systemd-service questions - Page 1

Sean

Asked: 2022-01-30 01:21:20 +0800 CST

Show a systemd unit file with its overrides merged in

2

systemctl cat myunit.service prints the contents of the main myunit.service file followed by any override files. Is there a way to print the unit file that systemd will actually use, i.e. the one formed from merging the overrides into the main unit?

Evy Bongers

Asked: 2021-07-05 22:47:42 +0800 CST

How can I run a systemd service after network link has been established?

3

A while ago I set up a systemd service to run after network comes online per the documentation. This is the unit file:

[Unit]
Description=Refresh Pacman mirrorlist with Reflector.
Documentation=https://wiki.archlinux.org/index.php/Reflector
Wants=network-online.target
After=network-online.target nss-lookup.target

[Service]
Type=oneshot
ExecStart=/usr/bin/reflector @/etc/xdg/reflector/reflector.conf
CacheDirectory=reflector
CapabilityBoundingSet=~CAP_SETUID CAP_SETGID CAP_SETPCAP CAP_SYS_ADMIN CAP_SYS_PTRACE CAP_CHOWN CAP_FSETID CAP_SETFCAP CAP_DAC_OVERRIDE CAP_DAC_READ_SEARCH CAP_FOWNER CAP_IPC_OWNER CAP_NET_ADMIN CAP_SYS_TIME CAP_AUDIT_CONTROL CAP_AUDIT_READ CAP_AUDIT_WRITE CAP_KILL CAP_NET_BIND_SERVICE CAP_NET_BROADCAST CAP_NET_RAW CAP_SYS_NICE CAP_SYS_RESOURCE CAP_MAC_ADMIN CAP_MAC_OVERRIDE CAP_SYS_BOOT CAP_LINUX_IMMUTABLE CAP_IPC_LOCK CAP_SYS_CHROOT CAP_BLOCK_SUSPEND CAP_LEASE CAP_SYS_PACCT CAP_SYS_TTY_CONFIG CAP_WAKE_ALARM
Environment=XDG_CACHE_HOME=/var/cache/reflector
LockPersonality=true
MemoryDenyWriteExecute=true
NoNewPrivileges=true
PrivateDevices=true
PrivateTmp=true
PrivateUsers=true
ProtectClock=true
ProtectControlGroups=true
ProtectHome=true
ProtectHostname=true
ProtectKernelTunables=true
ProtectKernelLogs=true
ProtectKernelModules=true
ProtectSystem=strict
ReadOnlyPaths=/etc/xdg/reflector/reflector.conf
ReadWritePaths=/etc/pacman.d/mirrorlist
RemoveIPC=true
RestrictAddressFamilies=~AF_AX25 AF_IPX AF_APPLETALK AF_X25 AF_DECnet AF_KEY AF_NETLINK AF_PACKET AF_RDS AF_PPPOX AF_LLC AF_IB AF_MPLS AF_CAN AF_TIPC AF_BLUETOOTH AF_ALG AF_VSOCK AF_KCM AF_UNIX AF_XDP
RestrictNamespaces=true
RestrictRealtime=true
RestrictSUIDSGID=true
SystemCallArchitectures=native
SystemCallFilter=@system-service
SystemCallFilter=~@resources @privileged
UMask=177

[Install]
WantedBy=multi-user.target

Per the documentation, the service should already be set up correctly to wait for network connectivity to be established (i.e.: I'm logged in, NetworkManager has connected to WiFi and the system has been assigned an IP).

network-online.target is a target that actively waits until the nework is "up", where the definition of "up" is defined by the network management software. Usually it indicates a configured, routable IP address of some kind. Its primary purpose is to actively delay activation of services until the network is set up.

I've also made sure that NetworkManager-wait-online.service is enabled.

$ systemctl is-enabled NetworkManager-wait-online.service systemd-networkd-wait-online.service
enabled
disabled

Instead of the service waiting to start until an internet connection has been established, I see an error on the system console almost as soon as I see my login prompt.

Jul 05 07:40:02 gadget systemd[1]: Starting Refresh Pacman mirrorlist with Reflector....
Jul 05 07:40:03 gadget reflector[564]: error: failed to retrieve mirrorstatus data: URLError: <urlopen error [Errno -3] Temporary failure in name resolution>
Jul 05 07:40:03 gadget systemd[1]: reflector.service: Main process exited, code=exited, status=1/FAILURE
Jul 05 07:40:03 gadget systemd[1]: reflector.service: Failed with result 'exit-code'.
Jul 05 07:40:03 gadget systemd[1]: Failed to start Refresh Pacman mirrorlist with Reflector..

Since it should wait for network to be online and DNS to be available, I also checked the status of NetworkManager-wait-online.service, network-online.target and nss-lookup.target:

$ systemctl status NetworkManager-wait-online.service
● NetworkManager-wait-online.service - Network Manager Wait Online
     Loaded: loaded (/usr/lib/systemd/system/NetworkManager-wait-online.service; enabled; vendor preset: disabled)
     Active: active (exited) since Mon 2021-07-05 07:40:02 CEST; 44min ago
       Docs: man:nm-online(1)
   Main PID: 544 (code=exited, status=0/SUCCESS)
      Tasks: 0 (limit: 38321)
     Memory: 0B
        CPU: 0
     CGroup: /system.slice/NetworkManager-wait-online.service

Jul 05 07:40:02 gadget systemd[1]: Starting Network Manager Wait Online...
Jul 05 07:40:02 gadget systemd[1]: Finished Network Manager Wait Online.
$ systemctl status network-online.target
● network-online.target - Network is Online
     Loaded: loaded (/usr/lib/systemd/system/network-online.target; static)
     Active: active since Mon 2021-07-05 07:40:02 CEST; 1h 5min ago
       Docs: man:systemd.special(7)
             https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget

Jul 05 07:40:02 gadget systemd[1]: Reached target Network is Online.
$ systemctl status nss-lookup.target
○ nss-lookup.target - Host and Network Name Lookups
     Loaded: loaded (/usr/lib/systemd/system/nss-lookup.target; static)
     Active: inactive (dead)
       Docs: man:systemd.special(7)

It strikes me as odd that NetworkManager-wait-online.service reports finished right after starting. Is there something else I need to configure? Is this a bug in NetworkManager and/or nm-online?

I've looked for similar topics and found these questions, but they don't answer my issue:

Chang Zhao

Asked: 2020-09-10 14:19:34 +0800 CST

why consul systemd service is failing?

2

This is my consul.service file.

[Unit]
Description="HashiCorp Consul - A service mesh solution"
Documentation=https://www.consul.io/
Requires=network-online.target
After=network-online.target

[Service]
Type=simple
User=consul
Group=consul
LimitNOFILE=1024
ExecStart=/usr/bin/consul agent  -config-dir=/etc/consul.d/
ExecReload=/bin/kill --signal HUP $MAINPID
KillMode=process
Restart=on-failure
RestartSec=5
KillSignal=SIGINT

[Install]
WantedBy=multi-user.target

I did sudo chown -R consul:consul /etc/consul.d/ because I created a consul user as well.

and this is my /etc/config.d directory:

$ tree /etc/consul.d/
/etc/consul.d/
├── bootstrap
│   └── config.json
├── client
└── server
    └── config.json

this is the server config. cat /etc/consul.d/server/config.json

{
    "bootstrap": false,
    "server": true,
    "datacenter": "lon",
    "advertise_addr": "192.168.0.16",
    "client_addr": "0.0.0.0",
    "bind_addr": "{{GetInterfaceIP \"eth0\"}}",
    "data_dir": "/var/consul/",
    "log_level": "INFO",
    "enable_syslog": true,
    "retry_join": ["192.168.0.16"]
}

cat /etc/consul.d/bootstrap/config.json

{
    "bootstrap": true,
    "server": true,
    "datacenter": "lon",
    "advertise_addr": "192.168.0.16",
    "client_addr": "0.0.0.0",
    "bind_addr": "{{GetInterfaceIP \"eth0\"}}",
    "data_dir": "/var/consul/",
    "log_level": "INFO",
    "enable_syslog": true,
    "retry_join": ["192.168.0.16"]
}

And I have validated the consul config for server and bootstrap configurations.

consul validate  /etc/consul.d/server/config.json 
Configuration is valid!

but I keep getting error saying:

 consul[21711]: ==> Multiple private IPv4 addresses found. Please configure one with 'bind' and/or 'advertise'.

I tried this command too

~/go/bin$ ./sockaddr eval GetPrivateIP
192.168.0.16

what am I missing ?

Spammy

Asked: 2020-07-05 10:32:13 +0800 CST

Systemd Timer Template after boot?

2

I have a templated timer that calls a templated unit. I use the following to enable and start them:

sudo systemctl enable [email protected]
sudo systemctl enable ping@service
sudo systemctl start [email protected]

This works as expected, and the timer activates [email protected] as expected. However this doesn't persist after reboots, presumably because I didn't enable the instance of the timer. But the following fails with a "does not exist" error:

sudo systemctl enable [email protected]

How can I have a templated timer start at each boot?

Amandasaurus

Asked: 2020-05-11 22:43:07 +0800 CST

Prevent a systemd service from starting if another systemd service is running

4

In systemd (v237 on UbuntuLinux 18.04 bionic), I can create a service file (for A.service), and specify another service Requisite=B.service. Meaning if I try to start A.service and B.service isn't already running, then A.service will not be started. It's a weak version of Requires, which will start B.service when I try to start A.service.

Is there an opposite? Can I say “If B.service is running, then don't start this service” / “If B.service is running, then A.service cannot start”?

The docs say if I do Conflicts=B.service, then starting A will stop B and then start A. But I don't want B stopped, I just want A to fail to start. I want something that's to Conflicts what Requisite is to Requires.

I could probably change the ExecStart to be a shell command that'll fail is systemctl is-active B.service or some sort of hack. Is there a proper solution?

Show a systemd unit file with its overrides merged in

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Systemd Timer Template after boot?

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