Terraform

© 2017 Capgemini. All rights reserved.1© 2017 Capgemini. All rights reserved.
An Introduction to Terraform
Chris Hollies
Capgemini UK Oracle IaaS lead

© 2017 Capgemini. All rights reserved.2 2© 2017 Capgemini. All rights reserved.2
I have worked with Oracle products since 1999,
focused around ERP.
Roles have included –
• Oracle PL/SQL & Pro*C Developer
• Oracle DBA
• Oracle E-Business Suite DBA
• Oracle Infrastructure Architect
• Oracle IaaS & PaaS Architect
• Technical Delivery Lead
• Oracle Pre-Sales Lead
Returned to Capgemini in 2016.
Capgemini UK Oracle IaaS Lead
Chris Hollies

© 2017 Capgemini. All rights reserved.3 3© 2017 Capgemini. All rights reserved.
© 2017 Capgemini. All rights reserved.3
Agenda
Overview of Terraform.
Why choose Terraform?
Terraform installation, structure, syntax,
characteristics and deployment
Sample use-cases and code examples
1
2
3
4 Best practices
5
Complementary tooling to incorporate
Terraform into a DevOps approach

Agenda
1
2
3
4 Best practices
5

© 2017 Capgemini. All rights reserved.5 5
Portable
• Binaries available for
various Linux distros, Mac
OS, Windows, Solaris
Declarative
• Specify the end-state and
Terraform derives the
execution plan
Multi-cloud
• Plug and play support for
over 100 different clouds
using lightweight provider
architecture
Simple & Fast
• Simple human readable
Hashicorp Configuration
Language
• Plain text
Why we chose Terraform

Why Terraform specifically, and which one?
Terraform is open source and licensed under the Mozilla Public Licence v2.0.
Terraform has a rich community and many Git repositories with sample code.
Since it supports over 100 different Infrastructure technologies and is open source,
Terraform does not lead to vendor lock-in unlike AWS CloudFormation, and is truly
multi-cloud unlike CloudFormation or Openstack Heat.
Like any good open source product, there are commercial versions available.
Terraform Pro adds collaboration and operations features whereas Terraform
Premium goes further with governance and policy management features.

Agenda
1
2
3
4 Best practices
5

Terraform Installation

• Created compartment (CJPH5)
• Created a Virtual Cloud Network in CJPH5 – 10.0.0.0/16 with
associated resources
• Created a VM called terra in the VCN
• Created a user called provtool
• Created an API signing key for the provtool user
Terraform Client Provisioning

Connect to terra1 and do this -
To install on OL7 do this –
sudo yum-config-manager --enable ol7_developer
sudo yum -y install terraform-0.11.7-1.el7 terraform-provider-oci-2.1.5-1.el7
Useradd terraform
Run terraform help
Tell them –
Sudo su – terra
mkdir –p terraform/base; cd terraform/base
Tell them we’re going to adopt dev practices, so we’re going to
install and use git; do so as a live demo
(https://git-scm.com/book/en/v2/Getting-Started-Installing-Git)
git init
This initialises the directory as a repo taking it under source code
control

• Terraform reads all ‘*.tf’ config files from current directory
• It reads them alphabetically
• It does not recurse
• Variables can be specified on command line, in standalone variables file or
for string variables, sourced as TF_VARS_ environment variables
Terraform – Infrastructure build process
• Terraform then builds a DAG – Directed Acyclic Graph with nodes
(resources) and edges (relationships)
• We can view these using graphviz

Terraform variables – Strings, Maps & Lists
Defined using a variable block.
• Name - Mandatory
• Type - Optional (default:string)
• Default - Optional
• Description - Optional

terraform.tfvars and *.auto.tfvars
Some variables are used so frequently that it makes sense to
abstract them into their own configuration file.
Special files will be automatically read by Terraform to set
variables –
• terraform.tfvars
• *.auto.tfvars
These files are a good place to store credentials and
connectivity configuration, but not the only place …

terraform.tfvars (and *.auto.tfvars)
# -- Tenant Information
tenancy_ocid =
"ocid1.tenancy.oc1..aaaaaaaahg2j4y6afjf6wzatofa4ojfkja…k64ba4a"
user_ocid = "ocid1.user.oc1..aaaaaaaaim55fbyubf673fcw…52k3lq"
compartment_ocid =
"ocid1.compartment.oc1..aaaaaaaa2ooed…durdy6rza5e3xhgjkncsk5ra
"
fingerprint = "b6:3b:16:3e:77:10:96:…:bb:92:80:6c"
private_key_path = "/home/oracle/.oci/oci_api_key.pem"
region = "eu-frankfurt-1"
# ---- availability domain (1, 2 or 3)
AD = "1"
The compartment we just created (CJPH1)

Agenda
1
2
3
4 Best practices
5

Building our first
infrastructure

a_provider.tf
variable "tenancy_ocid" {}
variable "user_ocid" {}
variable "fingerprint" {}
variable "private_key_path" {}
variable "region" {}
# Declare that we will use the OCI provider
provider "oci" {
region = "${var.region}"
tenancy_ocid = "${var.tenancy_ocid}"
user_ocid = "${var.user_ocid}"
fingerprint = "${var.fingerprint}"
private_key_path = "${var.private_key_path}"
}

Do the following –
git add terraform.tfvars
git add a_provider.tf
terraform init
This will show terraform downloading the provider
Can also vi a .gitignore containing –
.gitignore
.terraform
Now commit our files by doing this –
git commit -m "Configure the provider"

b_vcn.tf
# Need to pull in compartment ocid
variable compartment_ocid {}
# ------ Create VCN
resource "oci_core_virtual_network" “cjph-tst-vcn" {
cidr_block = “10.0.0.0/24"
compartment_id = "${var.compartment_ocid}"
display_name = “cjph-tst-vcn"
dns_label = “cjphtstvcn"
}
resource “resource_type” “resource_name” {}

b_vcn.tf

c_igw.tf
# ------ Create Internet Gateway
resource "oci_core_internet_gateway" “cjph-tst-igw" {
display_name = “cjph-tst-igw"
vcn_id = "${oci_core_virtual_network.cjph-tst-vcn.id}"
}

c_igw.tf

Terraform – Infrastructure build process
Use terraform plan to show the build process.
Pass the output to graphviz
Use graphviz dot to view the DAG.

Terraform data sources
Allow us to fetch or compute read-only data from outside
Terraform or from a Terraform configuration, such as –
• Image lists
• Availability domains
• Governance configurations
• Configuration Metadata
• Infrastructure resources
Every data source in Terraform is mapped to a provider based
on longest-prefix matching, such as aws_ for Amazon Web
Services or oci_ for Oracle Cloud Infrastructure.

datasources.tf
# -------- get the list of available ADs
data "oci_identity_availability_domains" "ADs" {
compartment_id = "${var.tenancy_ocid}"
}
data “datasource_type” “datasource_name” {}

d_subnets.tf
# ------ Create public subnets
resource "oci_core_subnet" "cjph-tst-ad1-admpub-subnet" {
availability_domain = "${lookup(data.oci_identity_availability_domains.ADs.availability_domains[0],"name")}"
cidr_block = "10.0.0.0/26"
display_name = "cjph-tst-ad1-admpub-subnet"
dns_label = "cjphtstadmpubsub"
}
resource "oci_core_subnet" "cjph-tst-ad1-apppub-subnet" {
cidr_block = "10.0.0.64/26"
display_name = "cjph-tst-ad1-apppub-subnet"
dns_label = "cjphtstapppubsub"
}
resource "oci_core_subnet" "cjph-tst-ad1-dbpub-subnet" {
cidr_block = "10.0.0.128/26"
display_name = "cjph-tst-ad1-dbpub-subnet"
dns_label = "cjphtstdbpubsub"
}

Tainting & destroying
infrastructure

Tainting a resource
Tainting a resource can be done manually
Tainting can be done by terraform during a failed apply operation
Tainted resources will be destroyed and recreated on next apply command
(terraform apply – does nothing
Terraform taint oci_core_internet_gateway.cjph-tst-igw
Terraform plan
Terraform apply

Destroying a resource
Resources can be selectively destroyed using –target=
Without options, terraform will destroy all resources

Agenda
1
2
3
4 Best practices
5

Suggested best practices
• Collaborate - Agree on a common approach and evolve it as a team
• Keep your configurations DRY
• Structure your configurations by environment/department/both
• Control your source code
• Keep groups of resources within configurations small –
blast radius

Agenda
1
2
3
4 Best practices
5

© 2017 Capgemini. All rights reserved.37 37Oracle Cloud | Johan Louwers | 2018 © 2017 Capgemini. All rights reserved.
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Terraform

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