Terraform批量创建BigTable表报错：列族属性需字符串类型

问题场景 #

使用Terraform批量创建GCP BigTable实例和多个表时，执行terraform plan报错，提示family属性需要字符串类型，但当前返回列表类型。

原模块代码 #

resource "google_project_service" "gcp_services" {
  for_each = toset(var.gcp_service_list)
  project  = var.project_id
  service  = each.key
}

resource "google_bigtable_instance" "instance" {
  name                = var.bigtable_instance_name
  project             = var.project_id
  deletion_protection = var.deletion_protection
  labels              = var.labels

  cluster {
    cluster_id   = var.bigtable_cluster_name
    zone         = var.zone
    storage_type = var.bigtable_storage_type
    autoscaling_config {
      min_nodes  = var.min_nodes
      max_nodes  = var.max_nodes
      cpu_target = var.cpu_target
    }
  }

  lifecycle {
    prevent_destroy = false
  }

  depends_on = [
    google_project_service.gcp_services
  ]
}
    
resource "google_bigtable_table" "table" {
  count = var.bigtable_count
  name = element(var.bigtable_table_name, count.index)
  instance_name = google_bigtable_instance.instance.name
  split_keys = [
    "a",
    "b",
    "c"]
  project = var.project_id

  lifecycle {
    prevent_destroy = false
  }

  column_family {
    family = lookup(var.family_type, element(var.bigtable_table_name, count.index ), [] )
  }
}

变量配置 #

variable "bigtable_count" {
  type = number
}
variable "family_type" {
  type = map(list(string))
  default = {
    "test-bigtable-tablename"= ["r", "s"]
    "test2-bigtable-tablename"= ["r", "o"]
  }
}

错误信息 #

on ../../main.tf line 48, in resource "google_bigtable_table" "table":
│   48:     family = lookup(var.family_type, element(var.bigtable_table_name, count.index ), [])
│     ├────────────────
│     │ count.index is a number, known only after apply
│     │ var.bigtable_table_name is a list of string, known only after apply
│     │ var.family_type is a map of list of string, known only after apply
│
│ Inappropriate value for attribute "family": string required.
╵
Operation failed: failed running terraform plan (exit 1)

错误原因 #

google_bigtable_table资源的column_family块中，family字段要求单个字符串类型的值，但当前代码直接将lookup(var.family_type, ...)返回的列族列表赋值给它，类型不匹配。每个列族需要单独定义一个column_family块，而非把多个列族塞进同一个块的family字段。

修正方案 #

使用Terraform的**动态块（dynamic block）**遍历每个表对应的列族列表，为每个列族生成独立的column_family块：

修正后的google_bigtable_table资源代码 #

resource "google_bigtable_table" "table" {
  count = var.bigtable_count
  name = element(var.bigtable_table_name, count.index)
  instance_name = google_bigtable_instance.instance.name
  split_keys = [
    "a",
    "b",
    "c"]
  project = var.project_id

  lifecycle {
    prevent_destroy = false
  }

  # 动态生成列族块
  dynamic "column_family" {
    # 遍历当前表对应的列族列表
    for_each = lookup(var.family_type, element(var.bigtable_table_name, count.index), [])
    content {
      family = column_family.value
    }
  }
}

说明 #

• dynamic "column_family"会根据for_each中的列表元素数量，自动生成对应数量的column_family块
• column_family.value取列表中的单个字符串值，匹配family字段的类型要求
• 如果某个表在family_type中没有对应配置，lookup会返回空列表，此时不会生成任何列族块

内容的提问来源于stack exchange，提问作者Ashok Reddy