website: CLI: Remove several ghost pages, update old links

- /docs/plugins/*
- /docs/commands/state/addressing.html

These were redundant pages.
This commit is contained in:
Nick Fagerlund 2021-01-19 14:51:44 -08:00
parent a60120477c
commit 33d2d9abb5
9 changed files with 6 additions and 456 deletions

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@ -25,7 +25,7 @@ within modules are listed last.
For complex infrastructures, the state can contain thousands of resources. For complex infrastructures, the state can contain thousands of resources.
To filter these, provide one or more patterns to the command. Patterns are To filter these, provide one or more patterns to the command. Patterns are
in [resource addressing format](/docs/commands/state/addressing.html). in [resource addressing format](/docs/cli/state/resource-addressing.html).
The command-line flags are all optional. The list of available flags are: The command-line flags are all optional. The list of available flags are:

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@ -36,7 +36,7 @@ for each state file.
This command requires a source and destination address of the item to move. This command requires a source and destination address of the item to move.
Addresses are Addresses are
in [resource addressing format](/docs/commands/state/addressing.html). in [resource addressing format](/docs/cli/state/resource-addressing.html).
The command-line flags are all optional. The list of available flags are: The command-line flags are all optional. The list of available flags are:

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@ -39,7 +39,7 @@ of this command, backups are required.
This command requires one or more addresses that point to a resources in the This command requires one or more addresses that point to a resources in the
state. Addresses are state. Addresses are
in [resource addressing format](/docs/commands/state/addressing.html). in [resource addressing format](/docs/cli/state/resource-addressing.html).
The command-line flags are all optional. The list of available flags are: The command-line flags are all optional. The list of available flags are:

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@ -21,7 +21,7 @@ state file that matches the given address.
This command requires an address that points to a single resource in the This command requires an address that points to a single resource in the
state. Addresses are state. Addresses are
in [resource addressing format](/docs/commands/state/addressing.html). in [resource addressing format](/docs/cli/state/resource-addressing.html).
The command-line flags are all optional. The list of available flags are: The command-line flags are all optional. The list of available flags are:

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@ -20,5 +20,5 @@ Converting a resource to be importable is also relatively simple, so if
you're interested in contributing that functionality, the Terraform team you're interested in contributing that functionality, the Terraform team
would be grateful. would be grateful.
To make a resource importable, please see the To make a resource importable, please see
[plugin documentation on writing a resource](/docs/plugins/provider.html). [Extending Terraform: Resources — Import](/docs/extend/resources/import.html).

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@ -1,20 +0,0 @@
---
layout: "docs"
page_title: "Command: state resource addressing"
sidebar_current: "docs-commands-state-address"
description: |-
The `terraform state` command is used for advanced state management.
---
# Resource Addressing
The `terraform state` subcommands use
[standard address syntax](/docs/cli/state/resource-addressing.html) to refer
to individual resources, resource instances, and modules. This is the same
syntax used for the `-target` option to the `apply` and `plan` commands.
Most state commands allow referring to individual resource instances, whole
resources (which may have multiple instances if `count` or `for_each` is used),
or even whole modules.
For more information on the syntax, see [Resource Addressing](/docs/cli/state/resource-addressing.html).

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@ -1,98 +0,0 @@
---
layout: "extend"
page_title: "Plugin Basics"
sidebar_current: "docs-plugins-basics"
description: |-
This page documents the basics of how the plugin system in Terraform works, and how to setup a basic development environment for plugin development if you're writing a Terraform plugin.
---
# Plugin Basics
~> **Advanced topic!** Plugin development is a highly advanced
topic in Terraform, and is not required knowledge for day-to-day usage.
If you don't plan on writing any plugins, this section of the documentation is
not necessary to read. For general use of Terraform, please see
[Intro to Terraform](/intro/index.html) or the
[Terraform: Get Started](https://learn.hashicorp.com/collections/terraform/aws-get-started?utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS)
collection on HashiCorp Learn.
This page documents the basics of how the plugin system in Terraform
works, and how to setup a basic development environment for plugin development
if you're writing a Terraform plugin.
## How it Works
Terraform providers and provisioners are provided via plugins. Each plugin
exposes an implementation for a specific service, such as AWS, or provisioner,
such as bash. Plugins are executed as a separate process and communicate with
the main Terraform binary over an RPC interface.
The code within the binaries must adhere to certain interfaces.
The network communication and RPC is handled automatically by higher-level
Terraform libraries. The exact interface to implement is documented
in its respective documentation section.
## Installing Plugins
The [provider plugins distributed by HashiCorp](/docs/providers/index.html) are
automatically installed by `terraform init`. Third-party plugins (both
providers and provisioners) can be manually installed into the user plugins
directory, located at `%APPDATA%\terraform.d\plugins` on Windows and
`~/.terraform.d/plugins` on other systems.
For more information, see:
- [Configuring Providers](/docs/language/providers/configuration.html)
For developer-centric documentation, see:
- [How Terraform Works: Plugin Discovery](/docs/extend/how-terraform-works.html#discovery)
## Developing a Plugin
Developing a plugin is simple. The only knowledge necessary to write
a plugin is basic command-line skills and basic knowledge of the
[Go programming language](http://golang.org).
-> **Note:** A common pitfall is not properly setting up a
<code>$GOPATH</code>. This can lead to strange errors. You can read more about
this [here](https://golang.org/doc/code.html) to familiarize
yourself.
Create a new Go project somewhere in your `$GOPATH`. If you're a
GitHub user, we recommend creating the project in the directory
`$GOPATH/src/github.com/USERNAME/terraform-NAME`, where `USERNAME`
is your GitHub username and `NAME` is the name of the plugin you're
developing. This structure is what Go expects and simplifies things down
the road.
The `NAME` should either begin with `provider-` or `provisioner-`,
depending on what kind of plugin it will be. The repository name will,
by default, be the name of the binary produced by `go install` for
your plugin package.
With the package directory made, create a `main.go` file. This project will
be a binary so the package is "main":
```golang
package main
import (
"github.com/hashicorp/terraform/plugin"
)
func main() {
plugin.Serve(new(MyPlugin))
}
```
The name `MyPlugin` is a placeholder for the struct type that represents
your plugin's implementation. This must implement either
`terraform.ResourceProvider` or `terraform.ResourceProvisioner`, depending
on the plugin type.
To test your plugin, the easiest method is to copy your `terraform` binary
to `$GOPATH/bin` and ensure that this copy is the one being used for testing.
`terraform init` will search for plugins within the same directory as the
`terraform` binary, and `$GOPATH/bin` is the directory into which `go install`
will place the plugin executable.

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@ -1,24 +0,0 @@
---
layout: "extend"
page_title: "Plugins"
sidebar_current: "docs-plugins"
description: |-
Terraform is built on a plugin-based architecture. All providers and provisioners that are used in Terraform configurations are plugins, even the core types such as AWS and Heroku. Users of Terraform are able to write new plugins in order to support new functionality in Terraform.
---
# Plugins
Terraform is built on a plugin-based architecture. All providers and
provisioners that are used in Terraform configurations are plugins, even
the core types such as AWS and Heroku. Users of Terraform are able to
write new plugins in order to support new functionality in Terraform.
This section of the documentation gives a high-level overview of how
to write plugins for Terraform. It does not hold your hand through the
process, however, and expects a relatively high level of understanding
of Go, provider semantics, Unix, etc.
~> **Advanced topic!** Plugin development is a highly advanced
topic in Terraform, and is not required knowledge for day-to-day usage.
If you don't plan on writing any plugins, we recommend not reading
this section of the documentation.

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@ -1,308 +0,0 @@
---
layout: "extend"
page_title: "Provider Plugins"
sidebar_current: "docs-plugins-provider"
description: |-
A provider in Terraform is responsible for the lifecycle of a resource: create, read, update, delete. An example of a provider is AWS, which can manage resources of type `aws_instance`, `aws_eip`, `aws_elb`, etc.
---
# Provider Plugins
~> **Advanced topic!** Plugin development is a highly advanced
topic in Terraform, and is not required knowledge for day-to-day usage.
If you don't plan on writing any plugins, this section of the documentation is
not necessary to read. For general use of Terraform, please see
[Intro to Terraform](/intro/index.html) or the
[Terraform: Get Started](https://learn.hashicorp.com/collections/terraform/aws-get-started?utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS)
collection on HashiCorp Learn.
> **Hands-on:** Try the [Call APIs with Terraform Providers](https://learn.hashicorp.com/collections/terraform/providers?utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS) collection on HashiCorp Learn.
A provider in Terraform is responsible for the lifecycle of a resource:
create, read, update, delete. An example of a provider is AWS, which
can manage resources of type `aws_instance`, `aws_eip`, `aws_elb`, etc.
The primary reasons to care about provider plugins are:
* You want to add a new resource type to an existing provider.
* You want to write a completely new provider for managing resource
types in a system not yet supported.
* You want to write a completely new provider for custom, internal
systems such as a private inventory management system.
If you're interested in provider development, then read on. The remainder
of this page will assume you're familiar with
[plugin basics](/docs/plugins/basics.html) and that you already have
a basic development environment setup.
## Provider Plugin Codebases
Provider plugins live outside of the Terraform core codebase in their own
source code repositories, and are typically published in a provider registry
such as [the public Terraform Registry](https://registry.terraform.io/).
When developing a provider plugin, it is recommended to use a common `GOPATH`
that includes both the core Terraform repository and the repositories of any
providers being changed. This makes it easier to use a locally-built
`terraform` executable and a set of locally-built provider plugins together
without further configuration.
For example, to download both Terraform and the `template` provider into
`GOPATH`:
```
$ go get github.com/hashicorp/terraform
$ go get github.com/terraform-providers/terraform-provider-template
```
These two packages are both "main" packages that can be built into separate
executables with `go install`:
```
$ go install github.com/hashicorp/terraform
$ go install github.com/terraform-providers/terraform-provider-template
```
After running the above commands, both Terraform core and the `template`
provider will both be installed in the current `GOPATH` and `$GOPATH/bin`
will contain both `terraform` and `terraform-provider-template` executables.
This `terraform` executable will find and use the `template` provider plugin
alongside it in the `bin` directory in preference to downloading and installing
an official release.
When constructing a new provider from scratch, it's recommended to follow
a similar repository structure as for the existing providers, with the main
package in the repository root and a library package in a subdirectory named
after the provider. For more information, see the
[Call APIs with Terraform Providers](https://learn.hashicorp.com/collections/terraform/providers?utm_source=WEBSITE/docs/extend/writing-custom-providers.htmlutm_medium=WEB_IO/docs/extend/writing-custom-providers.htmlutm_offer=ARTICLE_PAGE/docs/extend/writing-custom-providers.htmlutm_content=DOCS) collection on HashiCorp Learn.
When making changes only to files within the provider repository, it is _not_
necessary to re-build the main Terraform executable. Note that some packages
from the Terraform repository are used as library dependencies by providers,
such as `github.com/hashicorp/terraform/helper/schema`; it is recommended to
use `govendor` to create a local vendor copy of the relevant packages in the
provider repository, as can be seen in the repositories within the
`terraform-providers` GitHub organization.
## Low-Level Interface
The interface you must implement for providers is
[ResourceProvider](https://github.com/hashicorp/terraform/blob/master/terraform/resource_provider.go).
This interface is extremely low level, however, and we don't recommend
you implement it directly. Implementing the interface directly is error
prone, complicated, and difficult.
Instead, we've developed some higher level libraries to help you out
with developing providers. These are the same libraries we use in our
own core providers.
## helper/schema
The `helper/schema` package in the plugin SDK is a framework designed to allow
building providers at a higher level of abstraction than the raw plugin protocol
that Terraform expects. This is the same library we've used to build most
of the official providers.
For more information on `helper/schema`, see
[the `helper/schema` package reference documentation](https://pkg.go.dev/github.com/hashicorp/terraform-plugin-sdk/helper/schema).
## Provider
The first thing to do in your plugin is to create the
[schema.Provider](https://godoc.org/github.com/hashicorp/terraform/helper/schema#Provider) structure.
This structure implements the `ResourceProvider` interface. We
recommend creating this structure in a function to make testing easier
later. Example:
```golang
func Provider() *schema.Provider {
return &schema.Provider{
...
}
}
```
Within the `schema.Provider`, you should initialize all the fields. They
are documented within the godoc, but a brief overview is here as well:
* `Schema` - This is the configuration schema for the provider itself.
You should define any API keys, etc. here. Schemas are covered below.
* `ResourcesMap` - The map of resources that this provider supports.
All keys are resource names and the values are the
[schema.Resource](https://godoc.org/github.com/hashicorp/terraform/helper/schema#Resource) structures implementing this resource.
* `ConfigureFunc` - This function callback is used to configure the
provider. This function should do things such as initialize any API
clients, validate API keys, etc. The `interface{}` return value of
this function is the `meta` parameter that will be passed into all
resource [CRUD](https://en.wikipedia.org/wiki/Create,_read,_update_and_delete)
functions. In general, the returned value is a configuration structure
or a client.
As part of the unit tests, you should call `InternalValidate`. This is used
to verify the structure of the provider and all of the resources, and reports
an error if it is invalid. An example test is shown below:
```golang
func TestProvider(t *testing.T) {
if err := Provider().(*schema.Provider).InternalValidate(); err != nil {
t.Fatalf("err: %s", err)
}
}
```
Having this unit test will catch a lot of beginner mistakes as you build
your provider.
## Resources
Next, you'll want to create the resources that the provider can manage.
These resources are put into the `ResourcesMap` field of the provider
structure. Again, we recommend creating functions to instantiate these.
An example is shown below.
```golang
func resourceComputeAddress() *schema.Resource {
return &schema.Resource {
...
}
}
```
Resources are described using the
[schema.Resource](https://godoc.org/github.com/hashicorp/terraform/helper/schema#Resource)
structure. This structure has the following fields:
* `Schema` - The configuration schema for this resource. Schemas are
covered in more detail below.
* `Create`, `Read`, `Update`, and `Delete` - These are the callback
functions that implement CRUD operations for the resource. The only
optional field is `Update`. If your resource doesn't support update, then
you may keep that field nil.
* `Importer` - If this is non-nil, then this resource is
[importable](/docs/cli/import/importability.html). It is recommended to
implement this.
The CRUD operations in more detail, along with their contracts:
* `Create` - This is called to create a new instance of the resource.
Terraform guarantees that an existing ID is not set on the resource
data. That is, you're working with a new resource. Therefore, you are
responsible for calling `SetId` on your `schema.ResourceData` using a
value suitable for your resource. This ensures whatever resource
state you set on `schema.ResourceData` will be persisted in local state.
If you neglect to `SetId`, no resource state will be persisted.
* `Read` - This is called to resync the local state with the remote state.
Terraform guarantees that an existing ID will be set. This ID should be
used to look up the resource. Any remote data should be updated into
the local data. **No changes to the remote resource are to be made.**
If the resource is no longer present, calling `SetId`
with an empty string will signal its removal.
* `Update` - This is called to update properties of an existing resource.
Terraform guarantees that an existing ID will be set. Additionally,
the only changed attributes are guaranteed to be those that support
update, as specified by the schema. Be careful to read about partial
states below.
* `Delete` - This is called to delete the resource. Terraform guarantees
an existing ID will be set.
* `Exists` - This is called to verify a resource still exists. It is
called prior to `Read`, and lowers the burden of `Read` to be able
to assume the resource exists. `false` should be returned if
the resources is no longer present, which has the same effect
as calling `SetId("")` from `Read` (i.e. removal of the resource data
from state).
## Schemas
Both providers and resources require a schema to be specified. The schema
is used to define the structure of the configuration, the types, etc. It is
very important to get correct.
In both provider and resource, the schema is a `map[string]*schema.Schema`.
The key of this map is the configuration key, and the value is a schema for
the value of that key.
Schemas are incredibly powerful, so this documentation page won't attempt
to cover the full power of them. Instead, the API docs should be referenced
which cover all available settings.
We recommend viewing schemas of existing or similar providers to learn
best practices. A good starting place is the
[core Terraform providers](https://github.com/terraform-providers).
## Resource Data
The parameter to provider configuration as well as all the CRUD operations
on a resource is a
[schema.ResourceData](https://godoc.org/github.com/hashicorp/terraform/helper/schema#ResourceData).
This structure is used to query configurations as well as to set information
about the resource such as its ID, connection information, and computed
attributes.
The API documentation covers ResourceData well, as well as the core providers
in Terraform.
**Partial state** deserves a special mention. Occasionally in Terraform, create or
update operations are not atomic; they can fail halfway through. As an example,
when creating an AWS security group, creating the group may succeed,
but creating all the initial rules may fail. In this case, it is incredibly
important that Terraform record the correct _partial state_ so that a
subsequent `terraform apply` fixes this resource.
Most of the time, partial state is not required. When it is, it must be
specifically enabled. An example is shown below:
```golang
func resourceUpdate(d *schema.ResourceData, meta interface{}) error {
// Enable partial state mode
d.Partial(true)
if d.HasChange("tags") {
// If an error occurs, return with an error,
// we didn't finish updating
if err := updateTags(d, meta); err != nil {
return err
}
d.SetPartial("tags")
}
if d.HasChange("name") {
if err := updateName(d, meta); err != nil {
return err
}
d.SetPartial("name")
}
// We succeeded, disable partial mode
d.Partial(false)
return nil
}
```
In the example above, it is possible that setting the `tags` succeeds,
but setting the `name` fails. In this scenario, we want to make sure
that only the state of the `tags` is updated. To do this the
`Partial` and `SetPartial` functions are used.
`Partial` toggles partial-state mode. When disabled, all changes are merged
into the state upon result of the operation. When enabled, only changes
enabled with `SetPartial` are merged in.
`SetPartial` tells Terraform what state changes to adopt upon completion
of an operation. You should call `SetPartial` with every key that is safe
to merge into the state. The parameter to `SetPartial` is a prefix, so
if you have a nested structure and want to accept the whole thing,
you can just specify the prefix.