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Copyright 2011, Joyent Inc
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/lib/svc/bin/svc.startd
svc:/system/svc/restarter:default
svc.startd is the master restarter daemon for Service Management Facility (SMF) and the default restarter for all services. svc.startd starts, stops, and restarts services based on administrative requests, system failures, or application failures.
svc.startd maintains service state, as well as being responsible for managing faults in accordance with the dependencies of each service.
svc.startd is invoked automatically during system startup. It is restarted if any failures occur. svc.startd should never be invoked directly.
See smf_restarter(5) for information on configuration and behavior common to all restarters.
svcs(1) reports status for all services managed by the Service Configuration Facility. svcadm(1M) allows manipulation of service instances with respect to the service's restarter.
Environment variables with the "SMF_" prefix are reserved and may be overwritten.
svc.startd supplies the "SMF_" environment variables specified in smf_method(5) to the method. PATH is set to "/usr/sbin:/usr/bin" by default. By default, all other environment variables supplied to svc.startd are those inherited from init(1M).
Duplicate entries are reduced to a single entry. The value used is undefined. Environment entries that are not prefixed with "<name>=" are ignored.
svc.startd is not configured by command line options. Instead, configuration is read from the service configuration repository. You can use svccfg(1M) to set all options and properties.
The following configuration variables in the options property group are available to developers and administrators:
boot_messages
An astring (as defined in scf_value_is_type; see scf_value_is_type(3SCF)) that describes the default level of messages to print to the console during boot. The supported message options include quiet and verbose. The quiet option prints minimal messages to console during boot. The verbose option prints a single message per service started to indicate success or failure. You can use the boot -m option to override the boot_messages setting at boot time. See kernel(1M).
logging
Control the level of global service logging for svc.startd. An astring (as defined in scf_value_is_type; see scf_value_is_type(3SCF)) that describes the default level of messages to log to syslog (see syslog(3C) and svc.startd's global logfile, /var/svc/log/svc.startd.log. The supported message options include quiet, verbose, and debug. The quiet option sends error messages requiring administrative intervention to the console, syslog and svc.startd's global logfile. The verbose option sends error messages requiring administrative intervention to the console, syslog and svc.startd's global logfile, and information about errors which do not require administrative intervention to svc.startd's global logfile. A single message per service started is also sent to the console. The debug option sends svc.startd debug messages to svc.startd's global logfile, error messages requiring administrative intervention to the console, syslog and svc.startd's global logfile, and a single message per service started to the console.
milestone
An FMRI which determines the milestone used as the default boot level. Acceptable options include only the major milestones:
svc:/milestone/single-user:default svc:/milestone/multi-user:default svc:/milestone/multi-user-server:defaultor the special values all or none. all represents an idealized milestone that depends on every service. none is a special milestone where no services are running apart from the master svc:/system/svc/restarter:default. By default, svc.startd uses all, a synthetic milestone that depends on every service. If this property is specified, it overrides any initdefault setting in inittab(4).
Indicates that a reconfiguration reboot has been requested. Services with actions that must key off of a reconfiguration reboot may check that this property exists and is set to 1 to confirm a reconfiguration boot has been requested. This property is managed by svc.startd and should not be modified by the administrator.
Configuration errors, such as disabling svc.startd are logged by syslog, but ignored.
Services managed by svc.startd can appear in any of the states described in smf(5). The state definitions are unmodified by this restarter.
In addition to any logging done by the managed service, svc.startd provides a common set of service reporting and logging mechanisms.
Reporting properties svc.startd updates a common set of properties on all services it manages. These properties are a common interface that can be used to take action based on service instance health. The svcs(1) command can be used to easily display these properties.
The current and next (if currently in transition) state for an instance.
A caption detailing additional information about the current instance state. The auxiliary state available for services managed by svc.startd is:
maintenance
fault_threshold_reached stop_method_failed administrative_request
The time when the current state was reached.
The primary process contract ID, if any, that under which the service instance is executing.
Logs
By default, svc.startd provides logging of significant restarter actions for the service as well as method standard output and standard error file descriptors to /var/svc/log/service:instance.log. The level of logging to system global locations like /var/svc/log/svc.startd.log and syslog is controlled by the options/logging property.
When developing or configuring a service managed by svc.startd, a common set of properties are used to affect the interaction between the service instance and the restarter.
Methods
The general form of methods for the fork/exec model provided by svc.startd are presented in smf_method(5). The following methods are supported as required or optional by services managed by svc.startd.
refresh
Reload any appropriate configuration parameters from the repository or config file, without interrupting service. This is often implemented using SIGHUP for system daemons. If the service is unable to recognize configuration changes without a restart, no refresh method is provided. This method is optional.
start
Start the service. Return success only after the application is available to consumers. Fail if a conflicting instance is already running, or if the service is unable to start. This method is required.
stop
Stop the service. In some cases, the stop method can be invoked when some or all of the service has already been stopped. Only return an error if the service is not entirely stopped on method return. This method is required.
If the service does not need to take any action in a required method, it must specify the :true token for that method.
svc.startd honors any method context specified for the service or any specific method. The method expansion tokens described in smf_method(5) are available for use in all methods invoked by svc.startd.
Properties
An overview of the general properties is available in smf(5). The specific way in which these general properties interacts with svc.startd follows:
If enabled is set to true, the restarter attempts to start the service once all its dependencies are satisfied. If set to false, the service remains in the disabled state, not running.
If this FMRI property is empty or set to svc:/system/svc/restarter:default, the service is managed by svc.startd. Otherwise, the restarter specified is responsible (once it is available) for managing the service.
If single_instance is set to true, svc.startd only allows one instance of this service to transition to online or degraded at any time.
Additionally, svc.startd managed services can define the optional properties listed below in the startd property group.
startd/critical_failure_period
The critical_failure_count and critical_failure_period properties together specify the maximum number of service failures allowed in a given time interval before svc.startd transitions the service to maintenance. If the number of failures exceeds critical_failure_count in any period of critical_failure_period seconds, svc.startd will transition the service to maintenance.
The duration property defines the service's model. It can be set to transient, child also known as "wait" model services, or contract (the default).
The ignore_error property, if set, specifies a comma-separated list of ignored events. Legitimate string values in that list are core and signal. The default is to restart on all errors.
The need_session property, if set to true, indicates that the instance should be launched in its own session. The default is not to do so.
The utmpx_prefix string property defines that the instance requires a valid utmpx entry prior to start method execution. The default is not to create a utmpx entry.
svc.startd assumes that a method has failed if it returns a non-zero exit code or if fails to complete before the timeout specified expires. If $SMF_EXIT_ERR_CONFIG or $SMF_EXIT_ERR_FATAL is returned, svc.startd immediately places the service in the maintenance state. For all other failures, svc.startd places the service in the offline state. If a service is offline and its dependencies are satisfied, svc.startd tries again to start the service (see smf(5)).
If a contract or transient service does not return from its start method before its defined timeout elapses, svc.startd sends a SIGKILL to the method, and returns the service to the offline state.
If three failures happen in a row, or if the service is restarting more than once a second, svc.startd places the service in the maintenance state.
The conditions of service failure are defined by a combination of the service model (defined by the startd/duration property) and the value of the startd/ignore_error property.
A contract model service fails if any of the following conditions occur:
all processes in the service exit
any processes in the service produce a core dump
a process outside the service sends a service process a fatal signal (for example, an administrator terminates a service process with the pkill command)
The last two conditions may be ignored by the service by specifying core and/or signal in startd/ignore_error.
Defining a service as transient means that svc.startd does not track processes for that service. Thus, the potential faults described for contract model services are not considered failures for transient services. A transient service only enters the maintenance state if one of the method failure conditions occurs.
"Wait" model services are restarted whenever the child process associated with the service exits. A child process that exits is not considered an error for "wait" model services, and repeated failures do not lead to a transition to maintenance state.
svc.startd continues to provide support for services invoked during the startup run level transitions. Each /etc/rc?.d directory is processed after all managed services which constitute the equivalent run level milestone have transitioned to the online state. Standard init scripts placed in the /etc/rc?.d directories are run in the order of their sequence numbers.
The milestone to run-level mapping is:
Single-user (S)
Multi-user (2)
Multi-user with network services (3)
Additionally, svc.startd gives these legacy services visibility in SMF by inserting an instance per script into the repository. These legacy instances are visible using standard SMF interfaces such as svcs(1), always appear in the LEGACY-RUN state, cannot be modified, and can not be specified as dependencies of other services. The initial start time of the legacy service is captured as a convenience for the administrator.
Directory where svc.startd stores log files.
Directory where svc.startd stores log files in early stages of boot, before /var is mounted read-write.
Example 1 Turning on Verbose Logging
To turn on verbose logging, type the following:
# /usr/sbin/svccfg -s system/svc/restarter:default svc:/system/svc/restarter:default> addpg options application svc:/system/svc/restarter:default> setprop options/logging = \e astring: verbose svc:/system/svc/restarter:default> exit
This request will take effect on the next restart of svc.startd.
svcs(1), svcprop(1), kernel(1M), init(1M), svcadm(1M), svccfg(1M), svc.configd(1M), setsid(2), syslog(3C), libscf(3LIB), scf_value_is_type(3SCF), contract(4), init.d(4), process(4), inittab(4), attributes(5), smf(5), smf_method(5)