Im Eingangskapitel Grundlagen haben wir uns mit der Installation bereits befasst. Auch haben wir uns schon in den beiden Kapiteln Playbooks und YAML - was ist das? eingehend mit den Hintergrundinformationen beschäftigt, so dass wir uns nun mit unsere Playbooks beschäftigen können.

In folgendem Beispiel Nummer fünf wollen wir auf unseren CentOS 8-Hosts den NTP-Deamon chrony installieren und auch entsprechend als Client konfigurieren.

Das Script legen wir wie auch schon bei den anderen Beispielen zuvor im Verzeichnis ~/ansible an

 $ vim 05_chrony.yml

05_chrony.yml

---
- hosts: centos8
  become: true
  vars:
    sudoers: ansible
    config_file: /etc/chrony.conf
    # chronyd client config-options
    chrony_pool: "server time.dmz.nausch.org iburst"
    chrony_stratumweight: "stratumweight 0"
    chrony_makestep: "makestep 10 3"
 
  tasks:
    - name: Install chrony ntp Deamon
      dnf: 
      #https://docs.ansible.com/ansible/latest/modules/dnf_module.html
        name: chrony
        state: latest
 
    - name: Check if /etc/chrony.orig does exists
      stat:
      #https://docs.ansible.com/ansible/latest/modules/stat_module.html
        path: /etc/chrony.conf.orig
      register: stat_result
 
    - name: Make a copy of /etc/chrony.conf as /etc/chrony.conf.orig  
      copy:
      #https://docs.ansible.com/ansible/latest/modules/copy_module.html
        remote_src: yes
        src: /etc/chrony.conf
        dest: /etc/chrony.conf.orig
      when: stat_result.stat.exists == False
 
    - name: Copy template config-file in place
      template:
      #https://docs.ansible.com/ansible/latest/modules/template_module.html        
        src: templates/CentOS8/chrony-client.conf.j2 
        dest: "{{ config_file }}"
 
    - name: Make sure Chrony is started up
      service: 
      #https://docs.ansible.com/ansible/latest/modules/service_module.html
        name: chronyd 
        state: started 
        enabled: yes
...

Die Konfigurationsdatei unseres chrony-Daemon werden wir im Arbeitsbereich unserer ansible-Umgebung auf dem Admin-Rechner/-Server in einem eigenen Verzeichnis vorhalten. Diese Verzeichnis erstellen wir uns nun noch.

 $ mkdir -p ~/ansible/templates/CentOS8/

Ansible nutzt die Jinja2 Template Engine zum abgleich der verwendeten Variablen in einem Playbook. Wir werden also unsere Konfigurationsdatei entsprechend präparieren und dort ablegen. Als Datei-Extension verwenden wir hier .j2, um dies optisch abzutrennen. Wir könnten auch andere Datei-Extension verwenden, da Ansible selbst nur den Inhalt bzw. die Formatierung der Variablen interprätiert.

 $ vim ~/ansible/templates/CentOS8/chrony-client.conf.j2

~/ansible/templates/CentOS8/chrony-client.conf.j2

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
{{ chrony_pool }}
 
# Ignore stratum in source selection
{{ chrony_stratumweight }}
 
# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift
 
# Allow the system clock to be stepped in the first three updates
# if its offset is larger than 1 second.
makestep 1.0 3
 
# Enable kernel synchronization of the real-time clock (RTC).
rtcsync
 
# In first three updates step the system clock instead of slew
# if the adjustment is larger than 10 seconds.
{{ chrony_makestep }}
 
# Enable hardware timestamping on all interfaces that support it.
#hwtimestamp *
 
# Increase the minimum number of selectable sources required to adjust
# the system clock.
#minsources 2
 
# Allow NTP client access from local network.
#allow 192.168.0.0/16
 
# Serve time even if not synchronized to a time source.
#local stratum 10
 
# Specify file containing keys for NTP authentication.
keyfile /etc/chrony.keys
 
# Get TAI-UTC offset and leap seconds from the system tz database.
leapsectz right/UTC
 
# Specify directory for log files.
logdir /var/log/chrony
 
# Select which information is logged.
#log measurements statistics tracking

Die drei Konfigurationsoptionen, die wir für unsere chrony-client Konfiguration später setzen und ggf. verändern wollen haben wir hier mit einer Variable belegt:

• {{ chrony_pool }} : Server von dem bzw. denen wir später die Zeit beziehen wollen.
• {{ chrony_stratumweight }} : Ignorieren der stratum Bewertung, da wir hier nur einen Zielhost zur Zeit befragen
• {{ chrony_makestep }} : Definition wie bei den ersten Aktualisierungsschritten zu verfahren ist.

Im Playbook greifen wir auf folgende Ansible-Module zurück:

• dnf zum Installieren des Paketes
• stat und copy zum Sichern der originalen Konfigurationsdatei.
• template zur Konfiguration unseres Daemon
• service zum (automatischen) Starten (beim Systemstart des Hosts)).

In unserem Playbook werden am Anfang den entsprechenden Variablen ihre werte zugewiesen. Im Anschluss daran werden fünft tasks definiert:

1. Aufgabe: Installation des chrony NTP-Daemon
2. Aufgabe: Überprüfen ob von der Konfigurationsdatei, die das RPM-Paket mitbrachte schon eine Sicherungskopie erstellt wurde.
3. Aufgabe: Sofern bei der Prüfung in Aufgabe 2 noch keine Sicherungskopie erstellt wurde, wird eine Sicherungsopie erstellt.
4. Aufgabe: Konfigurieren unseres chrony-Daemon
5. Aufgabe: Starten des chrony-Daemon und aktivieren des automatischen Starts beim Starten des Hosts

Zum Kopieren der unterschiedlichen Dateien rufen wir nun unser Playbook wie folgt auf:

 $ ansible-playbook -v 05_chrony.yml 

Using /etc/ansible/ansible.cfg as config file
BECOME password: 

PLAY [centos8] *************************************************************************************************************************

TASK [Gathering Facts] *****************************************************************************************************************
ok: [www7.dmz.nausch.org]
ok: [www8.dmz.nausch.org]

TASK [Install chrony ntp Deamon] *******************************************************************************************************
changed: [www8.dmz.nausch.org] => {"changed": true, "msg": "", "rc": 0, "results": ["Installed: chrony", "Installed: chrony-3.3-3.el8.x86_64"]}

TASK [Check if /etc/chrony.orig does exists] *******************************************************************************************
ok: [www8.dmz.nausch.org] => {"changed": false, "stat": {"exists": false}}

TASK [Make a copy of /etc/chrony.conf as /etc/chrony.conf.orig] ************************************************************************
changed: [www8.dmz.nausch.org] => {"changed": true, "checksum": "89175e7c294dedf12bd473a952014e2cefd5766d", "dest": "/etc/chrony.conf.orig", "gid": 0, "group": "root", "md5sum": "97078948a9e2c1b99ab3e38d26a3311d", "mode": "0644", "owner": "root", "secontext": "system_u:object_r:etc_t:s0", "size": 1085, "src": "/etc/chrony.conf", "state": "file", "uid": 0}

TASK [Copy template config-file in place] **********************************************************************************************
changed: [www8.dmz.nausch.org] => {"changed": true, "checksum": "37539ecdd11393937e5596894db41a02c6121c5f", "dest": "/etc/chrony.conf", "gid": 0, "group": "root", "md5sum": "adde7eeb1766f7f83bd3fba6cc30ec23", "mode": "0644", "owner": "root", "secontext": "system_u:object_r:etc_t:s0", "size": 1265, "src": "/home/ansible/.ansible/tmp/ansible-tmp-1578323551.4891849-132640554634531/source", "state": "file", "uid": 0}

TASK [Make sure Chrony is started up] **************************************************************************************************
changed: [www8.dmz.nausch.org] => {"changed": true, "enabled": true, "name": "chronyd", "state": "started", "status": {"ActiveEnterTimestampMonotonic": "0", "ActiveExitTimestampMonotonic": "0", "ActiveState": "inactive", "After": "sysinit.target system.slice -.mount systemd-tmpfiles-setup.service sntp.service ntpdate.service tmp.mount systemd-journald.socket ntpd.service basic.target", "AllowIsolate": "no", "AmbientCapabilities": "", "AssertResult": "no", "AssertTimestampMonotonic": "0", "Before": "multi-user.target shutdown.target", "BlockIOAccounting": "no", "BlockIOWeight": "[not set]", "CPUAccounting": "no", "CPUQuotaPerSecUSec": "infinity", "CPUSchedulingPolicy": "0", "CPUSchedulingPriority": "0", "CPUSchedulingResetOnFork": "no", "CPUShares": "[not set]", "CPUUsageNSec": "[not set]", "CPUWeight": "[not set]", "CacheDirectoryMode": "0755", "CanIsolate": "no", "CanReload": "no", "CanStart": "yes", "CanStop": "yes", "CapabilityBoundingSet": "cap_chown cap_dac_override cap_dac_read_search cap_fowner cap_fsetid cap_kill cap_setgid cap_setuid cap_setpcap cap_linux_immutable cap_net_bind_service cap_net_broadcast cap_net_admin cap_net_raw cap_ipc_lock cap_ipc_owner cap_sys_module cap_sys_rawio cap_sys_chroot cap_sys_ptrace cap_sys_pacct cap_sys_admin cap_sys_boot cap_sys_nice cap_sys_resource cap_sys_time cap_sys_tty_config cap_mknod cap_lease cap_audit_write cap_audit_control cap_setfcap cap_mac_override cap_mac_admin cap_syslog cap_wake_alarm cap_block_suspend", "CollectMode": "inactive", "ConditionResult": "no", "ConditionTimestampMonotonic": "0", "ConfigurationDirectoryMode": "0755", "Conflicts": "systemd-timesyncd.service shutdown.target ntpd.service", "ControlPID": "0", "DefaultDependencies": "yes", "Delegate": "no", "Description": "NTP client/server", "DevicePolicy": "auto", "Documentation": "man:chronyd(8) man:chrony.conf(5)", "DynamicUser": "no", "EnvironmentFiles": "/etc/sysconfig/chronyd (ignore_errors=yes)", "ExecMainCode": "0", "ExecMainExitTimestampMonotonic": "0", "ExecMainPID": "0", "ExecMainStartTimestampMonotonic": "0", "ExecMainStatus": "0", "ExecStart": "{ path=/usr/sbin/chronyd ; argv[]=/usr/sbin/chronyd $OPTIONS ; ignore_errors=no ; start_time=[n/a] ; stop_time=[n/a] ; pid=0 ; code=(null) ; status=0/0 }", "ExecStartPost": "{ path=/usr/libexec/chrony-helper ; argv[]=/usr/libexec/chrony-helper update-daemon ; ignore_errors=no ; start_time=[n/a] ; stop_time=[n/a] ; pid=0 ; code=(null) ; status=0/0 }", "FailureAction": "none", "FileDescriptorStoreMax": "0", "FragmentPath": "/usr/lib/systemd/system/chronyd.service", "GID": "[not set]", "GuessMainPID": "yes", "IOAccounting": "no", "IOSchedulingClass": "0", "IOSchedulingPriority": "0", "IOWeight": "[not set]", "IPAccounting": "no", "IPEgressBytes": "18446744073709551615", "IPEgressPackets": "18446744073709551615", "IPIngressBytes": "18446744073709551615", "IPIngressPackets": "18446744073709551615", "Id": "chronyd.service", "IgnoreOnIsolate": "no", "IgnoreSIGPIPE": "yes", "InactiveEnterTimestampMonotonic": "0", "InactiveExitTimestampMonotonic": "0", "JobRunningTimeoutUSec": "infinity", "JobTimeoutAction": "none", "JobTimeoutUSec": "infinity", "KeyringMode": "private", "KillMode": "control-group", "KillSignal": "15", "LimitAS": "infinity", "LimitASSoft": "infinity", "LimitCORE": "infinity", "LimitCORESoft": "infinity", "LimitCPU": "infinity", "LimitCPUSoft": "infinity", "LimitDATA": "infinity", "LimitDATASoft": "infinity", "LimitFSIZE": "infinity", "LimitFSIZESoft": "infinity", "LimitLOCKS": "infinity", "LimitLOCKSSoft": "infinity", "LimitMEMLOCK": "16777216", "LimitMEMLOCKSoft": "16777216", "LimitMSGQUEUE": "819200", "LimitMSGQUEUESoft": "819200", "LimitNICE": "0", "LimitNICESoft": "0", "LimitNOFILE": "4096", "LimitNOFILESoft": "1024", "LimitNPROC": "31132", "LimitNPROCSoft": "31132", "LimitRSS": "infinity", "LimitRSSSoft": "infinity", "LimitRTPRIO": "0", "LimitRTPRIOSoft": "0", "LimitRTTIME": "infinity", "LimitRTTIMESoft": "infinity", "LimitSIGPENDING": "31132", "LimitSIGPENDINGSoft": "31132", "LimitSTACK": "infinity", "LimitSTACKSoft": "8388608", "LoadState": "loaded", "LockPersonality": "no", "LogLevelMax": "-1", "LogsDirectoryMode": "0755", "MainPID": "0", "MemoryAccounting": "yes", "MemoryCurrent": "[not set]", "MemoryDenyWriteExecute": "no", "MemoryHigh": "infinity", "MemoryLimit": "infinity", "MemoryLow": "0", "MemoryMax": "infinity", "MemorySwapMax": "infinity", "MountAPIVFS": "no", "MountFlags": "", "NFileDescriptorStore": "0", "NRestarts": "0", "Names": "chronyd.service", "NeedDaemonReload": "no", "Nice": "0", "NoNewPrivileges": "no", "NonBlocking": "no", "NotifyAccess": "none", "OOMScoreAdjust": "0", "OnFailureJobMode": "replace", "PIDFile": "/var/run/chrony/chronyd.pid", "PermissionsStartOnly": "no", "Perpetual": "no", "PrivateDevices": "no", "PrivateMounts": "no", "PrivateNetwork": "no", "PrivateTmp": "yes", "PrivateUsers": "no", "ProtectControlGroups": "no", "ProtectHome": "yes", "ProtectKernelModules": "no", "ProtectKernelTunables": "no", "ProtectSystem": "full", "RefuseManualStart": "no", "RefuseManualStop": "no", "RemainAfterExit": "no", "RemoveIPC": "no", "Requires": "sysinit.target -.mount system.slice", "RequiresMountsFor": "/var/tmp", "Restart": "no", "RestartUSec": "100ms", "RestrictNamespaces": "no", "RestrictRealtime": "no", "Result": "success", "RootDirectoryStartOnly": "no", "RuntimeDirectoryMode": "0755", "RuntimeDirectoryPreserve": "no", "RuntimeMaxUSec": "infinity", "SameProcessGroup": "no", "SecureBits": "0", "SendSIGHUP": "no", "SendSIGKILL": "yes", "Slice": "system.slice", "StandardError": "inherit", "StandardInput": "null", "StandardInputData": "", "StandardOutput": "journal", "StartLimitAction": "none", "StartLimitBurst": "5", "StartLimitIntervalUSec": "10s", "StartupBlockIOWeight": "[not set]", "StartupCPUShares": "[not set]", "StartupCPUWeight": "[not set]", "StartupIOWeight": "[not set]", "StateChangeTimestampMonotonic": "0", "StateDirectoryMode": "0755", "StatusErrno": "0", "StopWhenUnneeded": "no", "SubState": "dead", "SuccessAction": "none", "SyslogFacility": "3", "SyslogLevel": "6", "SyslogLevelPrefix": "yes", "SyslogPriority": "30", "SystemCallErrorNumber": "0", "TTYReset": "no", "TTYVHangup": "no", "TTYVTDisallocate": "no", "TasksAccounting": "yes", "TasksCurrent": "[not set]", "TasksMax": "26213", "TimeoutStartUSec": "1min 30s", "TimeoutStopUSec": "1min 30s", "TimerSlackNSec": "50000", "Transient": "no", "Type": "forking", "UID": "[not set]", "UMask": "0022", "UnitFilePreset": "enabled", "UnitFileState": "enabled", "UtmpMode": "init", "WantedBy": "multi-user.target", "WatchdogTimestampMonotonic": "0", "WatchdogUSec": "0"}}

PLAY RECAP ***************************************************************************************************************************************
www8.dmz.nausch.org        : ok=6    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Auf dem Zielhost finden wir nun die Sicherungskopie der originalen chrony.conf aus dem RPM-Paket.

 # ll /etc/chrony.conf*

-rw-r--r--. 1 root root 1265 Jan  6 16:12 /etc/chrony.conf
-rw-r--r--. 1 root root 1085 Apr  4  2018 /etc/chrony.conf.orig

Der Dienst chrony.conf wurde entsprechend gestartet und läuft:

 # systemctl status chronyd.service

● chronyd.service - NTP client/server
   Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2020-01-06 16:12:34 CET; 47s ago
     Docs: man:chronyd(8)
           man:chrony.conf(5)
  Process: 10697 ExecStartPost=/usr/libexec/chrony-helper update-daemon (code=exited, status=0/SUCCESS)
  Process: 10693 ExecStart=/usr/sbin/chronyd $OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 10695 (chronyd)
    Tasks: 1 (limit: 26213)
   Memory: 1.1M
   CGroup: /system.slice/chronyd.service
           └─10695 /usr/sbin/chronyd

Jan 06 16:12:34 vml000090.dmz.nausch.org systemd[1]: Starting NTP client/server...
Jan 06 16:12:34 vml000090.dmz.nausch.org chronyd[10695]: chronyd version 3.3 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +SIGND +ASYNCDNS +SECHASH +IPV6 +DEBUG)
Jan 06 16:12:34 vml000090.dmz.nausch.org chronyd[10695]: Initial frequency 10.454 ppm
Jan 06 16:12:34 vml000090.dmz.nausch.org chronyd[10695]: Using right/UTC timezone to obtain leap second data

 # systemctl is-enabled chronyd.service

enabled