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SysOps/DevOps Poznań MeetUp #5

Mikołaj Młodzikowski

        [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
Reddis comment on terraform

        [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

📖 Wikipedia definiton:
Infrastructure as code (IaC) is the process of managing and provisioning computer data centers through machine-readable definition files, rather than physical hardware configuration or interactive configuration tools.

A good starting article about IaC from thorntech



  • 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


  • 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
Go gopher writting code

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:
        // maps:


        // 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

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


        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}”
        module bucket {
            name = “my-bucket”
        resource aws_s3_bucket copy {
            name = “copy-of-my-bucket”
            policy = “${module.bucket.policy_ref.value}”


  • 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:

More helpful links