README
¶
#canoe
canoe was born to get the simplicity of Hashicorp's raft library with the full set of features you get with the raft library in etcd.
On the backend, canoe is a wrapper around etcd-raft.
canoe is currently not considered production ready. There are still several caveats which need to be worked out.
Documentation
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Index ¶
- Variables
- func Uint64UUID() uint64
- type FSM
- type FilterFn
- type InitializationBackoffArgs
- type LogData
- type Logger
- type Node
- func (rn *Node) Destroy() error
- func (rn *Node) IsIDRemoved(id uint64) bool
- func (rn *Node) IsRunning() bool
- func (rn *Node) Process(ctx context.Context, m raftpb.Message) error
- func (rn *Node) Propose(data []byte) error
- func (rn *Node) RegisterObserver(o *Observer)
- func (rn *Node) ReportSnapshot(id uint64, status raft.SnapshotStatus)
- func (rn *Node) ReportUnreachable(id uint64)
- func (rn *Node) Start() error
- func (rn *Node) Stop() error
- func (rn *Node) UniqueID() uint64
- func (rn *Node) UnregisterObserver(o *Observer)
- type NodeConfig
- type Observation
- type Observer
- type SnapshotConfig
- type SnapshotData
Constants ¶
This section is empty.
Variables ¶
var DefaultInitializationBackoffArgs = &InitializationBackoffArgs{ InitialInterval: 500 * time.Millisecond, RandomizationFactor: .5, Multiplier: 2, MaxInterval: 5 * time.Second, MaxElapsedTime: 2 * time.Minute, }
DefaultInitializationBackoffArgs are the default backoff args
var DefaultLogger = &logrus.Logger{ Out: os.Stderr, Formatter: &textFormatter{ Prefix: "canoe", FullTimestamp: true, }, Level: logrus.InfoLevel, }
DefaultLogger gives a default logger for canoe
var DefaultSnapshotConfig = &SnapshotConfig{ Interval: -1 * time.Minute, MinCommittedLogs: 0, }
DefaultSnapshotConfig is what is used for snapshotting when SnapshotConfig isn't specified Note: by default we do not snapshot
var ErrorRemovedFromCluster = errors.New("I have been removed from cluster")
ErrorRemovedFromCluster is returned when an operation failed because this Node has been removed from the cluster
var FSMAPIEndpoint = "/api"
FSMAPIEndpoint defines where the endpoint for the FSM handler will be
Functions ¶
Types ¶
type FSM ¶
type FSM interface {
// Apply is called whenever a new log is committed to raft.
// The FSM is responsible for applying it in an atomic fashion
Apply(entry LogData) error
// Snapshot should return a snapshot in the form of restorable info for the entire FSM
Snapshot() (SnapshotData, error)
// Restore should take a snapshot, and use it to restore the state of the FSM
Restore(snap SnapshotData) error
// RegisterAPI gives you the ability to register an endpoint to canoe's
// HTTP Server
// Add handlefuncs to the mux router to have them appear at endpoint
// 0.0.0.0:BIND_PORT/api/[endpoints]
RegisterAPI(router *mux.Router)
}
FSM is an interface for what your state machine needs to define in order to be compatible with canoe
type FilterFn ¶
type FilterFn func(o Observation) bool
FilterFn is a function used to filter what events an Observer gets piped
type InitializationBackoffArgs ¶
type InitializationBackoffArgs struct {
InitialInterval time.Duration
Multiplier float64
MaxInterval time.Duration
MaxElapsedTime time.Duration
RandomizationFactor float64
}
InitializationBackoffArgs defines the backoff arguments for initializing a Node into a cluster as attempts to join or bootstrap a cluster are dependent on other nodes
type LogData ¶
type LogData []byte
LogData is the format of data you should expect in Apply operations on the FSM. It is also what you should pass to Propose calls to a Node
type Logger ¶
type Logger interface {
Debug(v ...interface{})
Debugf(format string, v ...interface{})
Error(v ...interface{})
Errorf(format string, v ...interface{})
Info(v ...interface{})
Infof(format string, v ...interface{})
Warning(v ...interface{})
Warningf(format string, v ...interface{})
Fatal(v ...interface{})
Fatalf(format string, v ...interface{})
Panic(v ...interface{})
Panicf(format string, v ...interface{})
}
Logger is a clone of etcd.Logger interface. We have it cloned in case we want to add more functionality
type Node ¶
type Node struct {
// contains filtered or unexported fields
}
Node is a raft node. It is responsible for communicating with all other nodes on the cluster, and in general doing all the rafty things
func NewNode ¶
func NewNode(args *NodeConfig) (*Node, error)
NewNode creates a new node from the config options
func (*Node) Destroy ¶
Destroy is a HARD stop. It first reconfigures the raft cluster to remove itself(ONLY do this if you are intending to permenantly leave the cluster and know consequences around consensus) - read the raft paper's reconfiguration section before using this. It then halts all running goroutines
WARNING! - Destroy will recursively remove everything under <DataDir>/snap and <DataDir>/wal
func (*Node) IsIDRemoved ¶
IsIDRemoved fulfills the requirement for rafthttp.Raft interface
func (*Node) RegisterObserver ¶
RegisterObserver registers and begins to send observations down an Observer
func (*Node) ReportSnapshot ¶
func (rn *Node) ReportSnapshot(id uint64, status raft.SnapshotStatus)
ReportSnapshot fulfills the requirement for rafthttp.Raft
func (*Node) ReportUnreachable ¶
ReportUnreachable fulfills the interface for rafthttp.Raft
func (*Node) Stop ¶
Stop will stop the raft node.
Note: stopping will not remove this node from the cluster. This means that it will affect consensus and quorum
func (*Node) UniqueID ¶
UniqueID returns the unique id for the raft node. This can be useful to get when defining your state machine so you don't have to define a new ID for identification and ownership purposes if your application needs that
func (*Node) UnregisterObserver ¶
UnregisterObserver is called when one no longer needs to look for a particular raft event occuring
type NodeConfig ¶
type NodeConfig struct {
// If not specified or 0, will autogenerate a new UUID
// It is typically safe to let canoe autogenerate a UUID
ID uint64
// If not specified 0x100 will be used
ClusterID uint64
FSM FSM
RaftPort int
APIPort int
// BootstrapPeers is a list of peers which we believe to be part of a cluster we wish to join.
// For now, this list is ignored if the node is marked as a BootstrapNode
BootstrapPeers []string
// BootstrapNode is currently needed when bootstrapping a new cluster, a single node must mark itself
// as the bootstrap node.
BootstrapNode bool
// DataDir is where your data will be persisted to disk
// for use when either you need to restart a node, or
// it goes offline and needs to be restarted
DataDir string
InitBackoff *InitializationBackoffArgs
// if nil, then default to no snapshotting
SnapshotConfig *SnapshotConfig
Logger Logger
}
NodeConfig exposes all the configuration options of a Node
type Observation ¶
type Observation interface{}
Observation is sent out to each observer. An obeservation can have many different types. It is currently used to detect the successful addition of a node to a cluster during the cluster join or bootstrap phase
type Observer ¶
type Observer struct {
// contains filtered or unexported fields
}
Observer is a struct responsible for monitoring raft's internal operations if one wants to perform unpredicted operations
func NewObserver ¶
func NewObserver(channel chan Observation, filter FilterFn) *Observer
NewObserver gets an observer. Note, if you aren't actively consuming the observer, the observations will get lost
type SnapshotConfig ¶
type SnapshotConfig struct {
// How often do you want to Snapshot and compact logs?
Interval time.Duration
// If the interval ticks but not enough logs have been commited then ignore
// the snapshot this interval
// This can be useful if you expect your snapshot procedure to have an expensive base cost
MinCommittedLogs uint64
}
SnapshotConfig defines when you want raft to take a snapshot and compact the WAL
Source Files
Directories