aebec1d07b
This patch allows endpoints to complete servicing connections while being removed from a service. The fix is entirely within libnetwork and requires no changes to the moby codebase proper. It operates by initially down-weighting a container endpoint in the load balancer to 0 while keeping the endpoint present in the load balancer. This allows traffic to continue to flow to the endpoint while preventing new connections from going to the endpoint. This allows the container to complete requests during the "stop_grace_period" and then exit when finished without interruption of service. This change requires propagating the status of disabled service endpoints via the networkDB. Accordingly, the patch includes both code to generate and handle service update messages. It also augments the service structure with a ServiceDisabled boolean to convey whether an endpoint should ultimately be removed or just disabled. This, naturally, required a rebuild of the protocol buffer code. The protocol buffer encoding is designed to support additions of fields to messages in a backwards-compatible manner. Protocol buffer unmarshalling code automatically skips past any fields that it isn't aware of. As a result, an older moby daemon without this fix can receive and will process correctly networkDB messages from newer moby daemons with this patch. As it turns out, the additional field is simply a bool that is otherwise irrelevent on networkDB create and delete events. So its absence in older moby daemon processing has no impact. However, the fix leverages the "update" networkDB message which was previously unused in libnetwork. Although older libnetwork implementations parse the message cleanly, they will see the message as unexpected and as such issue a log at error level indicating the receipt of such. Other than this there should be no other negative impact for use of this patch in mixed environments. (Although older mobys won't be able to gracefully downgrade connections on their nodes of course.) Signed-off-by: Chris Telfer <ctelfer@docker.com> Upstream-commit: 50dbdeff9fd186bb0e9926996436e1f56529a831 Component: engine
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.
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("docker.io"))
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())
}
Future
Please refer to roadmap for more information.
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.