Variable helps in centralize and manage values in the configuration.
The variable block consist of
Type
Description
Default values.
We can create a file variable.tf or default file name terraform.tfvars. We can also specify flag for variable files.
For any other file name used to define variable, use the command flag, –var-file. You can specify more than one file, but they will be executed in sequence.
All environment variables are defined using prefix TF_VAR_<variable name>
Terraform as a built in variable called as PATH it’s basically used in modules.
We can have below variable types in Terraform
String – Can be Boolean True or False or simple string
Map – A collection type (Associate array or Hash Table, similar to dictonary of Python)
List – A collection type (List of item, starting with index Zero).
We can call variables four ways,Through command prompt
Environment variables
Default variables
Variable defined in files
Variables have name and optional parameters,
Type – if type is omitted then terraform consider it as by default string.
Default
Description
Variables definition,
To call the variable in terraform main file. We need to use the keyword var as prefix
To run terraform on your local system for your AWS, you will need to first configure AWS on your local system.
Create a folder .aws/credential and store the AWS credential details at C:\Users\<yourhome folder>\.aws
You can do the above also through AWS command line > aws configure
You can define credentials in four different ways,
Static
Environment Variable
Shared Credential file
EC2 Role
Static – it is basic method, we directly hard code the credentials in the .tf file provider section.
Environment Variable – Run the below command for windows machine, for Linux system use export commands.
Once configured the environmental variables, you can all the keys through provider sections.
Shared Credential files – You can access the credential files created using aws configure command. The file is by default at location $HOME/.aws/credentials. You can call the shared file like below in the provider section.
EC2 Role – If running under EC2, then you can directly create and assign role to EC2, this avoids use of hard coded credentials.
Assume role – We can provide role ARN, terraform will attempt this role. You can call the role ARN in provider section.
