WEBVTT

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Instructor: Until now, we have seen quite

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a few Terraform commands in action,

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such as the Terraform init, plan, and apply.

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Let us now take a look at some more commands

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available in Terraform.

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The first command we will take a look at

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is the terraform validate command.

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Once we write our configuration file,

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it's not necessary to run Terraform plan or apply

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to check if the syntax used is correct.

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Instead, we can make use of the Terraform validate command

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like this, and if everything is correct with the file,

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we should see a successful validation message like this.

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If there's an error in the configuration file,

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the validate command will show you the line in the file

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that is causing the error with the hints to fix it.

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In this example, we have used an incorrect argument

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for the local_file resource.

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It should be file_permission and not file_permissions.

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The next command that we are going

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to see is the terraform fmt or the Terraform format command.

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This command scans the configuration files

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in the current working directory and formats the code

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into a canonical format.

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This is a useful command to improve the readability

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of the Terraform configuration file.

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When we're on this command,

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the files that are changed in the configuration directory

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is displayed on the screen.

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The terraform show command prints out the current state

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of the infrastructure as seen by Terraform.

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In this example,

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we have already created the local_file resource

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and when we run the show command,

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it displays the current state of the resource,

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including all the attributes created by Terraform

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for that resource, such as the file name,

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file and directory permissions, content,

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and ID of the resource.

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Additionally, we can make use of the -json flag

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to print the contents in an JSON format.

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To see a list of all providers used

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in the configuration directory,

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use the terraform providers command.

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You can also make use of the mirror sub-command

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to copy provider plugins needed

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for the current configuration

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to another directory like this.

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This command will mirror the provider configuration

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in a new path /rout/terraform/new_ local_file.

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We saw how to use terraform output variables

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in one of the previous lectures.

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If you want to print all output variables

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in the configuration directory,

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use the command terraform output.

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You can also print the value of a specific variable

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by appending the name of the variable

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to the end of the output command like this.

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The Terraform refresh command is used to sync Terraform

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with the real world infrastructure.

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For example, if there are any changes made

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to a resource created by Terraform outside its control,

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such as a manual update,

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the terraform refresh command will pick it up

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and update the state file.

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This reconciliation is useful to determine

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what action to take during the next apply.

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This command will not modify any infrastructure resource,

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but it will modify the state file.

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As we saw earlier,

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terraform refresh is also run automatically by command,

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such as terraform plan and terraform apply,

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and this is done prior

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to Terraform generating an execution plan.

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This can however be bypassed

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by using the -refresh is equal to false option

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with the commands.

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The terraform graph command is used

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to create a visual representation

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of the dependencies in a Terraform configuration

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or an execution plan.

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In this example,

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the local_file in our main.tf file has a dependency

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on the random_pet resource.

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This command can be run as soon

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as you have the configuration file ready,

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even before you have initial configuration directory

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with Terraform in it.

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Upon running the terraform graph command,

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you should see an output like this.

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This text generated is hard to comprehend as it is,

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but it is a graph generated in a format called DOT.

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To make more sense of this graph,

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we can pass it through a graph visualization software,

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such as Graphviz

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and we can install it in Ubuntu using apt like this.

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Once installed, we can pass the output

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of the Terraform graph to the dot command,

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which we installed using the Graphviz package,

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and generate a graphic like this.

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We can now open this file via a browser

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and it should show a dependency graph like this.

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The root is the configuration directory

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where the configuration for this graph is located.

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We can see that there are two resources,

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the local_file called pet

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and the random_pet resource called my.pet

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that makes use of the local

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and the random provider respectively.

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And finally, we can see that the local_file called pet

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depends on the random_pet resource called my.pet

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as we have used the reference expression

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and the local_file resource

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that points to the ID of the random_pet.

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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 explore working with the Terraform commands

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that we learned in this lecture.