====== systemd ======

Voir aussi [[/informatique/system_admin/journalctl|journalctl]]

  * https://systemd.io/
  * https://www.freedesktop.org/software/systemd/man/latest/

Les directives:
  * https://www.freedesktop.org/software/systemd/man/latest/systemd.directives.html

Outil d'analyse:
  * https://www.freedesktop.org/software/systemd/man/latest/systemd-analyze.html

Pour envoyer une notification en cas d'échec d'exécution, créer un ''template service'' :
  * https://www.baeldung.com/linux/systemd-service-fail-notification
  * https://superuser.com/questions/1621517/having-all-systemd-timers-mail-to-root-on-error

''OnFailure'' est lié au démarrage du service. Pour traiter un retour d'erreur il faut créer un traitement dans ''ExecStopPost''.

===== Timer (Cron) =====

Avec Debian 12 (bookworm) cron/crontab n'est pas installé, il faut utiliser les [[https://www.freedesktop.org/software/systemd/man/latest/systemd.timer.html|systemd.timer]]. Pour la programmation voir la syntaxe [[https://www.freedesktop.org/software/systemd/man/latest/systemd.time.html#Calendar%20Events|Calendar Events]].

Pour tester la syntaxe OnCalendar: ''systemd-analyze calendar "*-*-* 00/2:00:00"''

Tutos pour créer des timers : 
- https://blog.stephane-robert.info/docs/admin-serveurs/linux/timers/
- https://www.siberoloji.com/how-to-use-systemd-timers-instead-of-cron-in-debian-12-bookworm/

==== Exemple ====

les stats de livraison d'emails avec Postfix sur handipause.fr :

Le service ''/etc/systemd/system/mail-stats.service''

<code>
#
# Génère des stats de delivery pour Postfix
#
# Doc:
# Timer: https://blog.stephane-robert.info/docs/admin-serveurs/linux/timers/
# Service: https://www.freedesktop.org/software/systemd/man/latest/systemd.service.html
# Unit: https://www.freedesktop.org/software/systemd/man/latest/systemd.unit.html
#
[Unit]
Description=Génère qlqs stats Postfix
# A space-separated list of one or more units that are activated when this unit enters the "failed" state.
OnFailure=onfailure-email@%N.service

[Service]
Type=oneshot
ExecStart=/usr/bin/php /home/debian/postfix-delivery-status/scripts/deliveryStats/deliveryStats.php /home/debian/postfix-delivery-status/conf/handipause.conf.php /var/www/html
# Additional commands that are executed after the service is stopped.
#ExecStopPost=
</code>

Le timer ''/etc/systemd/system/mail-stats.timer''

<code>
[Unit]
Description=Génère périodiquement qlqs stats Postfix

[Timer]
# https://www.freedesktop.org/software/systemd/man/latest/systemd.time.html#
# check format with `systemd-analyze calendar "*-*-* 00/2:00:00"`
OnCalendar=*-*-* 00/6:00:00
Persistent=true

[Install]
WantedBy=timers.target
</code>

===== Resolve =====

La gestion DSN par systemd.

  * [[https://www.malekal.com/configurer-cache-dns-linux-systemd-resolved-dnsmasq-bind/|Configurer un cache DNS sur Linux avec systemd-resolved, dnsmasq ou BIND]]
  * https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers/

<code bash>
sudo systemctl status systemd-resolved.service

# ==========

$ sudo resolvectl status
Global
       Protocols: +LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: uplink

Link 2 (ens3)
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 2001:41d0:3:163::1
       DNS Servers: 2001:41d0:3:163::1 213.186.33.99

Link 3 (ens4)
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 213.186.33.99
       DNS Servers: 213.186.33.99

# ==========

$ sudo resolvectl statistics
DNSSEC supported by current servers: no

Transactions              
Current Transactions: 0
  Total Transactions: 2906
                          
Cache                     
  Current Cache Size: 1
          Cache Hits: 478
        Cache Misses: 4417
                          
DNSSEC Verdicts           
              Secure: 0
            Insecure: 0
               Bogus: 0
       Indeterminate: 0

# ==========

$ sudo resolvectl query 1.1.1.1
1.1.1.1: one.one.one.one                       -- link: ens3
-- Information acquired via protocol DNS in 23.6ms.
-- Data is authenticated: no; Data was acquired via local or encrypted transport: no
-- Data from: network

</code>