mesos sys adminday

Mesos for dummiesGiving some sense to all this crap

Javier CortejosoUnai ArríenCredits: Mario Castro

Plan

What is Mesos?

How can I use Mesos?

What is mesos?

A long time ago...

Are you done with the

machine? I need to

load my cards

Lol no; maybe

tomorrow

In 1957...

Oh man! Let’s all

share the computer,

AT THE SAME TIME!

John McCarthy

In 2005...

Are you done with the

Hadoop cluster? I

need to run my

analytics jobsLol no; maybe

tomorrow

In 2010...

Oh man! Let’s all

share the cluster, AT

THE SAME TIME!

Ben Hindman

Good ideas today mirror good ideas of yesterday

So… the origin highlights:

● Project motivated from Google projects

Borg (later Omega and Kubernetes)

○ Borg, Omega, and Kubernetes

● In 2008, Berkeley Amplab started the

Nexus project (later Mesos)

● First version published in 2009

● Used by companies: Twitter, eBay,

Apple, Netflix, Airbnb, …

Mesos

Orchestration platform to share a computer cluster between many

applications and to use it as a single machine managing CPU, memory and

other resources.

No more “apps” in fixed machines.

Divided in Master nodes and Agent nodes (formerly known as Slaves)

Mesos Masters and Agents

Master:

Manages cluster resources.

Has the UI.

Knows everything about the cluster (Maintains some state).

One active master and 0+ passive master(s) (elected using ZK) for HA

Agents:

Launch and manage containers (LXC and Docker containers).

Provide UI access to slave specific data.

Mesos Architecture

Mesos Frameworks

Each framework has a scheduler that is a process that communicates with

Mesos Master to accept resources from the Master offers…

...and 0+ executor(s), which are launched by the scheduler and it’s

considered a worker. The scheduler sends tasks to the executors that will

work on them and provide status updates to the scheduler.

Mesos model

Resources are allocated via

resource offers

A resource offer represents a

snapshot of available resources

that a scheduler can use to run

tasks

Mesos model

Scheduler uses the offers

to decide what tasks to

run

“Two-level scheduling”

Mesos Resources

Mesos Resources

Tasks and executors

Schedulers can run one or more tasks within a

executor… and one or more tasks in a

specific container.

So an Executor is a “process container” that

run tasks.

A Task can adjust the size of the Executor’s

container.

How can I use mesos?

Example

A Mesos cluster, 3 Masters, 3

Zookeepers and 3 machines with

Marathon (in white).

9 Slaves (in grey).

2 Chronos (in orange) that schedu- les

2 executions (in blue) to send emails

and to dump a database.

Others frameworks are also running by

Marathon (in orange).

Mesos allocator

Allocator is the responsible for the offers given for each registered

framework

You can implement your custom allocator

By default it implements “Dominant Resource Fairness”, based on max-min

fairness.

Mesos principals, roles and quotas

Principals: It identifies an entity (i.e., a framework or an operator) that

interacts with Mesos

Role: It can be used to associate resources with frameworks in various ways.

Example: 20% of CPU and MEM resources for role production

When a framework run tasks, it can identify itself as some role

Principals are the entity that can be authenticated against Mesos

Users ←→ Groups analogy

Mesos volumes

A framework can reserve or ask for volumes.

These volumes are persisted out of the executor container

When launching the task, the volume is created if the volume is not present

If the volume is present, the content is attached directly to the container

Mesos framework implementation

Mesos components use Protobuf to communicate

Implementing a custom framework consist on implementing a Scheduler and an

Executor

There are bindings for several languages (C++, Java, Scala, Go, Python, Haskell)

Big major change in 1.0: Full REST API for framework developing

Not provided by Mesos

Service Discovery between nodes. You can use Mesos DNS

Persistence and Stateful apps (support added in 0.23). Frameworks for

databases are still in early stages.

Monitoring of Mesos itself. Mesos monitors its frameworks but Mesos itself

(the cluster) is not monitored.

Marathon

Framework to manage Frameworks

Orchestrates apps and frameworks

It simplifies launching your distributed (or not) applications in Mesos without

needing to develop a custom framework for your application

Can run in HA using ZK

It will monitor your app checking if it is healthy

Developed by Mesosphere

Chronos

Distributed and fault tolerant job scheduler for Mesos

‘Kind a’ distributed cron

It is also a framework of Mesos

Supports time intervals, triggers on job completions

Developed by Mesosphere

Aurora

Scheduler for services and jobs (i.e.: Marathon + Chronos)More complex and powerful than Marathon/ChronosAllow rolling updates/rollbackResource quota and Multi-user supportFrom Twitter

Questions