Terraform创建MongoDB Atlas集群无法生成标准格式连接字符串

问题场景 #

用Terraform创建MongoDB Atlas集群后，输出的连接字符串缺少用户名、密码、数据库名和必要参数，格式如下：

mongodb+srv://esc-app-dbcluster-devel.b59mwv7.mongodb.net

而实际需要的完整格式为：

mongodb+srv://admin:admin@esc-app-dbcluster-devel.b59mwv7.mongodb.net/development?retryWrites=true&w=majority

用户的Terraform代码：

terraform {
  required_providers {
    mongodbatlas = {
      source = "mongodb/mongodbatlas"
      version = "1.4.6"
    }
  }
}

provider "mongodbatlas" {
  public_key = var.atlas_public_key
  private_key = var.atlas_private_key
}

resource "mongodbatlas_cluster" "db-cluster" {
  project_id              = var.atlas_project_id
  name                    = var.db_cluster_name

  # Provider Settings "block"
  provider_name = "TENANT" //free tier
  backing_provider_name = "AWS"
  provider_region_name = "US_EAST_1" //free tier
  provider_instance_size_name = "M0" //free tier
}


resource "mongodbatlas_database_user" "dbuser" {
  username           = var.db_user
  password           = var.db_password
  project_id         = var.atlas_project_id
  auth_database_name = "admin"

  roles {
    role_name     = "readWrite"
    database_name = var.environment
  }

}

resource "mongodbatlas_project_ip_access_list" "test" {
  project_id = var.atlas_project_id
  cidr_block = var.cidr
}

output "db_cn_string" {
    value = mongodbatlas_cluster.db-cluster.connection_strings.0.standard_srv
}

连接代码示例：

const environment = process.env.ENVIRONMENT;
const uridb = "mongodb+srv://admin:admin@esc-app-dbcluster-devel.b59mwv7.mongodb.net/development?retryWrites=true&w=majority" // working format 
//dburi = "mongodb+srv://esc-app-dbcluster-devel.b59mwv7.mongodb.net" --- format from terraform

console.log('environment:::::', environment);

let ENVIRONMENT_VARIABLES = {
  'process.env.ENVIRONMENT': JSON.stringify(environment),
  'process.env.PORT': JSON.stringify('80'),
  'process.env.MONGO_CONNECTION_STRING': JSON.stringify(uridb)
};

解决方案 #

通过Terraform的字符串插值或format函数，将用户名、密码、目标数据库名和参数拼接进基础连接字符串即可：

方法1：字符串直接插值 #

修改output块为：

output "db_cn_string" {
  value = "mongodb+srv://${var.db_user}:${var.db_password}@${replace(mongodbatlas_cluster.db-cluster.connection_strings.0.standard_srv, "mongodb+srv://", "")}/${var.environment}?retryWrites=true&w=majority"
}

这里用replace函数去掉原连接字符串的mongodb+srv://前缀，避免重复拼接。

方法2：使用format函数（更易读） #

output "db_cn_string" {
  value = format(
    "mongodb+srv://%s:%s@%s/%s?retryWrites=true&w=majority",
    var.db_user,
    var.db_password,
    replace(mongodbatlas_cluster.db-cluster.connection_strings.0.standard_srv, "mongodb+srv://", ""),
    var.environment
  )
}

特殊字符处理 #

如果密码包含@、:、/等特殊URL字符，需要用urlencode函数转义，防止连接字符串失效：

output "db_cn_string" {
  value = format(
    "mongodb+srv://%s:%s@%s/%s?retryWrites=true&w=majority",
    var.db_user,
    urlencode(var.db_password),
    replace(mongodbatlas_cluster.db-cluster.connection_strings.0.standard_srv, "mongodb+srv://", ""),
    var.environment
  )
}

验证 #

执行terraform apply后，输出的db_cn_string就会是符合要求的完整连接字符串，可直接用于代码中的MONGO_CONNECTION_STRING变量。

内容的提问来源于stack exchange，提问作者randomuser