/usr/share/gocode/src/github.com/hashicorp/serf/serf/config.go is in golang-github-hashicorp-serf-dev 0.7.0~ds1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"io"
"os"
"time"
"github.com/hashicorp/memberlist"
)
// ProtocolVersionMap is the mapping of Serf delegate protocol versions
// to memberlist protocol versions. We mask the memberlist protocols using
// our own protocol version.
var ProtocolVersionMap map[uint8]uint8
func init() {
ProtocolVersionMap = map[uint8]uint8{
4: 2,
3: 2,
2: 2,
}
}
// Config is the configuration for creating a Serf instance.
type Config struct {
// The name of this node. This must be unique in the cluster. If this
// is not set, Serf will set it to the hostname of the running machine.
NodeName string
// The tags for this role, if any. This is used to provide arbitrary
// key/value metadata per-node. For example, a "role" tag may be used to
// differentiate "load-balancer" from a "web" role as parts of the same cluster.
// Tags are deprecating 'Role', and instead it acts as a special key in this
// map.
Tags map[string]string
// EventCh is a channel that receives all the Serf events. The events
// are sent on this channel in proper ordering. Care must be taken that
// this channel doesn't block, either by processing the events quick
// enough or buffering the channel, otherwise it can block state updates
// within Serf itself. If no EventCh is specified, no events will be fired,
// but point-in-time snapshots of members can still be retrieved by
// calling Members on Serf.
EventCh chan<- Event
// ProtocolVersion is the protocol version to speak. This must be between
// ProtocolVersionMin and ProtocolVersionMax.
ProtocolVersion uint8
// BroadcastTimeout is the amount of time to wait for a broadcast
// message to be sent to the cluster. Broadcast messages are used for
// things like leave messages and force remove messages. If this is not
// set, a timeout of 5 seconds will be set.
BroadcastTimeout time.Duration
// The settings below relate to Serf's event coalescence feature. Serf
// is able to coalesce multiple events into single events in order to
// reduce the amount of noise that is sent along the EventCh. For example
// if five nodes quickly join, the EventCh will be sent one EventMemberJoin
// containing the five nodes rather than five individual EventMemberJoin
// events. Coalescence can mitigate potential flapping behavior.
//
// Coalescence is disabled by default and can be enabled by setting
// CoalescePeriod.
//
// CoalescePeriod specifies the time duration to coalesce events.
// For example, if this is set to 5 seconds, then all events received
// within 5 seconds that can be coalesced will be.
//
// QuiescentPeriod specifies the duration of time where if no events
// are received, coalescence immediately happens. For example, if
// CoalscePeriod is set to 10 seconds but QuiscentPeriod is set to 2
// seconds, then the events will be coalesced and dispatched if no
// new events are received within 2 seconds of the last event. Otherwise,
// every event will always be delayed by at least 10 seconds.
CoalescePeriod time.Duration
QuiescentPeriod time.Duration
// The settings below relate to Serf's user event coalescing feature.
// The settings operate like above but only affect user messages and
// not the Member* messages that Serf generates.
UserCoalescePeriod time.Duration
UserQuiescentPeriod time.Duration
// The settings below relate to Serf keeping track of recently
// failed/left nodes and attempting reconnects.
//
// ReapInterval is the interval when the reaper runs. If this is not
// set (it is zero), it will be set to a reasonable default.
//
// ReconnectInterval is the interval when we attempt to reconnect
// to failed nodes. If this is not set (it is zero), it will be set
// to a reasonable default.
//
// ReconnectTimeout is the amount of time to attempt to reconnect to
// a failed node before giving up and considering it completely gone.
//
// TombstoneTimeout is the amount of time to keep around nodes
// that gracefully left as tombstones for syncing state with other
// Serf nodes.
ReapInterval time.Duration
ReconnectInterval time.Duration
ReconnectTimeout time.Duration
TombstoneTimeout time.Duration
// QueueDepthWarning is used to generate warning message if the
// number of queued messages to broadcast exceeds this number. This
// is to provide the user feedback if events are being triggered
// faster than they can be disseminated
QueueDepthWarning int
// MaxQueueDepth is used to start dropping messages if the number
// of queued messages to broadcast exceeds this number. This is to
// prevent an unbounded growth of memory utilization
MaxQueueDepth int
// RecentIntentBuffer is used to set the size of recent join and leave intent
// messages that will be buffered. This is used to guard against
// the case where Serf broadcasts an intent that arrives before the
// Memberlist event. It is important that this not be too small to avoid
// continuous rebroadcasting of dead events.
RecentIntentBuffer int
// EventBuffer is used to control how many events are buffered.
// This is used to prevent re-delivery of events to a client. The buffer
// must be large enough to handle all "recent" events, since Serf will
// not deliver messages that are older than the oldest entry in the buffer.
// Thus if a client is generating too many events, it's possible that the
// buffer gets overrun and messages are not delivered.
EventBuffer int
// QueryBuffer is used to control how many queries are buffered.
// This is used to prevent re-delivery of queries to a client. The buffer
// must be large enough to handle all "recent" events, since Serf will not
// deliver queries older than the oldest entry in the buffer.
// Thus if a client is generating too many queries, it's possible that the
// buffer gets overrun and messages are not delivered.
QueryBuffer int
// QueryTimeoutMult configures the default timeout multipler for a query to run if no
// specific value is provided. Queries are real-time by nature, where the
// reply is time sensitive. As a result, results are collected in an async
// fashion, however the query must have a bounded duration. We want the timeout
// to be long enough that all nodes have time to receive the message, run a handler,
// and generate a reply. Once the timeout is exceeded, any further replies are ignored.
// The default value is
//
// Timeout = GossipInterval * QueryTimeoutMult * log(N+1)
//
QueryTimeoutMult int
// QueryResponseSizeLimit and QuerySizeLimit limit the inbound and
// outbound payload sizes for queries, respectively. These must fit
// in a UDP packet with some additional overhead, so tuning these
// past the default values of 1024 will depend on your network
// configuration.
QueryResponseSizeLimit int
QuerySizeLimit int
// MemberlistConfig is the memberlist configuration that Serf will
// use to do the underlying membership management and gossip. Some
// fields in the MemberlistConfig will be overwritten by Serf no
// matter what:
//
// * Name - This will always be set to the same as the NodeName
// in this configuration.
//
// * Events - Serf uses a custom event delegate.
//
// * Delegate - Serf uses a custom delegate.
//
MemberlistConfig *memberlist.Config
// LogOutput is the location to write logs to. If this is not set,
// logs will go to stderr.
LogOutput io.Writer
// SnapshotPath if provided is used to snapshot live nodes as well
// as lamport clock values. When Serf is started with a snapshot,
// it will attempt to join all the previously known nodes until one
// succeeds and will also avoid replaying old user events.
SnapshotPath string
// RejoinAfterLeave controls our interaction with the snapshot file.
// When set to false (default), a leave causes a Serf to not rejoin
// the cluster until an explicit join is received. If this is set to
// true, we ignore the leave, and rejoin the cluster on start.
RejoinAfterLeave bool
// EnableNameConflictResolution controls if Serf will actively attempt
// to resolve a name conflict. Since each Serf member must have a unique
// name, a cluster can run into issues if multiple nodes claim the same
// name. Without automatic resolution, Serf merely logs some warnings, but
// otherwise does not take any action. Automatic resolution detects the
// conflict and issues a special query which asks the cluster for the
// Name -> IP:Port mapping. If there is a simple majority of votes, that
// node stays while the other node will leave the cluster and exit.
EnableNameConflictResolution bool
// DisableCoordinates controls if Serf will maintain an estimate of this
// node's network coordinate internally. A network coordinate is useful
// for estimating the network distance (i.e. round trip time) between
// two nodes. Enabling this option adds some overhead to ping messages.
DisableCoordinates bool
// KeyringFile provides the location of a writable file where Serf can
// persist changes to the encryption keyring.
KeyringFile string
// Merge can be optionally provided to intercept a cluster merge
// and conditionally abort the merge.
Merge MergeDelegate
}
// Init allocates the subdata structures
func (c *Config) Init() {
if c.Tags == nil {
c.Tags = make(map[string]string)
}
}
// DefaultConfig returns a Config struct that contains reasonable defaults
// for most of the configurations.
func DefaultConfig() *Config {
hostname, err := os.Hostname()
if err != nil {
panic(err)
}
return &Config{
NodeName: hostname,
BroadcastTimeout: 5 * time.Second,
EventBuffer: 512,
QueryBuffer: 512,
LogOutput: os.Stderr,
ProtocolVersion: ProtocolVersionMax,
ReapInterval: 15 * time.Second,
RecentIntentBuffer: 128,
ReconnectInterval: 30 * time.Second,
ReconnectTimeout: 24 * time.Hour,
QueueDepthWarning: 128,
MaxQueueDepth: 4096,
TombstoneTimeout: 24 * time.Hour,
MemberlistConfig: memberlist.DefaultLANConfig(),
QueryTimeoutMult: 16,
QueryResponseSizeLimit: 1024,
QuerySizeLimit: 1024,
EnableNameConflictResolution: true,
DisableCoordinates: false,
}
}
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