WEBVTT

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In this lecture, we will learn how to list
and manipulate the Terraform state

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using the Terraform state command.

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In one of the previous lectures,

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we saw that the Terraform state file
is stored in JSON format.

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It should not be edited manually
by opening it with a text editor.

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Terraform provides a set of commands that
allows us to list, pull and manipulate state.

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These should be used instead of
manually editing these files.

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The Terraform state command
uses a syntax like this,

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the command to be used is Terraform state.

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This is followed by a subcommand such as
list, move, pull, remove, show, et cetera.

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We will take a look at each of these next.

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The first command that we are going to take
a look at is the list command.

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This will list all the resources recorded
within the Terraform state file.

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As you can see from the output,
it will only print the resource address

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and no other details about the resource.

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We can also pass in an additional argument
to this command

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for a matching resource address like this.

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If available, the list command will return
the matching resource address from the state.

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To get detailed information about
a resource from the state file,

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we can make use of the Terraform state
show command.

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This command will show the attributes
of a single resource in the state file

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that matches the given address.

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For example, to print
all the attributes for an S3 bucket

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with the resource name finance-2020922,

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use the Terraform state
show command like this.

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Next, let's take a look at
the Terraform state move command.

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This command is used to move items
in a Terraform state file.

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The syntax of this command
has a source and a destination

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following the move or MV sub command.

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The items can be moved
within the same state file,

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which would mean moving a resource
from its current resource address to another,

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which essentially means renaming a resource,

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or it can move items from one state file
to another state file

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maintained by a different configuration
directory completely.

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For example, let's consider that
we have a configuration file

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that we have used to create
a dynamo-db table called state locking.

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Sure enough, the state file also has
the managed source under the same name.

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If you want to rename the resource name
from state-locking to, say, state-locking-db,

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one way to do it without having
to recreate the table

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would be to use the Terraform state
move command like this.

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Specify the source name as state-locking
and the target name as state-locking-db.

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Once this is done, the name of the resource
and the state file changes to the new name.

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Next, we must manually rename the resource name
in the configuration file.

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Now we run a Terraform apply, there should be
no changes to be applied for this resource.

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We saw earlier that when using remote state,

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the state file is no longer stored
in the configuration directory

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under the name terraform.tfstate.

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Then how do we view the contents
of this remote state?

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For this, we can make use of
the Terraform state pull command.

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With this command, we can download and display
the remote state on the screen like this.

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The output of this command can then
be passed to Json query tools like JQ

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to filter the required data.

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For example, to filter the hash key
used by the dynamodb table

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with the name state-locking-db,
we can make use of a query like this.

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This returns the value of lock ID as expected.

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The next state command is
the Terraform state rm or remove command.

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It is used to delete items
from the Terraform state file.

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This command is used when you no longer
wish to manage one or more resources

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via the current Terraform
configuration and state.

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The syntax of this command
is Terraform state rm

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followed by the resource address.

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Once it is removed from the state file,

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make sure to remove
the associated resource block

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from the configuration file as well.

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Please note that the resource
removed from a state file

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are not actually destroyed from
the real world infrastructure.

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It is only removed from
the Terraform management.

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That's it for this lecture.

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Now, let's head over to the hands-on labs

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and practice working with
Terraform state commands.