Prevent Unwanted Updates in Terraform with ignore_changes

Here’s a classic Terraform moment: You tweak a single variable, hit terraform plan, and suddenly Terraform wants to rebuild half your infrastructure because it noticed a change in something it shouldn’t even care about.

Yeah. That.

When you don’t want Terraform to get twitchy over things like metadata, external changes, or stuff it didn’t create in the first place — you need ignore_changes. No magic. No hacks. Just telling Terraform to back off where it makes sense.

Let me show you how to use it — properly — so your deployments stop acting like an overprotective robot.

What the Hell Is `ignore_changes`?#

It’s a Terraform lifecycle argument that tells the engine:

“Even if this attribute has changed, don’t touch it.”

When used right, it prevents Terraform from updating or replacing a resource just because some value drifted from your original config — especially when that change was intentional, external, or irrelevant.

The syntax lives inside the lifecycle block of a resource, like so:

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lifecycle {
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  ignore_changes = [some_attribute]
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}

No, it doesn’t ignore all changes. And no, it’s not a get-out-of-IaC-responsibility-free card. Used carelessly, it’ll bite you. Used wisely, it’ll save your uptime and your sanity.

When Should You Use `ignore_changes`?#

Let’s walk through real reasons you’d want to use it — not made-up edge cases.

1. External Systems Are Messing With Your Resources#

Example: a team updates tags in the cloud console, outside Terraform. Now every plan shows a diff. Fix? Ignore the tags.

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lifecycle {
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  ignore_changes = [tags]
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}

2. Terraform Keeps Picking Fights with Random Metadata#

Timestamps, version IDs, generated names — Terraform can’t help itself. You don’t want it to re-provision a resource because some backend system touched a metadata field.

Ignore those noisy attributes.

3. You’re Managing Part of the Resource Elsewhere#

Let’s say your networking is controlled by a platform team using another tool. You just need to reference the network_interface_ids — not own them.

Cool. Just ignore the changes:

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lifecycle {
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  ignore_changes = [network_interface_ids]
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}

4. Secrets Drift, and That’s Okay#

Passwords, keys, secrets — if they’re rotated externally (like via Vault or AWS Secrets Manager), Terraform will see a change and freak out.

Unless you tell it to chill:

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lifecycle {
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  ignore_changes = [admin_password]
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}

(But for the love of ops, don’t hardcode passwords in plain HCL. Ever.)

5. You Want to Lock a Resource in Place#

Sometimes you just want Terraform to stop touching a resource altogether — especially during migration, disaster recovery, or manual intervention.

Yes, this is a band-aid. But it’s better than destroying production during a Friday deploy.

Things to Know Before You Use It#

Don’t just copy-paste this like a Stack Overflow spell. Know what you’re doing:

ignore_changes is resource-specific — you define it inside the resource.
You must name each attribute exactly as Terraform sees it.
You can’t use it to ignore everything unless you explicitly tell it to.
It doesn’t stop Terraform from tracking changes — just stops it from acting on them.

Real-World Examples#

Azure VM: Ignore Volatile Attributes#

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resource "azurerm_virtual_machine" "example" {
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  name                  = "example-vm"
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  location              = "UK South"
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  resource_group_name   = azurerm_resource_group.example.name
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  network_interface_ids = [azurerm_network_interface.example.id]
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  vm_size               = "Standard_DS1_v2"
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  storage_os_disk {
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    name              = "example-os-disk"
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    caching           = "ReadWrite"
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    create_option     = "FromImage"
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    managed_disk_type = "Premium_LRS"
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  }
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  os_profile {
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    computer_name  = "examplevm"
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    admin_username = "adminuser"
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    admin_password = "3c19uA53FsTcLrB36g56" # 🔥 Don't store this here in real life
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  }
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  lifecycle {
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    ignore_changes = [
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      network_interface_ids,
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      storage_os_disk,
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      os_profile[0].computer_name,
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    ]
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  }
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}

This prevents Terraform from rewriting your VM every time something shifts in the disk or network interface — which Azure loves to tweak behind your back.

Ignore All Changes (Yes, Really)#

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resource "azurerm_storage_account" "example" {
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  name                     = "examplestorageaccount"
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  resource_group_name      = azurerm_resource_group.example.name
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  location                 = "East US"
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  account_tier             = "Standard"
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  account_replication_type = "LRS"
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  lifecycle {
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    ignore_changes = all
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  }
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}

Terraform will still track the resource, but it won’t try to update it. Useful when you need Terraform to “know” something exists without touching it.

Final Thoughts: Use It Like a Scalpel, Not a Sledgehammer#

ignore_changes is powerful. Too powerful, if you’re not careful.

Use it when:

You have external systems or human changes that you don’t want Terraform to reverse
You’re dealing with flaky, drift-prone metadata
You need Terraform to respect reality, not overwrite it with an idealized config

But always document why you’re using it — and review those ignores in every PR. What makes sense today can cause a surprise outage next month.

SIGNAL & INTEL#

The Private Order: Stop being a grunt. Become an Architect. Join The Private Order.

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