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--- Thanks & Regards Pankaj Kumar IDC Technologies Inc. Work: 408-457-9381- Ext-4102 Mailto: pankaj.ku...@idctechnologies.com --------------------------------------------------------- Empowering Technologies Services Remote Services | IT Services | BPO | IT Consulting | Staffing Solutions | --------------------------------------------------------- From: Francisco de Freitas [mailto:chicofranch...@gmail.com] Sent: Monday, September 17, 2018 9:05 AM To: Harsh J Cc: <user@hadoop.apache.org> Subject: Re: ZKFC ActiveBreadCrumb Value Thanks a lot Harsh. This is exactly what I did. I appreciate it for having the time to point the correct path as well. Cheers, Francisco On Sat, 15 Sep 2018 at 19:21, Harsh J <ha...@cloudera.com> wrote: As mentioned by Wellington, the path you're going down will not guarantee any compatibility in future. The format/encoding/content/location/etc. of the messages stored in ZK by the Failover Controller is not for public access and can change without formal deprecation/etc. A cleaner way without the use of commands could be to simply query the /jmx JSON and parse out the state, something like the below done with 'jq': ~> curl http://some-nn-host:webport/jmx | jq '.beans[] | select(.name=="Hadoop:service=NameNode,name=FSNamesystem") | .["tag.HAState"]' That said, the protocol-buffers structure used to encode the bytes in ZK is defined in the following file: https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/proto/HAZKInfo.proto You can use protoc with --go_out to compile that message into a struct definition, and then use it in a ZK program like this: https://gist.github.com/QwertyManiac/d3ff72a29e6defd59c353b8b6ca70418 On Fri, Sep 14, 2018 at 1:30 PM Francisco de Freitas <chicofranch...@gmail.com> wrote: > > Hi Harsh, thanks for your message. > > The thing is that I need to find that out via API programatically so that's > why I gave the zkCli command as an example. I'm using this Go Lib > (github.com/samuel/go-zookeeper/zk) and I get the same result. > > On Fri, 14 Sep 2018 at 02:22 Harsh J <ha...@cloudera.com> wrote: >> >> The value you are looking at directly in ZooKeeper is in a >> serialized/encoded form. Those are not separator characters but more >> likely an encoded integer binary value that your terminal is >> interpreting as a printable character. >> >> The standard way to find the active NameNode is to use the 'hdfs >> haadmin -getAllServiceState' command: >> >> [hdfs@host ~]# hdfs haadmin -getAllServiceState >> host1.com:8022 standby >> host2.com:8022 active >> >> You can then extract out just the active NameNode hostname: >> >> [hdfs@host ~]# hdfs haadmin -getAllServiceState | grep active | awk >> -F: '{ print $1; }' >> host1.com >> On Thu, Sep 13, 2018 at 9:39 PM Francisco de Freitas >> <chicofranch...@gmail.com> wrote: >> > >> > When querying different HDFS clusters I get different separators (don't >> > really know if they're actually separators). >> > >> > From zkCli.sh on different clusters, running the following I get: >> > >> > cmd: get /hadoop-ha/clusterX/ActiveBreadCrumb >> > >> > Cluster1 (comma): >> > cluster1active-nn1,active-nn1.example.com �>(�> >> > >> > Cluster2 (single double quote): >> > cluster2active-nn2"active-nn2.example.com �>(�> >> > >> > Cluster3 (dollar sign): >> > cluster3active-nn3$active-nn3.example.com �>(�> >> > >> > How can I effectively write a generic code deployed on different HDFS >> > clusters to effectively find out which is the active NN from querying ZK? >> > >> > Or am I doing something wrong? Is the behavior above expected? >> >> >> >> -- >> Harsh J -- Harsh J
