Terraform 在升级时销毁 RDS 集群内的实例

Question

我使用 terraform 创建了一个包含 2 个实例的 RDS 集群。当我从前端升级 RDS 时，它会修改集群。但是当我使用 terraform 做同样的事情时，它会破坏实例。

我们尝试了 create_before_destroy，但出现错误。

我们尝试使用 ignore_changes=引擎，但没有做出任何改变。

有什么办法可以预防吗？

resource "aws_rds_cluster" "rds_mysql" {
  cluster_identifier              = var.cluster_identifier
  engine                          = var.engine
  engine_version                  = var.engine_version
  engine_mode                     = var.engine_mode
  availability_zones              = var.availability_zones
  database_name                   = var.database_name
  port                            = var.db_port
  master_username                 = var.master_username
  master_password                 = var.master_password
  backup_retention_period         = var.backup_retention_period
  preferred_backup_window         = var.engine_mode == "serverless" ? null : var.preferred_backup_window
  db_subnet_group_name            = var.create_db_subnet_group == "true" ? aws_db_subnet_group.rds_subnet_group[0].id : var.db_subnet_group_name
  vpc_security_group_ids          = var.vpc_security_group_ids
  db_cluster_parameter_group_name = var.create_cluster_parameter_group == "true" ? aws_rds_cluster_parameter_group.rds_cluster_parameter_group[0].id : var.cluster_parameter_group
  skip_final_snapshot             = var.skip_final_snapshot
  deletion_protection             = var.deletion_protection
  allow_major_version_upgrade     = var.allow_major_version_upgrade
  lifecycle {
    create_before_destroy = false
    ignore_changes        = [availability_zones]
  }
}

resource "aws_rds_cluster_instance" "cluster_instances" {
  count                      = var.engine_mode == "serverless" ? 0 : var.cluster_instance_count
  identifier                 = "${var.cluster_identifier}-${count.index}"
  cluster_identifier         = aws_rds_cluster.rds_mysql.id
  instance_class             = var.instance_class
  engine                     = var.engine
  engine_version             = aws_rds_cluster.rds_mysql.engine_version
  db_subnet_group_name       = var.create_db_subnet_group == "true" ? aws_db_subnet_group.rds_subnet_group[0].id : var.db_subnet_group_name
  db_parameter_group_name    = var.create_db_parameter_group == "true" ? aws_db_parameter_group.rds_instance_parameter_group[0].id : var.db_parameter_group
  apply_immediately          = var.apply_immediately
  auto_minor_version_upgrade = var.auto_minor_version_upgrade
  lifecycle {
    create_before_destroy = false
    ignore_changes        = [engine_version]
  }
}

错误：

resource \"aws_rds_cluster_instance\" \"cluster_instances\" {\n\n\n\nError: error creating RDS Cluster (aurora-cluster-mysql) Instance: DBInstanceAlreadyExists: DB instance already exists\n\tstatus code: 400, request id: c6a063cc-4ffd-4710-aff2-eb0667b0774f\n\n on

计划产出：

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  ~ update in-place
+/- create replacement and then destroy

Terraform will perform the following actions:

  # module.rds_aurora_create[0].aws_rds_cluster.rds_mysql will be updated in-place
  ~ resource "aws_rds_cluster" "rds_mysql" {
      ~ allow_major_version_upgrade         = false -> true
      ~ engine_version                      = "5.7.mysql_aurora.2.07.1" -> "5.7.mysql_aurora.2.08.1"
        id                                  = "aurora-cluster-mysql"
        tags                                = {}
        # (33 unchanged attributes hidden)
    }

  # module.rds_aurora_create[0].aws_rds_cluster_instance.cluster_instances[0] must be replaced
+/- resource "aws_rds_cluster_instance" "cluster_instances" {
      ~ arn                             = "arn:aws:rds:us-east-1:account:db:aurora-cluster-mysql-0" -> (known after apply)
      ~ availability_zone               = "us-east-1a" -> (known after apply)
      ~ ca_cert_identifier              = "rds-ca-" -> (known after apply)
      ~ dbi_resource_id                 = "db-32432432SDF" -> (known after apply)
      ~ endpoint                        = "aurora-cluster-mysql-0.jkjk.us-east-1.rds.amazonaws.com" -> (known after apply)
      ~ engine_version                  = "5.7.mysql_aurora.2.07.1" -> "5.7.mysql_aurora.2.08.1" # forces replacement
      ~ id                              = "aurora-cluster-mysql-0" -> (known after apply)
      + identifier_prefix               = (known after apply)
      + kms_key_id                      = (known after apply)
      + monitoring_role_arn             = (known after apply)
      ~ performance_insights_enabled    = false -> (known after apply)
      + performance_insights_kms_key_id = (known after apply)
      ~ port                            = 3306 -> (known after apply)
      ~ preferred_backup_window         = "07:00-09:00" -> (known after apply)
      ~ preferred_maintenance_window    = "thu:06:12-thu:06:42" -> (known after apply)
      ~ storage_encrypted               = false -> (known after apply)
      - tags                            = {} -> null
      ~ tags_all                        = {} -> (known after apply)
      ~ writer                          = true -> (known after apply)
        # (12 unchanged attributes hidden)
    }

Plan: 1 to add, 1 to change, 1 to destroy.

Answer 1

Terraform 发现实例上的引擎版本发生变化，并将此检测为强制更换的操作。

删除（或忽略更改）aws_rds_cluster_instance 资源的 engine_version 输入。

AWS RDS 升级集群实例的引擎版本自身当您升级集群的引擎版本时（这就是为什么您可以通过 AWS 控制台进行就地升级的原因).

通过排除 engine_version 输入，Terraform 将看不到对 aws_rds_cluster_instance 所做的任何更改，并且不会执行任何操作。

AWS 将在内部处理实例的引擎升级。

如果您决定忽略更改，请在 lifecycle 块中使用 ignore_changes 参数：

resource "aws_rds_cluster_instance" "cluster_instance" {
  engine_version     = aws_rds_cluster.main.engine_version
  ...

  lifecycle {
    ignore_changes        = [engine_version]
  }
}

Answer 2

我不知道，但在谷歌搜索后我发现了这个： https://github.com/hashicorp/terraform-provider-aws/issues/10714

即向 AWS Terraform 提供商的错误报告：

resource/aws_rds_cluster_instance is being destroyed and re-created when updating engine_version while apply_immediately is set to false

这似乎与您面临的问题完全相同。

那里的一条评论似乎指出了解决方案：

As of v3.63.0 (EDITED) of the provider, updates to the engine_version parameter of aws_rds_cluster_instance resources no longer forces replacement of the resource.

原来的评论好像有错别字——3.36 对 3.63。

您可以尝试升级您的 aws Terraform 提供商吗？

Answer 3

我在 aws_rds_cluster 资源中看到 apply_immediately 参数不存在，您可以添加它并尝试。

Terraform 在升级时销毁 RDS 集群内的实例

Terraform destroys the instance inside RDS cluster when upgrading

amazon-rds

terraform

terraform-provider-aws