Ordina DockerOps - Speaker Deck

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NOMAD Mans Matulewicz

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Infra Engineer @ Ordina @ ING Twitter: @Mans_M Github: @MansM mans@mansm.io

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What is Nomad? § Distributed § Optimistically concurrent § Scheduler

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Nomad setup

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What is a scheduler? In short: A scheduler maps sets of work to a set of resources

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Schedulers around us

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Why do you want a scheduler? § Higher resource utilization − Bin packing − Over-subscription − Job queueing

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Scheduling § You decide what to run § Nomad decides where and how to run − But you can force Nomad’s hands by using constraints (examples coming up)

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Workloads Nomad can schedule § Docker containers § Rkt containers § Java § Isolated exec (chroot) § Raw exec § Qemu VM’s

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Job types § Service § Batch § System

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Evaluation enqueue

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Evaluation dequeue

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Plan generation

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Plan execution

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Nomad scheduling

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Jobs § nomad run jobfile.nomad job “name” { group “name” { task “name” { driver resources } } }

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Jobs Note: for a single task, you don’t need to create a taskgroup, as the group is created implicitly.

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Jobs - Constraints § Force Nomad’s hand on a scheduling location § Can be on job, taskgroup and/or task level § Hostname, kernel.version, os.name, os.version, platform.aws.ami-id, platform.aws.instance-type, arch, driver.docker.version, etc

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Jobs - Service Discovery • Consul needs to be installed on client machines • No need for in-container Consul agents • Nomad will register and deregister nodes/services

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Service Discovery § Container provides a service § Container runs service on unknown port § Consul-template queries Consul server for values and reloads nginx with new config file

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Jobs - Restart container

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Jobs - Restarts § Sorry Bryan § Note: batch jobs have slightly different defaults!

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Jobs - Scaling

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Jobs - Updates

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Jobs - Periodic

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Local development § Make sure docker env vars are set if you want docker driver active § Fingerprinter of Mac instead of Docker host

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Resources (Docker) § CPU − Based on shares − Will only kick in when Nomad client machine is under load § Memory − Based on total virtual memory, no swapping − Hard limit, app can crash or terminate when using more than specified! § Diskspace − Amount of GB’s that is required (including logs) § IO (Network planned for later releases)

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How to install Nomad § Install Nomad servers § Connect the Nomad servers to each other § Install the Nomad clients and connect them to the servers § Run the workloads!

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Unofficial roadmap § 0.4 − Persistent volumes − Multiple network cards − Enhancements to logging (Source: 0.3.0 release notes (current)) − ACL’s (Source: GitHub issue #589) § 0.5 − Vault (Source: Jim Benson ( Hashicorp solution eng @ Hashicorp meetup AMS March) § Hashicorp has not released an official roadmap

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What I don’t like about Nomad § No UI

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Demo setup

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Demo

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Questions § I might even have some answers § (and otherwise the guys after me)