cuirass: Add "--port" command line option.

* bin/cuirass.in (%options): Add "--port" and "-p" command line options.
(show-help): Adapt.
(main): Set default to 8080.  Call 'run-cuirass-server' with this.
* src/cuirass/http.scm (run-cuirass-server): Display the port number.
* doc/cuirass.texi (Invocation): Document new option.

bin/cuirass.in

@@ -37,6 +37,7 @@ exec ${GUILE:-@GUILE@} --no-auto-compile -e main -s "$0" "$@"
   -S  --specifications=SPECFILE
                             Add specifications from SPECFILE to database.
   -D  --database=DB         Use DB to store build results.
+  -p  --port=NUM            Port of the HTTP server.
   -I, --interval=N          Wait N seconds between each poll
       --use-substitutes     Allow usage of pre-built substitutes
   -V, --version             Display version
@@ -49,6 +50,7 @@ exec ${GUILE:-@GUILE@} --no-auto-compile -e main -s "$0" "$@"
     (cache-directory                  (value #t))
     (specifications (single-char #\S) (value #t))
     (database       (single-char #\D) (value #t))
+    (port           (single-char #\p) (value #t))
     (interval       (single-char #\I) (value #t))
     (use-substitutes                  (value #f))
     (version        (single-char #\V) (value #f))
@@ -76,6 +78,7 @@ exec ${GUILE:-@GUILE@} --no-auto-compile -e main -s "$0" "$@"
         (exit 0))
        (else
         (let ((one-shot? (option-ref opts 'one-shot #f))
+              (port      (string->number (option-ref opts 'port "8080")))
               (interval  (string->number (option-ref opts 'interval "10")))
               (specfile  (option-ref opts 'specifications #f)))
           (with-database db
@@ -94,4 +97,4 @@ exec ${GUILE:-@GUILE@} --no-auto-compile -e main -s "$0" "$@"
                      (while #t
                        (process-specs db (db-get-specifications db))
                        (sleep interval))))
-                  (run-cuirass-server db))))))))))
+                  (run-cuirass-server db #:port port))))))))))

doc/cuirass.texi

@@ -169,6 +169,11 @@ build results. Since @code{cuirass} uses SQLite as a database engine,
 @var{database} must be a file name.  If the file doesn't exist, it will
 be created.
 
+@item --port=@var{num}
+@itemx -p @var{num}
+Make the HTTP interface listen on port @var{num}.  Use port 8080 by
+default.
+
 @item --interval=@var{n}
 @itemx -I @var{n}
 Wait @var{n} seconds between each poll.

src/cuirass/http.scm

@@ -71,6 +71,7 @@
                                     (uri->string (request-uri request)))))))
 
 (define* (run-cuirass-server db #:key (port 8080))
+  (format (current-error-port) "listening on port ~A~%" port)
   (run-server url-handler
               'http                     ;server implementation
               `(#:port ,port)           ;implementation parameters