guix - Wojtek's customized Guix

about summary refs log tree commit diff

GNU Guix consists of Scheme code that implements the deployment model
of the Nix package management tool.  In fact, it currently talks to a
build daemon whose code comes from Nix (see the manual for details.)

Nix was initially written by Eelco Dolstra; other people have been
contributing to it.  See `nix/AUTHORS' for details.

The list of GNU Guix contributors is now generated from the output of
'git log' and written to this file, as can be seen in release tarballs.

etails. ;;; ;;; You should have received a copy of the GNU General Public License ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. (define-module (gnu services herd) #:use-module (srfi srfi-1) #:use-module (srfi srfi-9) #:use-module (srfi srfi-9 gnu) #:use-module (srfi srfi-11) #:use-module (srfi srfi-34) #:use-module (srfi srfi-35) #:use-module (ice-9 match) #:export (%shepherd-socket-file shepherd-message-port shepherd-error? service-not-found-error? service-not-found-error-service action-not-found-error? action-not-found-error-service action-not-found-error-action action-exception-error? action-exception-error-service action-exception-error-action action-exception-error-key action-exception-error-arguments unknown-shepherd-error? unknown-shepherd-error-sexp live-service live-service? live-service-provision live-service-requirement live-service-running live-service-transient? live-service-canonical-name with-shepherd-action current-service current-services unload-services unload-service load-services load-services/safe start-service stop-service restart-service wait-for-service)) ;;; Commentary: ;;; ;;; This module provides an interface to the GNU Shepherd, similar to the ;;; 'herd' command. Essentially it implements a subset of the (shepherd comm) ;;; module, but focusing only on the parts relevant to 'guix system ;;; reconfigure'. ;;; ;;; Code: (define %shepherd-socket-file (make-parameter "/var/run/shepherd/socket")) (define* (open-connection #:optional (file (%shepherd-socket-file))) "Open a connection to the daemon, using the Unix-domain socket at FILE, and return the socket." ;; The protocol is sexp-based and UTF-8-encoded. (with-fluids ((%default-port-encoding "UTF-8")) (let ((sock (socket PF_UNIX SOCK_STREAM 0)) (address (make-socket-address PF_UNIX file))) (catch 'system-error (lambda () (connect sock address) (setvbuf sock 'block 1024) sock) (lambda args (close-port sock) (apply throw args)))))) (define-syntax-rule (with-shepherd connection body ...) "Evaluate BODY... with CONNECTION bound to an open socket to PID 1." (let ((connection (open-connection))) (dynamic-wind (const #t) (lambda () body ...) (lambda () (close-port connection))))) (define-condition-type &shepherd-error &error shepherd-error?) (define-condition-type &service-not-found-error &shepherd-error service-not-found-error? (service service-not-found-error-service)) (define-condition-type &action-not-found-error &shepherd-error action-not-found-error? (service action-not-found-error-service) (action action-not-found-error-action)) (define-condition-type &action-exception-error &shepherd-error action-exception-error? (service action-exception-error-service) (action action-exception-error-action) (key action-exception-error-key) (args action-exception-error-arguments)) (define-condition-type &unknown-shepherd-error &shepherd-error unknown-shepherd-error? (sexp unknown-shepherd-error-sexp)) (define (raise-shepherd-error error) "Raise an error condition corresponding to ERROR, an sexp received by a shepherd client in reply to COMMAND, a command object. Return #t if ERROR does not denote an error." (match error (('error ('version 0 x ...) 'service-not-found service) (raise (condition (&service-not-found-error (service service))))) (('error ('version 0 x ...) 'action-not-found action service) (raise (condition (&action-not-found-error (service service) (action action))))) (('error ('version 0 x ...) 'action-exception action service key (args ...)) (raise (condition (&action-exception-error (service service) (action action) (key key) (args args))))) (('error . _) (raise (condition (&unknown-shepherd-error (sexp error))))) (#f ;not an error #t))) (define shepherd-message-port ;; Port where messages coming from shepherd are printed. (make-parameter (current-error-port))) (define (display-message message) (format (shepherd-message-port) "shepherd: ~a~%" message)) (define* (invoke-action service action arguments cont) "Invoke ACTION on SERVICE with ARGUMENTS. On success, call CONT with the list of results (one result per instance with the name SERVICE). Otherwise return #f." (with-shepherd sock (write `(shepherd-command (version 0) (action ,action) (service ,service) (arguments ,arguments) (directory ,(getcwd))) sock) (force-output sock) (match (read sock) (('reply ('version 0 _ ...) ('result result) ('error #f) ('messages messages)) (for-each display-message messages) (cont result)) (('reply ('version 0 x ...) ('result y) ('error error) ('messages messages)) (for-each display-message messages) (raise-shepherd-error error) #f) (x ;; invalid reply #f)))) (define-syntax-rule (with-shepherd-action service (action args ...) result body ...) "Invoke ACTION on SERVICE with the given ARGS, and evaluate BODY with RESULT bound to the action's result." (invoke-action service action (list args ...) (lambda (result) body ...))) (define-syntax alist-let* (syntax-rules () "Bind the given KEYs in EXP to the corresponding items in ALIST. ALIST is assumed to be a list of two-element tuples rather than a traditional list of pairs." ((_ alist (key ...) exp ...) (let ((key (and=> (assoc-ref alist 'key) car)) ...) exp ...)))) ;; Information about live Shepherd services. (define-record-type <live-service> (live-service provision requirement transient? running) live-service? (provision live-service-provision) ;list of symbols (requirement live-service-requirement) ;list of symbols (transient? live-service-transient?) ;Boolean (running live-service-running)) ;#f | object (define (live-service-canonical-name service) "Return the 'canonical name' of SERVICE." (first (live-service-provision service))) (define (current-service name) "Return the currently defined Shepherd service NAME, as a <live-service> object. Return #f if the service could not be obtained. As a special case, @code{(current-service 'root)} returns all the current services." (define (process-services services) (resolve-transients (map (lambda (service) (alist-let* service (provides requires running transient?) ;; The Shepherd 0.9.0 would not provide 'transient?' in ;; its status sexp. Thus, when it's missing, query it ;; via an "eval" request. (live-service provides requires (if (sloppy-assq 'transient? service) transient? (and running *unspecified*)) running))) services))) (with-shepherd-action name ('status) results ;; We get a list of results, one for each service with the name NAME. ;; In practice there's only one such service though. (match results ((services _ ...) (match services ((('service ('version 0 _ ...) _ ...) ...) ;; Summary of all services (when NAME is 'root or 'shepherd). (process-services services)) (('service ('version 0 _ ...) _ ...) ;single service (first (process-services (list services)))) (x #f)))))) ;singleton (define (current-services) "Return the list of currently defined Shepherd services, represented as <live-service> objects. Return #f if the list of services could not be obtained." (current-service 'root)) (define (resolve-transients services) "Resolve the subset of SERVICES whose 'transient?' field is undefined. This is necessary to deal with Shepherd 0.9.0, which did not communicate whether a service is transient." ;; All the fuss here is to make sure we make a single "eval root" request ;; for all of SERVICES. (let* ((unresolved (filter (compose unspecified? live-service-transient?) services)) (values (or (and (pair? unresolved) (eval-there `(and (defined? 'transient?) ;shepherd >= 0.9.0 (map (compose transient? lookup-running) ',(map (compose first live-service-provision) unresolved))))) (make-list (length unresolved) #f))) (resolved (map (lambda (unresolved transient?) (cons unresolved (set-field unresolved (live-service-transient?) transient?))) unresolved values))) (map (lambda (service) (or (assq-ref resolved service) service)) services))) (define (unload-service service) "Unload SERVICE, a symbol name; return #t on success." (with-shepherd-action 'root ('unload (symbol->string service)) result (first result))) (define (%load-file file) "Load FILE in the Shepherd." (with-shepherd-action 'root ('load file) result (first result))) (define (eval-there exp) "Eval EXP in the Shepherd." (with-shepherd-action 'root ('eval (object->string exp)) result (first result))) (define (load-services files) "Load and register the services from FILES, where FILES contain code that returns a shepherd <service> object." (eval-there `(register-services ,@(map (lambda (file) `(primitive-load ,file)) files)))) (define load-services/safe ;; Deprecated. It used to behave differently before service replacements ;; were a thing. load-services) (define* (start-service name #:optional (arguments '())) (invoke-action name 'start arguments (lambda (result) result))) (define (stop-service name) (with-shepherd-action name ('stop) result result)) (define (restart-service name) (with-shepherd-action name ('restart) result result)) (define* (wait-for-service name #:key (timeout 20)) "Wait for the service providing NAME, a symbol, to be up and running, and return its \"running value\". Give up after TIMEOUT seconds and raise a '&shepherd-error' exception. Raise a '&service-not-found-error' exception when NAME is not found." (define (relevant-service? service) (memq name (live-service-provision service))) (define start (car (gettimeofday))) ;; Note: As of Shepherd 0.9.1, we cannot just call the 'start' method and ;; wait for it: it would spawn an additional elogind process. Thus, poll. (let loop ((attempts 0)) (define services (current-services)) (define now (car (gettimeofday))) (when (>= (- now start) timeout) (raise (condition (&shepherd-error)))) ;XXX: better exception? (match (find relevant-service? services) (#f (raise (condition (&service-not-found-error (service name))))) (service (or (live-service-running service) (begin (sleep 1) (loop (+ attempts 1)))))))) ;; Local Variables: ;; eval: (put 'alist-let* 'scheme-indent-function 2) ;; eval: (put 'with-shepherd 'scheme-indent-function 1) ;; eval: (put 'with-shepherd-action 'scheme-indent-function 3) ;; End: ;;; herd.scm ends here