The TC flag in a DNS message indicates that the sender had to truncate it to fit within the length limit of the transmission channel. It does NOT indicate that part of the message was lost before reaching the recipient. Older versions of github.com/miekg/dns conflated the two cases by returning ErrTruncated from ReadMsg() if the message was parsed without error but had the TC flag set. The version of miekg/dns currently vendored no longer returns an error when a well-formed DNS message is received which has its TC flag set, but there was some confusion on how to update libnetwork to deal with this behaviour change. Truncated DNS replies are no longer different from any other reply message: they are normal replies which do not need any special- case handling to proxy back to the client. Signed-off-by: Cory Snider <csnider@mirantis.com>
libnetwork - networking for containers
Libnetwork provides a native Go implementation for connecting containers
The goal of libnetwork is to deliver a robust Container Network Model that provides a consistent programming interface and the required network abstractions for applications.
Design
Please refer to the design for more information.
Using libnetwork
There are many networking solutions available to suit a broad range of use-cases. libnetwork uses a driver / plugin model to support all of these solutions while abstracting the complexity of the driver implementations by exposing a simple and consistent Network Model to users.
package main
import (
"fmt"
"log"
"github.com/docker/docker/pkg/reexec"
"github.com/docker/docker/libnetwork"
"github.com/docker/docker/libnetwork/config"
"github.com/docker/docker/libnetwork/netlabel"
"github.com/docker/docker/libnetwork/options"
)
func main() {
if reexec.Init() {
return
}
// Select and configure the network driver
networkType := "bridge"
// Create a new controller instance
driverOptions := options.Generic{}
genericOption := make(map[string]interface{})
genericOption[netlabel.GenericData] = driverOptions
controller, err := libnetwork.New(config.OptionDriverConfig(networkType, genericOption))
if err != nil {
log.Fatalf("libnetwork.New: %s", err)
}
// Create a network for containers to join.
// NewNetwork accepts Variadic optional arguments that libnetwork and Drivers can use.
network, err := controller.NewNetwork(networkType, "network1", "")
if err != nil {
log.Fatalf("controller.NewNetwork: %s", err)
}
// For each new container: allocate IP and interfaces. The returned network
// settings will be used for container infos (inspect and such), as well as
// iptables rules for port publishing. This info is contained or accessible
// from the returned endpoint.
ep, err := network.CreateEndpoint("Endpoint1")
if err != nil {
log.Fatalf("network.CreateEndpoint: %s", err)
}
// Create the sandbox for the container.
// NewSandbox accepts Variadic optional arguments which libnetwork can use.
sbx, err := controller.NewSandbox("container1",
libnetwork.OptionHostname("test"),
libnetwork.OptionDomainname("example.com"))
if err != nil {
log.Fatalf("controller.NewSandbox: %s", err)
}
// A sandbox can join the endpoint via the join api.
err = ep.Join(sbx)
if err != nil {
log.Fatalf("ep.Join: %s", err)
}
// libnetwork client can check the endpoint's operational data via the Info() API
epInfo, err := ep.DriverInfo()
if err != nil {
log.Fatalf("ep.DriverInfo: %s", err)
}
macAddress, ok := epInfo[netlabel.MacAddress]
if !ok {
log.Fatalf("failed to get mac address from endpoint info")
}
fmt.Printf("Joined endpoint %s (%s) to sandbox %s (%s)\n", ep.Name(), macAddress, sbx.ContainerID(), sbx.Key())
}
Contributing
Want to hack on libnetwork? Docker's contributions guidelines apply.
Copyright and license
Code and documentation copyright 2015 Docker, inc. Code released under the Apache 2.0 license. Docs released under Creative commons.