[email protected] # whoami
    

• My name is Miko, my interests are: lingustics, travels and programing
• I’m going to start soon my career as a Build Automation Engineer, previously Java Developer and DevOps

    
        [email protected] # uname -a
    

• This presentations is focused on popularizing IaC approach using terraform as an example
• Terraform will be broadly presented as a tool with mostly easy examples
• Presentation is full of links, sources and referals so if you are interested in the topic - check out later the presentation online

    
        [email protected] # terraform plan -out=introduction
    

• Infrastructure as Code - short summary
• Terraform features specification
• HCL together with “${interpolation}”
• Modules and community tools
• Snippets!

IaC Approach

Pros

Operations:

• Infrastructure is self-documentating by its code
• Configuration can become part of Continuous Configuration Automation
• Keeping IaC inside VCS: changes tracking, easier rollbacks and reviewing process

💰 Buisness 💰:

• costs and risk reduction towards faster execution

Cons

• Mixing manual and automated setup leads to many problems
• High learning curve
• Some lacks in the documentations - both in tools and providers API

Facts about terraform

• Is declarative -> tell what you want
• Uses push configuration method
• Communication is JSON based
• Is extendable by plugins written in Golang

Digest of the providers set

• Clouds: AWS, GCP, Azure, Alibaba, DigitalOcean, Heroku, OpenStack
• Monitors: Datadog, Grafana, Icinga, New Relic, PagerDuty
• Software: Docker, Nomad, Consul, Vault, Chef, Kubernetes
• Networks: Cloudflare, DNS Servers, HTTP Requests
• Databases, scripts, archives, vcs, many more…

Terraform docs on providers

Terraform features

• Importing exsiting resources into your tfstate
• Mixing providers in one configuration
• Displaying plans before apply
• Data sources (immutable) and resources (mutable)
• Validating configuration and standard formatter
• Taint - marking resources for recreation
• Generating dependencies graph

HCL && “${interpolation}”

• HCL is compromise between human-friendly and machine-friendly configurations
• HCL is fusion of complete programing languages and data structure languages
• HCL is JSON-compatible - you can generate JSON and run it as HCL
• HCL supports comments and <<EOF syntax for multiline strings.

Exact specification on the language can be found in the Hashicorps repository

Data types

    
        // vars:
        “${var.aws_account_number}” //(0.11)
        var.aws_account_number // (0.12)
        // lists:
        “${var.aws_account_number[count.index]}”
        // maps:
        “${var.aws_account_number[‘client1’]}”
    

Loops

    
        // looping (0.11): creating ++like loops
        resource instance {
            count = 3
            name = “instance-${count.index}”
        }
        // looping (0.12): templating
        %{ for instance in aws_instance.example ~}
            server ${instance.id}
        %{ endfor }
    

Logical statements

    
        //if
        resource aws_vpc vpc {
            count = “${var.create_vpc}”
            // In HCL true/false is mapped to 1 and 0
        }
        //if-else
        // comprassions and boolean logic: == != > < >= <=
        resource aws_vpc vpc {
            subnet = “${
                var.env == “production” ?
                    var.prod_subnet : var.dev_subnet
            }”
        }
    

Refrences

    
        resource aws_ec2_instance manager {
            name = “swarm-manager”
        }
        resource aws_ec2_instance workers {
            counte = 3
            name = “swarm-worker-${count.index}”
        }
        module docker_swarm swarm {
            manager_ip = “${aws_ec2_instance.manager.ipv4}”
            workers_ips = “${aws_ec2_instance.workers.*.ipv4}”
        }
    

Referencing modules

    
        // module file
        resource s3_bucket data {
            name = “${var.name}”
        }
        output policy_ref {
            value = “${s3_bucket.policy.json}”
        }
        //main.tf
        module bucket {
            name = “my-bucket”
        }
        resource aws_s3_bucket copy {
            name = “copy-of-my-bucket”
            policy = “${module.bucket.policy_ref.value}”
        }
    

Functions

• Math functions: floor, abs, log, pow, max, signum, ${2 + 2}
• String functions: base64, concat, chomp, format, indent, join, lower
• Data types operations: chunklist, element, map, list, jsonencode, keys, sort, slice
• System calls: dirname, file, timestamp

All interpolations can be found in the docs.

What are terraform modules

• Modules are blackbox configuration in which only some set of parameters is provided in aim to create more complex infrastructure behind the scenes.
• Modules usually have a set of outputs which can be referenced in your terraform file.

Using modules

• First source is official terraform registry
• You can also find terraform modules on git repositories. There are plenty of them.
• If you don’t feel satisfied you can always create your own modules and reference them as local files
• Module is normal terraform project with: main.tf, variables.tf and optional outputs.

Terraform extensions

• Terragrunt - used for applying DRY ideology in your projects for e.g. if you have same configuration for three envs
• Terratest - go library which helps in writting http requests/api calls/ssh connetcions to test your infrastructure.
• Terraform dynamic inventory for ansible.

Terraform extensions

• VS Code plugin for terraform with syntax highligthing. There are also other plugins with snippets for AWS/Azure and generic HCL blocks.
• Terraform linter as addition to terraform fmt.
• Terraform landscape to help producing prettier output for terraform.

Thank you!

online @ https://mlodzikowski.pl/presentations/terraform

repo with snippets @ https://github.com/mkjmdski/terraform-examples

Sources and helpful links to study terraform:

• Jakub Jańczak article pointing terraform cons
• Alexander Savchuk post on CCA
• Pavan Belagatti’s analyze on popularity of terraform
• Two articles about terraform on AWS: provisioning AWS by Manisha Sahasrabudhe and terraform ECS cluster by Tom Trahan

More helpful links

• Hashicrop webinars on YT
• Introduction to terraform from Gruntwork.io which created terragrunt and terratest.
• Terraform training with 8 exercises from beginner to advanced.
• About loops and logic in terraform