Nomad 和端口映射

Question

Nomad 有三种不同的端口映射方式：

组级下的网络节
配置下的网络节 -> 资源级别
port_map 配置级别下的节

有什么区别，什么时候应该使用哪个？

Answer 1

首先port_map是弃用, 所以你不应该将它用作任务驱动程序配置的一部分。

Up until Nomad 0.12, ports could be specified in a task's resource stanza and set using the docker port_map field. As more features have been added to the group network resource allocation, task based network resources are deprecated. With it the port_map field is also deprecated and can only be used with task network resources.

Users should migrate their jobs to define ports in the group network stanza and specified which ports a task maps with the ports field.
port 在 group network 节中定义了可用于标识服务发现中的端口。此标签也用作环境变量名称的一部分指示您的应用程序应绑定到哪个端口。
ports 在任务级别指定网络节中的哪个 port 应该是在任务 allocation/container 中可用。来自官方文档

A Docker container typically specifies which port a service will listen on by specifying the EXPOSE directive in the Dockerfile.

Because dynamic ports will not match the ports exposed in your Dockerfile, Nomad will automatically expose any ports specified in the ports field.

TLDR;

所以正确的定义只有一个：

job "example" {
  group "example-group" {
    network {
      # Dynamic ports
      port "foo" {}
      port "bar" {}
      # Mapped ports
      port "http"  { to = 80 }
      port "https" { to = 443 }
      # Static ports
      port "lb" { static = 8080 }
    }

    task "task-1" {
      driver = "docker"
      config {

        ...
 
        ports = [
          "foo",
          "http",
        ]
      }
    }

    task "task-2" {
      driver = "docker"
      config {

        ...
 
        ports = [
          "bar",
          "https",
        ]
      }
    }

    task "task-3" {
      driver = "docker"
      config {

        ...
 
        ports = [
          "lb",
        ]
      }
    }
  }
}

考虑运行这种类型的作业文件（带有任何图像）。然后你会得到以下内容后端和容器之间的端口映射：

for port in $(docker ps --format "{{.Ports}}"); do echo $port; done | grep tcp | cut -d':' -f 2

# Dynamic ports 'foo' and 'bar'
# 25968->25968/tcp,
# 29080->29080/tcp,

# Mapped ports 'http' and 'https'
# 29936->80/tcp,
# 20987->443/tcp,

# Static port 'lb'
# 8080->8080/tcp,

现在，如果你进入 task-1 allocation/container 并检查环境变量，那么你如果您的任务需要与彼此。

env | grep NOMAD | grep PORT

# NOMAD_PORT_bar=29080
# NOMAD_HOST_PORT_bar=29080

# NOMAD_PORT_foo=25968
# NOMAD_HOST_PORT_foo=25968

# NOMAD_PORT_http=80
# NOMAD_HOST_PORT_http=29936

# NOMAD_PORT_https=443
# NOMAD_HOST_PORT_https=20987

# NOMAD_PORT_lb=8080
# NOMAD_HOST_PORT_lb=8080

为了让服务之间的通信更容易，最好使用服务发现，例如Consul（也来自 HashiCorp）并让你生活更容易考虑某种负载平衡器，例如 Fabio 或 Traefik。这是一个不错的博客 post 来自 HashiCorp 的工程师。

Nomad 和端口映射

Nomad and port mapping

networking

consul

nomad

TLDR;