czan pushed a commit to branch develop
in repository shepherd.
commit 0c4d8ec40bc97481eec6dab2b53bb4c33e897862
Author: Carlo Zancanaro <ca...@zancanaro.id.au>
Date: Sat Aug 25 20:32:11 2018 +1000
service: Restart dependent services on service restart
* modules/shepherd/service.scm (required-by?): New procedure.
(stop): Return a list of canonical-names for stopped dependent services,
including transitive dependencies.
(action)[restart]: Start services based on the return value of stop.
(fold-services): New procedure.
* doc/shepherd.texi (Jump Start): Clarify details about new behaviour of
restart.
* tests/restart.sh: New file.
* Makefile.am (TESTS): Add tests/restart.sh.
---
Makefile.am | 1 +
doc/shepherd.texi | 12 +++---
modules/shepherd/service.scm | 90 +++++++++++++++++++++++++++-----------------
tests/restart.sh | 77 +++++++++++++++++++++++++++++++++++++
4 files changed, 139 insertions(+), 41 deletions(-)
diff --git a/Makefile.am b/Makefile.am
index 4322d7f..d9e21e9 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -187,6 +187,7 @@ TESTS = \
tests/replacement.sh \
tests/respawn.sh \
tests/respawn-throttling.sh \
+ tests/restart.sh \
tests/misbehaved-client.sh \
tests/no-home.sh \
tests/pid-file.sh \
diff --git a/doc/shepherd.texi b/doc/shepherd.texi
index 1de6d80..f0498d6 100644
--- a/doc/shepherd.texi
+++ b/doc/shepherd.texi
@@ -267,12 +267,12 @@ this inconsistency is just to make it more intuitive to
get
information about the status of a service, see below).
These actions are @code{restart} and @code{status}. The default
-implementation of @code{restart} calls @code{stop} and @code{start} on
-the affected service in order, the @code{status} action displays some
-general information about the service, like what it provides, what it
-depends on and with which other services it conflicts (because they
-provide a virtual service that is also provided by that particular
-service).
+implementation of @code{restart} calls @code{stop} and @code{start} on the
+affected service, taking care to also restart any dependent services. The
+default implementation of @code{status} displays some general information
+about the service, like what it provides, what it depends on and with which
+other services it conflicts (because they provide a virtual service that is
+also provided by that particular service).
Another special action is @code{list-actions}, which displays a list
of the additional actions a service provides; obviously, it can also
diff --git a/modules/shepherd/service.scm b/modules/shepherd/service.scm
index 24c9224..be86621 100644
--- a/modules/shepherd/service.scm
+++ b/modules/shepherd/service.scm
@@ -358,61 +358,72 @@ NEW-SERVICE."
(for-each remove-service (provided-by old-service))
(register-services new-service)))
+(define (required-by? service dependent)
+ "Returns #t if DEPENDENT directly requires SERVICE in order to run. Returns
+#f otherwise."
+ (and (find (lambda (dependency)
+ (memq dependency (provided-by service)))
+ (required-by dependent))
+ #t))
+
;; Stop the service, including services that depend on it. If the
;; latter fails, continue anyway. Return `#f' if it could be stopped.
-(define-method (stop (obj <service>) . args)
+(define-method (stop (service <service>) . args)
+ "Stop SERVICE, and any services which depend on it. Returns a list of
+canonical names for all of the services which have been stopped (including
+transitive dependent services). This method will print a warning if SERVICE
+is not already running, and will return SERVICE's canonical name in a list."
;; Block asyncs so the SIGCHLD handler doesn't execute concurrently.
- ;; Notably, that makes sure the handler processes the SIGCHLD for OBJ's
- ;; process once we're done; otherwise, it could end up respawning OBJ.
+ ;; Notably, that makes sure the handler processes the SIGCHLD for SERVICE's
+ ;; process once we're done; otherwise, it could end up respawning SERVICE.
(call-with-blocked-asyncs
(lambda ()
- (if (not (running? obj))
- (local-output "Service ~a is not running." (canonical-name obj))
- (if (slot-ref obj 'stop-delay?)
+ (if (not (running? service))
+ (begin
+ (local-output "Service ~a is not running." (canonical-name service))
+ (list (canonical-name service)))
+ (if (slot-ref service 'stop-delay?)
(begin
- (slot-set! obj 'waiting-for-termination? #t)
+ (slot-set! service 'waiting-for-termination? #t)
(local-output "Service ~a pending to be stopped."
- (canonical-name obj)))
- (begin
- ;; Stop services that depend on it.
- (for-each-service
- (lambda (serv)
- (and (running? serv)
- (for-each (lambda (sym)
- (and (memq sym (provided-by obj))
- (stop serv)))
- (required-by serv)))))
-
+ (canonical-name service))
+ (list (canonical-name service)))
+ (let ((name (canonical-name service))
+ (stopped-dependents (fold-services (lambda (other acc)
+ (if (and (running?
other)
+ (required-by?
service other))
+ (append (stop
other) acc)
+ acc))
+ '())))
;; Stop the service itself.
(catch #t
(lambda ()
- (apply (slot-ref obj 'stop)
- (slot-ref obj 'running)
+ (apply (slot-ref service 'stop)
+ (slot-ref service 'running)
args))
(lambda (key . args)
;; Special case: 'root' may quit.
- (and (eq? root-service obj)
+ (and (eq? root-service service)
(eq? key 'quit)
(apply quit args))
(caught-error key args)))
- ;; OBJ is no longer running.
- (slot-set! obj 'running #f)
+ ;; SERVICE is no longer running.
+ (slot-set! service 'running #f)
;; Reset the list of respawns.
- (slot-set! obj 'last-respawns '())
+ (slot-set! service 'last-respawns '())
;; Replace the service with its replacement, if it has one
- (let ((replacement (slot-ref obj 'replacement)))
+ (let ((replacement (slot-ref service 'replacement)))
(when replacement
- (replace-service obj replacement)))
+ (replace-service service replacement)))
;; Status message.
- (let ((name (canonical-name obj)))
- (if (running? obj)
- (local-output "Service ~a could not be stopped." name)
- (local-output "Service ~a has been stopped." name))))))
- (slot-ref obj 'running))))
+ (if (running? service)
+ (local-output "Service ~a could not be stopped." name)
+ (local-output "Service ~a has been stopped." name))
+ (cons name stopped-dependents)))))))
;; Call action THE-ACTION with ARGS.
(define-method (action (obj <service>) the-action . args)
@@ -423,10 +434,9 @@ NEW-SERVICE."
;; Restarting is done in the obvious way.
((restart)
(lambda (running . args)
- (if running
- (stop obj)
- (local-output "~a was not running." (canonical-name obj)))
- (apply start obj args)))
+ (let ((stopped-services (stop obj)))
+ (for-each start stopped-services)
+ #t)))
((status)
;; Return the service itself. It is automatically converted to an sexp
;; via 'result->sexp' and sent to the client.
@@ -960,6 +970,16 @@ Return #f if service is not found."
(eq? name (canonical-name service)))
services))
+(define (fold-services proc init)
+ "Apply PROC to the registered services to build a result, and return that
+result. Works in a manner akin to `fold' from SRFI-1."
+ (hash-fold (lambda (name services acc)
+ (let ((service (lookup-canonical-service name services)))
+ (if service
+ (proc service acc)
+ acc)))
+ init %services))
+
(define (for-each-service proc)
"Call PROC for each registered service."
(hash-for-each (lambda (name services)
diff --git a/tests/restart.sh b/tests/restart.sh
new file mode 100644
index 0000000..92a1f79
--- /dev/null
+++ b/tests/restart.sh
@@ -0,0 +1,77 @@
+# GNU Shepherd --- Test restarting services.
+# Copyright © 2013, 2014, 2016 Ludovic Courtès <l...@gnu.org>
+# Copyright © 2018 Carlo Zancanaro <ca...@zancanaro.id.au>
+#
+# This file is part of the GNU Shepherd.
+#
+# The GNU Shepherd 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 3 of the License, or (at
+# your option) any later version.
+#
+# The GNU Shepherd 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.
+#
+# You should have received a copy of the GNU General Public License
+# along with the GNU Shepherd. If not, see <http://www.gnu.org/licenses/>.
+
+shepherd --version
+herd --version
+
+socket="t-socket-$$"
+conf="t-conf-$$"
+log="t-log-$$"
+pid="t-pid-$$"
+
+herd="herd -s $socket"
+
+trap "cat $log || true ;
+ rm -f $socket $conf $log;
+ test -f $pid && kill \`cat $pid\` || true ; rm -f $pid" EXIT
+
+cat > "$conf"<<EOF
+(register-services
+ (make <service>
+ #:provides '(test1)
+ #:start (const #t)
+ #:stop (const #t))
+ (make <service>
+ #:provides '(test2)
+ #:requires '(test1)
+ #:start (const #t)
+ #:stop (const #t))
+ (make <service>
+ #:provides '(test3)
+ #:requires '(test2)
+ #:start (const #t)
+ #:stop (const #t)))
+EOF
+
+rm -f "$pid"
+shepherd -I -s "$socket" -c "$conf" -l "$log" --pid="$pid" &
+
+while ! test -f "$pid" ; do sleep 0.3 ; done
+
+# Start some test services, and make sure they behave how we expect
+$herd start test1
+$herd start test2
+$herd status test1 | grep started
+$herd status test2 | grep started
+
+# Restart test1 and make sure that both services are still running (ie. that
+# test2 hasn't been stopped)
+$herd restart test1
+$herd status test1 | grep started
+$herd status test2 | grep started
+
+# Now let's test with a transitive dependency
+$herd start test3
+$herd status test3 | grep started
+
+# After restarting test1 we want test3 to still be running
+$herd restart test1
+$herd status test1 | grep started
+$herd status test2 | grep started
+$herd status test3 | grep started
