github.com/pdecat/terraform@v0.11.9-beta1/website/docs/state/workspaces.html.md (about)

     1  ---
     2  layout: "docs"
     3  page_title: "State: Workspaces"
     4  sidebar_current: "docs-state-workspaces"
     5  description: |-
     6    Workspaces allow the use of multiple states with a single configuration directory.
     7  ---
     8  
     9  # Workspaces
    10  
    11  Each Terraform configuration has an associated [backend](/docs/backends/index.html)
    12  that defines how operations are executed and where persistent data such as
    13  [the Terraform state](https://www.terraform.io/docs/state/purpose.html) are
    14  stored.
    15  
    16  The persistent data stored in the backend belongs to a _workspace_. Initially
    17  the backend has only one workspace, called "default", and thus there is only
    18  one Terraform state associated with that configuration.
    19  
    20  Certain backends support _multiple_ named workspaces, allowing multiple states
    21  to be associated with a single configuration. The configuration still
    22  has only one backend, but multiple distinct instances of that configuration
    23  to be deployed without configuring a new backend or changing authentication
    24  credentials.
    25  
    26  Multiple workspaces are currently supported by the following backends:
    27  
    28   * [AzureRM](/docs/backends/types/azurerm.html)
    29   * [Consul](/docs/backends/types/consul.html)
    30   * [GCS](/docs/backends/types/gcs.html)
    31   * [Local](/docs/backends/types/local.html)
    32   * [Manta](/docs/backends/types/manta.html)
    33   * [S3](/docs/backends/types/s3.html)
    34  
    35  In the 0.9 line of Terraform releases, this concept was known as "environment".
    36  It was renamed in 0.10 based on feedback about confusion caused by the
    37  overloading of the word "environment" both within Terraform itself and within
    38  organizations that use Terraform.
    39  
    40  ## Using Workspaces
    41  
    42  Terraform starts with a single workspace named "default". This
    43  workspace is special both because it is the default and also because
    44  it cannot ever be deleted. If you've never explicitly used workspaces, then
    45  you've only ever worked on the "default" workspace.
    46  
    47  Workspaces are managed with the `terraform workspace` set of commands. To
    48  create a new workspace and switch to it, you can use `terraform workspace new`;
    49  to switch workspaces you can use `terraform workspace select`; etc.
    50  
    51  For example, creating a new workspace:
    52  
    53  ```text
    54  $ terraform workspace new bar
    55  Created and switched to workspace "bar"!
    56  
    57  You're now on a new, empty workspace. Workspaces isolate their state,
    58  so if you run "terraform plan" Terraform will not see any existing state
    59  for this configuration.
    60  ```
    61  
    62  As the command says, if you run `terraform plan`, Terraform will not see
    63  any existing resources that existed on the default (or any other) workspace.
    64  **These resources still physically exist,** but are managed in another
    65  Terraform workspace.
    66  
    67  ## Current Workspace Interpolation
    68  
    69  Within your Terraform configuration, you may include the name of the current
    70  workspace using the `${terraform.workspace}` interpolation sequence. This can
    71  be used anywhere interpolations are allowed.
    72  
    73  Referencing the current workspace is useful for changing behavior based
    74  on the workspace. For example, for non-default workspaces, it may be useful
    75  to spin up smaller cluster sizes. For example:
    76  
    77  ```hcl
    78  resource "aws_instance" "example" {
    79    count = "${terraform.workspace == "default" ? 5 : 1}"
    80  
    81    # ... other arguments
    82  }
    83  ```
    84  
    85  Another popular use case is using the workspace name as part of naming or
    86  tagging behavior:
    87  
    88  ```hcl
    89  resource "aws_instance" "example" {
    90    tags {
    91      Name = "web - ${terraform.workspace}"
    92    }
    93  
    94    # ... other arguments
    95  }
    96  ```
    97  
    98  ## When to use Multiple Workspaces
    99  
   100  Named workspaces allow conveniently switching between multiple instances of
   101  a _single_ configuration within its _single_ backend. They are convenient in
   102  a number of situations, but cannot solve all problems.
   103  
   104  A common use for multiple workspaces is to create a parallel, distinct copy of
   105  a set of infrastructure in order to test a set of changes before modifying the
   106  main production infrastructure. For example, a developer working on a complex
   107  set of infrastructure changes might create a new temporary workspace in order
   108  to freely experiment with changes without affecting the default workspace.
   109  
   110  Non-default workspaces are often related to feature branches in version control.
   111  The default workspace might correspond to the "master" or "trunk" branch,
   112  which describes the intended state of production infrastructure. When a
   113  feature branch is created to develop a change, the developer of that feature
   114  might create a corresponding workspace and deploy into it a temporary "copy"
   115  of the main infrastructure so that changes can be tested without affecting
   116  the production infrastructure. Once the change is merged and deployed to the
   117  default workspace, the test infrastructure can be destroyed and the temporary
   118  workspace deleted.
   119  
   120  When Terraform is used to manage larger systems, teams should use multiple
   121  separate Terraform configurations that correspond with suitable architectural
   122  boundaries within the system so that different components can be managed
   123  separately and, if appropriate, by distinct teams. Workspaces _alone_
   124  are not a suitable tool for system decomposition, because each subsystem should
   125  have its own separate configuration and backend, and will thus have its own
   126  distinct set of workspaces.
   127  
   128  In particular, organizations commonly want to create a strong separation
   129  between multiple deployments of the same infrastructure serving different
   130  development stages (e.g. staging vs. production) or different internal teams.
   131  In this case, the backend used for each deployment often belongs to that
   132  deployment, with different credentials and access controls. Named workspaces
   133  are _not_ a suitable isolation mechanism for this scenario.
   134  
   135  Instead, use one or more [re-usable modules](/docs/modules/index.html) to
   136  represent the common elements, and then represent each instance as a separate
   137  configuration that instantiates those common elements in the context of a
   138  different backend. In that case, the root module of each configuration will
   139  consist only of a backend configuration and a small number of `module` blocks
   140  whose arguments describe any small differences between the deployments.
   141  
   142  Where multiple configurations are representing distinct system components
   143  rather than multiple deployments, data can be passed from one component to
   144  another using paired resources types and data sources. For example:
   145  
   146  * Where a shared [Consul](https://consul.io/) cluster is available, use
   147    [`consul_key_prefix`](/docs/providers/consul/r/key_prefix.html) to
   148    publish to the key/value store and [`consul_keys`](/docs/providers/consul/d/keys.html)
   149    to retrieve those values in other configurations.
   150  
   151  * In systems that support user-defined labels or tags, use a tagging convention
   152    to make resources automatically discoverable. For example, use
   153    [the `aws_vpc` resource type](/docs/providers/aws/r/vpc.html)
   154    to assign suitable tags and then
   155    [the `aws_vpc` data source](/docs/providers/aws/d/vpc.html)
   156    to query by those tags in other configurations.
   157  
   158  * For server addresses, use a provider-specific resource to create a DNS
   159    record with a predictable name and then either use that name directly or
   160    use [the `dns` provider](/docs/providers/dns/index.html) to retrieve
   161    the published addresses in other configurations.
   162  
   163  * If a Terraform state for one configuration is stored in a remote backend
   164    that is accessible to other configurations then
   165    [`terraform_remote_state`](/docs/providers/terraform/d/remote_state.html)
   166    can be used to directly consume its root module outputs from those other
   167    configurations. This creates a tighter coupling between configurations,
   168    but avoids the need for the "producer" configuration to explicitly
   169    publish its results in a separate system.
   170  
   171  ## Workspace Internals
   172  
   173  Workspaces are technically equivalent to renaming your state file. They
   174  aren't any more complex than that. Terraform wraps this simple notion with
   175  a set of protections and support for remote state.
   176  
   177  For local state, Terraform stores the workspace states in a directory called
   178  `terraform.tfstate.d`. This directory should be be treated similarly to
   179  local-only `terraform.tfstate`; some teams commit these files to version
   180  control, although using a remote backend instead is recommended when there are
   181  multiple collaborators.
   182  
   183  For [remote state](/docs/state/remote.html), the workspaces are stored
   184  directly in the configured [backend](/docs/backends). For example, if you
   185  use [Consul](/docs/backends/types/consul.html), the workspaces are stored
   186  by appending the workspace name to the state path. To ensure that
   187  workspace names are stored correctly and safely in all backends, the name
   188  must be valid to use in a URL path segment without escaping.
   189  
   190  The important thing about workspace internals is that workspaces are
   191  meant to be a shared resource. They aren't a private, local-only notion
   192  (unless you're using purely local state and not committing it).
   193  
   194  The "current workspace" name is stored only locally in the ignored
   195  `.terraform` directory. This allows multiple team members to work on
   196  different workspaces concurrently.