Terraform

Terraform is to automate infrastructure process

I am using VSCode to write terraform code

once you created the terraform files,

inititalise the code

run terraform init – which will create working directory and install all plugins and modules

run terraform plan – will preivew changes before applying them

run terraform apply – which will apply all the changes

Now you will see in console

+ shows creating respource 

– deleting resouce 

~ modifying resouce 

now run terraform apply it says refreshing 

i will show codebase .

a provider needs to be created which can be aws or azure

i want to create aws instance and modify that instance by adding tag

tags = {
  Name = "phani"
}

Now run terraform apply, you can see update in place with tild symbol

Now go to AWS and check it

Now lets desroy,  phani-server resouce is going to destroy 

Terraform destroy

Now its terminated 

Now terraform apply again, which will deploy resource . created new one which shows as running. old one will be terminated

Now if you comment code in resource, terraform is intelligent enough to understand there are no rsources 

It will destroy

Unitl now we done deploying aws instances

Lets see other resources 

Now lets create subnet in vpc 

To quickly check it, 

Type terraform aws subnet in google

for subnet, we need to get vpc id. Terrform is intelligent to get it when typing

  vpc_id     = aws_vpc.phani_vpc.id 

Now run terraform apply and see all changes applied 

Now you can see aws subnet and aws vpc created

we can see cider block

Now lets go to subnet

There are default subnets created 

Lets see one created and you can seee vpc this subnet resides in 

And cider block 10.0.1.0/24

Also the order doesnt matter in code, you can create resource subnet first and then vpc. Terraform doesnt care about that 

Form console you can see code is writtern as subnet first and vpc later , 

In console, terraform creats vpc first and subnet later 

Note: after terrfaorm apply, we dont need to do yes all tht time. To overcome that just use 

terraform apply –auto-approve

Now lets do small project. please check the code

1. Create VPC

    2. Create Internet Gateway

    3. Create route table

    4. Create subnet

    5. Associate subnet with Route table

    6. Create security group to allow port 22, 80, 443

    7. create a network interface with an ip in the subnet that was created in step 4

    8. Assign an elastic IP to the network interface crated in step 7

    9. Cretae ubuntu server and install/enable apache2

    Code can be found in my github

    https://github.com/pbndru/Phani-Terraform/blob/main/main.tf

    Before running the code, you need to set 2 things access_key and secret_key where you can find them in your AWS account security credentials. create new access key from here. save the keys somewhere. Later it will be difficult to get it

    provider "aws" {
    region = "us-east-1"
    access_key = "" //set these values
    secret_key = ""
    }

    And you need to create key pair. go to EC2 Instances and go to key pair and create one. here i created main-key for webserver instance. it will be created with pem file. we need this file later

    key_name = "main-key"

    Now run terraform apply, it will create all resources in aws

    Now lets use putty and putty gen. please download these. we need these for connections to webserver with different protocols

    open putty gen

    Load the main-key.pem file created before and save private key to pkf file format 

    Now open putty 

    We need pem files for mac and ppk files for windows 

    Open putty and add host as ubuntu@ipaddress 

    Now load the ppk file. Now you will be connected to device 

    FOR MAC

    For MAc 

    We need to use  

    Chmod 400 main-key.pem 

    And then 

    Ssh –i main-key.pem ubuntu@34.226.80.181 

    Now you will be connected to device 

    TERRAFORM STATE COMMANDS

    If you want to see all resouces in command line quickly 

    RUN Terraform state list 

    Now you wll see all resources 

    to look into parituclar resource like aws_eip

    >terraform state show aws_eip.one

    We can see actual details like id , id instance, network interfae , ppublic ip and more

    TERRAFROM OUTPUT

    Everytime seeing state list and showing is bit typing 

    What about terraform do it when using terraform apply 

    We can use output and value to do what you want

    Here you can see , i created output which is like a log showing for 

    output "phani_server_public_ip" {
     value = aws_eip.one.public_ip
    }

    Output result as 

    phani_server_public_ip = "50.16.131.74" 

    You can also use terraform output to output all values for those resouces

    Now we dont want to accidently delete or deploy 

    We can use terraform reresh whichrefresh the state

    To delete paritcular resource we can use  –

    terraform destroy -target aws_instance.web-server-instance 

    To create it back use 

    terraform apply -target aws_instance.web-server-instance  

    Now you can see only 1 plan created 

    VARIBLES

    Here i creaed subnet_prefix variable and used in subnet 

    i created a file for variables trraform.tfvars where we use the variables

    subnet_prefix = ["10.0.1.0/24"]

    hope you enjoyed the article.

    Code in my github https://github.com/pbndru/Phani-Terraform/tree/main

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