42 lines
1.7 KiB
Markdown
42 lines
1.7 KiB
Markdown
---
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layout: "docs"
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page_title: "State: Locking"
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sidebar_current: "docs-state-locking"
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description: |-
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Terraform stores state which caches the known state of the world the last time Terraform ran.
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---
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# State Locking
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If supported by your [backend](/docs/backends), Terraform will lock your
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state for all operations that could write state. This prevents
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others from acquiring the lock and potentially corrupting your state.
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State locking happens automatically on all operations that could write
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state. You won't see any message that it is happening. If state locking fails,
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Terraform will not continue. You can disable state locking for most commands
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with the `-lock` flag but it is not recommended.
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If acquiring the lock is taking longer than expected, Terraform will output
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a status message. If Terraform doesn't output a message, state locking is
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still occurring if your backend supports it.
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Not all [backends](/docs/backends) support locking. Please view the list
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of [backend types](/docs/backends/types) for details on whether a backend
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supports locking or not.
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## Force Unlock
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Terraform has a [force-unlock command](/docs/commands/force-unlock.html)
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to manually unlock the state if unlocking failed.
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**Be very careful with this command.** If you unlock the state when someone
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else is holding the lock it could cause multiple writers. Force unlock should
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only be used to unlock your own lock in the situation where automatic
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unlocking failed.
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To protect you, the `force-unlock` command requires a unique lock ID. Terraform
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will output this lock ID if unlocking fails. This lock ID acts as a
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[nonce](https://en.wikipedia.org/wiki/Cryptographic_nonce), ensuring
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that locks and unlocks target the correct lock.
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