If one of the tasks in the Luigi graph need to run on a remote Hadoop cluster, is that possible? The machine on which Luigi runs is different from the Hadoop cluster. Can luigi still check the if the HDFS file in the remote cluster exists?
I tried to find documentation for this but wasn't able to.
You can run a job that launches any script.
The HDFS target documentation is here:
https://luigi.readthedocs.io/en/stable/api/luigi.contrib.hdfs.html
https://luigi.readthedocs.io/en/stable/api/luigi.contrib.hdfs.target.html
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Often in a hadoop environment, you are required to run a command or a script or copy a file to all nodes in the cluster.
What are efficient ways of doing that (without having to ssh to each node separately)?
Example:
When upgrading Ambari, you are required to run many commands on all nodes where a certain component is installed - e.g. Infra, SmartSense, etc.
I use Ansible to do that. It will do the job for you.
But you can use puppet or Salt or Chef.
I am wondering if we can setup a cloudera cluster on amazon and kick off a hadoop job from my local linux without ssh into amazon's node.
Is there anything like a client to do this communication?
The tips from the following tutorial really work. You should be able to put a working Hadoop Cluster in under 20 minutes, from cold iron to production ready, using just his guidance:
Hadoop Quickstart: Build a Cluster In The Cloud In 20 Minutes
Really worth checking it.
You can install an Hadoop client in your local linux and use the "hadoop jar" command with your own jar. Specify the option mapred.job.tracker in the command line and the client will push your jar to the jobtracker and duplicate it in all the tasktrackers that will be used for this job.
I installed hadoop quite a while ago but I somehow have forgotten if I installed in pseudo distributed mode or not.How can I check it? while my hadoop is running
To know if you are running hadoop in Standalone or Pseudo distributed mode, verify your configuration files. Below information might help.
The tool jps lists out all running Java processes. From the console you can run
$ jps
and check whether JobTracker, TaskTracker and the HDFS daemons are running.
Check your configuration files:-
Go to directory where hadoop configurations are kept (/etc/hadoop in case of Ubuntu)
Look at slaves and masters files, if both have only localhost or (local IP) it is pseudo-distributed. In case slaves file is empty it is standalone.
I am a newbie in hadoop and I am trying to run a hadoop jar on Amazon EC2. I have started my amazon ec2 instance through the console, uploaded my files to the dfs and then was able to successfully run the job jar and generate output on the instance.
But still I am confused on one part. I am not sure if the job was run on a single machine in amazon ec2 or was it ran on a cluster? How do I find the number of worker nodes involved for my jar run?
In some reference links I see we have to use launch-cluster command , for example "bin/hadoop-ec2 launch-cluster test-cluster 2" . What is the difference in starting the instance from the console and using this command like launch-cluster.
Hadoop streaming will run the process in "local" mode when there is no hadoop instance running on the box. I have a shell script that is controlling a set of hadoop streaming jobs in sequence and I need to condition copying files from HDFS to local depending on whether the jobs have been running locally or not. Is there a standard way to accomplish this test? I could do a "ps aux | grep something" but that seems ad-hoc.
Hadoop streaming will run the process in "local" mode when there is no hadoop instance running on the box.
Can you pl point to the reference for this?
A regular or a streaming job will run the way it is configured, so we know ahead of time in which mode a Job is run. Check the documentation for configuring Hadoop on a Single Node and Cluster in different modes.
Rather than trying to detect at run time which mode the process is operating, it is probably better to wrap the tool you are developing in a bash script that explicitly selects local vs cluster operatide. The O'Reilly Hadoop describes how to explicitly choose local using a configuration file override:
hadoop v2.MaxTemperatureDriver -conf conf/hadoop-local.xml input/ncdc/micro max-temp
where conf-local.xml is an XML file configured for local operation.
I haven't tried this yet, but I think you can just read out the mapred.job.tracker configuration setting.