Day / October 2, 2018

by Eric Lin

What an experience applying Indian Visa

I need to travel to India at the end of November this year to train up our new colleagues in the Chennai new office, so I have started applying the Indian Visa online through their offical website IndiaVisaOnline. After trying several times, I finally got through the final stage, however, I would like to share my extreme experience in the last couple of weeks.

1. I crashed their website at least 5-6 times on the same page, and each time took them around 5 minutes to be back and running again. Based on my test, I believe entering a website without “http://” prefix could crash it. I am really thinking about to test it again..

2. I had to squeeze in phone numbers and addresses into the same field that has 80 character limit, which forced me to truncate random characters to make them fit and at the same time it became totally unrecognisable address. So what’s the point here??

3. The passport and business card need to be uploaded in PDF format, well, fair enough, but why 300K limit? I had to keep shrinking the size in PNG format, convert and then repeat the loop, until I can barely see the text on my passport!! THIS ISN’T 1980s folks!!! GO TO OFFICEWORKS AND BUY A HARD DRIVE!!!

4. Now, after several hours of trying, I finally got to the last step. And what a surprise in the success message, with every piece of information missing on the confirmation page. I am wondering, should I call them to confirm if I made through or not?

Use my manager’s word, “A monkey with no arms could code better than whatever el-cheapo graduate they fished out of the fail pond to write this website”!!

I am sure that there are other guys out there have the same experience as mine, has anyone complained to the officials?

by Eric Lin

How to Disable Actions in Oozie

Oozie is an orchestration system for managing Hadoop jobs. Currently it supports various actions, including, but not limited to, Spark1, Spark2, Shell, SSH, Hive, Sqoop and Java etc. However, due to certain business requirements, sometimes we want to disable some of the actions so that we can control how users use Oozie to run jobs.

For example, currently when you setup a SSH action, it is required that you need to setup passwordless login for a certain user from Oozie server host to the target host. This will also allow any user to be able to setup a job to run on the remote machine, so long as you know the username and remote host domain name. This is a security concern. There are thoughts on how to improve it, but not yet have a solution at this stage.

So if business has such concerns, we can disable SSH action easily. Please follow below steps (assuming that you are using Cloudera Manager to manage CDH Hadoop):

1. Go to Cloudera Manager home page > Oozie > Configuration
2. Locate configuration called “Oozie Server Advanced Configuration Snippet (Safety Valve) for oozie-site.xml”
3. Click on the “Add” button and enter “oozie.service.ActionService.executor.classes” for name and value as below:

org.apache.oozie.action.decision.DecisionActionExecutor,org.apache.oozie.action.hadoop.JavaActionExecutor,org.apache.oozie.action.hadoop.FsActionExecutor,org.apache.oozie.action.hadoop.MapReduceActionExecutor,org.apache.oozie.action.hadoop.PigActionExecutor,org.apache.oozie.action.hadoop.HiveActionExecutor,org.apache.oozie.action.hadoop.ShellActionExecutor,org.apache.oozie.action.hadoop.SqoopActionExecutor,org.apache.oozie.action.hadoop.DistcpActionExecutor,org.apache.oozie.action.hadoop.Hive2ActionExecutor,org.apache.oozie.action.oozie.SubWorkflowActionExecutor,org.apache.oozie.action.email.EmailActionExecutor,org.apache.oozie.action.hadoop.SparkActionExecutor

The full list is:

org.apache.oozie.action.decision.DecisionActionExecutor,org.apache.oozie.action.hadoop.JavaActionExecutor,org.apache.oozie.action.hadoop.FsActionExecutor,org.apache.oozie.action.hadoop.MapReduceActionExecutor,org.apache.oozie.action.hadoop.PigActionExecutor,org.apache.oozie.action.hadoop.HiveActionExecutor,org.apache.oozie.action.hadoop.ShellActionExecutor,org.apache.oozie.action.hadoop.SqoopActionExecutor,org.apache.oozie.action.hadoop.DistcpActionExecutor,org.apache.oozie.action.hadoop.Hive2ActionExecutor,org.apache.oozie.action.ssh.SshActionExecutor,org.apache.oozie.action.oozie.SubWorkflowActionExecutor,org.apache.oozie.action.email.EmailActionExecutor,org.apache.oozie.action.hadoop.SparkActionExecutor

so we just need to remove org.apache.oozie.action.ssh.SshActionExecutor action class. Basically, just remove the corresponding action classes that you do not want Oozie to support.

4. Save and restart Oozie

After that, if you try to run a SSH action through Oozie, it will fail. And sample error from Hue looks like below:

Please keep in mind that if you do make this change, remember to check the version of Oozie that you will upgrade to in the future, to make sure that the new supported classes are added to this list, otherwise other jobs will fail. For example, currently Oozie can only support running Spark1 action, Spark2 is not supported. However, in latest CDH version 6.x, Spark2 is now supported and the list will need to be updated.