WEBVTT

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In this lecture, we will learn
how to make use of an S3 bucket

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and a DynamoDB table
to configure a remote backend

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for our terraform configuration.

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For this, we need two things,

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an S3 bucket which will be used
to store the terraform state file

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and a DynamoDB table which will be used
to implement state locking

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and consistency checks.

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First, make sure that these two prerequisites
have been completed

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before beginning to configure
a remote backend.

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After these two services have been created,

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keep a note of the bucket name,
the key to be used, the region,

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and the name of the DynamoDB table.

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Now let's go over
to our configuration directory.

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We have a main.tf file
that creates a local file resource.

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When we run terraform apply,
the resource is created

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and as expected, terraform creates
a local state file called terraform.tfstate.

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To configure a remote backend in terraform,

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we must define additional settings
by making use of the terraform block.

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As a recap, we have already used
the terraform block once

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when we wanted a specific version
of the provider plugin

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to be used within our configuration.

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In this case, we want to configure
a remote backend for storing the state file

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and for that, the terraform block
should now look like this.

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Within the terraform block,
we specify another block called backend.

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Here, we provide the values we recorded
as part of the prerequisite step.

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The backend name specifies the type
of the backend that we want to use

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and for making use of an AWS S3 as the backend,
we use the name S3.

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The backend block with S3
expects three arguments.

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First is the name of the existing S3 bucket.

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Next is the key, which is an S3 object part
where the state file should be stored.

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In this case, we want to store the terraform
state file within a folder called finance,

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and this folder should exist within a bucket
called kodekloud-terraform-state-bucket01.

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The final argument that is required
is the region.

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This is the region
where the S3 bucket has been created

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and in this example, it is set to US-West-1.

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In order to achieve state locking,
we can optionally provide a DynamoDB table.

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This table should have a primary
or a hash key with the name lockID.

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We have already created a DynamoDB table
called state-locking for this purpose.

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As a standard practice, let's not store
the terraform block inside the main.tf file,

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instead, let's move it to a separate file
called terraform.tf.

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We now have the infrastructure configuration
and the backend configuration

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segregated into main.tf
and terraform.tf file respectively.

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The terraform state is now configured
to be stored in a remote S3 bucket.

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However, if we run the terraform
apply command now,

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we will see an error that says
backend reinitialization required.

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Running the terraform init command
will initialize the new backend to be used.

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Since we already have a local state file
in the configuration directory

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the init process gives us an option
to copy the terraform state file

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into the remote S3 backend.

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Giving a value of yes will copy
the state file to the S3 bucket.

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We can now delete the local state file
from the configuration directory.

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Running a terraform plan or apply now
will lock the state file

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and pull it down from the S3 bucket
into the memory.

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Any subsequent changes to the state will be
uploaded to the backend instantaneously

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and once the operation is complete,
the lock will be released.

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The state file will not be stored in
the local configuration directory anymore.

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That's it for this lecture.

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Let's head over to the hands-on labs

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and practice working with
remote backends in terraform.