I have created some resources in Azure using Terraform such as VNETS, VMs, NSGs etc. Let's assume if I create another VM in the same VNET which was created by Terraform, I want to know if I rerun the Terraform script, will the manually created VM gets destroyed since the manually created VM is not in the state file?
No, Terraform does not interfere with resources that are created outside of terraform. It only manages resources that are included in its state file.
However, if you make manual changes to resources that you created through terraform(for example VNET in your case), terraform would reset them to what is declared in terraform code on the next run/execution.
Related
Background
I was kind of dropped into an IaC project that uses Packer => Terraform => Ansible to create RHEL Virtual Machines on an on-prem VMware Vsphere cluster.
Our vmware module registers output variables that we use once the VMs are created, those variables feed a local_file resource template to build an Ansible inventory with the vm names and some other variables.
Ansible is then run using local_exec with the above created inventory to do configuration actions and run scripts both on the newly deployed VM's and against some external management applications, for example to join the VM to a domain (FreeIPA, sadly no TF good provider is available).
Issue Description
The issue that I have been wrestling with is when we run a terraform destroy (or apply with some VM count changes that destroy a VM resource), we would like to be able to repeat the process in reverse.
Capture the names of the VMs to be destroyed(Output vars from resource creation) so they can be removed from the IPA domain and have some general cleanup.
We've tried different approaches with Destroy Time Provisioners and it just seems like it would require a fundamental change in the approach outlined above to make that work.
Question
I'm wondering if there is a way to get an output variable on destroy that could be used to populate a list the VMs that would be removed.
So far my search has turned up nothing. Thanks for your time.
In general, it is good to plan first, even when destroying:
terraform plan -destroy -out tfplan
Then, you you can proceed with the destroy:
terraform apply tfplan
But at this moment (or before actual destroy), you have a plan what was destroyed, and you can do any analysis or automation on it. Example:
terraform show -json tfplan | jq > tfplan.json
Source:
https://learn.hashicorp.com/tutorials/terraform/plan
This would appear to be a fairly simple and basic scenario but I'm frankly at a loss on how to get around this using Terraform and would appreciate any suggestions.
The issue is this. In Azure, I have a number of resource groups, each containing a number of resources, including virtual networks, subnets, storage accounts, etc. What I would now like to do is add new resources to one or two of the resource groups. Typical example, I would like to provision a new virtual machine in each of the resource groups.
Now, so far all of the documentation and blogs I seem to come across only provide guidance on how to create resources whereby you also create a new resource group, vnet, subnet, from scratch. This is definitely not what I wish to do.
All I'm looking to do is get Terraform to add a single virtual machine to an existing resource group, going on to configure it to connect to existing networking resources such as a VNet, Subnet, etc. Any ideas?
I tested for ECS by destroying the launch configuration.
terraform destroy -target module.ecs.module.ec2_alb.aws_launch_configuration.launchcfg
I recreated the launch configuration and it worked:
terraform plan -target=module.ecs.module.ec2_alb.aws_launch_configuration
terraform apply -target=module.ecs.module.ec2_alb.aws_launch_configuration
Also, you can go read more on Terraform target here: https://learn.hashicorp.com/tutorials/terraform/resource-targeting
If you just want to be able to reference your existing resources in your TF script, you normally would use data sources in TF to fetch their information.
So for resource group, you would use data source azurerm_resource_group, for vnet there is azurerm_virtual_network and so forth.
These data sources would allow you to only reference and get details of existing resources, not to manage them in your TF script. Thus if you would like to actually manage these resources using TF (modify, delete, etc), you would have to import them first to TF.
I am using Terraform scripts to create azure services, I am having some doubts regarding Terraform,
1) If I have one environment let say dev in azure having some azure resources how can I copy all the resources to new environment lest say prod using terraform script.
2)what are the impact of re-run the terraform file with additional azure resources, what it will do.
3)What if I want to create an app service with the same name from Terraform script that already present in the azure will it update the resource or do nothing after terraform execution completed.
Please feel free to answer the question, it will be great help.
To answer your questions:
You could create a new workspace with terraform workspace new and copy all configuration files (.tf) to the new environment, then run terraform init, plan, apply.
The terraform will compare the content in your current state file with your configuration file, then update the new attributes or creating new resources other than re-creating the existing resources.
You could run terraform import to import existing infrastructure into Terraform. For referencing existing resources in the portal, you can use data sources.
I have pre-existing VMs in vmware vsphere that I would like to delete and/or rename. I see that terraform is capable of creating and destroying resources that are created by terraform itself by checking the statefiles.
Is this possible to operate on other non-terraform created resources?
I am creating multiple servers on Azure using Terraform template in a same Azure "Resource group", However when i try to run the template for individual servers each time, it is deleting the previous server while creating for next one.
Any idea how i can i reuse the same template for creating multiple server in a same Resource Group.
Thanks.
Terraform is intended to be idempotent, meaning that reapplying the same template makes no changes. If you edit the template, Terraform will edit the environment to reflect any changes or deletions.
If you need multiple VMs, you have at least two options:
Define multiple VM resources in your template.
Define a VM scale set and simply specify the number of VMs that you need.
I was able to achieve this, Here is what i did.
I created 2 separate .tf files under different folders.
1) For creating Resource group, NSG, Storage account, Vnet
2) For creating public ip, network interface and VM itself.
So i could use second configuration file for creating multiple server by just changing the values though parameters