alertmanager/cluster/advertise.go
Devin Trejo fad796931b
Add feature flag to enable discovery and use of public IPaddr for clustering. (#2719)
* Add feature flag to enable discovery and use of public IPaddr for clustering.

Before this change, Alertmanager would refuse to startup if using a
advertise address binding to any address (0.0.0.0), and the host only
had an interface with a public IP address. After this change we feature
flag permitting the use of a discovered public address for cluster
gossiping.

Signed-off-by: Devin Trejo <dtrejo@palantir.com>
2021-11-10 17:40:48 +01:00

87 lines
2.8 KiB
Go

// Copyright 2018 Prometheus Team
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package cluster
import (
"net"
"github.com/hashicorp/go-sockaddr"
"github.com/pkg/errors"
)
type getIPFunc func() (string, error)
// These are overridden in unit tests to mock the sockaddr functions.
var getPrivateAddress getIPFunc = sockaddr.GetPrivateIP
var getPublicAddress getIPFunc = sockaddr.GetPublicIP
// calculateAdvertiseAddress attempts to clone logic from deep within memberlist
// (NetTransport.FinalAdvertiseAddr) in order to surface its conclusions to the
// application, so we can provide more actionable error messages if the user has
// inadvertently misconfigured their cluster.
//
// https://github.com/hashicorp/memberlist/blob/022f081/net_transport.go#L126
func calculateAdvertiseAddress(bindAddr, advertiseAddr string, allowInsecureAdvertise bool) (net.IP, error) {
if advertiseAddr != "" {
ip := net.ParseIP(advertiseAddr)
if ip == nil {
return nil, errors.Errorf("failed to parse advertise addr '%s'", advertiseAddr)
}
if ip4 := ip.To4(); ip4 != nil {
ip = ip4
}
return ip, nil
}
if isAny(bindAddr) {
return discoverAdvertiseAddress(allowInsecureAdvertise)
}
ip := net.ParseIP(bindAddr)
if ip == nil {
return nil, errors.Errorf("failed to parse bind addr '%s'", bindAddr)
}
return ip, nil
}
// discoverAdvertiseAddress will attempt to get a single IP address to use as
// the advertise address when one is not explicitly provided. It defaults to
// using a private IP address, and if not found then using a public IP if
// insecure advertising is allowed.
func discoverAdvertiseAddress(allowInsecureAdvertise bool) (net.IP, error) {
addr, err := getPrivateAddress()
if err != nil {
return nil, errors.Wrap(err, "failed to get private IP")
}
if addr == "" && !allowInsecureAdvertise {
return nil, errors.New("no private IP found, explicit advertise addr not provided")
}
if addr == "" {
addr, err = getPublicAddress()
if err != nil {
return nil, errors.Wrap(err, "failed to get public IP")
}
if addr == "" {
return nil, errors.New("no private/public IP found, explicit advertise addr not provided")
}
}
ip := net.ParseIP(addr)
if ip == nil {
return nil, errors.Errorf("failed to parse discovered IP '%s'", addr)
}
return ip, nil
}