Name: Terraform
Availability: InStock
Author: ivangdavila

Local state gets corrupted/lost — use remote backend (S3, GCS, Terraform Cloud)
Multiple people running simultaneously — enable state locking with DynamoDB or equivalent
Never edit state manually — use
```
terraform state mv
```
,
```
rm
```
,
```
import
```
State contains secrets in plain text — encrypt at rest, restrict access

```
count
```
uses index — removing item 0 shifts all indices, forces recreation
```
for_each
```
uses keys — stable, removing one doesn't affect others
Can't use both on same resource — choose one
```
for_each
```
requires set or map —
```
toset()
```
to convert list

```
prevent_destroy = true
```
— blocks accidental deletion, must be removed to destroy
```
create_before_destroy = true
```
— new resource created before old destroyed, for zero downtime
```
ignore_changes
```
for external modifications —
```
ignore_changes = [tags]
```
ignores drift
```
replace_triggered_by
```
to force recreation — when dependency changes

Implicit via reference —
```
aws_instance.foo.id
```
creates automatic dependency
```
depends_on
```
for hidden dependencies — when reference isn't in config

depends_on

accepts list —

depends_on = [aws_iam_role.x, aws_iam_policy.y]

Pin module versions —
```
source = "org/name/aws?version=1.2.3"
```
```
terraform init -upgrade
```
to update — doesn't auto-update
Module outputs must be explicitly defined — can't access internal resources from outside
Nested modules: output must bubble up — each layer needs to export

No type = any — explicit

type = string

list(string)

map(object({...}))

```
terraform destroy
```
is permanent — no undo, use
```
-target
```
carefully
Plan succeeded ≠ apply succeeds — API errors, quotas, permissions discovered at apply
Renaming resource = delete + create — use
```
moved
```
block or
```
terraform state mv
```
Workspaces not for environments — use separate state files/backends per env
Provisioners are last resort — use cloud-init, user_data, or config management instead

terraform import aws_instance.foo i-1234

— imports existing resource to state

Terraform