Networking

Currently, ops supports two networking modes; usermode and bridged. In this document we will dive into the differences between these networking modes and when it makes sense to select one over the other.

Native Networking

Note that by default you should probably just use the native networking provided by your cloud provider. These instructions only exist if you wish to build your own private cloud.

Usermode Network

Usermode is the default and simplest mode of networking. It utilizes the ready available network connection and shares it with the ops instance.

It is worth noting that the simplicity of usermode does come at a performance cost. Therefore, while usermode is a good option for demos, testing, and local development; it may not be a good choice for production environments.

No action is required to configure usermode networking, it is used by default.

Usermode does nat on a port but sometimes you'll want to add dns. This is fairly straight-forward to do. Again - this is only for dev/test not production deploys:

server:

package main

import (
  "fmt"
  "net/http"
)

func main() {
  http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Welcome to my website!")
  })

  fs := http.FileServer(http.Dir("static/"))
  http.Handle("/static/", http.StripPrefix("/static/", fs))

  http.ListenAndServe(":8080", nil)
}

build/run:

GO111MODULE=off GOOS=linux go build
ops run -p 8080 g

client:

package main

import (
  "fmt"
  "io/ioutil"
  "net/http"
)

func main() {
  resp, err := http.Get("http://bob:8080")
  if err != nil {
    fmt.Println(err)
  }

  body, err := ioutil.ReadAll(resp.Body)
  if err != nil {
    fmt.Println(err)
  }

  fmt.Println(string(body))
}

You just need to include a /etc/hosts entry for your client to talk to 10.0.2.2:

Sample config:

➜  z tree
.
├── config.json
├── etc
│   └── hosts
├── main.go
└── z

➜  z cat etc/hosts
10.0.2.2       bob

ops run -c config.json z

Bridged Network

Bridged networking connects a virtual machine to a network using the host computer's Ethernet adapter. For more information about bridged networking, see this article.

We only recommend running bridge networking for local dev environments or environments where you are planning on having full control over orchestration. We do not recommend running this on the cloud as it'll be slow. You should instead use the native cloud deploy options (eg: ops instance create -t gcp) as they will be using bridges underneath.

Via Instance Create

If you are on a Mac M1, M2 or M3 we recommend grabbing OPS desktop as it has vmnet-bridged support enabled by default and is pre-setup to run correctly. This way of working with bridges is much nicer too as you don't have to configure anything. Using this 'ops instance create' for the on-prem target will use bridge networking by default.

If you want to build yourself you need at least qemu 7.1 or qemu HEAD from brew. You currently need to be root, or in a proper group or set the suid bit (chmod +s) to the qemu binary.

On Mac creating a new instance with bridge support is easy as running:

ops instance create -p 8080 mywebserver

On Linux:

To create a new network and attach a dhcp server to it:

ops network create

Then you can create a new instance with this sample config:

{
    "RunConfig": {
        "Bridged": true,
        "TapName": "tap1",
        "BridgeName": "br1"
    }
}

Then you can run it:

ops instance create -c myconfig.json mywebserver -p 8080

Via Ops Run

Ops run currently only supports using a bridge on linux - not a mac. If you are on a mac you should use 'instance create' with the 'onprem' provider. This automatically manages bridges for you.

Here is a simple Go example demonstrating two applications sitting on their respective tap interfaces:

package main
import (
  "fmt"
  "io/ioutil"
  "log"
  "net/http"
  "os"
  "time"
)
func main() {
  clientIP := os.Args[1]
  URL := fmt.Sprintf("http://%s/hello", clientIP)
  client := http.Client{
    Timeout: time.Duration(5 * time.Second),
  }
  request, err := http.NewRequest("GET", URL, nil)
  if err != nil {
    log.Fatal(err)
  }
  ticker := time.NewTicker(5 * time.Second)
  quit := make(chan struct{})
  for {
    select {
    case <-ticker.C:
      resp, err := client.Do(request)
      if err != nil {
        fmt.Println(err)
      } else {
        defer resp.Body.Close()
        body, err := ioutil.ReadAll(resp.Body)
        if err != nil {
          fmt.Println(err)
        } else {
          fmt.Print(string(body))
        }
      }
    case <-quit:
      ticker.Stop()
      return
    }
  }
}

package main
import (
  "fmt"
  "net/http"
)
func main() {
  hello := func(w http.ResponseWriter, req *http.Request) {
    fmt.Fprintf(w, "hello test 2\n")
  }
  headers := func(w http.ResponseWriter, req *http.Request) {
    for name, headers := range req.Header {
      for _, h := range headers {
        fmt.Fprintf(w, "%v: %v\n", name, h)
      }
    }
  }
  http.HandleFunc("/hello", hello)
  http.HandleFunc("/headers", headers)
  http.ListenAndServe(":8081", nil)
}

You'll either need the appropriate permissions or you can just give yourself sudo then you can run:

ops run server -p 8081 -b -t tap0 --ip-address 192.168.42.19
ops run client -a 192.168.42.19:8081 -b -t tap1 --ip-address 192.168.42.20

You may also optionally set the bridgeip like so:

ops run server -p 8081 -b -t tap0 --ip-address 192.168.42.19 --bridgeipaddress 192.168.42.2

Note: On the mac for 'ops run', you won't be able to use this syntax as there is no actual ethernet card (for most laptops).

IPv6

IPv6 support varies from cloud to cloud. Please consult the individual instructions found for each cloud:

Google Cloud AWS Azure