Module org.elasticsearch.server

Package org.elasticsearch.reservedstate.service

Class FileSettingsService

java.lang.Object

org.elasticsearch.common.component.AbstractLifecycleComponent

org.elasticsearch.common.file.AbstractFileWatchingService

org.elasticsearch.common.file.MasterNodeFileWatchingService

org.elasticsearch.reservedstate.service.FileSettingsService

All Implemented Interfaces:

Closeable, AutoCloseable, ClusterStateListener, LifecycleComponent, Releasable

public class FileSettingsService
extends MasterNodeFileWatchingService
implements ClusterStateListener

File based settings applier service which watches an 'operator` directory inside the config directory.

The service expects that the operator directory will contain a single JSON file with all the settings that need to be applied to the cluster state. The name of the file is fixed to be settings.json. The operator directory name can be configured by setting the 'path.config.operator_directory' in the node properties.

The FileSettingsService is active always, but enabled only on the current master node. We register the service as a listener to cluster state changes, so that we can enable the file watcher thread when this node becomes a master node.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	NAMESPACE
static final String	OPERATOR_DIRECTORY
static final String	SETTINGS_FILE_NAME

Fields inherited from class org.elasticsearch.common.component.AbstractLifecycleComponent

lifecycle

Constructor Summary

Constructors

Constructor	Description
FileSettingsService(ClusterService clusterService, ReservedClusterStateService stateService, Environment environment)	Constructs the FileSettingsService

Method Summary

Modifier and Type	Method	Description
void	handleSnapshotRestore(ClusterState clusterState, Metadata.Builder mdBuilder)	Used by snapshot restore service RestoreService to prepare the reserved state of the snapshot for the current cluster.
protected void	processFileChanges()	Read settings and pass them to ReservedClusterStateService for application
protected boolean	shouldRefreshFileState(ClusterState clusterState)	If the file settings metadata version is set to zero, then we have restored from a snapshot and must reprocess the file.

Methods inherited from class org.elasticsearch.common.file.MasterNodeFileWatchingService

clusterChanged, doStart, doStop

Methods inherited from class org.elasticsearch.common.file.AbstractFileWatchingService

addFileChangedListener, doClose, startWatcher, stopWatcher, watchedFile, watchedFileDir, watcherThread, watching

Methods inherited from class org.elasticsearch.common.component.AbstractLifecycleComponent

addLifecycleListener, close, lifecycleState, start, stop

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.elasticsearch.cluster.ClusterStateListener

clusterChanged

Field Details

SETTINGS_FILE_NAME

public static final String SETTINGS_FILE_NAME

See Also:

• Constant Field Values

NAMESPACE

public static final String NAMESPACE

See Also:

• Constant Field Values

OPERATOR_DIRECTORY

public static final String OPERATOR_DIRECTORY

See Also:

• Constant Field Values

Constructor Details

FileSettingsService

public FileSettingsService(ClusterService clusterService,
 ReservedClusterStateService stateService,
 Environment environment)

Constructs the FileSettingsService

Parameters:

clusterService - so we can register ourselves as a cluster state change listener

stateService - an instance of the immutable cluster state controller, so we can perform the cluster state changes

environment - we need the environment to pull the location of the config and operator directories

Method Details

handleSnapshotRestore

public void handleSnapshotRestore(ClusterState clusterState,
 Metadata.Builder mdBuilder)

Used by snapshot restore service RestoreService to prepare the reserved state of the snapshot for the current cluster.

If the current cluster where we are restoring the snapshot into has any operator file based settings, we'll reset the reserved state version to 0.

If there's no file based settings file in this cluster, we'll remove all state reservations for file based settings from the cluster state.

Parameters:

clusterState - the cluster state before snapshot restore

mdBuilder - the current metadata builder for the new cluster state

shouldRefreshFileState

protected boolean shouldRefreshFileState(ClusterState clusterState)

If the file settings metadata version is set to zero, then we have restored from a snapshot and must reprocess the file.

Overrides:

shouldRefreshFileState in class MasterNodeFileWatchingService

Parameters:

clusterState - State of the cluster

Returns:

true if file settings metadata version is exactly 0, false otherwise.

processFileChanges

protected void processFileChanges()
                           throws ExecutionException,
InterruptedException,
IOException

Read settings and pass them to ReservedClusterStateService for application

Specified by:

processFileChanges in class AbstractFileWatchingService

Throws:

IOException - if there is an error reading the file itself

ExecutionException - if there is an issue while applying the changes from the file

InterruptedException - if the file processing is interrupted by another thread.