20161122 from terraform to saltstack and beyondfiles.meetup.com/18628440/from terraform to... ·...

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From Terraform to SaltStack and beyondAlexandru Herișanu, Site Reliability Engineer


Agenda

§ Case Study 1: Create MongoDB sharded cluster in AWS§ MongoDB 101§ The challenge!§ Case Study 2: Create N MongoDB sharded clusters in AWS§ The challenge! (2)§ Questions


Case Study 1: Create MongoDB sharded cluster in AWS

“Create a MongoDB sharded cluster in an AWS environment. This cluster should be authenticated,should contain at least 2 replica sets and contain three given databases and a pre-defined user foreach.”


How to build a MongoDB cluster in 3 easy steps …

Step 1 • Create the infrastructure

Step 2 • Bootstrap the cluster

Step 3 • Manage the cluster


MongoDB 101 – In 3 little steps


MongoDB 101

§ You need 3 roles:§ MongoDB Replica Set

§ MongoDB Configuration Replica Set

§ Mongos Routers


The challenge ! (1)

§ To me able to use a sharded, authentication-enabled MongoDB Cluster you need to:§ Enable authentication§ Initialize the replica set (times how many replica sets there are)§ Initialize the configuration server replica set§ Create the shard setup§ Manage users and databases

§ Before actually starting using it


Manage the cluster

Roles

• A host has only one role

Profiles

• A host may implement many profiles

Resources

• Configures one "thing"

Code Data


How do I know which which is which?

§ How does a VM know it’s role?

§ In case of a MongoDB cluster, how do I know the cluster I’m part of?

ITIL -> CMDB

hostnames

AWS Tag

Static file


Bootstrap the cluster

§ How do you start a VM and bootstrap it?

§ Bash script – CSSH

§ Ansible playbook / Runbook

§ Central orchestration system: Saltstack

§ Cloudformation Magic (cloud-init)

Pros / Cons

S3New VM

bootstrap.sh

But, what about permissions boss?


Create the infrastructure

Cloudformation Terraform Other


Yes, but … but ... but

§ What happens when you need ordering between actions?§ Say you use CloudFormation + cloud-init

§ Block until condition is met

§ How would you implement this?


How it all looks from far, far away


Case Study 2: Create N MongoDB sharded clusters in AWS

§ “In the previous setup, change your configuration around to be able to spin up N number of clusters. Re-create this setup in multiple AWS regions.”

§ Strong requirement: We want to be able to start and bootstrap the cluster without touching any key


The challenge ! (2)

§ How do you define different clusters now?

§ Where is the data regarding your infrastructure?§ Custom facters (puppet), grains (Saltstack)§ DynamoDB tables§ S3 buckets with files

§ How do you ensure the ordering in this case?


You need something new

§ Scratch space where you can read/write what data you need§ Saltstack SDB – Postgresql BJSON

§ Queueing system?§ HTTP API over Zookeeper§ Saltstack Queues – Postgres DB§ ETCD§ S3 files ending in .done

§ Event system?§ Saltstack ZeroMQ with Postgresql backend

20161122 from terraform to saltstack and beyondfiles.meetup.com/18628440/from terraform to... ·...

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