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Posted to user@hadoop.apache.org by Francisco de Freitas <ch...@gmail.com> on 2018/09/13 16:09:37 UTC
ZKFC ActiveBreadCrumb Value
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?
Re: ZKFC ActiveBreadCrumb Value
Posted by Wellington Chevreuil <we...@gmail.com>.
You could still use Harsh's solution programatically, or maybe an
easier way is to use HAUtil.getAddressOfActive() [1] for that? Ideally
we should not need to query ZK directly.
[1] https://github.com/c9n/hadoop/blob/master/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/HAUtil.java#L341
Em sex, 14 de set de 2018 às 09:00, Francisco de Freitas
<ch...@gmail.com> escreveu:
>
> 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 $1; }'
>> host1.com
>> On Thu, Sep 13, 2018 at 9:39 PM Francisco de Freitas
>> <ch...@gmail.com> wrote:
>> >
>> > When querying different HDFS clusters I get different separators (don't really know if they're actually separators).
>> >
>> > From zkCli.sh on different clusters, running the following I get:
>> >
>> > cmd: get /hadoop-ha/clusterX/ActiveBreadCrumb
>> >
>> > Cluster1 (comma):
>> > cluster1active-nn1,active-nn1.example.com �>(�>
>> >
>> > Cluster2 (single double quote):
>> > cluster2active-nn2"active-nn2.example.com �>(�>
>> >
>> > Cluster3 (dollar sign):
>> > cluster3active-nn3$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
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RE: ZKFC ActiveBreadCrumb Value
Posted by Pankaj Kumar <pa...@idctechnologies.com>.
Remove me.
---
Thanks & Regards
Pankaj Kumar
IDC Technologies Inc.
Work: 408-457-9381- Ext-4102
Mailto: pankaj.kumar@idctechnologies.com
---------------------------------------------------------
Empowering Technologies Services
Remote Services | IT Services | BPO |
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From: Francisco de Freitas [mailto:chicofranchico@gmail.com]
Sent: Monday, September 17, 2018 9:05 AM
To: Harsh J
Cc: <us...@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
<ch...@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 $1; }'
>> host1.com
>> On Thu, Sep 13, 2018 at 9:39 PM Francisco de Freitas
>> <ch...@gmail.com> wrote:
>> >
>> > When querying different HDFS clusters I get different separators (don't really know if they're actually separators).
>> >
>> > From zkCli.sh on different clusters, running the following I get:
>> >
>> > cmd: get /hadoop-ha/clusterX/ActiveBreadCrumb
>> >
>> > Cluster1 (comma):
>> > cluster1active-nn1,active-nn1.example.com �>(�>
>> >
>> > Cluster2 (single double quote):
>> > cluster2active-nn2"active-nn2.example.com �>(�>
>> >
>> > Cluster3 (dollar sign):
>> > cluster3active-nn3$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
Re: ZKFC ActiveBreadCrumb Value
Posted by Francisco de Freitas <ch...@gmail.com>.
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
> <ch...@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 $1; }'
> >> host1.com
> >> On Thu, Sep 13, 2018 at 9:39 PM Francisco de Freitas
> >> <ch...@gmail.com> wrote:
> >> >
> >> > When querying different HDFS clusters I get different separators
> (don't really know if they're actually separators).
> >> >
> >> > From zkCli.sh on different clusters, running the following I get:
> >> >
> >> > cmd: get /hadoop-ha/clusterX/ActiveBreadCrumb
> >> >
> >> > Cluster1 (comma):
> >> > cluster1active-nn1,active-nn1.example.com �>(�>
> >> >
> >> > Cluster2 (single double quote):
> >> > cluster2active-nn2"active-nn2.example.com �>(�>
> >> >
> >> > Cluster3 (dollar sign):
> >> > cluster3active-nn3$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
>
Re: ZKFC ActiveBreadCrumb Value
Posted by Harsh J <ha...@cloudera.com.INVALID>.
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
<ch...@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 $1; }'
>> host1.com
>> On Thu, Sep 13, 2018 at 9:39 PM Francisco de Freitas
>> <ch...@gmail.com> wrote:
>> >
>> > When querying different HDFS clusters I get different separators (don't really know if they're actually separators).
>> >
>> > From zkCli.sh on different clusters, running the following I get:
>> >
>> > cmd: get /hadoop-ha/clusterX/ActiveBreadCrumb
>> >
>> > Cluster1 (comma):
>> > cluster1active-nn1,active-nn1.example.com �>(�>
>> >
>> > Cluster2 (single double quote):
>> > cluster2active-nn2"active-nn2.example.com �>(�>
>> >
>> > Cluster3 (dollar sign):
>> > cluster3active-nn3$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
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Re: ZKFC ActiveBreadCrumb Value
Posted by Francisco de Freitas <ch...@gmail.com>.
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 $1; }'
> host1.com
> On Thu, Sep 13, 2018 at 9:39 PM Francisco de Freitas
> <ch...@gmail.com> wrote:
> >
> > When querying different HDFS clusters I get different separators (don't
> really know if they're actually separators).
> >
> > From zkCli.sh on different clusters, running the following I get:
> >
> > cmd: get /hadoop-ha/clusterX/ActiveBreadCrumb
> >
> > Cluster1 (comma):
> > cluster1active-nn1,active-nn1.example.com �>(�>
> >
> > Cluster2 (single double quote):
> > cluster2active-nn2"active-nn2.example.com �>(�>
> >
> > Cluster3 (dollar sign):
> > cluster3active-nn3$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
>
Re: ZKFC ActiveBreadCrumb Value
Posted by Harsh J <ha...@cloudera.com.INVALID>.
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 $1; }'
host1.com
On Thu, Sep 13, 2018 at 9:39 PM Francisco de Freitas
<ch...@gmail.com> wrote:
>
> When querying different HDFS clusters I get different separators (don't really know if they're actually separators).
>
> From zkCli.sh on different clusters, running the following I get:
>
> cmd: get /hadoop-ha/clusterX/ActiveBreadCrumb
>
> Cluster1 (comma):
> cluster1active-nn1,active-nn1.example.com �>(�>
>
> Cluster2 (single double quote):
> cluster2active-nn2"active-nn2.example.com �>(�>
>
> Cluster3 (dollar sign):
> cluster3active-nn3$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
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