using saltstack to auto triage and remediate production systems

Michael Kehoe Senior Site Reliability Engineer

LinkedIn

Using SaltStack to Auto Triage and Remediate Production Systems

Topics

• $ whoami• Salt @ LinkedIn• LinkedIn’s auto remediation story• Nurse• Salt API• Auto-remediation Salt Modules• How to get started

$ whoami

Salt @ LinkedIn

• 11-14k minions per master• Up to 8.5 events/ second per master• Deployment system heavily utilizes Salt• 5 dedicated SRE’s work on LinkedIn’s Salt infrastructure

• Number of SRE’s who also contribute

Alert Growth vs NOC EngineersLinkedIn’s Auto-remediation Story

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The problemLinkedIn’s Auto-remediation Story

• Growing number of high priority alerts vs Engineers to watch• Complicated ITR’s (runbooks) took time for NOC engineers to

execute and escalate• SRE’s would forget to run diagnostic tooling during outages• Longer MTTR == Bad experience for members

Building the SolutionLinkedIn’s Auto-Remediation Story

• LinkedIn needed a workflow engine• Requirements

• Take automated actions against applications/ hosts• Perform the run book automatically• Appropriate auditing• Scalable

What’s already out thereAutoremediation

• StackStorm• fbar• SaltStack

Started building an in-house solution in Mid-2014

Nurse

Image:freeflaticons.com

Nurse

• ‘Event based’ system• Built on top of LinkedIn’s existing monitoring infrastructure• Allows for manual execution via Web UI• Allows for other systems to plug-in via REST API

• Built in rules-engine• Allows for complicated checks/ branching

• Global environment awareness• Scalable!

The basicsSalt REST API

• RESTful interface to SALT• Allows for external-authentication

• PAM• LDAP• Your own plugin…

• Built on top of CherryPy

InterfaceSalt REST API

• /login - Log in to receive a session token• /logout - Remove or invalidate sessions• /minions – Working directly with minions• /jobs - Getting lists of previously run jobs or getting the return from a single job• /run - Run commands without normal session handling• /events - Expose the Salt event bus• /hook - A generic web hook entry point that fires an event on Salt's event bus• /keys – Wrapper around key management• /ws - Open a WebSocket connection to Salt's event bus• /stats - Return a dump of statistics collected from the CherryPy server

https://docs.saltstack.com/en/latest/ref/netapi/all/salt.netapi.rest_cherrypy.html




ConfigurationSalt REST API

external_auth: ldap: headless-nurse: - '*': - test.* - nurse.* - '@jobs'


/etc/salt/master.d/salt-api.conf




rest_cherrypy: port: 8888 ssl_crt: /etc/salt/pki/api/salt-api.crt ssl_key: /etc/salt/pki/api/salt-api.key






auth.ldap.basedn: 'dc=example,dc=com'auth.ldap.binddn: ’readonly-ldap@example'auth.ldap.bindpw: ’password'auth.ldap.filter: sAMAccountName={{ username }}auth.ldap.server: ldap.example.comauth.ldap.tls: Trueauth.ldap.persontype: 'person'auth.ldap.groupclass: 'group'auth.ldap.groupou: 'Users’

https://docs.saltstack.com/en/latest/topics/eauth/index.html




Code InterfacesSalt REST API

• There is a Python interface to the Salt API – pepper• Provides basic wrapper around REST API• https://github.com/saltstack/pepper/

• See https://github.com/SUSE/salt-netapi-client for JAVA bindings

https://github.com/saltstack/pepper/

https://github.com/saltstack/pepper/

https://github.com/SUSE/salt-netapi-client

https://github.com/SUSE/salt-netapi-client

Python Code exampleSalt REST API

from pepper.libpepper import Pepper

api = Pepper('https://salt.example.com:8888')api.login('saltdev', 'saltdev', ’ldap')

# Run simple functionapi.low([{'client': 'local', 'tgt': '*', 'fun': 'test.ping'}])

# Execute a runner functionapi.runner('jobs.lookup_jid', jid=12345)

GoalsAuto-remediation Salt Modules

• Auto-triage issues• Reduce context-switching• Run labor intensive tasks automatically• Gather data while engineer is logging in after escalation

• Auto-remediate issues• Let the engineer sleep• Faster MTTR

ImplementationAuto-remediation Salt Modules

• Auto-triage issues• Identify abusive clients• Collect & analyses thread/ heap dumps• Parse & summarize log files


• Auto-remediate issues• Restart/ OOR applications• Scale-up applications• Blocking abusive clients• Update A/ B experiment definitions• Otherwise escalate…


• Plenty of Salt modules/ runners already out there• Over 300 modules are available in Salt core• Modules to take remediate & notify

• Write your own• Make sure you test!

SuccessLinkedIn’s Auto-remediation Story

• 854k actions taken• 100% of service health check alerts are on boarded• ~37k man hours have now been automated• Now automating ~1100 hours/ week

SuccessLinkedIn’s Auto-remediation Story

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Some lessons learntHow to get started

• Need to make decision on how you architecture YOUR ‘event bus’

• Use external monitoring to trigger Salt via API• Use reactors/ beacons internally within Salt’s event bus• See ‘Thorium’ documentation for Salt’s new reactor engine

• Auditing is important!• Need to know what/ who triggered actions

Some lessons learntHow to get started

• Reporting is important!• Need to know how often automated actions are being taken• Find failure hotspots• Leverage event-bus or returners

• Safety first• Don’t give yourself too much rope…

Conclusion

• Think carefully about your ‘Event-Driven-Automation’ architecture

• The sky is the limit with Salt…don’t limit yourself• Again…safety first

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Questions?Thank You

using saltstack to auto triage and remediate production systems

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