02/02: hydra: berlin: Add mcron btrfs balance job.

[Maxim Cournoyer]

apteryx pushed a commit to branch master
in repository maintenance.

commit 36d610130e5d2354039bcdf678fe34afdc2dfaba
Author: Maxim Cournoyer <maxim.cournoyer@gmail.com>
AuthorDate: Mon Oct 3 11:32:22 2022 -0400

    hydra: berlin: Add mcron btrfs balance job.
    
    * hydra/berlin.scm (btrfs-balance-job): New variable.
    [services]: Register the job in the mcron-configuration inherited from
    the frontend-services.
---
 hydra/berlin.scm | 41 +++++++++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/hydra/berlin.scm b/hydra/berlin.scm
index 07f8771..dc30fe1 100644
--- a/hydra/berlin.scm
+++ b/hydra/berlin.scm
@@ -16,7 +16,7 @@
              ((guix build utils) #:select (find-files))
              (srfi srfi-1)
              (ice-9 match))
-(use-service-modules avahi base databases dns monitoring networking admin
+(use-service-modules avahi base databases dns mcron monitoring networking admin
                      rsync shepherd ssh vpn web)
 (use-package-modules admin base certs databases disk emacs linux mail 
monitoring
                      screen ssh tls tor vim package-management
@@ -211,6 +211,16 @@ at MOUNT-POINT."
               (cons (cons "subvol" name)
                     %common-btrfs-options)))))
 
+(define btrfs-balance-job
+  ;; Re-allocate chunks which are using less than 5% of their chunk
+  ;; space, to regain Btrfs 'unallocated' space.  The usage is kept
+  ;; low (5%) to minimize wear on the SSD.  Runs at 5 AM every 3 days.
+  #~(job '(next-hour-from (next-day (range 1 31 3)) '(5))
+         (lambda ()
+           (execl #$(file-append btrfs-progs "/bin/btrfs") "btrfs"
+                  "balance" "start" "-dusage=5" "/"))
+         "btrfs-balance"))
+
 (define (anonip-service file)
   (service anonip-service-type
            (anonip-configuration
@@ -486,14 +496,21 @@ at MOUNT-POINT."
              (append
               (map anonip-service %anonip-log-files)
               (website-services)
-              (frontend-services %sysadmins
-                                 ;; Make sure we get enough build users.
-                                 #:authorized-keys %build-node-keys
-                                 #:build-accounts-to-max-jobs-ratio 5
-                                 #:gc-threshold (* 15 TiB)
-                                 #:systems '("x86_64-linux" "i686-linux"
-                                             "aarch64-linux"
-                                             "powerpc64le-linux")
-                                 #:motd %motd
-                                 #:publish-workers 8
-                                 #:max-jobs 20)))))
+              (modify-services
+                  (frontend-services %sysadmins
+                                     ;; Make sure we get enough build users.
+                                     #:authorized-keys %build-node-keys
+                                     #:build-accounts-to-max-jobs-ratio 5
+                                     #:gc-threshold (* 15 TiB)
+                                     #:systems '("x86_64-linux" "i686-linux"
+                                                 "aarch64-linux"
+                                                 "powerpc64le-linux")
+                                     #:motd %motd
+                                     #:publish-workers 8
+                                     #:max-jobs 20)
+                (mcron-service-type
+                 config => (mcron-configuration
+                            (inherit config)
+                            (jobs (cons btrfs-balance-job
+                                        (mcron-configuration-jobs
+                                         config))))))))))