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7 .TH SMF_METHOD 5 "Dec 4, 2017"
8 .SH NAME
9 smf_method \- service management framework conventions for methods
10 .SH DESCRIPTION
11 .LP
12 The class of services managed by \fBsvc.startd\fR(1M) in the service management
13 framework, \fBsmf\fR(5), consists of applications that fit a simple
14 \fBfork\fR(2)-\fBexec\fR(2) model. The \fBsvc.startd\fR(1M) master daemon and
15 other restarters support the \fBfork\fR(2)-\fBexec\fR(2) model, potentially
16 with additional capabilities. The \fBsvc.startd\fR(1M) daemon and other
17 restarters require that the methods which activate, manipulate, or examine a
18 service instance follow the conventions described in this manual page.
19 .SS "Invocation form"
20 .LP
21 The form of a method invocation is not dictated by convention. In some cases, a
22 method invocation might consist of the direct invocation of the daemon or other
23 binary executable that provides the service. For cases in which an executable
24 script or other mediating executable is used, the convention recommends the
25 form:
26 .sp
27 .in +2
28 .nf
29 /path/to/method_executable abbr_method_name
30 .fi
31 .in -2
32
33 .sp
34 .LP
35 The \fIabbr_method_name\fR used for the recommended form is a supported method
36 such as \fBstart\fR or \fBstop\fR. The set of methods supported by a restarter
37 is given on the related restarter page. The \fBsvc.startd\fR(1M) daemon
38 supports \fBstart\fR, \fBstop\fR, and \fBrefresh\fR methods.
39 .sp
40 .LP
41 A restarter might define other kinds of methods beyond those referenced in this
42 page. The conventions surrounding such extensions are defined by the restarter
43 and might not be identical to those given here.
44 .SS "Environment Variables"
45 .LP
46 The restarter provides four environment variables to the method that determine
47 the context in which the method is invoked.
48 .sp
49 .ne 2
50 .na
51 \fB\fBSMF_FMRI\fR\fR
52 .ad
53 .sp .6
54 .RS 4n
55 The service fault management resource identifier (FMRI) of the instance for
56 which the method is invoked.
57 .RE
58
59 .sp
60 .ne 2
61 .na
62 \fB\fBSMF_METHOD\fR\fR
63 .ad
64 .sp .6
65 .RS 4n
66 The full name of the method being invoked, such as \fBstart\fR or \fBstop\fR.
67 .RE
68
69 .sp
70 .ne 2
71 .na
72 \fB\fBSMF_RESTARTER\fR\fR
73 .ad
74 .sp .6
75 .RS 4n
76 The service FMRI of the restarter that invokes the method
77 .RE
78
79 .sp
80 .ne 2
81 .na
82 \fB\fBSMF_ZONENAME\fR\fR
83 .ad
84 .sp .6
85 .RS 4n
86 The name of the zone in which the method is running. This can also be obtained
87 by using the \fBzonename\fR(1) command.
88 .RE
89
90 .sp
91 .LP
92 These variables should be removed from the environment prior to the invocation
93 of any persistent process by the method. A convenience shell function,
94 \fBsmf_clear_env\fR, is given for service authors who use Bourne-compatible
95 shell scripting to compose service methods in the include file described below.
96 .sp
97 .LP
98 The method context can cause other environment variables to be set as described
99 below.
100 .SS "Method Definition"
101 .LP
102 A method is defined minimally by three properties in a propertygroup of type
103 \fBmethod\fR.
104 .sp
105 .LP
106 These properties are:
107 .sp
108 .ne 2
109 .na
110 \fBexec (\fIastring\fR)\fR
111 .ad
112 .RS 27n
113 Method executable string.
114 .RE
115
116 .sp
117 .ne 2
118 .na
119 \fBtimeout_seconds (\fIcount\fR)\fR
120 .ad
121 .RS 27n
122 Number of seconds before method times out. See the \fBTimeouts\fR section for
123 more detail.
124 .RE
125
126 .sp
127 .ne 2
128 .na
129 \fBtype (\fIastring\fR)\fR
130 .ad
131 .RS 27n
132 Method type. Currently always set to \fBmethod\fR.
133 .RE
134
135 .sp
136 .LP
137 A Method Context can be defined to further refine the execution environment of
138 the method. See the \fBMethod Context\fR section for more information.
139 .SS "Method Tokens"
140 .LP
141 When defined in the \fBexec\fR string of the method by the restarter
142 \fBsvc.startd\fR, a set of tokens are parsed and expanded with appropriate
143 value. Other restarters might not support method tokens. The delegated
144 restarter for inet services, \fBinetd\fR(1M), does not support the following
145 method expansions.
146 .sp
147 .ne 2
148 .na
149 \fB\fB%%\fR\fR
150 .ad
151 .sp .6
152 .RS 4n
153 %
154 .RE
155
156 .sp
157 .ne 2
158 .na
159 \fB\fB%r\fR\fR
160 .ad
161 .sp .6
162 .RS 4n
163 Name of the restarter, such as \fBsvc.startd\fR
164 .RE
165
166 .sp
167 .ne 2
168 .na
169 \fB\fB%m\fR\fR
170 .ad
171 .sp .6
172 .RS 4n
173 The full name of the method being invoked, such as \fBstart\fR or \fBstop\fR.
174 .RE
175
176 .sp
177 .ne 2
178 .na
179 \fB\fB%s\fR\fR
180 .ad
181 .sp .6
182 .RS 4n
183 Name of the service
184 .RE
185
186 .sp
187 .ne 2
188 .na
189 \fB\fB%i\fR\fR
190 .ad
191 .sp .6
192 .RS 4n
193 Name of the instance
194 .RE
195
196 .sp
197 .ne 2
198 .na
199 \fB\fB\fR\fB%f\fR\fR
200 .ad
201 .sp .6
202 .RS 4n
203 FMRI of the instance
204 .RE
205
206 .sp
207 .ne 2
208 .na
209 \fB\fB%{prop[:,]}\fR\fR
210 .ad
211 .sp .6
212 .RS 4n
213 Value(s) of a property. The \fBprop\fR might be a property FMRI, a property
214 group name and a property name separated by a \fB/\fR, or a property name in
215 the \fBapplication\fR property group. These values can be followed by a \fB,\fR
216 (comma) or \fB:\fR (colon). If present, the separators are used to separate
217 multiple values. If absent, a space is used. The following shell metacharacters
218 encountered in string values are quoted with a \ (backslash):
219 .sp
220 .in +2
221 .nf
222 ; & ( ) | ^ < > newline space tab \ " '
223 .fi
224 .in -2
225
226 An invalid expansion constitutes method failure.
227 .RE
228
229 .sp
230 .LP
231 Two explicit tokens can be used in the place of method commands.
232 .sp
233 .ne 2
234 .na
235 \fB\fB:kill [-signal]\fR\fR
236 .ad
237 .sp .6
238 .RS 4n
239 Sends the specified signal, which is \fBSIGTERM\fR by default, to all processes
240 in the primary instance contract. Always returns \fBSMF_EXIT_OK\fR. This token
241 should be used to replace common \fBpkill\fR invocations.
242 .RE
243
244 .sp
245 .ne 2
246 .na
247 \fB\fB:true\fR\fR
248 .ad
249 .sp .6
250 .RS 4n
251 Always returns \fBSMF_EXIT_OK\fR. This token should be used for methods that
252 are required by the restarter but which are unnecessary for the particular
253 service implementation.
254 .RE
255
256 .SS "Exiting and Exit Status"
257 .LP
258 The required behavior of a start method is to delay exiting until the service
259 instance is ready to answer requests or is otherwise functional.
260 .sp
261 .LP
262 The following exit status codes are defined in \fB<libscf.h>\fR and in the
263 shell support file.
264 .sp
265
266 .sp
267 .TS
268 l l l
269 l l l .
270 \fBSMF_EXIT_OK\fR \fB0\fR T{
271 Method exited, performing its operation successfully.
272 T}
273 \fBSMF_EXIT_ERR_FATAL\fR \fB95\fR T{
274 Method failed fatally and is unrecoverable without administrative intervention.
275 T}
276 \fBSMF_EXIT_ERR_CONFIG\fR \fB96\fR T{
277 Unrecoverable configuration error. A common condition that returns this exit status is the absence of required configuration files for an enabled service instance.
278 T}
279 \fBSMF_EXIT_MON_DEGRADE\fR \fB97\fR T{
280 Method encountered some problems and may not be fully functional.
281 T}
282 \fBSMF_EXIT_ERR_NOSMF\fR \fB99\fR T{
283 Method has been mistakenly invoked outside the \fBsmf\fR(5) facility. Services that depend on \fBsmf\fR(5) capabilities should exit with this status value.
284 T}
285 \fBSMF_EXIT_ERR_PERM\fR \fB100\fR T{
286 Method requires a form of permission such as file access, privilege, authorization, or other credential that is not available when invoked.
287 T}
288 \fBSMF_EXIT_ERR_OTHER\fR \fBnon-zero\fR T{
289 Any non-zero exit status from a method is treated as an unknown error. A series of unknown errors can be diagnosed as a fault by the restarter or on behalf of the restarter.
290 T}
291 .TE
292
293 .sp
294 .LP
295 Use of a precise exit code allows the responsible restarter to categorize an
296 error response as likely to be intermittent and worth pursuing restart or
297 permanent and request administrative intervention.
298 .SS "Timeouts"
299 .LP
300 Each method can have an independent timeout, given in seconds. The choice of a
301 particular timeout should be based on site expectations for detecting a method
302 failure due to non-responsiveness. Sites with replicated filesystems or other
303 failover resources can elect to lengthen method timeouts from the default.
304 Sites with no remote resources can elect to shorten the timeouts. Method
305 timeout is specified by the \fBtimeout_seconds\fR property.
306 .sp
307 .LP
308 If you specify \fB0 timeout_seconds\fR for a method, it declares to the
309 restarter that there is no timeout for the service. This setting is not
310 preferred, but is available for services that absolutely require it.
311 .sp
312 .LP
313 \fB-1 timeout_seconds\fR is also accepted, but is a deprecated specification.
314 .SS "Shell Programming Support"
315 .LP
316 A set of environment variables that define the above exit status values is
317 provided with convenience shell functions in the file
318 \fB/lib/svc/share/smf_include.sh\fR. This file is a Bourne shell script
319 suitable for inclusion via the source operator in any Bourne-compatible shell.
320 .sp
321 .LP
322 To assist in the composition of scripts that can serve as SMF methods as well
323 as \fB/etc/init.d\fR scripts, the \fBsmf_present()\fR shell function is
324 provided. If the \fBsmf\fR(5) facility is not available, \fBsmf_present()\fR
325 returns a non-zero exit status.
326 .sp
327 .LP
328 One possible structure for such a script follows:
329 .sp
330 .in +2
331 .nf
332 if smf_present; then
333 # Shell code to run application as managed service
334 ....
335
336 smf_clear_env
337 else
338 # Shell code to run application as /etc/init.d script
339 ....
340 fi
341 .fi
342 .in -2
343
344 .sp
345 .LP
346 This example shows the use of both convenience functions that are provided.
347 .SS "Method Context"
348 .LP
349 The service management facility offers a common mechanism set the context in
350 which the \fBfork\fR(2)-\fBexec\fR(2) model services execute.
351 .sp
352 .LP
353 The desired method context should be provided by the service developer. All
354 service instances should run with the lowest level of privileges possible to
355 limit potential security compromises.
356 .sp
357 .LP
358 A method context can contain the following properties:
359 .sp
360 .ne 2
361 .na
362 \fB\fBuse_profile\fR\fR
363 .ad
364 .sp .6
365 .RS 4n
366 A boolean that specifies whether the profile should be used instead of the
367 \fBuser\fR, \fBgroup\fR, \fBprivileges\fR, and \fBlimit_privileges\fR
368 properties.
369 .RE
370
371 .sp
372 .ne 2
373 .na
374 \fBenvironment\fR
375 .ad
376 .sp .6
377 .RS 4n
378 Environment variables to insert into the environment of the method, in the form
379 of a number of \fBNAME=value\fR strings.
380 .RE
381
382 .sp
383 .ne 2
384 .na
385 \fB\fBprofile\fR\fR
386 .ad
387 .sp .6
388 .RS 4n
389 The name of an RBAC (role-based access control) profile which, along with the
390 method executable, identifies an entry in \fBexec_attr\fR(4).
391 .RE
392
393 .sp
394 .ne 2
395 .na
396 \fB\fBuser\fR\fR
397 .ad
398 .sp .6
399 .RS 4n
400 The user ID in numeric or text form.
401 .RE
402
403 .sp
404 .ne 2
405 .na
406 \fB\fBgroup\fR\fR
407 .ad
408 .sp .6
409 .RS 4n
410 The group ID in numeric or text form.
411 .RE
412
413 .sp
414 .ne 2
415 .na
416 \fB\fBsupp_groups\fR\fR
417 .ad
418 .sp .6
419 .RS 4n
420 An optional string that specifies the supplemental group memberships by ID, in
421 numeric or text form.
422 .RE
423
424 .sp
425 .ne 2
426 .na
427 \fB\fBprivileges\fR\fR
428 .ad
429 .sp .6
430 .RS 4n
431 An optional string specifying the privilege set as defined in
432 \fBprivileges\fR(5).
433 .RE
434
435 .sp
436 .ne 2
437 .na
438 \fB\fBlimit_privileges\fR\fR
439 .ad
440 .sp .6
441 .RS 4n
442 An optional string specifying the limit privilege set as defined in
443 \fBprivileges\fR(5).
444 .RE
445
446 .sp
447 .ne 2
448 .na
449 \fB\fBworking_directory\fR\fR
450 .ad
451 .sp .6
452 .RS 4n
453 The home directory from which to launch the method. \fB:home\fR can be used as
454 a token to indicate the home directory of the user whose \fBuid\fR is used to
455 launch the method. If the property is unset, \fB:home\fR is used.
456 .RE
457
458 .sp
459 .ne 2
460 .na
461 \fB\fBsecurity_flags\fR\fR
462 .ad
463 .sp .6
464 .RS 4n
465 The security flags to apply when launching the method. See \fBsecurity-flags\fR(5).
466 .sp
467 .LP
468 The "default" keyword specifies those flags specified in
469 \fBsvc:/system/process-security\fR. The "all" keyword enables all flags, the
470 "none" keyword enables no flags. The "current" keyword specifies the current
471 flags. Flags may be added by specifying their name (optionally preceded
472 by '+'), and removed by preceding their name with '-').
473 .sp
474 .LP
475 Use of "all" has associated risks, as future versions of the system may
476 include further flags which may harm poorly implemented software.
477 .RE
478
479 .sp
480 .ne 2
481 .na
482 \fB\fBcorefile_pattern\fR\fR
483 .ad
484 .sp .6
485 .RS 4n
486 An optional string that specifies the corefile pattern to use for the service,
487 as per \fBcoreadm\fR(1M). Most restarters supply a default. Setting this
488 property overrides local customizations to the global core pattern.
489 .RE
490
491 .sp
492 .ne 2
493 .na
494 \fB\fBproject\fR\fR
495 .ad
496 .sp .6
497 .RS 4n
498 The project ID in numeric or text form. \fB:default\fR can be used as a token
499 to indicate a project identified by \fBgetdefaultproj\fR(3PROJECT) for the user
500 whose \fBuid\fR is used to launch the method.
501 .RE
502
503 .sp
504 .ne 2
505 .na
506 \fB\fBresource_pool\fR\fR
507 .ad
508 .sp .6
509 .RS 4n
510 The resource pool name on which to launch the method. \fB:default\fR can be
511 used as a token to indicate the pool specified in the \fBproject\fR(4) entry
512 given in the \fBproject\fR attribute above.
513 .RE
514
515 .sp
516 .LP
517 The method context can be set for the entire service instance by specifying a
518 \fBmethod_context\fR property group for the service or instance. A method might
519 override the instance method context by providing the method context properties
520 on the method property group.
521 .sp
522 .LP
523 Invalid method context settings always lead to failure of the method, with the
524 exception of invalid environment variables that issue warnings.
525 .sp
526 .LP
527 In addition to the context defined above, many \fBfork\fR(2)-\fBexec\fR(2)
528 model restarters also use the following conventions when invoking executables
529 as methods:
530 .sp
531 .ne 2
532 .na
533 \fBArgument array\fR
534 .ad
535 .sp .6
536 .RS 4n
537 The arguments in \fBargv[]\fR are set consistently with the result \fB/bin/sh
538 -c\fR of the \fBexec\fR string.
539 .RE
540
541 .sp
542 .ne 2
543 .na
544 \fBFile descriptors\fR
545 .ad
546 .sp .6
547 .RS 4n
548 File descriptor \fB0\fR is \fB/dev/null\fR. File descriptors \fB1\fR and
549 \fB2\fR are recommended to be a per-service log file.
550 .RE
551
552 .SH FILES
553 .ne 2
554 .na
555 \fB\fB/lib/svc/share/smf_include.sh\fR\fR
556 .ad
557 .sp .6
558 .RS 4n
559 Definitions of exit status values.
560 .RE
561
562 .sp
563 .ne 2
564 .na
565 \fB\fB/usr/include/libscf.h\fR\fR
566 .ad
567 .sp .6
568 .RS 4n
569 Definitions of exit status codes.
570 .RE
571
572 .SH SEE ALSO
573 .LP
574 \fBzonename\fR(1), \fBcoreadm\fR(1M), \fBinetd\fR(1M), \fBsvccfg\fR(1M),
575 \fBsvc.startd\fR(1M), \fBexec\fR(2), \fBfork\fR(2),
576 \fBgetdefaultproj\fR(3PROJECT), \fBexec_attr\fR(4), \fBproject\fR(4),
577 \fBservice_bundle\fR(4), \fBattributes\fR(5), \fBprivileges\fR(5),
578 \fBrbac\fR(5), \fBsmf\fR(5), \fBsmf_bootstrap\fR(5), \fBzones\fR(5),
579 \fBsecurity-flags\fR(5)
580 .SH NOTES
581 .LP
582 The present version of \fBsmf\fR(5) does not support multiple repositories.
583 .sp
584 .LP
585 When a service is configured to be started as root but with privileges
586 different from \fBlimit_privileges\fR, the resulting process is privilege
587 aware. This can be surprising to developers who expect \fBseteuid(<non-zero
588 UID>)\fR to reduce privileges to basic or less.