/**
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hbase.zookeeper;
import java.io.Closeable;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.CountDownLatch;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Abortable;
import org.apache.hadoop.hbase.AuthUtil;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.security.Superusers;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooDefs.Perms;
import org.apache.zookeeper.data.ACL;
import org.apache.zookeeper.data.Id;
import org.apache.zookeeper.data.Stat;
/**
* Acts as the single ZooKeeper Watcher. One instance of this is instantiated
* for each Master, RegionServer, and client process.
*
* <p>This is the only class that implements {@link Watcher}. Other internal
* classes which need to be notified of ZooKeeper events must register with
* the local instance of this watcher via {@link #registerListener}.
*
* <p>This class also holds and manages the connection to ZooKeeper. Code to
* deal with connection related events and exceptions are handled here.
*/
@InterfaceAudience.Private
public class ZooKeeperWatcher implements Watcher, Abortable, Closeable {
private static final Log LOG = LogFactory.getLog(ZooKeeperWatcher.class);
// Identifier for this watcher (for logging only). It is made of the prefix
// passed on construction and the zookeeper sessionid.
private String prefix;
private String identifier;
// zookeeper quorum
private String quorum;
// zookeeper connection
private final RecoverableZooKeeper recoverableZooKeeper;
// abortable in case of zk failure
protected Abortable abortable;
// Used if abortable is null
private boolean aborted = false;
public final ZNodePaths znodePaths;
// listeners to be notified
private final List<ZooKeeperListener> listeners = new CopyOnWriteArrayList<>();
// Used by ZKUtil:waitForZKConnectionIfAuthenticating to wait for SASL
// negotiation to complete
public CountDownLatch saslLatch = new CountDownLatch(1);
private final Configuration conf;
/* A pattern that matches a Kerberos name, borrowed from Hadoop's KerberosName */
private static final Pattern NAME_PATTERN = Pattern.compile("([^/@]*)(/([^/@]*))?@([^/@]*)");
/**
* Instantiate a ZooKeeper connection and watcher.
* @param identifier string that is passed to RecoverableZookeeper to be used as
* identifier for this instance. Use null for default.
* @throws IOException
* @throws ZooKeeperConnectionException
*/
public ZooKeeperWatcher(Configuration conf, String identifier,
Abortable abortable) throws ZooKeeperConnectionException, IOException {
this(conf, identifier, abortable, false);
}
/**
* Instantiate a ZooKeeper connection and watcher.
* @param conf
* @param identifier string that is passed to RecoverableZookeeper to be used as identifier for
* this instance. Use null for default.
* @param abortable Can be null if there is on error there is no host to abort: e.g. client
* context.
* @param canCreateBaseZNode
* @throws IOException
* @throws ZooKeeperConnectionException
*/
public ZooKeeperWatcher(Configuration conf, String identifier,
Abortable abortable, boolean canCreateBaseZNode)
throws IOException, ZooKeeperConnectionException {
this.conf = conf;
this.quorum = ZKConfig.getZKQuorumServersString(conf);
this.prefix = identifier;
// Identifier will get the sessionid appended later below down when we
// handle the syncconnect event.
this.identifier = identifier + "0x0";
this.abortable = abortable;
this.znodePaths = new ZNodePaths(conf);
PendingWatcher pendingWatcher = new PendingWatcher();
this.recoverableZooKeeper = ZKUtil.connect(conf, quorum, pendingWatcher, identifier);
pendingWatcher.prepare(this);
if (canCreateBaseZNode) {
try {
createBaseZNodes();
} catch (ZooKeeperConnectionException zce) {
try {
this.recoverableZooKeeper.close();
} catch (InterruptedException ie) {
LOG.debug("Encountered InterruptedException when closing " + this.recoverableZooKeeper);
Thread.currentThread().interrupt();
}
throw zce;
}
}
}
private void createBaseZNodes() throws ZooKeeperConnectionException {
try {
// Create all the necessary "directories" of znodes
ZKUtil.createWithParents(this, znodePaths.baseZNode);
ZKUtil.createAndFailSilent(this, znodePaths.rsZNode);
ZKUtil.createAndFailSilent(this, znodePaths.drainingZNode);
ZKUtil.createAndFailSilent(this, znodePaths.tableZNode);
ZKUtil.createAndFailSilent(this, znodePaths.splitLogZNode);
ZKUtil.createAndFailSilent(this, znodePaths.backupMasterAddressesZNode);
ZKUtil.createAndFailSilent(this, znodePaths.tableLockZNode);
ZKUtil.createAndFailSilent(this, znodePaths.recoveringRegionsZNode);
ZKUtil.createAndFailSilent(this, znodePaths.masterMaintZNode);
} catch (KeeperException e) {
throw new ZooKeeperConnectionException(
prefix("Unexpected KeeperException creating base node"), e);
}
}
/** Returns whether the znode is supposed to be readable by the client
* and DOES NOT contain sensitive information (world readable).*/
public boolean isClientReadable(String node) {
// Developer notice: These znodes are world readable. DO NOT add more znodes here UNLESS
// all clients need to access this data to work. Using zk for sharing data to clients (other
// than service lookup case is not a recommended design pattern.
return
node.equals(znodePaths.baseZNode) ||
znodePaths.isAnyMetaReplicaZNode(node) ||
node.equals(znodePaths.masterAddressZNode) ||
node.equals(znodePaths.clusterIdZNode)||
node.equals(znodePaths.rsZNode) ||
// /hbase/table and /hbase/table/foo is allowed, /hbase/table-lock is not
node.equals(znodePaths.tableZNode) ||
node.startsWith(znodePaths.tableZNode + "/");
}
/**
* On master start, we check the znode ACLs under the root directory and set the ACLs properly
* if needed. If the cluster goes from an unsecure setup to a secure setup, this step is needed
* so that the existing znodes created with open permissions are now changed with restrictive
* perms.
*/
public void checkAndSetZNodeAcls() {
if (!ZKUtil.isSecureZooKeeper(getConfiguration())) {
LOG.info("not a secure deployment, proceeding");
return;
}
// Check the base znodes permission first. Only do the recursion if base znode's perms are not
// correct.
try {
List<ACL> actualAcls = recoverableZooKeeper.getAcl(znodePaths.baseZNode, new Stat());
if (!isBaseZnodeAclSetup(actualAcls)) {
LOG.info("setting znode ACLs");
setZnodeAclsRecursive(znodePaths.baseZNode);
}
} catch(KeeperException.NoNodeException nne) {
return;
} catch(InterruptedException ie) {
interruptedException(ie);
} catch (IOException|KeeperException e) {
LOG.warn("Received exception while checking and setting zookeeper ACLs", e);
}
}
/**
* Set the znode perms recursively. This will do post-order recursion, so that baseZnode ACLs
* will be set last in case the master fails in between.
* @param znode
*/
private void setZnodeAclsRecursive(String znode) throws KeeperException, InterruptedException {
List<String> children = recoverableZooKeeper.getChildren(znode, false);
for (String child : children) {
setZnodeAclsRecursive(ZKUtil.joinZNode(znode, child));
}
List<ACL> acls = ZKUtil.createACL(this, znode, true);
LOG.info("Setting ACLs for znode:" + znode + " , acl:" + acls);
recoverableZooKeeper.setAcl(znode, acls, -1);
}
/**
* Checks whether the ACLs returned from the base znode (/hbase) is set for secure setup.
* @param acls acls from zookeeper
* @return whether ACLs are set for the base znode
* @throws IOException
*/
private boolean isBaseZnodeAclSetup(List<ACL> acls) throws IOException {
if (LOG.isDebugEnabled()) {
LOG.debug("Checking znode ACLs");
}
String[] superUsers = conf.getStrings(Superusers.SUPERUSER_CONF_KEY);
// Check whether ACL set for all superusers
if (superUsers != null && !checkACLForSuperUsers(superUsers, acls)) {
return false;
}
// this assumes that current authenticated user is the same as zookeeper client user
// configured via JAAS
String hbaseUser = UserGroupInformation.getCurrentUser().getShortUserName();
if (acls.isEmpty()) {
if (LOG.isDebugEnabled()) {
LOG.debug("ACL is empty");
}
return false;
}
for (ACL acl : acls) {
int perms = acl.getPerms();
Id id = acl.getId();
// We should only set at most 3 possible ACLs for 3 Ids. One for everyone, one for superuser
// and one for the hbase user
if (Ids.ANYONE_ID_UNSAFE.equals(id)) {
if (perms != Perms.READ) {
if (LOG.isDebugEnabled()) {
LOG.debug(String.format("permissions for '%s' are not correct: have 0x%x, want 0x%x",
id, perms, Perms.READ));
}
return false;
}
} else if (superUsers != null && isSuperUserId(superUsers, id)) {
if (perms != Perms.ALL) {
if (LOG.isDebugEnabled()) {
LOG.debug(String.format("permissions for '%s' are not correct: have 0x%x, want 0x%x",
id, perms, Perms.ALL));
}
return false;
}
} else if ("sasl".equals(id.getScheme())) {
String name = id.getId();
// If ZooKeeper recorded the Kerberos full name in the ACL, use only the shortname
Matcher match = NAME_PATTERN.matcher(name);
if (match.matches()) {
name = match.group(1);
}
if (name.equals(hbaseUser)) {
if (perms != Perms.ALL) {
if (LOG.isDebugEnabled()) {
LOG.debug(String.format("permissions for '%s' are not correct: have 0x%x, want 0x%x",
id, perms, Perms.ALL));
}
return false;
}
} else {
if (LOG.isDebugEnabled()) {
LOG.debug("Unexpected shortname in SASL ACL: " + id);
}
return false;
}
} else {
if (LOG.isDebugEnabled()) {
LOG.debug("unexpected ACL id '" + id + "'");
}
return false;
}
}
return true;
}
/*
* Validate whether ACL set for all superusers.
*/
private boolean checkACLForSuperUsers(String[] superUsers, List<ACL> acls) {
for (String user : superUsers) {
boolean hasAccess = false;
// TODO: Validate super group members also when ZK supports setting node ACL for groups.
if (!AuthUtil.isGroupPrincipal(user)) {
for (ACL acl : acls) {
if (user.equals(acl.getId().getId())) {
if (acl.getPerms() == Perms.ALL) {
hasAccess = true;
} else {
if (LOG.isDebugEnabled()) {
LOG.debug(String.format(
"superuser '%s' does not have correct permissions: have 0x%x, want 0x%x",
acl.getId().getId(), acl.getPerms(), Perms.ALL));
}
}
break;
}
}
if (!hasAccess) {
return false;
}
}
}
return true;
}
/*
* Validate whether ACL ID is superuser.
*/
public static boolean isSuperUserId(String[] superUsers, Id id) {
for (String user : superUsers) {
// TODO: Validate super group members also when ZK supports setting node ACL for groups.
if (!AuthUtil.isGroupPrincipal(user) && new Id("sasl", user).equals(id)) {
return true;
}
}
return false;
}
@Override
public String toString() {
return this.identifier + ", quorum=" + quorum + ", baseZNode=" + znodePaths.baseZNode;
}
/**
* Adds this instance's identifier as a prefix to the passed <code>str</code>
* @param str String to amend.
* @return A new string with this instance's identifier as prefix: e.g.
* if passed 'hello world', the returned string could be
*/
public String prefix(final String str) {
return this.toString() + " " + str;
}
/**
* Get the znodes corresponding to the meta replicas from ZK
* @return list of znodes
* @throws KeeperException
*/
public List<String> getMetaReplicaNodes() throws KeeperException {
List<String> childrenOfBaseNode = ZKUtil.listChildrenNoWatch(this, znodePaths.baseZNode);
List<String> metaReplicaNodes = new ArrayList<>(2);
if (childrenOfBaseNode != null) {
String pattern = conf.get("zookeeper.znode.metaserver","meta-region-server");
for (String child : childrenOfBaseNode) {
if (child.startsWith(pattern)) metaReplicaNodes.add(child);
}
}
return metaReplicaNodes;
}
/**
* Register the specified listener to receive ZooKeeper events.
* @param listener
*/
public void registerListener(ZooKeeperListener listener) {
listeners.add(listener);
}
/**
* Register the specified listener to receive ZooKeeper events and add it as
* the first in the list of current listeners.
* @param listener
*/
public void registerListenerFirst(ZooKeeperListener listener) {
listeners.add(0, listener);
}
public void unregisterListener(ZooKeeperListener listener) {
listeners.remove(listener);
}
/**
* Clean all existing listeners
*/
public void unregisterAllListeners() {
listeners.clear();
}
/**
* Get a copy of current registered listeners
*/
public List<ZooKeeperListener> getListeners() {
return new ArrayList<>(listeners);
}
/**
* @return The number of currently registered listeners
*/
public int getNumberOfListeners() {
return listeners.size();
}
/**
* Get the connection to ZooKeeper.
* @return connection reference to zookeeper
*/
public RecoverableZooKeeper getRecoverableZooKeeper() {
return recoverableZooKeeper;
}
public void reconnectAfterExpiration() throws IOException, KeeperException, InterruptedException {
recoverableZooKeeper.reconnectAfterExpiration();
}
/**
* Get the quorum address of this instance.
* @return quorum string of this zookeeper connection instance
*/
public String getQuorum() {
return quorum;
}
/**
* Get the znodePaths.
* <p>
* Mainly used for mocking as mockito can not mock a field access.
*/
public ZNodePaths getZNodePaths() {
return znodePaths;
}
/**
* Method called from ZooKeeper for events and connection status.
* <p>
* Valid events are passed along to listeners. Connection status changes
* are dealt with locally.
*/
@Override
public void process(WatchedEvent event) {
LOG.debug(prefix("Received ZooKeeper Event, " +
"type=" + event.getType() + ", " +
"state=" + event.getState() + ", " +
"path=" + event.getPath()));
switch(event.getType()) {
// If event type is NONE, this is a connection status change
case None: {
connectionEvent(event);
break;
}
// Otherwise pass along to the listeners
case NodeCreated: {
for(ZooKeeperListener listener : listeners) {
listener.nodeCreated(event.getPath());
}
break;
}
case NodeDeleted: {
for(ZooKeeperListener listener : listeners) {
listener.nodeDeleted(event.getPath());
}
break;
}
case NodeDataChanged: {
for(ZooKeeperListener listener : listeners) {
listener.nodeDataChanged(event.getPath());
}
break;
}
case NodeChildrenChanged: {
for(ZooKeeperListener listener : listeners) {
listener.nodeChildrenChanged(event.getPath());
}
break;
}
}
}
// Connection management
/**
* Called when there is a connection-related event via the Watcher callback.
* <p>
* If Disconnected or Expired, this should shutdown the cluster. But, since
* we send a KeeperException.SessionExpiredException along with the abort
* call, it's possible for the Abortable to catch it and try to create a new
* session with ZooKeeper. This is what the client does in HCM.
* <p>
* @param event
*/
private void connectionEvent(WatchedEvent event) {
switch(event.getState()) {
case SyncConnected:
this.identifier = this.prefix + "-0x" +
Long.toHexString(this.recoverableZooKeeper.getSessionId());
// Update our identifier. Otherwise ignore.
LOG.debug(this.identifier + " connected");
break;
// Abort the server if Disconnected or Expired
case Disconnected:
LOG.debug(prefix("Received Disconnected from ZooKeeper, ignoring"));
break;
case Expired:
String msg = prefix(this.identifier + " received expired from " +
"ZooKeeper, aborting");
// TODO: One thought is to add call to ZooKeeperListener so say,
// ZooKeeperNodeTracker can zero out its data values.
if (this.abortable != null) {
this.abortable.abort(msg, new KeeperException.SessionExpiredException());
}
break;
case ConnectedReadOnly:
case SaslAuthenticated:
case AuthFailed:
break;
default:
throw new IllegalStateException("Received event is not valid: " + event.getState());
}
}
/**
* Forces a synchronization of this ZooKeeper client connection.
* <p>
* Executing this method before running other methods will ensure that the
* subsequent operations are up-to-date and consistent as of the time that
* the sync is complete.
* <p>
* This is used for compareAndSwap type operations where we need to read the
* data of an existing node and delete or transition that node, utilizing the
* previously read version and data. We want to ensure that the version read
* is up-to-date from when we begin the operation.
*/
public void sync(String path) throws KeeperException {
this.recoverableZooKeeper.sync(path, null, null);
}
/**
* Handles KeeperExceptions in client calls.
* <p>
* This may be temporary but for now this gives one place to deal with these.
* <p>
* TODO: Currently this method rethrows the exception to let the caller handle
* <p>
* @param ke
* @throws KeeperException
*/
public void keeperException(KeeperException ke)
throws KeeperException {
LOG.error(prefix("Received unexpected KeeperException, re-throwing exception"), ke);
throw ke;
}
/**
* Handles InterruptedExceptions in client calls.
* <p>
* This may be temporary but for now this gives one place to deal with these.
* <p>
* TODO: Currently, this method does nothing.
* Is this ever expected to happen? Do we abort or can we let it run?
* Maybe this should be logged as WARN? It shouldn't happen?
* <p>
* @param ie
*/
public void interruptedException(InterruptedException ie) {
LOG.debug(prefix("Received InterruptedException, doing nothing here"), ie);
// At least preserver interrupt.
Thread.currentThread().interrupt();
// no-op
}
/**
* Close the connection to ZooKeeper.
*
*/
@Override
public void close() {
try {
recoverableZooKeeper.close();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
public Configuration getConfiguration() {
return conf;
}
@Override
public void abort(String why, Throwable e) {
if (this.abortable != null) this.abortable.abort(why, e);
else this.aborted = true;
}
@Override
public boolean isAborted() {
return this.abortable == null? this.aborted: this.abortable.isAborted();
}
}