guix - Wojtek's customized Guix

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shepherd-service-respawn? shepherd-service-start shepherd-service-stop shepherd-service-free-form shepherd-service-auto-start? shepherd-service-modules shepherd-action shepherd-action? shepherd-action-name shepherd-action-documentation shepherd-action-procedure shepherd-configuration-action %default-modules shepherd-service-file shepherd-service-lookup-procedure shepherd-service-back-edges shepherd-service-upgrade user-processes-service-type assert-valid-graph)) ;;; Commentary: ;;; ;;; Instantiating system services as a shepherd configuration file. ;;; ;;; Code: (define-record-type* <shepherd-configuration> shepherd-configuration make-shepherd-configuration shepherd-configuration? (shepherd shepherd-configuration-shepherd (default shepherd-0.10)) ; file-like (services shepherd-configuration-services (default '()))) ; list of <shepherd-service> (define (shepherd-boot-gexp config) "Return a gexp starting the shepherd service." (let ((shepherd (shepherd-configuration-shepherd config)) (services (shepherd-configuration-services config))) #~(begin ;; Keep track of the booted system. (false-if-exception (delete-file "/run/booted-system")) ;; Make /run/booted-system, an indirect GC root, point to the store item ;; /run/current-system points to. Use 'canonicalize-path' rather than ;; 'readlink' to make sure we get the store item. (symlink (canonicalize-path "/run/current-system") "/run/booted-system") ;; Ensure open file descriptors are close-on-exec so shepherd doesn't ;; inherit them. (let loop ((fd 3)) (when (< fd 1024) (false-if-exception (let ((flags (fcntl fd F_GETFD))) (when (zero? (logand flags FD_CLOEXEC)) (fcntl fd F_SETFD (logior FD_CLOEXEC flags))))) (loop (+ fd 1)))) ;; Start shepherd. (execl #$(file-append shepherd "/bin/shepherd") "shepherd" "--config" #$(shepherd-configuration-file services shepherd))))) (define shepherd-packages (compose list shepherd-configuration-shepherd)) (define shepherd-root-service-type (service-type (name 'shepherd-root) ;; Extending the root shepherd service (aka. PID 1) happens by ;; concatenating the list of services provided by the extensions. (compose concatenate) (extend (lambda (config extra-services) (shepherd-configuration (inherit config) (services (append (shepherd-configuration-services config) extra-services))))) (extensions (list (service-extension boot-service-type shepherd-boot-gexp) (service-extension profile-service-type shepherd-packages))) (default-value (shepherd-configuration)) (description "Run the GNU Shepherd as PID 1---i.e., the operating system's first process. The Shepherd takes care of managing services such as daemons by ensuring they are started and stopped in the right order."))) (define %shepherd-root-service ;; The root shepherd service, aka. PID 1. Its parameter is a ;; <shepherd-configuration>. (service shepherd-root-service-type)) (define-syntax shepherd-service-type (syntax-rules (description) "Return a <service-type> denoting a simple shepherd service--i.e., the type for a service that extends SHEPHERD-ROOT-SERVICE-TYPE and nothing else. When DEFAULT is given, use it as the service's default value." ((_ service-name proc default (description text)) (service-type (name service-name) (extensions (list (service-extension shepherd-root-service-type (compose list proc)))) (default-value default) (description text))) ((_ service-name proc (description text)) (service-type (name service-name) (extensions (list (service-extension shepherd-root-service-type (compose list proc)))) (description text))))) (define %default-imported-modules ;; Default set of modules imported for a service's consumption. '((guix build utils) (guix build syscalls))) (define %default-modules ;; Default set of modules visible in a service's file. `((shepherd service) ((guix build utils) #:hide (delete)) (guix build syscalls))) (define-with-syntax-properties (validate-provision (provision properties)) (match provision (((? symbol?) ..1) provision) (_ (raise (make-compound-condition (condition (&error-location (location (source-properties->location properties)))) (formatted-message (G_ "'provision' must be a non-empty list of symbols"))))))) (define-record-type* <shepherd-service> shepherd-service make-shepherd-service shepherd-service? (documentation shepherd-service-documentation ;string (default "[No documentation.]")) (provision shepherd-service-provision ;list of symbols (sanitize validate-provision)) (requirement shepherd-service-requirement ;list of symbols (default '())) (one-shot? shepherd-service-one-shot? ;Boolean (default #f)) (respawn? shepherd-service-respawn? ;Boolean (default #t)) (respawn-limit shepherd-service-respawn-limit (default #f)) (respawn-delay shepherd-service-respawn-delay (default #f)) (free-form shepherd-service-free-form ;#f | g-expression (service) (default #f)) (start shepherd-service-start ;g-expression (procedure) (default #~(const #t))) (stop shepherd-service-stop ;g-expression (procedure) (default #~(const #f))) (actions shepherd-service-actions ;list of <shepherd-action> (default '())) (auto-start? shepherd-service-auto-start? ;Boolean (default #t)) (modules shepherd-service-modules ;list of module names (default %default-modules))) (define-record-type* <shepherd-action> shepherd-action make-shepherd-action shepherd-action? (name shepherd-action-name) ;symbol (procedure shepherd-action-procedure) ;gexp (documentation shepherd-action-documentation)) ;string (define (shepherd-service-canonical-name service) "Return the 'canonical name' of SERVICE." (first (shepherd-service-provision service))) (define (assert-valid-graph services) "Raise an error if SERVICES does not define a valid shepherd service graph, for instance if a service requires a nonexistent service, or if more than one service uses a given name. These are constraints that shepherd's 'register-service' verifies but we'd better verify them here statically than wait until PID 1 halts with an assertion failure." (define provisions ;; The set of provisions (symbols). Bail out if a symbol is given more ;; than once. (fold (lambda (service set) (define (assert-unique symbol) (when (set-contains? set symbol) (raise (condition (&message (message (format #f (G_ "service '~a' provided more than once") symbol))))))) (for-each assert-unique (shepherd-service-provision service)) (fold set-insert set (shepherd-service-provision service))) (setq 'shepherd) services)) (define (assert-satisfied-requirements service) ;; Bail out if the requirements of SERVICE aren't satisfied. (for-each (lambda (requirement) (unless (set-contains? provisions requirement) (raise (condition (&message (message (format #f (G_ "service '~a' requires '~a', \ which is not provided by any service") (match (shepherd-service-provision service) ((head . _) head) (_ service)) requirement))))))) (shepherd-service-requirement service))) (for-each assert-satisfied-requirements services)) (define %store-characters ;; Valid store characters; see 'checkStoreName' in the daemon. (string->char-set "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+-._?=")) (define (shepherd-service-file-name service) "Return the file name where the initialization code for SERVICE is to be stored." (let ((provisions (string-join (map symbol->string (shepherd-service-provision service))))) (string-append "shepherd-" (string-map (lambda (chr) (if (char-set-contains? %store-characters chr) chr #\-)) provisions) ".scm"))) (define (shepherd-service-file/regular service) "Return a file defining SERVICE, a service whose 'free-form' field is #f." (scheme-file (shepherd-service-file-name service) (with-imported-modules %default-imported-modules #~(begin (use-modules #$@(shepherd-service-modules service)) (service '#$(shepherd-service-provision service) #:documentation '#$(shepherd-service-documentation service) #:requirement '#$(shepherd-service-requirement service) ;; The 'one-shot?' slot is new in Shepherd 0.6.0. ;; Older versions ignore it. #:one-shot? '#$(shepherd-service-one-shot? service) #:respawn? '#$(shepherd-service-respawn? service) #$@(if (shepherd-service-respawn-limit service) `(#:respawn-limit ,(shepherd-service-respawn-limit service)) '()) #$@(if (shepherd-service-respawn-delay service) `(#:respawn-delay ,(shepherd-service-respawn-delay service)) '()) #:start #$(shepherd-service-start service) #:stop #$(shepherd-service-stop service) #:actions (actions #$@(map (match-lambda (($ <shepherd-action> name proc doc) #~(#$name #$doc #$proc))) (shepherd-service-actions service)))))))) (define (shepherd-service-file/free-form service) "Return a file defining SERVICE, a service whose 'free-form' field is set." (scheme-file (shepherd-service-file-name service) (with-imported-modules %default-imported-modules #~(begin (use-modules #$@(shepherd-service-modules service)) #$(shepherd-service-free-form service))))) (define (shepherd-service-file service) "Return a file defining SERVICE." (if (shepherd-service-free-form service) (shepherd-service-file/free-form service) (shepherd-service-file/regular service))) (define (scm->go file shepherd) "Compile FILE, which contains code to be loaded by shepherd's config file, and return the resulting '.go' file. SHEPHERD is used as shepherd package." (define shepherd&co (cons shepherd (match (lookup-package-input shepherd "guile-fibers") (#f '()) (fibers (list fibers))))) (let-system (system target) (with-extensions shepherd&co (computed-file (string-append (basename (scheme-file-name file) ".scm") ".go") #~(begin (use-modules (system base compile) (system base target)) ;; Do the same as the Shepherd's 'load-in-user-module'. (let ((env (make-fresh-user-module))) (module-use! env (resolve-interface '(shepherd service))) (with-target #$(or target #~%host-type) (lambda _ (compile-file #$file #:output-file #$output #:env env))))) ;; It's faster to build locally than to download. #:options '(#:local-build? #t #:substitutable? #f))))) (define (shepherd-configuration-action file) "Return a 'configuration' action to display FILE, which should be the name of the service's configuration file." (shepherd-action (name 'configuration) (documentation "Display the name of this service's configuration file.") (procedure #~(lambda (_) (format #t "~a~%" #$file) #$file)))) (define (shepherd-configuration-file services shepherd) "Return the shepherd configuration file for SERVICES. SHEPHERD is used as shepherd package." (assert-valid-graph services) (let ((files (map shepherd-service-file services)) (scm->go (cute scm->go <> shepherd))) (define config #~(begin (use-modules (srfi srfi-1)) (define (make-user-module) ;; Copied from (shepherd support), where it's private. (let ((m (make-fresh-user-module))) (module-use! m (resolve-interface '(shepherd service))) m)) ;; There's code run from shepherd that uses 'call-with-input-file' & ;; co.--e.g., the 'urandom-seed' service. Starting from Shepherd ;; 0.9.2, users need to make sure not to leak non-close-on-exec file ;; descriptors to child processes. To address that, replace the ;; standard bindings with O_CLOEXEC variants. (set! call-with-input-file (lambda (file proc) (call-with-port (open file (logior O_RDONLY O_CLOEXEC)) proc))) (set! call-with-output-file (lambda (file proc) (call-with-port (open file (logior O_WRONLY O_CREAT O_CLOEXEC)) proc))) ;; Specify the default environment visible to all the services. ;; Without this statement, all the environment variables of PID 1 ;; are inherited by child services. (default-environment-variables '("PATH=/run/current-system/profile/bin")) ;; Booting off a DVD, especially on a slow machine, can make ;; everything slow. Thus, increase the timeout compared to the ;; default 5s in the Shepherd 0.7.0. See ;; <https://bugs.gnu.org/40572>. (default-pid-file-timeout 30) ;; Load service files one by one; filter out those that could not be ;; loaded--e.g., due to an unbound variable--such that an error in ;; one service definition does not prevent the system from booting. (register-services (parameterize ((current-warning-port (%make-void-port "w"))) (filter-map (lambda (file) (with-exception-handler (lambda (exception) (format #t "Exception caught \ while loading '~a': ~s~%" file exception) #f) (lambda () (save-module-excursion (lambda () (set-current-module (make-user-module)) (load-compiled file)))) #:unwind? #t)) '#$(map scm->go files)))) (format #t "starting services...~%") (let ((services-to-start '#$(append-map shepherd-service-provision (filter shepherd-service-auto-start? services)))) (start-in-the-background services-to-start) ;; Hang up stdin. At this point, we assume that 'start' methods ;; that required user interaction on the console (e.g., ;; 'cryptsetup open' invocations, post-fsck emergency REPL) have ;; completed. User interaction becomes impossible after this ;; call; this avoids situations where services wrongfully lead ;; PID 1 to read from stdin (the console), which users may not ;; have access to (see <https://bugs.gnu.org/23697>). (redirect-port (open "/dev/null" (logior O_RDONLY O_CLOEXEC)) (current-input-port))))) (scheme-file "shepherd.conf" config))) (define* (shepherd-service-lookup-procedure services #:optional (provision shepherd-service-provision)) "Return a procedure that, when passed a symbol, return the item among SERVICES that provides this symbol. PROVISION must be a one-argument procedure that takes a service and returns the list of symbols it provides." (let ((services (fold (lambda (service result) (fold (cut vhash-consq <> service <>) result (provision service))) vlist-null services))) (lambda (name) (match (vhash-assq name services) ((_ . service) service) (#f #f))))) (define* (shepherd-service-back-edges services #:key (provision shepherd-service-provision) (requirement shepherd-service-requirement)) "Return a procedure that, when given a <shepherd-service> from SERVICES, returns the list of <shepherd-service> that depend on it. Use PROVISION and REQUIREMENT as one-argument procedures that return the symbols provided/required by a service." (define provision->service (shepherd-service-lookup-procedure services provision)) (define edges (fold (lambda (service edges) (fold (lambda (requirement edges) (vhash-consq (provision->service requirement) service edges)) edges (requirement service))) vlist-null services)) (lambda (service) (vhash-foldq* cons '() service edges))) (define (shepherd-service-upgrade live target) "Return two values: the subset of LIVE (a list of <live-service>) that needs to be unloaded, and the subset of TARGET (a list of <shepherd-service>) that need to be restarted to complete their upgrade." (define (essential? service) (memq (first (live-service-provision service)) '(root shepherd))) (define lookup-target (shepherd-service-lookup-procedure target shepherd-service-provision)) (define lookup-live (shepherd-service-lookup-procedure live live-service-provision)) (define (running? service) (and=> (lookup-live (shepherd-service-canonical-name service)) live-service-running)) (define live-service-dependents (shepherd-service-back-edges live #:provision live-service-provision #:requirement live-service-requirement)) (define (obsolete? service) (match (lookup-target (first (live-service-provision service))) (#f (every obsolete? (live-service-dependents service))) (_ #f))) (define to-restart ;; Restart services that are currently running. (filter running? target)) (define to-unload ;; Unload services that are no longer required. Essential services must ;; be kept and transient services such as inetd child services should be ;; kept as well--they'll vanish eventually. (remove (lambda (live) (or (essential? live) (live-service-transient? live))) (filter obsolete? live))) (values to-unload to-restart)) ;;; ;;; User processes. ;;; (define %do-not-kill-file ;; Name of the file listing PIDs of processes that must survive when halting ;; the system. Typical example is user-space file systems. "/etc/shepherd/do-not-kill") (define (user-processes-shepherd-service requirements) "Return the 'user-processes' Shepherd service with dependencies on REQUIREMENTS (a list of service names). This is a synchronization point used to make sure user processes and daemons get started only after crucial initial services have been started---file system mounts, etc. This is similar to the 'sysvinit' target in systemd." (define grace-delay ;; Delay after sending SIGTERM and before sending SIGKILL. 4) (list (shepherd-service (documentation "When stopped, terminate all user processes.") (provision '(user-processes)) (requirement requirements) (start #~(const #t)) (stop #~(lambda _ (define (kill-except omit signal) ;; Kill all the processes with SIGNAL except those listed ;; in OMIT and the current process. (let ((omit (cons (getpid) omit))) (for-each (lambda (pid) (unless (memv pid omit) (false-if-exception (kill pid signal)))) (processes)))) (define omitted-pids ;; List of PIDs that must not be killed. (if (file-exists? #$%do-not-kill-file) (map string->number (call-with-input-file #$%do-not-kill-file (compose string-tokenize (@ (ice-9 rdelim) read-string)))) '())) (define (now) (car (gettimeofday))) (define (sleep* n) ;; Really sleep N seconds. ;; Work around <http://bugs.gnu.org/19581>. (define start (now)) (let loop ((elapsed 0)) (when (> n elapsed) (sleep (- n elapsed)) (loop (- (now) start))))) (define lset= (@ (srfi srfi-1) lset=)) (display "sending all processes the TERM signal\n") (if (null? omitted-pids) (begin ;; Easy: terminate all of them. (kill -1 SIGTERM) (sleep* #$grace-delay) (kill -1 SIGKILL)) (begin ;; Kill them all except OMITTED-PIDS. XXX: We would ;; like to (kill -1 SIGSTOP) to get a fixed list of ;; processes, like 'killall5' does, but that seems ;; unreliable. (kill-except omitted-pids SIGTERM) (sleep* #$grace-delay) (kill-except omitted-pids SIGKILL) (delete-file #$%do-not-kill-file))) (let wait () ;; Reap children, if any, so that we don't end up with ;; zombies and enter an infinite loop. (let reap-children () (define result (false-if-exception (waitpid WAIT_ANY (if (null? omitted-pids) 0 WNOHANG)))) (when (and (pair? result) (not (zero? (car result)))) (reap-children))) (let ((pids (processes))) (unless (lset= = pids (cons 1 omitted-pids)) (format #t "waiting for process termination\ (processes left: ~s)~%" pids) (sleep* 2) (wait)))) (display "all processes have been terminated\n") #f)) (respawn? #f)))) (define user-processes-service-type (service-type (name 'user-processes) (extensions (list (service-extension shepherd-root-service-type user-processes-shepherd-service))) (compose concatenate) (extend append) ;; The value is the list of Shepherd services 'user-processes' depends on. ;; Extensions can add new services to this list. (default-value '()) (description "The @code{user-processes} service is responsible for terminating all the processes so that the root file system can be re-mounted read-only, just before rebooting/halting. Processes still running after a few seconds after @code{SIGTERM} has been sent are terminated with @code{SIGKILL}."))) ;;; shepherd.scm ends here


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