github.com/hugorut/terraform@v1.1.3/website/docs/language/state/backends.mdx (about)

     1  ---
     2  page_title: 'Backends: State Storage and Locking'
     3  description: >-
     4    Backends are configured directly in Terraform files in the `terraform`
     5    section.
     6  ---
     7  
     8  # State Storage and Locking
     9  
    10  Backends are responsible for storing state and providing an API for
    11  [state locking](/language/state/locking). State locking is optional.
    12  
    13  Despite the state being stored remotely, all Terraform commands such
    14  as `terraform console`, the `terraform state` operations, `terraform taint`,
    15  and more will continue to work as if the state was local.
    16  
    17  ## State Storage
    18  
    19  Backends determine where state is stored. For example, the local (default)
    20  backend stores state in a local JSON file on disk. The Consul backend stores
    21  the state within Consul. Both of these backends happen to provide locking:
    22  local via system APIs and Consul via locking APIs.
    23  
    24  When using a non-local backend, Terraform will not persist the state anywhere
    25  on disk except in the case of a non-recoverable error where writing the state
    26  to the backend failed. This behavior is a major benefit for backends: if
    27  sensitive values are in your state, using a remote backend allows you to use
    28  Terraform without that state ever being persisted to disk.
    29  
    30  In the case of an error persisting the state to the backend, Terraform will
    31  write the state locally. This is to prevent data loss. If this happens the
    32  end user must manually push the state to the remote backend once the error
    33  is resolved.
    34  
    35  ## Manual State Pull/Push
    36  
    37  You can still manually retrieve the state from the remote state using
    38  the `terraform state pull` command. This will load your remote state and
    39  output it to stdout. You can choose to save that to a file or perform any
    40  other operations.
    41  
    42  You can also manually write state with `terraform state push`. **This
    43  is extremely dangerous and should be avoided if possible.** This will
    44  overwrite the remote state. This can be used to do manual fixups if necessary.
    45  
    46  When manually pushing state, Terraform will attempt to protect you from
    47  some potentially dangerous situations:
    48  
    49  - **Differing lineage**: The "lineage" is a unique ID assigned to a state
    50    when it is created. If a lineage is different, then it means the states
    51    were created at different times and its very likely you're modifying a
    52    different state. Terraform will not allow this.
    53  
    54  - **Higher serial**: Every state has a monotonically increasing "serial"
    55    number. If the destination state has a higher serial, Terraform will
    56    not allow you to write it since it means that changes have occurred since
    57    the state you're attempting to write.
    58  
    59  Both of these protections can be bypassed with the `-force` flag if you're
    60  confident you're making the right decision. Even if using the `-force` flag,
    61  we recommend making a backup of the state with `terraform state pull`
    62  prior to forcing the overwrite.
    63  
    64  ## State Locking
    65  
    66  Backends are responsible for supporting [state locking](/language/state/locking)
    67  if possible.
    68  
    69  Not all backends support locking. The
    70  [documentation for each backend](/language/settings/backends)
    71  includes details on whether it supports locking or not.
    72  
    73  For more information on state locking, view the
    74  [page dedicated to state locking](/language/state/locking).