system: examples: Add postfix.tmpl.

* gnu/system/examples/postfix.tmpl: New file.

gnu/system/examples/postfix.tmpl

@@ -0,0 +1,52 @@
+;; This is an operating system configuration template for testing postfix.
+
+(use-modules (gnu))
+(use-service-modules mail networking ssh)
+(use-package-modules ssh)
+
+(operating-system
+  (host-name "komputilo")
+  (timezone "Europe/Berlin")
+  (locale "en_US.utf8")
+
+  ;; Boot in "legacy" BIOS mode, assuming /dev/sdX is the
+  ;; target hard disk, and "my-root" is the label of the target
+  ;; root file system.
+  (bootloader (bootloader-configuration
+                (bootloader grub-bootloader)
+                (target "/dev/sdX")))
+
+  ;; Allow run-vm.sh --nographic
+  (kernel-arguments '("console=tty0" "console=ttyS0"))
+  (file-systems (cons (file-system
+                        (device (file-system-label "guix"))
+                        (mount-point "/")
+                        (type "ext4"))
+                      %base-file-systems))
+
+  ;; This is where user accounts are specified.  The "root"
+  ;; account is implicit, and is initially created with the
+  ;; empty password.
+  (users (cons (user-account
+                (name "alice")
+                (comment "Bob's sister")
+                (group "users")
+
+                ;; Adding the account to the "wheel" group
+                ;; makes it a sudoer.
+                (supplementary-groups '("wheel")))
+               %base-user-accounts))
+
+  ;; Add services to the baseline: a DHCP client, POSTFIX and
+  ;; an SSH server.
+  (services (append (list (service dhcp-client-service-type)
+                          (service openssh-service-type
+                             (openssh-configuration
+                              (openssh openssh-sans-x)
+                              (use-pam? #f)
+                              (port-number 2222)
+                              (permit-root-login #t)
+                              (allow-empty-passwords? #t)
+                              (password-authentication? #t)))
+                          (service postfix-service-type))
+                    %base-services)))