终于成功创建hdfs repository，在创建snapshot，遇到了问题：
[my_hdfs_repo] could not read repository data from index blob
elasticsearch日志:
[2016-12-12T11:38:04,417][WARN ][r.suppressed ] path: /_snapshot/my_hdfs_repo/20161209-snapshot, params: {repository=my_hdfs_repo, snapshot=20161209-snapshot}
org.elasticsearch.transport.RemoteTransportException: [node-2][10.90.6.234:9340][cluster:admin/snapshot/create]
Caused by: org.elasticsearch.repositories.RepositoryException: [my_hdfs_repo] could not read repository data from index blob
......
Caused by: java.io.IOException: com.google.protobuf.ServiceException: java.security.AccessControlException: access denied ("javax.security.auth.PrivateCredentialPermission" "org.apache.hadoop.security.Credentials" "read")
......
Caused by: org.elasticsearch.common.io.stream.NotSerializableExceptionWrapper: service_exception: java.security.AccessControlException: access denied ("javax.security.auth.PrivateCredentialPermission" "org.apache.hadoop.security.Credentials" "read")
......
Caused by: java.lang.SecurityException: access denied ("javax.security.auth.PrivateCredentialPermission" "org.apache.hadoop.security.Credentials" "read")
......
该问题很简单：JVM的JSM安全校验导致的，修改相关配置即可。
修改plugin-security.policy文件：
grant {
// Hadoop UserGroupInformation, HdfsConstants, PipelineAck clinit
permission java.lang.RuntimePermission "getClassLoader";
// UserGroupInformation (UGI) Metrics clinit
permission java.lang.RuntimePermission "accessDeclaredMembers";
permission java.lang.reflect.ReflectPermission "suppressAccessChecks";
// org.apache.hadoop.util.StringUtils clinit
permission java.util.PropertyPermission "*", "read,write";
// org.apache.hadoop.util.ShutdownHookManager clinit
permission java.lang.RuntimePermission "shutdownHooks";
// JAAS is used always, we use a fake subject, hurts nobody
permission javax.security.auth.AuthPermission "getSubject";
permission javax.security.auth.AuthPermission "doAs";
permission javax.security.auth.AuthPermission "modifyPrivateCredentials";
permission java.lang.RuntimePermission "accessDeclaredMembers";
permission java.lang.RuntimePermission "getClassLoader";
permission java.lang.RuntimePermission "shutdownHooks";
permission java.lang.reflect.ReflectPermission "suppressAccessChecks";
permission javax.security.auth.AuthPermission "doAs";
permission javax.security.auth.AuthPermission "getSubject";
permission javax.security.auth.AuthPermission "modifyPrivateCredentials";
permission java.security.AllPermission;
permission java.util.PropertyPermission "*", "read,write";
permission javax.security.auth.PrivateCredentialPermission "org.apache.hadoop.security.Credentials * \"*\"", "read";
};
然后在jvm.options文件或者启动参数中加入：
-Djava.security.policy=/usr/share/elasticsearch/plugins/repository-hdfs/plugin-security.policy
