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@KeithResar
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@KeithResar
SYSTEMD BY EXAMPLE
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FAMILIARITY WITH SYSTEMD?
Time
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ARGUMENTS IN THE CORRECT ORDER?
(% OF TIME )
Time
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SURVEY
Have you used systemd?
@KeithResar
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SURVEY
Have you created custom unit files?
@KeithResar
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SURVEY
Have you extended system unit files?
@KeithResar
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SURVEY
Have you used non-service
functionality?
@KeithResar
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systemd Basics Intro
Very brief introduction on systemd 101
Some Fun Examples
Share some interesting use cases I stumbled across
AGENDA
@KeithResar
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SERVICE MANAGEMENT VIA SYSTEMD
# Basic service management
> service ssh { start | stop | reload | .. }
# Translates directly to...
> systemctl ssh { start | stop | reload | .. }
@KeithResar
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SERVICE MANAGEMENT VIA SYSTEMD
# Basic service management
> service httpd { start | stop | reload | .. }
# Translates directly to...
> systemctl { start | stop | reload | .. } httpd ...
@KeithResar
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BASIC SERVICE UNIT FILE
1 [Unit]
2 Description=OpenSSH server daemon
3 Documentation=man:sshd(8) man:sshd_config(5)
4 After=network.target sshd-keygen.target
5 Wants=sshd-keygen.target
6 [Install]
7 WantedBy=multi-user.target
8 [Service]
9 Type=notify
10 EnvironmentFile=-/etc/sysconfig/sshd
11 ExecStart=/usr/sbin/sshd -D $OPTIONS $CRYPTO_POLICY
12 ExecReload=/bin/kill -HUP $MAINPID
13 Restart=on-failure
14 RestartSec=42s
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UNIT FILE LOCATIONS
# Default system location
/usr/lib/systemd/system
# Local unit files live in
/etc/systemd/system
# Modifications reside in a drop-in directory
/etc/systemd/system/$unit.d
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SYSTEMD BY EXAMPLE
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BASH COMPLETION
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SYSTEMD-CGTOP
Control Group %CPU Memory Input/s Output/s
/ - 391.3M - -
/user.slice 0.6 66.4M - -
/user.slice/user-1000.slice 0.6 66.4M - -
/user.slice/user-1000.slice/session-1.scope 0.6 37.2M - -
/system.slice 0.1 248.5M - -
/system.slice/httpd.service 0.1 21.1M - -
/system.slice/rsyslog.service 0.0 15.0M - -
/system.slice/sssd.service 0.0 35.5M - -
/system.slice/lvm2-lvmetad.service 0.0 536.0K - -
/system.slice/rngd.service 0.0 3.2M - -
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SYSTEMD.RESOURCE-CONTROL
# Enable accounting
CPUAccounting, MemoryAccounting, IOAccouting, IPAccounting
# Weight 1 - 10,000, quota in % of a single CPU
CPUWeight, StartupCPUWeight, CPUQuota
# Best effort optimization and hard limits
MemoryLow, MemoryHigh, MemoryMax, MemorySwapMax
# Hard limits applied to provided device and bytes
IOReadBandwidthMax, IOWriteBandwidthMax
@KeithResar
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CPU PINNING FOR NUMA OPTIMIZATION
@KeithResar
0 1
4 5
CPU
Local Memory
Node 0
Socket 0
2 3
6 7
CPU
Local Memory
Node 1
Socket 1
[Service]
CPUAffinity=0 1 4 5
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DYNAMIC USERS
[Service]
DynamicUser=yes
# Optional, explicitly note user name
User=foo
@KeithResar
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SYSTEMD TIMERS
● Jobs can be easily started independently of their timers. This simplifies
debugging.
● Each job can be configured to run in a specific environment
● Jobs can be attached to cgroups.
● Jobs can be set up to depend on other systemd units.
● Jobs are logged in the systemd journal for easy debugging.
@KeithResar
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SOCKETS VIA COCKPIT
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SYSTEMD FOR ADMINISTRATORS BLOG SERIES
#1: Verifying Bootup
#2: Which Service Owns Which Processes?
#3: How Do I Convert A SysV Init Script Into A systemd Service File?
#4: Killing Services
#5: The Three Levels of "Off"
#6: Changing Roots
#7: The Blame Game
#8: The New Configuration Files
#9: On /etc/sysconfig and /etc/default
#10: Instantiated Services
#11: Converting inetd Services
#12: Securing Your Services
#13: Log and Service Status
#14: The Self-Explanatory Boot
#15: Watchdogs
#16: Gettys on Serial Consoles (and Elsewhere)
#17: Using the Journal
#18: Managing Resources
#19: Detecting Virtualization
#20: Socket Activated Internet Services and OS Containers
#21: Container Integration
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SUMMARY
● HUGE upside to kernel integration
● No bash means consistency and reliability
● More than just services
@KeithResar
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@KeithResar
THANKS!