services: Add MongoDB.

* gnu/services/databases.scm (%default-mongodb-configuration-file,
  %mongodb-accounts, mongodb-service-type): New variables.
  (<mongodb-configuration>): New record type.
  (mongodb-activation, mongodb-shepherd-service): New procedures.
* gnu/tests/databases.scm (%test-mongodb): New variable.
* doc/guix.texi (Database Services): Add MongoDB documentation.

doc/guix.texi

@@ -12120,6 +12120,32 @@ Additional command line options to pass to @code{memcached}.
 @end table
 @end deftp
 
+@defvr {Scheme Variable} mongodb-service-type
+This is the service type for @uref{https://www.mongodb.com/, MongoDB}.
+The value for the service type is a @code{mongodb-configuration} object.
+@end defvr
+
+@example
+(service mongodb-service-type)
+@end example
+
+@deftp {Data Type} mongodb-configuration
+Data type representing the configuration of mongodb.
+
+@table @asis
+@item @code{mongodb} (default: @code{mongodb})
+The MongoDB package to use.
+
+@item @code{config-file} (default: @code{%default-mongodb-configuration-file})
+The configuration file for MongoDB.
+
+@item @code{data-directory} (default: @code{"/var/lib/mongodb"})
+This value is used to create the directory, so that it exists and is
+owned by the mongodb user.  It should match the data-directory which
+MongoDB is configured to use through the configuration file.
+@end table
+@end deftp
+
 @defvr {Scheme Variable} redis-service-type
 This is the service type for the @uref{https://redis.io/, Redis}
 key/value store, whose value is a @code{redis-configuration} object.

gnu/services/databases.scm

@@ -44,6 +44,14 @@
             memcached-configuration-udp-port
             memcached-configuration-additional-options
 
+            <mongodb-configuration>
+            mongodb-configuration
+            mongodb-configuration?
+            mongodb-configuration-mongodb
+            mongodb-configuration-config-file
+            mongodb-configuration-data-directory
+            mongodb-service-type
+
             mysql-service
             mysql-service-type
             mysql-configuration
@@ -262,6 +270,87 @@ and stores the database cluster in @var{data-directory}."
                                           (const %memcached-accounts))))
                 (default-value (memcached-configuration))))
 
+
+;;;
+;;; MongoDB
+;;;
+
+(define %default-mongodb-configuration-file
+  (plain-file
+   "mongodb.yaml"
+   "# GNU Guix: MongoDB default configuration file
+processManagement:
+  pidFilePath: /var/run/mongodb/pid
+storage:
+  dbPath: /var/lib/mongodb
+"))
+
+
+(define-record-type* <mongodb-configuration>
+  mongodb-configuration make-mongodb-configuration
+  mongodb-configuration?
+  (mongodb             mongodb-configuration-mongodb
+                       (default mongodb))
+  (config-file         mongodb-configuration-config-file
+                       (default %default-mongodb-configuration-file))
+  (data-directory      mongodb-configuration-data-directory
+                       (default "/var/lib/mongodb")))
+
+(define %mongodb-accounts
+  (list (user-group (name "mongodb") (system? #t))
+        (user-account
+         (name "mongodb")
+         (group "mongodb")
+         (system? #t)
+         (comment "Mongodb server user")
+         (home-directory "/var/lib/mongodb")
+         (shell (file-append shadow "/sbin/nologin")))))
+
+(define mongodb-activation
+  (match-lambda
+    (($ <mongodb-configuration> mongodb config-file data-directory)
+     #~(begin
+         (use-modules (guix build utils))
+         (let ((user (getpwnam "mongodb")))
+           (for-each
+            (lambda (directory)
+              (mkdir-p directory)
+              (chown directory
+                     (passwd:uid user) (passwd:gid user)))
+            '("/var/run/mongodb" #$data-directory)))))))
+
+(define mongodb-shepherd-service
+  (match-lambda
+    (($ <mongodb-configuration> mongodb config-file data-directory)
+     (shepherd-service
+      (provision '(mongodb))
+      (documentation "Run the Mongodb daemon.")
+      (requirement '(user-processes loopback))
+      (start #~(make-forkexec-constructor
+                `(,(string-append #$mongodb "/bin/mongod")
+                  "--config"
+                  ,#$config-file)
+                #:user "mongodb"
+                #:group "mongodb"
+                #:pid-file "/var/run/mongodb/pid"
+                #:log-file "/var/log/mongodb.log"))
+      (stop #~(make-kill-destructor))))))
+
+(define mongodb-service-type
+  (service-type
+   (name 'mongodb)
+   (description "Run the MongoDB document database server.")
+   (extensions
+    (list (service-extension shepherd-root-service-type
+                             (compose list
+                                      mongodb-shepherd-service))
+          (service-extension activation-service-type
+                             mongodb-activation)
+          (service-extension account-service-type
+                             (const %mongodb-accounts))))
+   (default-value
+     (mongodb-configuration))))
+
 
 ;;;
 ;;; MySQL.

gnu/tests/databases.scm

@@ -25,9 +25,11 @@
   #:use-module (gnu services)
   #:use-module (gnu services databases)
   #:use-module (gnu services networking)
+  #:use-module (gnu packages databases)
   #:use-module (guix gexp)
   #:use-module (guix store)
-  #:export (%test-memcached))
+  #:export (%test-memcached
+            %test-mongodb))
 
 (define %memcached-os
   (simple-operating-system
@@ -121,3 +123,85 @@
    (name "memcached")
    (description "Connect to a running MEMCACHED server.")
    (value (run-memcached-test))))
+
+(define %mongodb-os
+  (operating-system
+    (inherit
+     (simple-operating-system
+      (dhcp-client-service)
+      (service mongodb-service-type)))
+    (packages (cons* mongodb
+                     %base-packages))))
+
+(define* (run-mongodb-test #:optional (port 27017))
+  "Run tests in %MONGODB-OS, forwarding PORT."
+  (define os
+    (marionette-operating-system
+     %mongodb-os
+     #:imported-modules '((gnu services herd)
+                          (guix combinators))))
+
+  (define vm
+    (virtual-machine
+     (operating-system os)
+     (memory-size 1024)
+     (disk-image-size (* 1024 (expt 2 20)))
+     (port-forwardings `((27017 . ,port)))))
+
+  (define test
+    (with-imported-modules '((gnu build marionette))
+      #~(begin
+          (use-modules (srfi srfi-11) (srfi srfi-64)
+                       (gnu build marionette)
+                       (ice-9 popen)
+                       (ice-9 rdelim))
+
+          (define marionette
+            (make-marionette (list #$vm)))
+
+          (mkdir #$output)
+          (chdir #$output)
+
+          (test-begin "mongodb")
+
+          (test-assert "service running"
+            (marionette-eval
+             '(begin
+                (use-modules (gnu services herd))
+                (match (start-service 'mongodb)
+                  (#f #f)
+                  (('service response-parts ...)
+                   (match (assq-ref response-parts 'running)
+                     ((pid) (number? pid))))))
+             marionette))
+
+          (test-eq "test insert"
+            0
+            (system* (string-append #$mongodb "/bin/mongo")
+                     "test"
+                     "--eval"
+                     "db.testCollection.insert({data: 'test-data'})"))
+
+          (test-equal "test find"
+            "test-data"
+            (let* ((port (open-pipe*
+                          OPEN_READ
+                          (string-append #$mongodb "/bin/mongo")
+                          "test"
+                          "--quiet"
+                          "--eval"
+                          "db.testCollection.findOne().data"))
+                   (output (read-line port))
+                   (status (close-pipe port)))
+              output))
+
+          (test-end)
+          (exit (= (test-runner-fail-count (test-runner-current)) 0)))))
+
+  (gexp->derivation "mongodb-test" test))
+
+(define %test-mongodb
+  (system-test
+   (name "mongodb")
+   (description "Connect to a running MONGODB server.")
+   (value (run-mongodb-test))))