背景介绍

Terraform是HashiCorp公司开源的工具，目前众多的云厂商支持使用terraform进行资源编排。Terraform采用插件的方式对接不同种类和厂家资源，涉及计算、存储、网络、数据库等。因为插件的可扩展性强，未来会支持更多种类的资源操作以及编排。目前我司也有相应的云服务插件。

跑通Kubernetes样例

1、下载terraform二进制(https://www.terraform.io/downloads.html)，保存到$PATH目录。

2、Terraform拉取Plugins, 运行 terraform init；如果是内网运行可能遇到错误(x509: certificate signed by unknown authority)，记得注册公司的根证书。

provider "kubernetes" {
  config_path = "~/.kube/config"
}

3、编写需要部署的资源文件deploy.tf, 需要注意的Terraform与yaml语法略微有差别，文章后面有介绍。

resource "kubernetes_deployment" "test"
      |                            |                          |
资源语法关键字  资源类型      Terraform能识别的资源名称

provider "kubernetes" {
  config_path = "~/.kube/config"
}
resource "kubernetes_namespace" "test" {
  metadata {
    name = "nginx"
  }
}
resource "kubernetes_deployment" "test" {
  metadata {
    name      = "nginx"
    namespace = kubernetes_namespace.test.metadata.0.name
  }
  spec {
    replicas = 1
    selector {
      match_labels = {
        app = "MyTestApp"
      }
    }
    template {
      metadata {
        labels = {
          app = "MyTestApp"
        }
      }
      spec {
        container {
          image = "nginx"
          name  = "nginx-container"
          port {
            container_port = 80
          }
        }
      }
    }
  }
}

4、运行terraform plan查看资源概览

# kubernetes_deployment.test:
resource "kubernetes_deployment" "test" {
    id               = "nginx/nginx"
    wait_for_rollout = true

    metadata {
        generation       = 1
        name             = "nginx"
        namespace        = "nginx"
        resource_version = "138151370"
        uid              = "610b9bd5-da91-405e-9beb-5559a8031a5b"
    }

    spec {
        min_ready_seconds         = 0
        paused                    = false
        progress_deadline_seconds = 600
        replicas                  = "1"
        revision_history_limit    = 10

        selector {
            match_labels = {
                "app" = "MyTestApp"
            }
        }

        strategy {
            type = "RollingUpdate"

            rolling_update {
                max_surge       = "25%"
                max_unavailable = "25%"
            }
        }

        template {
            metadata {
                generation = 0
                labels     = {
                    "app" = "MyTestApp"
                }
            }

            spec {
                active_deadline_seconds          = 0
                automount_service_account_token  = true
                dns_policy                       = "ClusterFirst"
                enable_service_links             = true
                host_ipc                         = false
                host_network                     = false
                host_pid                         = false
                restart_policy                   = "Always"
                share_process_namespace          = false
                termination_grace_period_seconds = 30

                container {
                    image                      = "nginx"
                    image_pull_policy          = "Always"
                    name                       = "nginx-container"
                    stdin                      = false
                    stdin_once                 = false
                    termination_message_path   = "/dev/termination-log"
                    termination_message_policy = "File"
                    tty                        = false

                    port {
                        container_port = 80
                        host_port      = 0
                        protocol       = "TCP"
                    }

                    resources {}
                }
            }
        }
    }
}

# kubernetes_namespace.test:
resource "kubernetes_namespace" "test" {
    id = "nginx"

    metadata {
        generation       = 0
        name             = "nginx"
        resource_version = "138151336"
        uid              = "d9a012f4-f2e3-4af9-932f-073ada5fdefc"
    }
}

5、执行terraform apply，部署Kuberntes资源，部署过程Terraform会持久化状态文件：terraform.tfstate(注意不要删除该文件)。

5、部署后，运行terraform show查看刚刚部署的资源。

# kubernetes_deployment.test:
resource "kubernetes_deployment" "test" {
    id               = "nginx/nginx"
    wait_for_rollout = true

    metadata {
           ...
    }

    spec {
           ...
    }
}

# kubernetes_namespace.test:
resource "kubernetes_namespace" "test" {
    id = "nginx"

    metadata {
            ...  
    }
}

6、资源更新，更新deploy镜像，修改deploy.tf，运行terraform apply。

QA：

1、如何定义资源的先后关系？

2、如果引用其他资源的属性？

参考

1、Terraform语法，例如list、map格式。