Infrastructure as code with terraform and packer

Infrastructure as code with
Terraform and Packer
Alex Landa
Head of DevOps and BigData technologies at Trainologic

We will talk about
•Why infrastructure as code?
•How to build images with Packer?
•Managing cloud environments with
Terraform

Story time
• Once upon a time a cool Machine Learning startup raised seed
money - lets call them CyberTemp
• They wrote in Python and used AWS

The story part ||
• They wanted use Auto-Scaling so they created an AMI
• By hand
• Took a day to configure

And then they had to update..
• They wanted to use a different base AMI that support GPUs

So what went wrong?
• No automatic way to configure the server
• Error prone
• No connection to the CI process
• No way to track changes

Infrastructure as Code
• Writing code to manage configuration, provisioning and deployment
• Scripts
• Ansible
• Docker
• Terraform
• ..
• Using software development practices:
• Source control
• Testing
• Code reviews
• Design
• 3rd libraries
• Knowledge sharing

What if CyberTemp
• Has to deploy on several cloud providers?
• It wants to create an automatic deployment?
• Want to create a VM images for on premise deployment?

Packer
• “An open source tool for creating identical machine images
for multiple platforms from a single source configuration”
• Machine image contains pre-configures OS and installed
software which is used to create and run machines
• AMI for EC2
• VMDK/VMX for VMware
• OVF for VirtualBox
• Different cloud providers

Packer template
• A JSON file that contains the build configuration
• Composed of several parts:
• Builders – Create the machines and generates the images from them
in the configured platform
• Provisioners – Install and configure on the machine
• Post-processors – Take the result of a builder or another post-
processor
• Variables – key value strings to parametrize templates

Builders
• Responsible for creating the machine
• Provide a way to run the Provisioners there – communicator
• SSH
• WinRM for Windows machines
• Packages the machine into a deployable image
• Every build definition maps to a single build.

Provisioners
• Use built-in and existing module to install and configure the
machine after booting
• Installing packages
• Applying patches
• Creating users and folders
• Downloading or copying application code
• The Provisioners are executed in the order they are defined

Post Processors
• Optional section to run processing on the built image
• Compression, tagging, uploading files, etc..
• Every post processor will be ran on every build image (unless
configured otherwise)

Variables
• The way to pass environment variables to packer
• Templating the build

So we have an image..
• Cloud deployments are complex
• Contain
• Permissions
• Network definitions
• Machines
• Load balancers
• Databases
• Other managed services

Now lets deploy in Europe
If only we had our infrastructure in code..

Terraform
• An open-source tool for building, updating and managing
infrastructure
• Uses declarative approach – the state that I want to achieve
instead of set of instructions
• Configuration files are written in HCL, also support JSON
• Written in Go

The Terraform work flow
• Define – create or update your configuration file
• Init – initializes the terraform environment and provider binaries
• Plan – Terraform creates an execution plan from the configuration
files and the current state
• Apply – Applies the execution plan, modify the cloud infrastructure
• Destroy (optional  ) – removes all the resources specified in the
configuration

Simple example
resource "aws_instance" "web" {
ami = "ami-679d3f1e"
instace_type = "t2.micro
}

Resource
• Everything with life cycle – machine, load balancers, network …
• Has a type – different for every resource type and cloud provider
• Has a unique name – for internal reference
• Uses attributes – configuration for the type
• Uses Interpolation – a way to reference other resources and manipulate values

Terraform plan
• Terraform creates a resource graph
• It calculates the dependencies of every resource and the action that
should happen – the result is a plan
+ aws_instance.web
id: <computed>
ami: "ami-679d3f1e"
associate_public_ip_address: <computed>
...
get_password_data: "false"
instance_state: <computed>
instance_type: "t2.micro"
...

Reading the Terraform plan
•+ a resource will be created
• - resource will be destroyed
• ~ resource will be updated in place
• -/+ resource will be destroyed and recreated

Terraform apply
• Generates an execution plan if not given
• Asks for confirmation for the changes to come
• Executes the plan
• Updates the state

State of the “Art”
• Used by Terraform to map between the “actual” cloud resources
to the configured one
• Contains resource metadata - the real dependencies between
resources
• Refreshed before actions to validate the “State of the world”
• A JSON file created in the local directory with the name
terraform.tfstate

Remote state
• Local state is an issue when a team works together
• Remote state allows Terraform to synchronize state across different
machines
• Uses “backends” – determines how state is loaded and updated:
• S3
• Consul
• ETCD
• Terraform enterprise …

Templating Terraform
• Terraform allows to template configuration by using variables
• As convention defined in variables.tf
• Support lists and maps
• Can be set:
• In a file terraform.tfvars
• As a command line flags -var ‘region=us-west-2’
• UI
• Defaults
variable "region" {}

Output
• A way to organize data back to the user
• Tells Terraform what data is important
• Can be viewed as part of the ”apply” command result,
or by using terraform output web_ip
•
output "web_ip" {
value = "${aws_instance.web.public_ip}"
}

Terraform modules
• A way to structure Terraform to reusable pieces
• Self-contained packages that are managed as a group
• Terraform registry – a public repository for popular modules
• To use a module:
• Declare in config
• Run terraform init – downloads the module
module "vpc" {
source = "terraform-aws-modules/vpc/aws"
name = "my-vpc"
cidr = "10.0.0.0/16
…

Questions?
variable "questions" {
type = "list"
description = "???"
}

Infrastructure as code with terraform and packer

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