com.netflix.discovery

Class DiscoveryClient

java.lang.Object

com.netflix.discovery.DiscoveryClient

All Implemented Interfaces:

EurekaClient, LookupService

@Singleton
public class DiscoveryClient
extends java.lang.Object
implements EurekaClient

The class that is instrumental for interactions with Eureka Server.

Eureka Client is responsible for a) Registering the instance with Eureka Server b) Renewalof the lease with Eureka Server c) Cancellation of the lease from Eureka Server during shutdown

d) Querying the list of services/instances registered with Eureka Server

Eureka Client needs a configured list of Eureka Server URLs to talk to.These URLs are typically amazon elastic eips which do not change. All of the functions defined above fail-over to other URLs specified in the list in the case of failure.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DiscoveryClient.DiscoveryClientOptionalArgs
class	DiscoveryClient.Stats Stats is used to track useful attributes of the DiscoveryClient.

Field Summary

Fields

Modifier and Type	Field and Description
protected EurekaClientConfig	clientConfig
static java.lang.String	HTTP_X_DISCOVERY_ALLOW_REDIRECT
protected EurekaTransportConfig	transportConfig

Constructor Summary

Constructors

Constructor and Description
DiscoveryClient(ApplicationInfoManager applicationInfoManager, EurekaClientConfig config)
DiscoveryClient(ApplicationInfoManager applicationInfoManager, EurekaClientConfig config, AbstractDiscoveryClientOptionalArgs args)
DiscoveryClient(ApplicationInfoManager applicationInfoManager, EurekaClientConfig config, AbstractDiscoveryClientOptionalArgs args, EndpointRandomizer randomizer)
DiscoveryClient(ApplicationInfoManager applicationInfoManager, EurekaClientConfig config, DiscoveryClient.DiscoveryClientOptionalArgs args) Deprecated. use the version that take AbstractDiscoveryClientOptionalArgs instead
DiscoveryClient(InstanceInfo myInfo, EurekaClientConfig config) Deprecated. use constructor that takes ApplicationInfoManager instead of InstanceInfo directly
DiscoveryClient(InstanceInfo myInfo, EurekaClientConfig config, AbstractDiscoveryClientOptionalArgs args) Deprecated. use constructor that takes ApplicationInfoManager instead of InstanceInfo directly
DiscoveryClient(InstanceInfo myInfo, EurekaClientConfig config, DiscoveryClient.DiscoveryClientOptionalArgs args) Deprecated. use constructor that takes ApplicationInfoManager instead of InstanceInfo directly

Method Summary

Modifier and Type	Method and Description
protected void	fireEvent(EurekaEvent event) Send the given event on the EventBus if one is available
java.util.Set<java.lang.String>	getAllKnownRegions()
Application	getApplication(java.lang.String appName) Returns the corresponding Application object which is basically a container of all registered appName InstanceInfos.
ApplicationInfoManager	getApplicationInfoManager()
Applications	getApplications() Returns the Applications object which is basically a container of all currently registered Applications.
Applications	getApplications(java.lang.String serviceUrl) Get all applications registered with a specific eureka service.
Applications	getApplicationsForARegion(java.lang.String region)
java.util.List<java.lang.String>	getDiscoveryServiceUrls(java.lang.String zone) Deprecated. see replacement in EndpointUtils
static java.util.Set<java.lang.String>	getEC2DiscoveryUrlsFromZone(java.lang.String dnsName, EndpointUtils.DiscoveryUrlType type) Deprecated. see replacement in EndpointUtils Get the list of EC2 URLs given the zone name.
EurekaClientConfig	getEurekaClientConfig()
static java.util.List<java.lang.String>	getEurekaServiceUrlsFromConfig(java.lang.String instanceZone, boolean preferSameZone) Deprecated. use getServiceUrlsFromConfig(String, boolean) instead.
HealthCheckHandler	getHealthCheckHandler()
InstanceInfo.InstanceStatus	getInstanceRemoteStatus()
java.util.List<InstanceInfo>	getInstancesById(java.lang.String id) Returns the List of InstanceInfos matching the the passed in id.
java.util.List<InstanceInfo>	getInstancesByVipAddress(java.lang.String vipAddress, boolean secure) Gets the list of instances matching the given VIP Address.
java.util.List<InstanceInfo>	getInstancesByVipAddress(java.lang.String vipAddress, boolean secure, java.lang.String region) Gets the list of instances matching the given VIP Address in the passed region.
java.util.List<InstanceInfo>	getInstancesByVipAddressAndAppName(java.lang.String vipAddress, java.lang.String appName, boolean secure) Gets the list of instances matching the given VIP Address and the given application name if both of them are not null.
long	getLastSuccessfulHeartbeatTimePeriod()
long	getLastSuccessfulRegistryFetchTimePeriod()
InstanceInfo	getNextServerFromEureka(java.lang.String virtualHostname, boolean secure) Gets the next possible server to process the requests from the registry information received from eureka.
static java.lang.String	getRegion() Deprecated. see replacement in EndpointUtils Get the region that this particular instance is in.
java.util.List<java.lang.String>	getServiceUrlsFromConfig(java.lang.String instanceZone, boolean preferSameZone) Deprecated. see replacement in EndpointUtils Get the list of all eureka service urls from properties file for the eureka client to talk to.
java.util.List<java.lang.String>	getServiceUrlsFromDNS(java.lang.String instanceZone, boolean preferSameZone) Deprecated. see replacement in EndpointUtils Get the list of all eureka service urls from DNS for the eureka client to talk to. The client picks up the service url from its zone and then fails over to other zones randomly. If there are multiple servers in the same zone, the client once again picks one randomly. This way the traffic will be distributed in the case of failures.
DiscoveryClient.Stats	getStats() Gets stats for the DiscoveryClient.
static java.lang.String	getZone(InstanceInfo myInfo) Deprecated. see InstanceInfo.getZone(String[], com.netflix.appinfo.InstanceInfo) Get the zone that a particular instance is in.
int	localRegistrySize()
protected BackupRegistry	newBackupRegistryInstance() Deprecated. Use injection to provide BackupRegistry implementation.
protected void	onCacheRefreshed() Invoked every time the local registry cache is refreshed (whether changes have been detected or not).
protected void	onRemoteStatusChanged(InstanceInfo.InstanceStatus oldStatus, InstanceInfo.InstanceStatus newStatus) Invoked when the remote status of this client has changed.
void	registerEventListener(EurekaEventListener eventListener) Register EurekaEventListener with the eureka client.
void	registerHealthCheck(HealthCheckHandler healthCheckHandler) Register HealthCheckHandler with the eureka client.
void	registerHealthCheckCallback(HealthCheckCallback callback) Deprecated. Use
void	shutdown() Shuts down Eureka Client.
boolean	unregisterEventListener(EurekaEventListener eventListener) Unregister a EurekaEventListener previous registered with EurekaClient.registerEventListener(com.netflix.discovery.EurekaEventListener) or injected into the constructor of DiscoveryClient

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

HTTP_X_DISCOVERY_ALLOW_REDIRECT

public static final java.lang.String HTTP_X_DISCOVERY_ALLOW_REDIRECT

See Also:

Constant Field Values

clientConfig

protected final EurekaClientConfig clientConfig

transportConfig

protected final EurekaTransportConfig transportConfig

Constructor Detail

DiscoveryClient

@Deprecated
public DiscoveryClient(InstanceInfo myInfo,
                                   EurekaClientConfig config)

Deprecated. use constructor that takes ApplicationInfoManager instead of InstanceInfo directly

Assumes applicationInfoManager is already initialized

DiscoveryClient

@Deprecated
public DiscoveryClient(InstanceInfo myInfo,
                                   EurekaClientConfig config,
                                   DiscoveryClient.DiscoveryClientOptionalArgs args)

Deprecated. use constructor that takes ApplicationInfoManager instead of InstanceInfo directly

Assumes applicationInfoManager is already initialized

DiscoveryClient

@Deprecated
public DiscoveryClient(InstanceInfo myInfo,
                                   EurekaClientConfig config,
                                   AbstractDiscoveryClientOptionalArgs args)

Deprecated. use constructor that takes ApplicationInfoManager instead of InstanceInfo directly

DiscoveryClient

public DiscoveryClient(ApplicationInfoManager applicationInfoManager,
                       EurekaClientConfig config)

DiscoveryClient

@Deprecated
public DiscoveryClient(ApplicationInfoManager applicationInfoManager,
                                   EurekaClientConfig config,
                                   DiscoveryClient.DiscoveryClientOptionalArgs args)

Deprecated. use the version that take AbstractDiscoveryClientOptionalArgs instead

DiscoveryClient

public DiscoveryClient(ApplicationInfoManager applicationInfoManager,
                       EurekaClientConfig config,
                       AbstractDiscoveryClientOptionalArgs args)

DiscoveryClient

public DiscoveryClient(ApplicationInfoManager applicationInfoManager,
                       EurekaClientConfig config,
                       AbstractDiscoveryClientOptionalArgs args,
                       EndpointRandomizer randomizer)

Method Detail

getEurekaClientConfig

public EurekaClientConfig getEurekaClientConfig()

Specified by:

getEurekaClientConfig in interface EurekaClient

Returns:

the configuration of this eureka client

getApplicationInfoManager

public ApplicationInfoManager getApplicationInfoManager()

Specified by:

getApplicationInfoManager in interface EurekaClient

Returns:

the application info manager of this eureka client

getApplication

public Application getApplication(java.lang.String appName)

Description copied from interface: LookupService

Returns the corresponding Application object which is basically a container of all registered appName InstanceInfos.

Specified by:

getApplication in interface LookupService

Returns:

a Application or null if we couldn't locate any app of the requested appName

getApplications

public Applications getApplications()

Description copied from interface: LookupService

Returns the Applications object which is basically a container of all currently registered Applications.

Specified by:

getApplications in interface LookupService

Returns:

Applications

getApplicationsForARegion

public Applications getApplicationsForARegion(@Nullable
                                              java.lang.String region)

Specified by:

getApplicationsForARegion in interface EurekaClient

Parameters:

region - the region that the Applications reside in

Returns:

an Applications for the matching region. a Null value is treated as the local region.

getAllKnownRegions

public java.util.Set<java.lang.String> getAllKnownRegions()

Specified by:

getAllKnownRegions in interface EurekaClient

Returns:

in String form all regions (local + remote) that can be accessed by this client

getInstancesById

public java.util.List<InstanceInfo> getInstancesById(java.lang.String id)

Description copied from interface: LookupService

Returns the List of InstanceInfos matching the the passed in id. A single InstanceInfo can possibly be registered w/ more than one Applications

Specified by:

getInstancesById in interface LookupService

Returns:

List of InstanceInfos or Collections.emptyList()

registerHealthCheckCallback

@Deprecated
public void registerHealthCheckCallback(HealthCheckCallback callback)

Deprecated. Use

Register HealthCheckCallback with the eureka client. Once registered, the eureka client will invoke the HealthCheckCallback in intervals specified by EurekaClientConfig.getInstanceInfoReplicationIntervalSeconds().

Specified by:

registerHealthCheckCallback in interface EurekaClient

Parameters:

callback - app specific healthcheck.

registerHealthCheck

public void registerHealthCheck(HealthCheckHandler healthCheckHandler)

Description copied from interface: EurekaClient

Register HealthCheckHandler with the eureka client. Once registered, the eureka client will first make an onDemand update of the registering instanceInfo by calling the newly registered healthcheck handler, and subsequently invoke the HealthCheckHandler in intervals specified by EurekaClientConfig.getInstanceInfoReplicationIntervalSeconds().

Specified by:

registerHealthCheck in interface EurekaClient

Parameters:

healthCheckHandler - app specific healthcheck handler.

registerEventListener

public void registerEventListener(EurekaEventListener eventListener)

Description copied from interface: EurekaClient

Register EurekaEventListener with the eureka client. Once registered, the eureka client will invoke EurekaEventListener.onEvent(com.netflix.discovery.EurekaEvent) whenever there is a change in eureka client's internal state. Use this instead of polling the client for changes. EurekaEventListener.onEvent(com.netflix.discovery.EurekaEvent) is called from the context of an internal thread and must therefore return as quickly as possible without blocking.

Specified by:

registerEventListener in interface EurekaClient

unregisterEventListener

public boolean unregisterEventListener(EurekaEventListener eventListener)

Description copied from interface: EurekaClient

Unregister a EurekaEventListener previous registered with EurekaClient.registerEventListener(com.netflix.discovery.EurekaEventListener) or injected into the constructor of DiscoveryClient

Specified by:

unregisterEventListener in interface EurekaClient

Returns:

True if removed otherwise false if the listener was never registered.

getInstancesByVipAddress

public java.util.List<InstanceInfo> getInstancesByVipAddress(java.lang.String vipAddress,
                                                             boolean secure)

Gets the list of instances matching the given VIP Address.

Specified by:

getInstancesByVipAddress in interface EurekaClient

Parameters:

vipAddress - - The VIP address to match the instances for.

secure - - true if it is a secure vip address, false otherwise

Returns:

- The list of InstanceInfo objects matching the criteria

getInstancesByVipAddress

public java.util.List<InstanceInfo> getInstancesByVipAddress(java.lang.String vipAddress,
                                                             boolean secure,
                                                             @Nullable
                                                             java.lang.String region)

Gets the list of instances matching the given VIP Address in the passed region.

Specified by:

getInstancesByVipAddress in interface EurekaClient

Parameters:

vipAddress - - The VIP address to match the instances for.

secure - - true if it is a secure vip address, false otherwise

region - - region from which the instances are to be fetched. If null then local region is assumed.

Returns:

- The list of InstanceInfo objects matching the criteria, empty list if not instances found.

getInstancesByVipAddressAndAppName

public java.util.List<InstanceInfo> getInstancesByVipAddressAndAppName(java.lang.String vipAddress,
                                                                       java.lang.String appName,
                                                                       boolean secure)

Gets the list of instances matching the given VIP Address and the given application name if both of them are not null. If one of them is null, then that criterion is completely ignored for matching instances.

Specified by:

getInstancesByVipAddressAndAppName in interface EurekaClient

Parameters:

vipAddress - - The VIP address to match the instances for.

appName - - The applicationName to match the instances for.

secure - - true if it is a secure vip address, false otherwise.

Returns:

- The list of InstanceInfo objects matching the criteria.

getNextServerFromEureka

public InstanceInfo getNextServerFromEureka(java.lang.String virtualHostname,
                                            boolean secure)

Description copied from interface: LookupService

Gets the next possible server to process the requests from the registry information received from eureka.

The next server is picked on a round-robin fashion. By default, this method just returns the servers that are currently with InstanceInfo.InstanceStatus.UP status. This configuration can be controlled by overriding the EurekaClientConfig.shouldFilterOnlyUpInstances(). Note that in some cases (Eureka emergency mode situation), the instances that are returned may not be unreachable, it is solely up to the client at that point to timeout quickly and retry the next server.

Specified by:

getNextServerFromEureka in interface LookupService

Parameters:

virtualHostname - the virtual host name that is associated to the servers.

secure - indicates whether this is a HTTP or a HTTPS request - secure means HTTPS.

Returns:

the InstanceInfo information which contains the public host name of the next server in line to process the request based on the round-robin algorithm.

getApplications

public Applications getApplications(java.lang.String serviceUrl)

Get all applications registered with a specific eureka service.

Specified by:

getApplications in interface EurekaClient

Parameters:

serviceUrl - - The string representation of the service url.

Returns:

- The registry information containing all applications.

getServiceUrlsFromConfig

@Deprecated
public java.util.List<java.lang.String> getServiceUrlsFromConfig(java.lang.String instanceZone,
                                                                             boolean preferSameZone)

Deprecated. see replacement in EndpointUtils Get the list of all eureka service urls from properties file for the eureka client to talk to.

Specified by:

getServiceUrlsFromConfig in interface EurekaClient

Parameters:

instanceZone - The zone in which the client resides

preferSameZone - true if we have to prefer the same zone as the client, false otherwise

Returns:

The list of all eureka service urls for the eureka client to talk to

shutdown

@PreDestroy
public void shutdown()

Shuts down Eureka Client. Also sends a deregistration request to the eureka server.

Specified by:

shutdown in interface EurekaClient

getInstanceRemoteStatus

public InstanceInfo.InstanceStatus getInstanceRemoteStatus()

Specified by:

getInstanceRemoteStatus in interface EurekaClient

Returns:

Return he current instance status as seen on the Eureka server.

getServiceUrlsFromDNS

@Deprecated
public java.util.List<java.lang.String> getServiceUrlsFromDNS(java.lang.String instanceZone,
                                                                          boolean preferSameZone)

Deprecated. see replacement in EndpointUtils Get the list of all eureka service urls from DNS for the eureka client to talk to. The client picks up the service url from its zone and then fails over to other zones randomly. If there are multiple servers in the same zone, the client once again picks one randomly. This way the traffic will be distributed in the case of failures.

Specified by:

getServiceUrlsFromDNS in interface EurekaClient

Parameters:

instanceZone - The zone in which the client resides.

preferSameZone - true if we have to prefer the same zone as the client, false otherwise.

Returns:

The list of all eureka service urls for the eureka client to talk to.

getDiscoveryServiceUrls

@Deprecated
public java.util.List<java.lang.String> getDiscoveryServiceUrls(java.lang.String zone)

Deprecated. see replacement in EndpointUtils

Specified by:

getDiscoveryServiceUrls in interface EurekaClient

Parameters:

zone - the zone in which the client resides

Returns:

The list of all eureka service urls for the eureka client to talk to.

getEC2DiscoveryUrlsFromZone

@Deprecated
public static java.util.Set<java.lang.String> getEC2DiscoveryUrlsFromZone(java.lang.String dnsName,
                                                                                      EndpointUtils.DiscoveryUrlType type)

Deprecated. see replacement in EndpointUtils Get the list of EC2 URLs given the zone name.

Parameters:

dnsName - The dns name of the zone-specific CNAME

type - CNAME or EIP that needs to be retrieved

Returns:

The list of EC2 URLs associated with the dns name

getHealthCheckHandler

public HealthCheckHandler getHealthCheckHandler()

Specified by:

getHealthCheckHandler in interface EurekaClient

Returns:

the current registered healthcheck handler

newBackupRegistryInstance

@Deprecated
 @Nullable
protected BackupRegistry newBackupRegistryInstance()
                                                                   throws java.lang.ClassNotFoundException,
                                                                          java.lang.IllegalAccessException,
                                                                          java.lang.InstantiationException

Deprecated. Use injection to provide BackupRegistry implementation.

Throws:

java.lang.ClassNotFoundException

java.lang.IllegalAccessException

java.lang.InstantiationException

onRemoteStatusChanged

protected void onRemoteStatusChanged(InstanceInfo.InstanceStatus oldStatus,
                                     InstanceInfo.InstanceStatus newStatus)

Invoked when the remote status of this client has changed. Subclasses may override this method to implement custom behavior if needed.

Parameters:

oldStatus - the previous remote InstanceInfo.InstanceStatus

newStatus - the new remote InstanceInfo.InstanceStatus

onCacheRefreshed

protected void onCacheRefreshed()

Invoked every time the local registry cache is refreshed (whether changes have been detected or not). Subclasses may override this method to implement custom behavior if needed.

fireEvent

protected void fireEvent(EurekaEvent event)

Send the given event on the EventBus if one is available

Parameters:

event - the event to send on the eventBus

getZone

@Deprecated
public static java.lang.String getZone(InstanceInfo myInfo)

Deprecated. see InstanceInfo.getZone(String[], com.netflix.appinfo.InstanceInfo) Get the zone that a particular instance is in.

Parameters:

myInfo - - The InstanceInfo object of the instance.

Returns:

- The zone in which the particular instance belongs to.

getRegion

@Deprecated
public static java.lang.String getRegion()

Deprecated. see replacement in EndpointUtils Get the region that this particular instance is in.

Returns:

- The region in which the particular instance belongs to.

getEurekaServiceUrlsFromConfig

@Deprecated
public static java.util.List<java.lang.String> getEurekaServiceUrlsFromConfig(java.lang.String instanceZone,
                                                                                          boolean preferSameZone)

Deprecated. use getServiceUrlsFromConfig(String, boolean) instead.

getLastSuccessfulHeartbeatTimePeriod

public long getLastSuccessfulHeartbeatTimePeriod()

getLastSuccessfulRegistryFetchTimePeriod

public long getLastSuccessfulRegistryFetchTimePeriod()

localRegistrySize

@Monitor(name="eurekaClient.registry.localRegistrySize",
         description="Count of instances in the local registry",
         type=GAUGE)
public int localRegistrySize()

getStats

public DiscoveryClient.Stats getStats()

Gets stats for the DiscoveryClient.

Returns:

The DiscoveryClientStats instance.