roxyresolver

package
v0.4.6 Latest Latest
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 Go to latest Published: May 19, 2021 License: Apache-2.0 Imports: 36 Imported by: 0

Documentation

Overview

Package roxyresolver provides advanced implementations of gRPC-compatible address resolution strategies.

Index

Constants

View Source 
const (
	// MembershipAttrKey is the gRPC attributes.Attributes key for
	// retrieving the original *membership.Roxy, if any.
	MembershipAttrKey = attrKey("roxy.Membership")

	// ResolvedAttrKey is the gRPC attributes.Attributes key for retrieving
	// the Resolved address.
	ResolvedAttrKey = attrKey("roxy.Resolved")
)
View Source 
const (
	// ShardIDContextKey is the context.Context key for attaching a shard ID.
	ShardIDContextKey = contextKey("roxy.ShardID")

	// ZKConnContextKey is the context.Context key for attaching a *zk.Conn.
	ZKConnContextKey = contextKey("roxy.zk.Conn")

	// V3ClientContextKey is the context.Context key for attaching an etcd.io *v3.Client.
	V3ClientContextKey = contextKey("roxy.etcd.V3Client")

	// ATCClientContextKey is the context.Context key for attaching an *atcclient.ATCClient.
	ATCClientContextKey = contextKey("roxy.atc.Client")
)
View Source 
const DefaultCooldownInterval = 30 * time.Second

DefaultCooldownInterval is the default value of CooldownInterval if not specified.

View Source 
const DefaultPollInterval = 5 * time.Minute

DefaultPollInterval is the default value of PollInterval if not specified.

View Source 
const MaxPollInterval = 24 * time.Hour

MaxPollInterval is the maximum permitted value of PollInterval.

Variables

This section is empty.

Functions

func EnableCheck 

func EnableCheck()

EnableCheck enables performance-degrading data integrity checks. Meant only for internal use.

func GetATCClient 

func GetATCClient(ctx context.Context) *atcclient.ATCClient

GetATCClient retrieves the attached ATC client.

func GetEtcdV3Client 

func GetEtcdV3Client(ctx context.Context) *v3.Client

GetEtcdV3Client retrieves the attached etcd.io client.

func GetMembership 

func GetMembership(addr resolver.Address) *membership.Roxy

GetMembership retrieves the attached *membership.Roxy, or nil if none attached.

func GetShardID 

func GetShardID(ctx context.Context) (shardID int32, ok bool)

GetShardID retrieves the attached shard ID.

func GetZKConn 

func GetZKConn(ctx context.Context) *zk.Conn

GetZKConn retrieves the attached ZooKeeper client connection.

func Logger 

func Logger() *zerolog.Logger

Logger returns the global logger to use for Resolver background threads.

func MapEtcdError 

func MapEtcdError(err error) error

MapEtcdError converts an etcd.io-specific error to a generic error.

func MapZKError 

func MapZKError(err error) error

MapZKError converts a ZooKeeper-specific error to a generic error.

func NewATCBalancerBuilder 

func NewATCBalancerBuilder() balancer.Builder

NewATCBalancerBuilder returns a gRPC balancer.Builder for the ATC load balancing algorithm.

func NewATCBuilder 

func NewATCBuilder(ctx context.Context, rng *rand.Rand, client *atcclient.ATCClient) resolver.Builder

NewATCBuilder constructs a new gRPC resolver.Builder for the "atc" scheme.

func NewDNSBuilder 

func NewDNSBuilder(ctx context.Context, rng *rand.Rand, serviceConfigJSON string) resolver.Builder

NewDNSBuilder constructs a new gRPC resolver.Builder for the "dns" scheme.

func NewEtcdBuilder 

func NewEtcdBuilder(ctx context.Context, rng *rand.Rand, etcd *v3.Client, serviceConfigJSON string) resolver.Builder

NewEtcdBuilder constructs a new gRPC resolver.Builder for the "etcd" scheme.

func NewIPBuilder 

func NewIPBuilder(rng *rand.Rand, serviceConfigJSON string) resolver.Builder

NewIPBuilder constructs a new gRPC resolver.Builder for the "ip" scheme.

func NewSRVBuilder 

func NewSRVBuilder(ctx context.Context, rng *rand.Rand, serviceConfigJSON string) resolver.Builder

NewSRVBuilder constructs a new gRPC resolver.Builder for the "srv" scheme.

func NewZKBuilder 

func NewZKBuilder(ctx context.Context, rng *rand.Rand, zkconn *zk.Conn, serviceConfigJSON string) resolver.Builder

NewZKBuilder constructs a new gRPC resolver.Builder for the "zk" scheme.

func SetLogger 

func SetLogger(logger zerolog.Logger)

SetLogger sets the global logger to use for Resolver background threads.

func WithATCClient 

func WithATCClient(ctx context.Context, client *atcclient.ATCClient) context.Context

WithATCClient attaches an ATC client to the given context.

func WithEtcdV3Client 

func WithEtcdV3Client(ctx context.Context, etcd *v3.Client) context.Context

WithEtcdV3Client attaches an etcd.io client to the given context.

func WithMembership 

func WithMembership(addr resolver.Address, r *membership.Roxy) resolver.Address

WithMembership returns a copy of addr with the given *membership.Roxy attached.

func WithResolved 

func WithResolved(addr resolver.Address, data Resolved) resolver.Address

WithResolved returns a copy of addr with the given Resolved attached.

func WithShardID 

func WithShardID(ctx context.Context, shardID int32) context.Context

WithShardID attaches a shard ID to the given context.

func WithStandardResolvers 

func WithStandardResolvers(ctx context.Context) grpc.DialOption

WithStandardResolvers returns a gRPC DialOption that enables as many Target schemes as possible on the gRPC ClientConn being created.

func WithZKConn 

func WithZKConn(ctx context.Context, zkconn *zk.Conn) context.Context

WithZKConn attaches a ZooKeeper client connection to the given context.

Types

type BalancerType 

type BalancerType uint8

BalancerType indicates which load balancer algorithm is in use. 

const (
	// RandomBalancer chooses an address with uniform probability.
	RandomBalancer BalancerType = iota

	// RoundRobinBalancer chooses an address from a random permutation.
	// The permutation changes each time an address is added, changed, or
	// deleted.
	RoundRobinBalancer

	// WeightedRandomBalancer chooses an address with weighted probability.
	WeightedRandomBalancer

	// WeightedRoundRobinBalancer chooses an address from a random shuffle
	// that has zero or more copies of each address, each in proportion to
	// that address's weight.  The shuffle changes each time an address is
	// added, changed, or deleted.
	WeightedRoundRobinBalancer

	// SRVBalancer chooses an address using the rules for DNS SRV records.
	SRVBalancer
)

func ParseATCTarget 

func ParseATCTarget(rt Target) (lbName, lbLocation, lbUnique string, balancer BalancerType, isDSC bool, serverName string, err error)

ParseATCTarget breaks apart a Target into component data.

func ParseDNSTarget 

func ParseDNSTarget(rt Target, defaultPort string) (res *net.Resolver, host string, port string, balancer BalancerType, pollInterval time.Duration, cdInterval time.Duration, serverName string, err error)

ParseDNSTarget breaks apart a Target into component data.

func ParseEtcdTarget 

func ParseEtcdTarget(rt Target) (etcdPath string, etcdPort string, balancer BalancerType, serverName string, err error)

ParseEtcdTarget breaks apart a Target into component data.

func ParseIPTarget 

func ParseIPTarget(rt Target, defaultPort string) (tcpAddrs []*net.TCPAddr, balancer BalancerType, serverName string, err error)

ParseIPTarget breaks apart a Target into component data.

func ParseSRVTarget 

func ParseSRVTarget(rt Target) (res *net.Resolver, name string, service string, balancer BalancerType, pollInterval time.Duration, cdInterval time.Duration, serverName string, err error)

ParseSRVTarget breaks apart a Target into component data.

func ParseUnixTarget 

func ParseUnixTarget(rt Target) (unixAddr *net.UnixAddr, balancer BalancerType, serverName string, err error)

ParseUnixTarget breaks apart a Target into component data.

func ParseZKTarget 

func ParseZKTarget(rt Target) (zkPath string, zkPort string, balancer BalancerType, serverName string, err error)

ParseZKTarget breaks apart a Target into component data.

func (BalancerType) GoString 

func (t BalancerType) GoString() string

GoString returns the Go constant name.

func (BalancerType) MarshalJSON 

func (t BalancerType) MarshalJSON() ([]byte, error)

MarshalJSON fulfills json.Marshaler.

func (*BalancerType) Parse 

func (t *BalancerType) Parse(str string) error

Parse parses the string representation.

func (BalancerType) String 

func (t BalancerType) String() string

String returns the string representation.

func (*BalancerType) UnmarshalJSON 

func (t *BalancerType) UnmarshalJSON(raw []byte) error

UnmarshalJSON fulfills json.Unmarshaler.

type Dynamic 

type Dynamic struct {
	// contains filtered or unexported fields
}

Dynamic represents the mutable, mutex-protected data associated with one or more Resolved addresses.

func (*Dynamic) IsHealthy 

func (dynamic *Dynamic) IsHealthy() bool

IsHealthy returns true if this server is healthy.

func (*Dynamic) Update 

func (dynamic *Dynamic) Update(opts UpdateOptions)

Update changes the status of this server.

type Event 

type Event struct {
	// Type is the type of event, i.e. which data has changed.
	Type EventType

	// Err is the global error.
	//
	// Valid for: ErrorEvent.
	Err error

	// Key is the unique identifier for this address.
	//
	// Valid for: UpdateEvent, DeleteEvent, BadDataEvent, StatusChangeEvent.
	Key string

	// Data is the resolved address data.
	//
	// Valid for: UpdateEvent, StatusChangeEvent.
	Data Resolved

	// ServiceConfigJSON is the new gRPC service config.
	//
	// Valid for: NewServiceConfigEvent.
	ServiceConfigJSON string
}

Event represents the Resolver state changes triggered by some event.

func (Event) Check 

func (event Event) Check()

Check verifies the data integrity of all fields.

type EventType 

type EventType uint8

EventType indicates the type of an Event. 

const (
	// NoOpEvent is an Event with no data.
	NoOpEvent EventType = iota

	// ErrorEvent is an Event with a global error.
	ErrorEvent

	// UpdateEvent is an Event with a new or changed address.
	UpdateEvent

	// DeleteEvent is an Event with a deleted address.
	DeleteEvent

	// BadDataEvent is an Event with an erroneous address.
	BadDataEvent

	// StatusChangeEvent is an Event with an address whose metadata has
	// changed.
	StatusChangeEvent

	// NewServiceConfigEvent is an Event with a new gRPC service config.
	NewServiceConfigEvent
)

func (EventType) GoString 

func (t EventType) GoString() string

GoString returns the Go constant name.

func (EventType) MarshalJSON 

func (t EventType) MarshalJSON() ([]byte, error)

MarshalJSON fulfills json.Marshaler.

func (*EventType) Parse 

func (t *EventType) Parse(str string) error

Parse parses the string representation.

func (EventType) String 

func (t EventType) String() string

String returns the string representation.

func (*EventType) UnmarshalJSON 

func (t *EventType) UnmarshalJSON(raw []byte) error

UnmarshalJSON fulfills json.Unmarshaler.

type Options 

type Options struct {
	// Context is the context within which the resolver runs.  If this
	// context is cancelled or reaches its deadline, the resolver will
	// stop.
	//
	// This field is mandatory.
	Context context.Context

	// Random is the source of randomness for balancer algorithms that need
	// one.
	//
	// If provided, it MUST be thread-safe; see the syncrand package for
	// more information.  If nil, the syncrand.Global() instance will be
	// used.
	Random *rand.Rand

	// Target is the resolve target.  The target's Scheme field determines
	// which Resolver implementation will be used.
	//
	// This field is mandatory.
	Target Target

	// IsTLS should be set to true iff the consumer of the resolved
	// addresses will be using TLS to communicate with them.  It is used
	// for automatic port guessing.
	IsTLS bool
}

Options holds options related to constructing a new Resolver.

type PollingResolveFunc 

type PollingResolveFunc func() ([]Resolved, error)

PollingResolveFunc represents a closure that will be called periodically to resolve addresses. It will be called at least once every PollInterval, and no less than CooldownInterval will pass between calls.

func MakeDNSResolveFunc 

func MakeDNSResolveFunc(ctx context.Context, res *net.Resolver, host string, port string, serverName string) PollingResolveFunc

MakeDNSResolveFunc constructs a PollingResolveFunc for building your own custom PollingResolver with the "dns" scheme.

func MakeSRVResolveFunc 

func MakeSRVResolveFunc(ctx context.Context, res *net.Resolver, name string, service string, serverName string) PollingResolveFunc

MakeSRVResolveFunc constructs a PollingResolveFunc for building your own custom PollingResolver with the "srv" scheme.

type PollingResolver 

type PollingResolver struct {
	// contains filtered or unexported fields
}

PollingResolver is an implementation of the Resolver interface that periodically polls for record changes.

func NewPollingResolver 

func NewPollingResolver(opts PollingResolverOptions) (*PollingResolver, error)

NewPollingResolver constructs a new PollingResolver.

func (*PollingResolver) CancelWatch 

func (res *PollingResolver) CancelWatch(id WatchID)

CancelWatch cancels a previous call to Watch.

func (*PollingResolver) Close 

func (res *PollingResolver) Close()

Close stops the resolver and frees all resources.

func (*PollingResolver) Err 

func (res *PollingResolver) Err() error

Err returns any errors encountered since the last call to Err or ResolveAll.

func (*PollingResolver) Resolve 

func (res *PollingResolver) Resolve() (Resolved, error)

Resolve returns the resolved address of a healthy backend, if one is available, or else returns the error that prevented it from doing so.

func (*PollingResolver) ResolveAll 

func (res *PollingResolver) ResolveAll() ([]Resolved, error)

ResolveAll returns all resolved addresses, plus any errors encountered since the last call to Err or ResolveAll.

func (*PollingResolver) ResolveNow 

func (res *PollingResolver) ResolveNow(opts resolver.ResolveNowOptions)

ResolveNow forces a poll immediately, or as soon as possible if an immediate poll would violate the CooldownInterval.

func (*PollingResolver) Update 

func (res *PollingResolver) Update(opts UpdateOptions)

Update changes the status of a server.

func (*PollingResolver) Watch 

func (res *PollingResolver) Watch(fn WatchFunc) WatchID

Watch registers a WatchFunc. The WatchFunc will be called immediately with synthetic events for each resolved address currently known, plus it will be called whenever the Resolver's state changes.

type PollingResolverOptions 

type PollingResolverOptions struct {
	// Context is the context within which the resolver runs.  If this
	// context is cancelled or reaches its deadline, the resolver will
	// stop.
	//
	// This field is mandatory.
	Context context.Context

	// Random is the source of randomness for balancer algorithms that need
	// one.
	//
	// If provided, it MUST be thread-safe; see the syncrand package for
	// more information.  If nil, the syncrand.Global() instance will be
	// used.
	Random *rand.Rand

	// PollInterval is the interval between automatic calls to ResolveFunc.
	// If zero, DefaultPollInterval is used.  If negative, MaxPollInterval
	// is used.
	PollInterval time.Duration

	// CooldownInterval is the minimum interval between calls to
	// ResolveFunc, whether automatic or triggered by ResolveNow.  If zero,
	// DefaultCooldownInterval is used.  If negative, the final value of
	// PollInterval is used.
	CooldownInterval time.Duration

	// Balancer selects which load balancer algorithm to use.
	Balancer BalancerType

	// ResolveFunc will be called periodically to resolve addresses.
	//
	// This field is mandatory.
	ResolveFunc PollingResolveFunc

	// ClientConn is a gRPC ClientConn that will receive state updates.
	ClientConn resolver.ClientConn

	// ServiceConfigJSON is the gRPC Service Config which will be provided
	// to ClientConn on each state update.
	ServiceConfigJSON string
}

PollingResolverOptions holds options related to constructing a new PollingResolver.

type Resolved 

type Resolved struct {
	// Unique is a stable unique identifier for this server.
	Unique string

	// Location is a string denoting the geographic location of this server.
	//
	// This field is only set by the ATC resolver.
	Location string

	// ServerName is either the empty string or the recommended value of
	// the "crypto/tls".(*Config).ServerName field.
	ServerName string

	// SRVPriority is the priority field of this SRV record.
	//
	// This field is only set by the SRV resolver.
	SRVPriority uint16

	// SRVWeight is the weight field of this SRV record.
	//
	// This field is only set by the SRV resolver.
	SRVWeight uint16

	// ShardID is the shard ID number.
	//
	// This field is only set by some resolvers.
	ShardID uint32

	// Weight is the proportional weight for this server.
	//
	// This field is only set by some resolvers.
	Weight float32

	// HasSRV is true if both SRVPriority and SRVWeight are set.
	HasSRV bool

	// HasShardID is true if ShardID is set.
	HasShardID bool

	// HasWeight is true if Weight is set.
	HasWeight bool

	// Err is the error encountered while resolving this server's address.
	Err error

	// Addr is the address of this server.
	Addr net.Addr

	// Address is the address of this server, in gRPC format.
	Address resolver.Address

	// Dynamic points to mutable, mutex-protected data associated with this
	// server.  Two Resolved addresses can share the same *Dynamic if they
	// point to the same server (e.g. have the same IP address).
	Dynamic *Dynamic
}

Resolved represents a resolved address.

func GetResolved 

func GetResolved(addr resolver.Address) (data Resolved, ok bool)

GetResolved retrieves the attached Resolved.

func (Resolved) Check 

func (data Resolved) Check()

Check verifies the data integrity of all fields.

func (Resolved) Equal 

func (data Resolved) Equal(other Resolved) bool

Equal returns true iff the two Resolved addresses are identical.

func (Resolved) IsHealthy 

func (data Resolved) IsHealthy() bool

IsHealthy returns true if this server is healthy.

type ResolvedList 

type ResolvedList []Resolved

ResolvedList is a sorted list of Resolved addresses.

func (ResolvedList) Len 

func (list ResolvedList) Len() int

Len fulfills sort.Interface.

func (ResolvedList) Less 

func (list ResolvedList) Less(i, j int) bool

Less fulfills sort.Interface.

func (ResolvedList) Sort 

func (list ResolvedList) Sort()

Sort is a convenience method for sort.Sort(list).

func (ResolvedList) Swap 

func (list ResolvedList) Swap(i, j int)

Swap fulfills sort.Interface.

type Resolver 

type Resolver interface {
	// Err returns any errors encountered since the last call to Err or
	// ResolveAll.
	Err() error

	// ResolveAll returns all resolved addresses, plus any errors
	// encountered since the last call to Err or ResolveAll.
	ResolveAll() ([]Resolved, error)

	// Resolve returns the resolved address of a healthy backend, if one is
	// available, or else returns the error that prevented it from doing
	// so.
	Resolve() (Resolved, error)

	// Update changes the status of a server.
	Update(opts UpdateOptions)

	// Watch registers a WatchFunc.  The WatchFunc will be called
	// immediately with synthetic events for each resolved address
	// currently known, plus it will be called whenever the Resolver's
	// state changes.
	Watch(WatchFunc) WatchID

	// CancelWatch cancels a previous call to Watch.
	CancelWatch(WatchID)

	// ResolveNow requests that the resolver issue a re-resolve poll ASAP,
	// if that makes sense for the particular Resolver implementation.
	ResolveNow(resolver.ResolveNowOptions)

	// Close stops the resolver and frees all resources.
	Close()
}

Resolver is an interface for obtaining resolved addresses and/or watching for address resolution changes.

func New 

func New(opts Options) (Resolver, error)

New constructs a new Resolver.

func NewATCResolver 

func NewATCResolver(opts Options) (Resolver, error)

NewATCResolver constructs a new Resolver for the "atc" scheme.

func NewDNSResolver 

func NewDNSResolver(opts Options) (Resolver, error)

NewDNSResolver constructs a new Resolver for the "dns" scheme.

func NewEtcdResolver 

func NewEtcdResolver(opts Options) (Resolver, error)

NewEtcdResolver constructs a new Resolver for the "etcd" scheme.

func NewIPResolver 

func NewIPResolver(opts Options) (Resolver, error)

NewIPResolver constructs a new Resolver for the "ip" scheme.

func NewSRVResolver 

func NewSRVResolver(opts Options) (Resolver, error)

NewSRVResolver constructs a new Resolver for the "srv" scheme.

func NewUnixResolver 

func NewUnixResolver(opts Options) (Resolver, error)

NewUnixResolver constructs a new Resolver for the "unix" scheme.

func NewZKResolver 

func NewZKResolver(opts Options) (Resolver, error)

NewZKResolver constructs a new Resolver for the "zk" scheme.

type StaticResolver 

type StaticResolver struct {
	// contains filtered or unexported fields
}

StaticResolver is an implementation of the Resolver interface that returns the same static records every time.

func NewStaticResolver 

func NewStaticResolver(opts StaticResolverOptions) (*StaticResolver, error)

NewStaticResolver constructs a new StaticResolver.

func (*StaticResolver) CancelWatch 

func (res *StaticResolver) CancelWatch(id WatchID)

CancelWatch cancels a previous call to Watch.

func (*StaticResolver) Close 

func (res *StaticResolver) Close()

Close stops the resolver and frees all resources.

func (*StaticResolver) Err 

func (res *StaticResolver) Err() error

Err returns any errors encountered since the last call to Err or ResolveAll.

func (*StaticResolver) Resolve 

func (res *StaticResolver) Resolve() (Resolved, error)

Resolve returns the resolved address of a healthy backend, if one is available, or else returns the error that prevented it from doing so.

func (*StaticResolver) ResolveAll 

func (res *StaticResolver) ResolveAll() ([]Resolved, error)

ResolveAll returns all resolved addresses, plus any errors encountered since the last call to Err or ResolveAll.

func (*StaticResolver) ResolveNow 

func (res *StaticResolver) ResolveNow(opts resolver.ResolveNowOptions)

ResolveNow is a no-op.

func (*StaticResolver) Update 

func (res *StaticResolver) Update(opts UpdateOptions)

Update changes the status of a server.

func (*StaticResolver) Watch 

func (res *StaticResolver) Watch(fn WatchFunc) WatchID

Watch registers a WatchFunc. The WatchFunc will be called immediately with synthetic events for each resolved address currently known, plus it will be called whenever the Resolver's state changes.

type StaticResolverOptions 

type StaticResolverOptions struct {
	// Records lists the Resolved addresses for this resolver to return.
	Records []Resolved

	// Random is the source of randomness for balancer algorithms that need
	// one.
	//
	// If provided, it MUST be thread-safe; see the syncrand package for
	// more information.  If nil, the syncrand.Global() instance will be
	// used.
	Random *rand.Rand

	// Balancer selects which load balancer algorithm to use.
	Balancer BalancerType

	// ClientConn is a gRPC ClientConn that will receive state updates.
	ClientConn resolver.ClientConn

	// ServiceConfigJSON is the gRPC Service Config which will be provided
	// to ClientConn on each state update.
	ServiceConfigJSON string
}

StaticResolverOptions holds options related to constructing a new StaticResolver.

type StatusError added in v0.4.6 

type StatusError struct {
	Status membership.ServerSetStatus
}

StatusError indicates that a server is in a bad state.

func (StatusError) Error added in v0.4.6 

func (err StatusError) Error() string

Error fulfills the error interface.

func (StatusError) Is added in v0.4.6 

func (err StatusError) Is(other error) bool

Is returns true for fs.ErrNotExist.

type Target 

type Target struct {
	// Scheme indicates which Resolver implementation to use.
	//
	// If not specified, "dns" is assumed.
	Scheme string

	// Authority provides information about which server to query to do the
	// resolving.
	//
	// Most schemes do not permit the Authority field to be specified.
	Authority string

	// Endpoint provides information about which name to resolve.
	//
	// This field is mandatory.
	Endpoint string

	// ServerName is the value to use for the
	// "crypto/tls".(*Config).ServerName field.
	ServerName string

	// Query is a collection of key-value mappings.
	Query url.Values
}

Target represents a parsed Resolver target name.

func (Target) AppendTo added in v0.4.6 

func (rt Target) AppendTo(out *strings.Builder)

AppendTo appends the string representation of this Target to the provided Builder.

func (Target) AsGRPCTarget added in v0.4.6 

func (rt Target) AsGRPCTarget() resolver.Target

AsGRPCTarget converts this Target to an equivalent resolver.Target.

func (*Target) FromGRPCTarget added in v0.4.6 

func (rt *Target) FromGRPCTarget(target resolver.Target) error

FromGRPCTarget tries to make this Target identical to the given resolver.Target.

func (Target) MarshalJSON added in v0.4.6 

func (rt Target) MarshalJSON() ([]byte, error)

MarshalJSON fulfills json.Marshaler.

func (*Target) Parse added in v0.4.6 

func (rt *Target) Parse(str string) error

Parse parses the given string representation.

func (Target) String added in v0.4.6 

func (rt Target) String() string

String returns the string representation of this Target.

func (*Target) UnmarshalJSON added in v0.4.6 

func (rt *Target) UnmarshalJSON(raw []byte) error

UnmarshalJSON fulfills json.Unmarshaler.

type UpdateOptions 

type UpdateOptions struct {
	// Addr is the address of the server to act upon.
	Addr net.Addr

	// HasHealthy is true if Healthy has a value.
	HasHealthy bool

	// Healthy is true if the server is ready to serve, false if it is not.
	Healthy bool
}

UpdateOptions holds options for the Resolver.Update method.

type WatchFunc 

type WatchFunc func([]Event)

WatchFunc denotes a callback which will be called whenever a Resolver's state changes.

type WatchID 

type WatchID uint64

WatchID uniquely identifies a call to Resolver.Watch.

type WatchingResolveFunc 

type WatchingResolveFunc func(ctx context.Context, wg *sync.WaitGroup, backoff expbackoff.ExpBackoff) (<-chan []Event, error)

WatchingResolveFunc represents a closure that will be called as needed to start a resolver subscription. If it spawns any goroutines, they should register themselves with the provided WaitGroup. If it needs to retry any external I/O, it should use the provided ExpBackoff.

func MakeATCResolveFunc 

func MakeATCResolveFunc(client *atcclient.ATCClient, lbName, lbLocation, lbUnique string, dsc bool, serverName string) WatchingResolveFunc

MakeATCResolveFunc constructs a WatchingResolveFunc for building your own custom WatchingResolver with the "atc" scheme.

func MakeEtcdResolveFunc 

func MakeEtcdResolveFunc(etcdClient *v3.Client, etcdPath string, etcdPort string, serverName string) WatchingResolveFunc

MakeEtcdResolveFunc constructs a WatchingResolveFunc for building your own custom WatchingResolver with the "etcd" scheme.

func MakeZKResolveFunc 

func MakeZKResolveFunc(zkconn *zk.Conn, zkPath string, zkPort string, serverName string) WatchingResolveFunc

MakeZKResolveFunc constructs a WatchingResolveFunc for building your own custom WatchingResolver with the "zk" scheme.

type WatchingResolver 

type WatchingResolver struct {
	// contains filtered or unexported fields
}

WatchingResolver is an implementation of the Resolver interface that subscribes to an event-oriented resolution source.

func NewWatchingResolver 

func NewWatchingResolver(opts WatchingResolverOptions) (*WatchingResolver, error)

NewWatchingResolver constructs a new WatchingResolver.

func (*WatchingResolver) CancelWatch 

func (res *WatchingResolver) CancelWatch(id WatchID)

CancelWatch cancels a previous call to Watch.

func (*WatchingResolver) Close 

func (res *WatchingResolver) Close()

Close stops the resolver and frees all resources.

func (*WatchingResolver) Err 

func (res *WatchingResolver) Err() error

Err returns any errors encountered since the last call to Err or ResolveAll.

func (*WatchingResolver) Resolve 

func (res *WatchingResolver) Resolve() (Resolved, error)

Resolve returns the resolved address of a healthy backend, if one is available, or else returns the error that prevented it from doing so.

func (*WatchingResolver) ResolveAll 

func (res *WatchingResolver) ResolveAll() ([]Resolved, error)

ResolveAll returns all resolved addresses, plus any errors encountered since the last call to Err or ResolveAll.

func (*WatchingResolver) ResolveNow 

func (res *WatchingResolver) ResolveNow(opts resolver.ResolveNowOptions)

ResolveNow is a no-op.

func (*WatchingResolver) Update 

func (res *WatchingResolver) Update(opts UpdateOptions)

Update changes the status of a server.

func (*WatchingResolver) Watch 

func (res *WatchingResolver) Watch(fn WatchFunc) WatchID

Watch registers a WatchFunc. The WatchFunc will be called immediately with synthetic events for each resolved address currently known, plus it will be called whenever the Resolver's state changes.

type WatchingResolverOptions 

type WatchingResolverOptions struct {
	// Context is the context within which the resolver runs.  If this
	// context is cancelled or reaches its deadline, the resolver will
	// stop.
	//
	// This field is mandatory.
	Context context.Context

	// Random is the source of randomness for balancer algorithms that need
	// one.
	//
	// If provided, it MUST be thread-safe; see the syncrand package for
	// more information.  If nil, the syncrand.Global() instance will be
	// used.
	Random *rand.Rand

	// Balancer selects which load balancer algorithm to use.
	Balancer BalancerType

	// ResolveFunc will be called as needed to (re)start the event stream.
	//
	// This field is mandatory.
	ResolveFunc WatchingResolveFunc

	// ClientConn is a gRPC ClientConn that will receive state updates.
	ClientConn resolver.ClientConn

	// ServiceConfigJSON is the gRPC Service Config which will be provided
	// to ClientConn on each state update.
	ServiceConfigJSON string
}

WatchingResolverOptions holds options related to constructing a new WatchingResolver.

Source Files

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