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Ondrej Holecek (aaannz)
Software Engineer @ SUSE
[email protected]
Saltboot
Salt managed PXE boot
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Agenda
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Network boot
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Salt
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Saltboot
– client side
– server side
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Network boot
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Network boot
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A method of having computer boot using only its network card
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Purpose?
– Thin client
– Computer provisioning
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Network boot
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A method of having computer boot using only its network card
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Purpose?
– Thin client
– Computer provisioning
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How does it work?
– BIOS → PXE → DHCP → Download NBP via TFTP → NBP → Boot
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Preboot eXecution Environment (PXE)
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Part of the NIC firmware or UEFI
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Client side configuration
– enable PXE/Network boot option in BIOS/UEFI
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Server side configuration
– DHCP
– DHCP response must include PXE related information
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DHCP with network boot support
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subnet configuration with location of tftp server and NBP file
option domain-name-servers 1.1.1.1, 8.8.8.8;
default-lease-time 86400;
max-lease-time 604800;
authoritative;
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.70 192.168.1.100;
filename "pxelinux.0";
next-server 192.168.1.50;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255;
option routers 192.168.1.1;
}
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TFTP, PXELINUX (NBD)
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Trivial FTP for Network Boot Program provisioning
– Default configuration is usually fine
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PXELINUX (part of syslinux package)
– /usr/share/syslinux/pxelinux.0 → /srv/tftpboot/pxelinux.0
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pxelinux.cfg
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/srv/tftpboot/pxelinux.cfg:
DEFAULT netboot
LABEL netboot
kernel linux
append initrd=initrd.gz panic=60 ramdisk_size=710000
ramdisk_blocksize=4096 vga=0x314 splash=silent console=tty0
console=ttyS0,115200 ramdisk_size=1310000
IPAPPEND 3
LABEL localboot
localboot 0
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Boot image
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netboot image
– kernel
– netboot initrd
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downloaded via tftp
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Salt
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SaltStack Salt
“The most intelligent, powerful and flexible open source
software for remote execution, configuration automation,
cloud control and event-driven orchestration”
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SaltStack Salt
“The most intelligent, powerful and flexible open source
software for remote execution, configuration automation,
cloud control and event-driven orchestration”
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Keywords:
– event driven
– remote execution
– configuration automation
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Architecture
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Salt Master
– Central node
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Architecture
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Salt Master
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Salt Minions
– Managed systems
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Architecture
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Salt Master
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Salt Minion
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Execution Modules
– Ad hoc commands
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Architecture
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Salt Master
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Salt Minion
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Execution Modules
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States
– Representation of system
configuration
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Architecture
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Salt Master
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Salt Minion
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Execution Modules
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States
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Pillars
– Data stored on the Salt Master
– Treated as trusted
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Architecture
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Salt Minion
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Execution Modules
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States
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Pillars
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Grains
– Variable provided by minions
– Not necessarily trustworthy
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Architecture
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Execution Modules
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States
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Pillars
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Grains
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Runners
– Modules running on Salt Master
– Orchestrate runner for coordination across many minions
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Architecture
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States
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Pillars
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Grains
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Runners
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Reactor
– Predefined and custom events
– Trigger states based on events
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Saltboot
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Saltboot stack
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Client
– Initrd
– Grains, Events
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Server
– States, Runners, Execution modules, Reactor handlers
– Pillars
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Saltboot Initrd aka Salt boot control
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LinuxRC script ends with system boot
– need a way to stop the execution
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Saltboot Initrd aka Salt boot control
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LinuxRC script ends with system boot
– need a way to stop the execution
→ insert start of salt-minion in the process
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salt-minion must be started as foreground process
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Saltboot Initrd aka Salt boot control
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salt-minion blocks linuxrc execution until it is told to terminate
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control of the machine is now handled to Salt master
→ Last command to continue boot must be salt-minion
termination
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Salt minion registration
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By default minion wait until approved on master
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Successful registration ends with generic minion event
`salt/minion/*/start`
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Salt master reactor configuration:
reactor:
- 'salt/minion/*/start':
- salt://saltboot-reactor/minion_start.sls
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saltboot-reactor/minion_start.sls
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Salt master saltboot
entry point
disk_partitioned:
module.run:
- name: partition.mkpartfs
- device: /dev/sda
- part_type: primary
- fs_type: btrfs
- start: 2048
- end: 65535
stop_minion:
cmd_run:
- name: “kill `cat /var/run/salt-minion.pid`”
- require:
- module: disk_partitioned
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Jinja for the rescue
{% set disks = pillar.get(‘disks’) %}
{% set start = 2048 %}
{% for d, s in disks.items() %}
disk_{{ p }}_partitioned:
module.run:
- name: partition.mkpartfs
- device: {{ p }}
- part_type: primary
- fs_type: btrfs
- start: {{ start }}
- end: {{ s }}
{% start = start + s %}
{% endfor %}
…
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Pythonado
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_states/saltboot.py →
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saltboot.sls:
def check_existing(partitions, device):
ok = True
existing = __salt__['partition.list'](device)
for idx, part_id in enumerate(sorted(partitions)):
p['exists'] = False
for enum in existing['partitions'].keys():
e = existing['partitions'][enum]
if e[‘end’] - e['start'] != p[‘size’]:
ok = False
if not ok:
repartition_disk(partitions, device)
...
check_partitions:
saltboot.check_existing:
- partitions: {{ partitions }}
- device: {{ d }}
...
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Taking server notes
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Salt states executes on minions
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Taking server notes
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Salt states executes on minions
→ send event to start a runner
…
{% set name = “groot” %}
i_am_{{ name }}:
module.run:
- name: event.send
- tag: Home/Machines/Update
- with_env: False
- with_grains: True
...
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Taking server notes
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Salt states executes on minions
→ send event to start a runner
…
{% set name = “groot” %}
i_am_{{ name }}:
module.run:
- name: event.send
- tag: Home/Machines/Update
- with_env: False
- with_grains: True
...
reactor:
- 'salt/minion/*/start':
- salt://saltboot-reactor/minion_start.sls
- ‘Home/Machine/Update’:
- salt://saltboot-reactor/machinelist.sls
machinelist:
salt.runner:
- name: salt.cmd
- fun: file.append
- path: “/srv/mymachinelist.list”
- args: “minion_id: {{ minion_id }}, {{ grains }}”
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Sweet result
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Q&A
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Join Us at www.opensuse.org
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