $!\n";
90 return 0;
91 }
92 }
93 else
94 {
95 die "serviceControl: Unsupported BACKGROUND=>$background";
96 }
97 }
98 }
99 else
100 {
101 die "serviceControl: Unknown serviceAction $serviceAction";
102 }
103 return 1;
104}
Systemd Integration possibilities
this is intended to make an open discussion about possibilities, in order to choose the best SME approach to systemd.
Issue to solve :
- SME vs upstream
- make unit files aware of service status in e-smith db configuration
- have our services boot in the right sequence
- journald vs rsyslogd
- plain file log vs special file format
- enabling /disabling /masking services
Table 1. Load path when running in system mode (--system). [1]
| Path | Description |
|---|---|
/etc/systemd/system.control
|
Persistent and transient configuration created using the dbus API |
/run/systemd/system.control
| |
/run/systemd/transient
|
Dynamic configuration for transient units |
/run/systemd/generator.early
|
Generated units with high priority (see early-dir in systemd.generator(7))
|
/etc/systemd/system
|
System units created by the administrator |
/run/systemd/system
|
Runtime units |
/run/systemd/generator
|
Generated units with medium priority (see normal-dir in systemd.generator(7))
|
/usr/local/lib/systemd/system
|
System units installed by the administrator |
/usr/lib/systemd/system
|
System units installed by the distribution package manager |
/run/systemd/generator.late
|
Generated units with low priority (see late-dir in systemd.generator(7))
|
generators
there have been suggestions about using a generator, it is not clear how and why it would help. This approach would be more complex. and according to the doc[2]:
- Units written by generators are removed when the configuration is reloaded. That means the lifetime of the generated units is closely bound to the reload cycles of systemd itself.
- Generators should only be used to generate unit files and symlinks to them, not any other kind of configuration. Due to the lifecycle logic mentioned above, generators are not a good fit to generate dynamic configuration for other services. If you need to generate dynamic configuration for other services, do so in normal services you order before the service in question.
systemctl daemon-reload has be run after each modification of a unit. Hence generated files by generators will be erase and generators rerun. [3]
Overide upstream vendor preset : templated unit files or not ? where ?
Thinking of the example of a service unit provided by upstream vendor. Should we simply create a template and expand it over the unit.service in /lib/systemd/system/ or offer a different way to override upstream vendor settings ? Further more should we template our file to point to /lib/ or to /etc/. In other words, should we fight with admin space trying to overwrite changes in its dedicated space or should we fight with upstream vendors and overwrite their files or find a way to override them.
hence the questions
- where: /etc or /lib/
- How : template or not
- How: overwrite or selective overriding
unit files created in /etc/systemd/system/ or in /lib/systemd/system/
as a vendor we should work in /lib/systemd/system/, but as an admin helper we might want to play in /etc/systemd/system/ and rather offer a way to admin to use our template-custom or config db.
template or not
the first easy way to think to override ones service could be to simply template the file /lib/systemd/system/servicename.service and expand it every time a reconfiguration or a boot occurs.
Going futher we could ensure the stability of the system by making this in /etc/systemd/system/servicename.service
unitname.d/file.conf versus overwrite uniname.service
dot d folder can be created both int etc and lib from readings and inspection in a few systems.
There are two methods of overriding vendor settings in unit files: copying the unit file from /usr/lib/systemd/system to /etc/systemd/system and modifying the chosen settings. Alternatively, one can create a directory named unit.d//etc/systemd/system and place a drop-in file name.conf
The advantage of the first method is that one easily overrides the complete unit, the vendor unit is not parsed at all anymore. It has the disadvantage that improvements to the unit file by the vendor are not automatically incorporated on updates.
The advantage of the second method is that one only overrides the settings one specifically wants, where updates to the unit by the vendor automatically apply. This has the disadvantage that some future updates by the vendor might be incompatible with the local changes. [4]
uninstalling /masking unwanted/conflicting services: example of firewalld.
we can plan to uninstall firewalld for example, but some packages will reinstall as a requirement. It might even be started, which could conflict with masq.
