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本文主要研究一下 storm client 的 nimbus.seeds 参数
NIMBUS_SEEDS
storm-core-1.1.0-sources.jar!/org/apache/storm/Config.java
/**
* The host that the master server is running on, added only for backward compatibility,
* the usage deprecated in favor of nimbus.seeds config.
*/
@Deprecated
@isString
public static final String NIMBUS_HOST = “nimbus.host”;
/**
* List of seed nimbus hosts to use for leader nimbus discovery.
*/
@isStringList
public static final String NIMBUS_SEEDS = “nimbus.seeds”;
可以看到这里废除了 nimbus.host 参数，而 nimbus.seeds 参数主要用于发现 nimbus leader
StormSubmitter
storm-core-1.1.0-sources.jar!/org/apache/storm/StormSubmitter.java
public static void submitTopologyAs(String name, Map stormConf, StormTopology topology, SubmitOptions opts, ProgressListener progressListener, String asUser)
throws AlreadyAliveException, InvalidTopologyException, AuthorizationException, IllegalArgumentException {
if(!Utils.isValidConf(stormConf)) {
throw new IllegalArgumentException(“Storm conf is not valid. Must be json-serializable”);
}
stormConf = new HashMap(stormConf);
stormConf.putAll(Utils.readCommandLineOpts());
Map conf = Utils.readStormConfig();
conf.putAll(stormConf);
stormConf.putAll(prepareZookeeperAuthentication(conf));
validateConfs(conf, topology);
Map<String,String> passedCreds = new HashMap<>();
if (opts != null) {
Credentials tmpCreds = opts.get_creds();
if (tmpCreds != null) {
passedCreds = tmpCreds.get_creds();
}
}
Map<String,String> fullCreds = populateCredentials(conf, passedCreds);
if (!fullCreds.isEmpty()) {
if (opts == null) {
opts = new SubmitOptions(TopologyInitialStatus.ACTIVE);
}
opts.set_creds(new Credentials(fullCreds));
}
try {
if (localNimbus!=null) {
LOG.info(“Submitting topology ” + name + ” in local mode”);
if (opts!=null) {
localNimbus.submitTopologyWithOpts(name, stormConf, topology, opts);
} else {
// this is for backwards compatibility
localNimbus.submitTopology(name, stormConf, topology);
}
LOG.info(“Finished submitting topology: ” + name);
} else {
String serConf = JSONValue.toJSONString(stormConf);
try (NimbusClient client = NimbusClient.getConfiguredClientAs(conf, asUser)) {
if (topologyNameExists(name, client)) {
throw new RuntimeException(“Topology with name `” + name + “` already exists on cluster”);
}
// Dependency uploading only makes sense for distributed mode
List<String> jarsBlobKeys = Collections.emptyList();
List<String> artifactsBlobKeys;
DependencyUploader uploader = new DependencyUploader();
try {
uploader.init();
jarsBlobKeys = uploadDependencyJarsToBlobStore(uploader);
artifactsBlobKeys = uploadDependencyArtifactsToBlobStore(uploader);
} catch (Throwable e) {
// remove uploaded jars blobs, not artifacts since they’re shared across the cluster
uploader.deleteBlobs(jarsBlobKeys);
uploader.shutdown();
throw e;
}
try {
setDependencyBlobsToTopology(topology, jarsBlobKeys, artifactsBlobKeys);
submitTopologyInDistributeMode(name, topology, opts, progressListener, asUser, conf, serConf, client);
} catch (AlreadyAliveException | InvalidTopologyException | AuthorizationException e) {
// remove uploaded jars blobs, not artifacts since they’re shared across the cluster
// Note that we don’t handle TException to delete jars blobs
// because it’s safer to leave some blobs instead of topology not running
uploader.deleteBlobs(jarsBlobKeys);
throw e;
} finally {
uploader.shutdown();
}
}
}
} catch(TException e) {
throw new RuntimeException(e);
}
invokeSubmitterHook(name, asUser, conf, topology);
}
StormSubmitter 的 submitTopologyAs 通过 NimbusClient.getConfiguredClientAs(conf, asUser) 创建 NimbusClient
NimbusClient
storm-core-1.1.0-sources.jar!/org/apache/storm/utils/NimbusClient.java
public static NimbusClient getConfiguredClientAs(Map conf, String asUser) {
if (conf.containsKey(Config.STORM_DO_AS_USER)) {
if (asUser != null && !asUser.isEmpty()) {
LOG.warn(“You have specified a doAsUser as param {} and a doAsParam as config, config will take precedence.”
, asUser, conf.get(Config.STORM_DO_AS_USER));
}
asUser = (String) conf.get(Config.STORM_DO_AS_USER);
}
List<String> seeds;
if(conf.containsKey(Config.NIMBUS_HOST)) {
LOG.warn(“Using deprecated config {} for backward compatibility. Please update your storm.yaml so it only has config {}”,
Config.NIMBUS_HOST, Config.NIMBUS_SEEDS);
seeds = Lists.newArrayList(conf.get(Config.NIMBUS_HOST).toString());
} else {
seeds = (List<String>) conf.get(Config.NIMBUS_SEEDS);
}
for (String host : seeds) {
int port = Integer.parseInt(conf.get(Config.NIMBUS_THRIFT_PORT).toString());
NimbusSummary nimbusSummary;
NimbusClient client = null;
try {
client = new NimbusClient(conf, host, port, null, asUser);
nimbusSummary = client.getClient().getLeader();
if (nimbusSummary != null) {
String leaderNimbus = nimbusSummary.get_host() + “:” + nimbusSummary.get_port();
LOG.info(“Found leader nimbus : {}”, leaderNimbus);
if (nimbusSummary.get_host().equals(host) && nimbusSummary.get_port() == port) {
NimbusClient ret = client;
client = null;
return ret;
}
try {
return new NimbusClient(conf, nimbusSummary.get_host(), nimbusSummary.get_port(), null, asUser);
} catch (TTransportException e) {
throw new RuntimeException(“Failed to create a nimbus client for the leader ” + leaderNimbus, e);
}
}
} catch (Exception e) {
LOG.warn(“Ignoring exception while trying to get leader nimbus info from ” + host
+ “. will retry with a different seed host.”, e);
continue;
} finally {
if (client != null) {
client.close();
}
}
throw new NimbusLeaderNotFoundException(“Could not find a nimbus leader, please try ” +
“again after some time.”);
}
throw new NimbusLeaderNotFoundException(
“Could not find leader nimbus from seed hosts ” + seeds + “. ” +
“Did you specify a valid list of nimbus hosts for config ” +
Config.NIMBUS_SEEDS + “?”);
}
这里仍然兼容 NIMBUS_HOST 参数，如果有 NIMBUS_HOST 参数则从中读取 seeds，没有则从 NIMBUS_SEEDS 参数获取
之后遍历 seeds，根据每个 seed 创建 NimbusClient，然后调用 client.getClient().getLeader() 获取 leader 信息，如果获取成功，则判断 leader 是否当前连接的 seed，如果是则直接返回，如果不是则根据 leader 的 host 和 port 创建新的 NimbusClient 返回
如果 nimbusSummary 为 null，则会抛出 NimbusLeaderNotFoundException(“Could not find a nimbus leader, please try again after some time.”)
如果连接 leader 出现异常，则遍历下一个 seed，进行 retry 操作，如果所有 seed 都 retry 失败，则跳出循环，最后抛出 NimbusLeaderNotFoundException(“Could not find leader nimbus from seed hosts ” + seeds + “. Did you specify a valid list of nimbus hosts for config nimbus.seeds?”)
小结
对于 storm client 来说，nimbus.seeds 参数用于 client 进行寻找 nimbus leader，而 nimbus.host 参数已经被废弃
寻找 nimbus leader 的过程就是挨个遍历 seeds 配置的 host，进行连接，然后获取 leader 的信息，如果获取成功但是 nimbusSummary 为 null，则抛出 NimbusLeaderNotFoundException(“Could not find a nimbus leader, please try again after some time.”)。
如果有异常则遍历下一个 seed 进行 retry，如果都不成功，则最后跳出循环，抛出 NimbusLeaderNotFoundException(“Could not find leader nimbus from seed hosts ” + seeds + “. Did you specify a valid list of nimbus hosts for config nimbus.seeds?”)
doc
Setting-up-a-Storm-cluster
