Terraform部署ECS任务定义时mount_points与port_mappings丢失求助

问题描述 #

使用Terraform部署包含两个共享EBS卷的aws_ecs_task_definition时，部署流程可完成并更新任务/容器定义，但在AWS控制台查看容器定义时，mountPoints和portMappings始终为空数组。执行terraform plan时，Terraform也未识别到已配置的挂载点和端口映射。

相关Terraform代码 #

locals {
  volume_name = "ebs_test"
}

resource "aws_ebs_volume" "ebs_test" {
  availability_zone = "zone"
  size = 51

  tags = {
    Name = local.volume_name
  }
}

data "aws_ecr_image" "container_1_image" {
  repository_name = "Container1"
  image_tag = "latest"
}

data "aws_ecr_image" "container_2_image" {
  repository_name = "Container2"
  image_tag = "latest"
}

resource "aws_ecs_task_definition" "test_task" {
  family = "container_family"
  requires_compatibilities = ["EC2"]
  execution_role_arn = aws_iam_role.ecs_task_execution_role.arn
  task_role_arn = aws_iam_role.execution_role.arn
  placement_constraints {
    type = "memberOf"
    expression = "ec2InstanceId == ${module.instance.instance_id}"
  }

  volume {
    name = local.volume_name
    docker_volume_configuration {
      scope = "shared"
      autoprovision = true
      driver = "rexray/ebs"
    }
  }

  container_definitions = jsonencode([
    {
      name = "Container1"
      memory = 256
      essential = true
      image = "${var.account_id}.dkr.ecr.${var.region}.amazonaws.com/${data.aws_ecr_image.container_1_image.repository_name}:latest@${data.aws_ecr_image.container_1_image.image_digest}"
      mount_points = [
        {
          container_path = "/mnt/${local.volume_name}"
          source_volume = local.volume_name
        }
      ]
      port_mappings = [
        {
          host_port = 80
          container_port = 80
        }
      ]
    },
    {
      name = "Container2"
      memory = 256
      image = "${var.account_id}.dkr.ecr.${var.region}.amazonaws.com/${data.aws_ecr_image.container_2_image.repository_name}:latest@${data.aws_ecr_image.container_2_image.image_digest}"
      mount_points = [
        {
          source_volume = local.volume_name
          container_path = "/mnt/${local.volume_name}"
        }
      ]
      port_mappings = [
        {
          host_port = 80
          container_port = 80
        }
      ]
    }
  ])
}

异常现象 #

• AWS返回的任务JSON中显示：

  "portMappings": [],
  "mountPoints": [],
  

• terraform plan输出中未识别到挂载点和端口映射配置：

  ~ container_definitions    = jsonencode(
        ~ [
            ~ {
                - cpu              = 0
                ~ memory           = 256 -> 512
                - mountPoints      = []
                  name             = "Container1"
                - portMappings     = []
                - systemControls   = []
                - volumesFrom      = []
                  # (4 unchanged attributes hidden)
              },
            ~ {
                - cpu              = 0
                - mountPoints      = []
                  name             = "Container2"
                - portMappings     = []
                - systemControls   = []
                - volumesFrom      = []
                  # (5 unchanged attributes hidden)
              },
          ] # forces replacement
      )
  

解决方案 #

问题根源是ECS容器定义的JSON字段要求使用驼峰式命名，而代码中使用了下划线命名（mount_points、port_mappings、container_path、source_volume、host_port、container_port），这些不符合AWS API规范的字段会被直接忽略，导致配置不生效。

需要将所有下划线命名的字段替换为对应的驼峰式字段：

• mount_points → mountPoints
• port_mappings → portMappings
• container_path → containerPath
• source_volume → sourceVolume
• host_port → hostPort
• container_port → containerPort

修正后的容器定义代码 #

container_definitions = jsonencode([
  {
    name = "Container1"
    memory = 256
    essential = true
    image = "${var.account_id}.dkr.ecr.${var.region}.amazonaws.com/${data.aws_ecr_image.container_1_image.repository_name}:latest@${data.aws_ecr_image.container_1_image.image_digest}"
    mountPoints = [
      {
        containerPath = "/mnt/${local.volume_name}"
        sourceVolume = local.volume_name
      }
    ]
    portMappings = [
      {
        hostPort = 80
        containerPort = 80
      }
    ]
  },
  {
    name = "Container2"
    memory = 256
    image = "${var.account_id}.dkr.ecr.${var.region}.amazonaws.com/${data.aws_ecr_image.container_2_image.repository_name}:latest@${data.aws_ecr_image.container_2_image.image_digest}"
    mountPoints = [
      {
        sourceVolume = local.volume_name
        containerPath = "/mnt/${local.volume_name}"
      }
    ]
    portMappings = [
      {
        hostPort = 80
        containerPort = 80
      }
    ]
  }
])

修正后重新执行terraform apply，挂载点和端口映射配置会正常同步到AWS，terraform plan也会正确识别这些字段。

内容的提问来源于stack exchange，提问作者Cogito Ergo Sum