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website: more-elaborate "terraform init" docs 

The "terraform init" command has a lot of different functionality now,
making it hard to follow all of the options in the previous presentation.
Instead, here we describe each of the steps and its associated options
separately, hopefully making it easier to understand what each option
relates to.

In addition, much of the detail around backend partial configuration is
factored out into the backend configuration page, where it seems more
"at home"; previously it felt hard to follow exactly how partial
configuration would be used, due to the information on it being split over
two different pages.
This commit is contained in:
Martin Atkins 2017-07-24 17:04:28 -07:00
parent 539f0db74e
commit 23ef0e3247
2 changed files with 141 additions and 94 deletions
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80
website/docs/backends/config.html.md
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@ -18,7 +18,7 @@ Below, we show a complete example configuring the "consul" backend:
terraform {
backend "consul" {
address = "demo.consul.io"
path = "tfdocs"
path = "example_app/terraform_state"
}
}
```
@ -48,35 +48,46 @@ a configuration in the future: create the new configuration and run
## Partial Configuration
You do not need to specify every required attribute in the configuration.
This may be desirable to avoid storing secrets (such as access keys) within
the configuration itself. We call this specifying only a _partial_ configuration.
You do not need to specify every required argument in the backend configuration.
Omitting certain arguments may be desirable to avoid storing secrets, such as
access keys, within the main configuration. When some or all of the arguments
are ommitted, we call this a _partial configuration_.
With a partial configuration, the remaining configuration is expected as
part of the [initialization](/docs/backends/init.html) process. There are
a few ways to supply the remaining configuration:
With a partial configuration, the remaining configuration arguments must be
provided as part of
[the initialization process](/docs/backends/init.html#backend-initialization).
There are several ways to supply the remaining arguments:
* **Interactively**: Terraform will interactively ask you for the required
values. Terraform will not ask you for optional values.
values, unless interactive input is disabled. Terraform will not prompt for
optional values.
* **File**: A configuration file may be specified via the command line.
This file can then be sourced via some secure means (such as
[Vault](https://www.vaultproject.io)).
* **File**: A configuration file may be specified via the `init` command line.
To specify a file, use the `-backend-config=PATH` option when running
`terraform init`. If the file contains secrets it may be kept in
a secure data store, such as
[Vault](https://www.vaultproject.io/), in which case it must be downloaded
to the local disk before running Terraform.
* **Command-line key/value pairs**: Key/value pairs in the format of
`key=value` can be specified as part of the init command. Note that
many shells retain command-line flags in a history file, so this isn't
recommended for secrets.
* **Command-line key/value pairs**: Key/value pairs can be specified via the
`init` command line. Note that many shells retain command-line flags in a
history file, so this isn't recommended for secrets. To specify a single
key/value pair, use the `-backend-config="KEY=VALUE"` option when running
`terraform init`.
In all cases, the final configuration is stored on disk in the
".terraform" directory, which should be ignored from version control.
If backend settings are provided in multiple locations, the top-level
settings are merged such that any command-line options override the settings
in the main configuration and then the command-line options are processed
in order, with later options overriding values set by earlier options.
This means that sensitive information can be omitted from version control
but it ultimately still lives on disk. In the future, Terraform may provide
basic encryption on disk so that values are at least not plaintext.
The final, merged configuration is stored on disk in the `.terraform`
directory, which should be ignored from version control. This means that
sensitive information can be omitted from version control, but it will be
present in plain text on local disk when running Terraform.
When using partial configuration, Terraform requires at a minimum that
an empty backend configuration is in the Terraform files. For example:
an empty backend configuration is specified in one of the root Terraform
configuration files, to specify the backend type. For example:
```hcl
terraform {
@ -84,10 +95,23 @@ terraform {
}
```
This minimal requirement allows Terraform to detect _unsetting_ backends.
We cannot accept the backend type on the command-line because while it is
technically possible, Terraform would then be unable to detect if you
want to unset your backend (and move back to local state).
A backend configuration file has the contents of the `backend` block as
top-level attributes, without the need to wrap it in another `terraform`
or `backend` block:
```hcl
address = "demo.consul.io"
path = "example_app/terraform_state"
```
The same settings can alternatively be specified on the command line as
follows:
```
$ terraform init \
-backend-config="address=demo.consul.io" \
-backend-config="path=example_app/terraform_state"
```
## Changing Configuration
@ -101,9 +125,9 @@ the reinitialization process, Terraform will ask if you'd like to migrate
your existing state to the new configuration. This allows you to easily
switch from one backend to another.
If you're using [state environments](/docs/state/environments.html),
Terraform is able to copy all environments to the destination. If Terraform
detects you have multiple states, it will ask if this is what you want to do.
If you're using multiple [workspaces](/docs/state/workspaces.html),
Terraform can copy all workspaces to the destination. If Terraform detects
you have multiple workspaces, it will ask if this is what you want to do.
If you're just reconfiguring the same backend, Terraform will still ask if you
want to migrate your state. You can respond "no" in this scenario.

153
website/docs/commands/init.html.markdown
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@ -17,90 +17,113 @@ from version control. It is safe to run this command multiple times.
Usage: `terraform init [options] [DIR]`
Initialize a new or existing Terraform working directory by creating
initial files, loading any remote state, downloading modules, etc.
This command performs several different initialization steps in order to
prepare a working directory for use. More details on these are in the
sections below, but in most cases it is not necessary to worry about these
individual steps.
This is the first command that should be run for any new or existing
Terraform configuration per machine. This sets up all the local data
necessary to run Terraform that is typically not committed to version
control.
This command is always safe to run multiple times, to bring the working
directory up to date with changes in the configuration. Though subsequent runs
may give errors, this command will never delete your existing configuration or
state.
This command is always safe to run multiple times. Though subsequent runs
may give errors, this command will never delete your configuration or
state. Even so, if you have important information, please back it up prior
to running this command, just in case.
If no arguments are given, the configuration in the current working directory
is initialized. It is recommended to run Terraform with the current working
directory set to the root directory of the configuration, and omit the `DIR`
argument.
If no arguments are given, the configuration in this working directory
is initialized.
## General Options
The command-line flags are all optional. The list of available flags are:
* `-backend=true` - Initialize the [backend](/docs/backends) for this configuration.
* `-backend-config=path` This can be either a path to an HCL file with key/value
assignments (same format as terraform.tfvars) or a 'key=value' format. This is
merged with what is in the configuration file. This can be specified multiple
times. The backend type must be in the configuration itself.
* `-force-copy` Suppress prompts about copying state data. This is
equivalent to providing a "yes" to all confirmation prompts.
* `-get=true` Download any modules for this configuration.
* `-get-plugins=true` Download any missing plugins for this configuration.
The following options apply to all of (or several of) the initialization steps:
* `-input=true` Ask for input if necessary. If false, will error if
input was required.
* `-lock=true` Lock the state file when locking is supported.
* `-lock=false` Disable locking of state files during state-related operations.
* `-lock-timeout=0s` Duration to retry a state lock.
* `-lock-timeout=<duration>` Override the time Terraform will wait to acquire
a state lock. The default is `0s` (zero seconds), which causes immediate
failure if the lock is already held by another process.
* `-no-color` If specified, output won't contain any color.
* `-no-color` Disable color codes in the command output.
* `-plugin-dir` Directory containing plugin binaries. This overrides all
default search paths for plugins, and prevents the automatic installation of
plugins. This flag can be used multiple times.
* `-upgrade` Opt to upgrade modules and plugins as part of their respective
installation steps. See the seconds below for more details.
* `-reconfigure` Reconfigure the backend, ignoring any saved configuration.
## Backend Initialization
* `-upgrade=false` If installing modules (-get) or plugins (-get-plugins),
ignore previously-downloaded objects and install the latest version allowed
within configured constraints.
During init, the root configuration directory is consulted for
[backend configuration](/docs/backends/config.html) and the chosen backend
is initialized using the given configuration settings.
* `-verify-plugins=true` Verify the authenticity and integrity of automatically
downloaded plugins.
Re-running init with an already-initalized backend will update the working
directory to use the new backend settings. Depending on what changed, this
may result in interactive prompts to confirm migration of workspace states.
The `-force-copy` option suppresses these prompts and answers "yes" to the
migration questions. The `-reconfigure` option disregards any existing
configuration, preventing migration of any existing state.
## Backend Config
To skip backend configuration, use `-backend=false`. Note that some other init
steps require an initialized backend, so it's recommended to use this flag only
when the working directory was already previously initialized for a particular
backend.
The `-backend-config` can take a path or `key=value` pair to specify additional
backend configuration when [initializing a backend](/docs/backends/init.html).
The `-backend-config=...` option can be used for
[partial backend configuration](/docs/backends/config.html#partial-configuration),
in situations where the backend settings are dynamic or sensitive and so cannot
be statically specified in the configuration file.
This is particularly useful for
[partial configuration of backends](/docs/backends/config.html). Partial
configuration lets you keep sensitive information out of your Terraform
configuration.
## Child Module Installation
For path values, the backend configuration file is a basic HCL file with key/value pairs.
The keys are configuration keys for your backend. You do not need to wrap it
in a `terraform` block. For example, the following file is a valid backend
configuration file for the Consul backend type:
During init, the configuration is searched for `module` blocks, and the source
code for referenced [modules](/docs/modules/) is retrieved from the locations
given in their `source` arguments.
```hcl
address = "demo.consul.io"
path = "newpath"
```
Re-running init with modules already installed will install the sources for
any modules that were added to configuration since the last init, but will not
change any already-installed modules. Use `-upgrade` to override this behavior,
updating all modules to the latest available source code.
If the value contains an equal sign (`=`), it is parsed as a `key=value` pair.
The format of this flag is identical to the `-var` flag for plan, apply,
etc. but applies to configuration keys for backends. For example:
To skip child module installation, use `-get=false`. Note that some other init
steps can complete only when the module tree is complete, so it's recommended
to use this flag only when the working directory was already previously
initialized with its child modules.
```shell
$ terraform init \
-backend-config 'address=demo.consul.io' \
-backend-config 'path=newpath'
```
## Plugin Installation
These two formats can be mixed. In this case, the values will be merged by
key with keys specified later in the command-line overriding conflicting
keys specified earlier.
During init, the configuration is searched for both direct and indirect
references to [providers](/docs/configuration/providers.html), and the plugins
for the providers are retrieved from the plugin repository. The downloaded
plugins are installed to a subdirectory of the working directory, and are thus
local to that working directory.
Re-running init with plugins already installed will install plugins only for
any providers that were added to the configuration since the last init. Use
`-upgrade` to additionally update already-installed plugins to the latest
versions that comply with the version constraints given in configuration.
To skip plugin installation, use `-get-plugins=false`.
The automatic plugin installation behavior can be overridden by extracting
the desired providers into a local directory and using the additonal option
`-plugin-dir=PATH`. When this option is specified, _only_ the given directory
is consulted, which prevents Terraform from making requests to the plugin
repository or looking for plugins in other local directories.
When plugins are automatically downloaded and installed, by default the
contents are verified against an official HashiCorp release signature to
ensure that they were not corrupted or tampered with during download. It is
recommended to allow Terraform to make these checks, but if desired they may
be disabled using the option `-verify-plugins=false`.
## Running `terraform init` in automation
For teams that use Terraform as a key part of a change management and
deployment pipeline, it can be desirable to orchestrate Terraform runs in some
sort of automation in order to ensure consistency between runs, and provide
other interesting features such as integration with version control hooks.
There are some special concerns when running `init` in such an environment,
including optionally making plugins available locally to avoid repeated
re-installation. For more information, see
[`Running Terraform in Automation`](/guides/running-terraform-in-automation.html).