使用之前首先必須將 Terraform 安裝在你的機器上。Terraform 是以二進制安裝包發佈的，它可以支持所有的平臺和架構。在本章節我們將不會涉及如何通過源代碼編譯 Terraform，但是對於那些需要通過源代碼編譯來構建可信任的二進制的用戶，我們在指南的其他章節會有闡述。
- 安裝 Terraform
Terraform 安裝包是zip格式的壓縮文件，安裝之前需首先根據系統類型下載合適的安裝包。
Terraform 安裝包下載完成後進行解壓。Terraform 是一個名稱爲 terraform 的可執行的二進制文件，包中的其他任何文件都可以刪除也不影響 Terraform 正常工作。
最後，確保 terraform 二進制文件路徑添加到 PATH 環境變量中。請參見本指南中關於在Linux、Mac、Windows上如何設置 PATH。
- 驗證安裝
Terraform 安裝完成之後，打開終端檢查 terraform 是否可用，執行 terraform 命令可以看到如下類似的幫助提示：
$ terraform
Usage: terraform [--version] [--help] <command> [args]
The available commands for execution are listed below.
The most common, useful commands are shown first, followed by
less common or more advanced commands. If you're just getting
started with Terraform, stick with the common commands. For the
other commands, please read the help and docs before usage.
Common commands:
apply Builds or changes infrastructure
console Interactive console for Terraform interpolations
# ...
如果看到 terrform 無法找到的錯誤信息，那麼就是 PATH 環境變量沒有設置正確。請檢查確保 PATH 變量包含 Terrform 的安裝路徑。
- 獲取幫助
Terraform CLI 內置了在線幫助，所有命令都可以使用 --help 參數來獲得幫助信息，例如：
$ terraform -help
Usage: terraform [-version] [-help] <command> [args]
The available commands for execution are listed below.
The most common, useful commands are shown first, followed by
less common or more advanced commands. If you are just getting
started with Terraform, stick with the common commands. For the
other commands, please read the help and docs before usage.
Common commands:
apply Builds or changes infrastructure
console Interactive console for Terraform interpolations
destroy Destroy Terraform-managed infrastructure
env Workspace management
fmt Rewrites config files to canonical format
get Download and install modules for the configuration
graph Create a visual graph of Terraform resources
import Import existing infrastructure into Terraform
init Initialize a Terraform working directory
output Read an output from a state file
plan Generate and show an execution plan
providers Prints a tree of the providers used in the configuration
refresh Update local state file against real resources
show Inspect Terraform state or plan
taint Manually mark a resource for recreation
untaint Manually unmark a resource as tainted
validate Validates the Terraform files
version Prints the Terraform version
workspace Workspace management
All other commands:
0.12upgrade Rewrites pre-0.12 module source code for v0.12
debug Debug output management (experimental)
force-unlock Manually unlock the terraform state
push Obsolete command for Terraform Enterprise legacy (v1)
state Advanced state management
任意這些子命令都可以加上 --help 參數獲取更多的幫助信息，例如：
$ terraform --help plan
Usage: terraform plan [options] [DIR]
Generates an execution plan for Terraform.
This execution plan can be reviewed prior to running apply to get a
sense for what Terraform will do. Optionally, the plan can be saved to
a Terraform plan file, and apply can take this plan file to execute
this plan exactly.
Options:
-destroy If set, a plan will be generated to destroy all resources
managed by the given configuration and state.
-detailed-exitcode Return detailed exit codes when the command exits. This
will change the meaning of exit codes to:
0 - Succeeded, diff is empty (no changes)
1 - Errored
2 - Succeeded, there is a diff
-input=true Ask for input for variables if not directly set.
-lock=true Lock the state file when locking is supported.
-lock-timeout=0s Duration to retry a state lock.
-no-color If specified, output will not contain any color.
-out=path Write a plan file to the given path. This can be used as
input to the "apply" command.
-parallelism=n Limit the number of concurrent operations. Defaults to 10.
-refresh=true Update state prior to checking for differences.
-state=statefile Path to a Terraform state file to use to look
up Terraform-managed resources. By default it will
use the state "terraform.tfstate" if it exists.
-target=resource Resource to target. Operation will be limited to this
resource and its dependencies. This flag can be used
multiple times.
-var "foo=bar" Set a variable in the Terraform configuration. This
flag can be set multiple times.
-var-file=foo Set variables in the Terraform configuration from
a file. If "terraform.tfvars" or any ".auto.tfvars"
files are present, they will be automatically loaded.
