wesher/config.go

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package main
import (
"fmt"
"net"
"github.com/costela/wesher/cluster"
"github.com/hashicorp/go-sockaddr"
"github.com/pkg/errors"
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"github.com/stevenroose/gonfig"
)
type config struct {
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ClusterKey []byte `id:"cluster-key" desc:"shared key for cluster membership; must be 32 bytes base64 encoded; will be generated if not provided"`
Join []string `desc:"comma separated list of hostnames or IP addresses to existing cluster members; if not provided, will attempt resuming any known state or otherwise wait for further members."`
Rejoin int `desc:"interval at which join nodes are joined again if away, 0 disables rejoining altogether" default:"0"`
Init bool `desc:"whether to explicitly (re)initialize the cluster; any known state from previous runs will be forgotten"`
BindAddr string `id:"bind-addr" desc:"IP address to bind to for cluster membership traffic (cannot be used with --bind-iface)"`
BindIface string `id:"bind-iface" desc:"Interface to bind to for cluster membership traffic (cannot be used with --bind-addr)"`
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ClusterPort int `id:"cluster-port" desc:"port used for membership gossip traffic (both TCP and UDP); must be the same across cluster" default:"7946"`
WireguardPort int `id:"wireguard-port" desc:"port used for wireguard traffic (UDP); must be the same across cluster" default:"51820"`
OverlayNet *network `id:"overlay-net" desc:"the network in which to allocate addresses for the overlay mesh network (CIDR format); smaller networks increase the chance of IP collision" default:"10.0.0.0/8"`
RoutedNet *network `id:"routed-net" desc:"network used to filter routes that nodes are allowed to announce (CIDR format)" default:"0.0.0.0/32"`
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Interface string `desc:"name of the wireguard interface to create and manage" default:"wgoverlay"`
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NoEtcHosts bool `id:"no-etc-hosts" desc:"disable writing of entries to /etc/hosts"`
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LogLevel string `id:"log-level" desc:"set the verbosity (debug/info/warn/error)" default:"warn"`
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Version bool `desc:"display current version and exit"`
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// for easier local testing; will break etchosts entry
UseIPAsName bool `id:"ip-as-name" default:"false" opts:"hidden"`
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}
func loadConfig() (*config, error) {
var config config
err := gonfig.Load(&config, gonfig.Conf{EnvPrefix: "WESHER_"})
if err != nil {
return nil, err
}
// perform some validation
if len(config.ClusterKey) != 0 && len(config.ClusterKey) != cluster.KeyLen {
return nil, fmt.Errorf("unsupported cluster key length; expected %d, got %d", cluster.KeyLen, len(config.ClusterKey))
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}
if bits, _ := ((*net.IPNet)(config.OverlayNet)).Mask.Size(); bits%8 != 0 {
return nil, fmt.Errorf("unsupported overlay network size; net mask must be multiple of 8, got %d", bits)
}
if config.BindAddr != "" && config.BindIface != "" {
return nil, fmt.Errorf("setting both bind address and bind interface is not supported")
} else if config.BindIface != "" {
// Compute the actual bind address based on the provided interface
iface, err := net.InterfaceByName(config.BindIface)
if err != nil {
return nil, errors.Wrapf(err, "could not get interface by name %s", config.BindIface)
}
addrs, err := iface.Addrs()
if err != nil {
return nil, errors.Wrapf(err, "could not get addresses for interface %s", config.BindIface)
}
if len(addrs) > 0 {
if addr, ok := addrs[0].(*net.IPNet); ok {
config.BindAddr = addr.IP.String()
}
}
} else if config.BindAddr == "" && config.BindIface == "" {
// FIXME: this is a workaround for memberlist refusing to listen on public IPs if BindAddr==0.0.0.0
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detectedBindAddr, err := sockaddr.GetPublicIP()
if err != nil {
return nil, err
}
// if we cannot find a public IP, let memberlist do its thing
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if detectedBindAddr != "" {
config.BindAddr = detectedBindAddr
} else {
config.BindAddr = "0.0.0.0"
}
}
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return &config, nil
}
type network net.IPNet
// UnmarshalText parses the provided byte array into the network receiver
func (n *network) UnmarshalText(data []byte) error {
_, ipnet, err := net.ParseCIDR(string(data))
if err != nil {
return err
}
*n = network(*ipnet)
return nil
}