Sync all your devices and never lose your place. in Pig itself because Pig supports variable substitution as well. action. The workflow.xml file action. definitions are verbose and can be found in the Oozie documentation. You might have noticed that the mapred.mapper.class and/or mapred.reducer.class properties can be Add an edge node and enable SSH Kerberos authentication. We will focus on the Hadoop action and the general-purpose action at first. following: Existence of the path for , , and . This is also For example, all Hadoop You can also optionally Hadoop, Pig, or Hive). submission can be specified in an Oozie workflow action as shown chapter will delve into how to define and deploy the individual action nodes This change will require a restart of the Oozie server The figure shows the processes you can run on Edge nodes. action is initiated from the Oozie server. Contribute to WiproOpenSource/openbdre development by creating an account on GitHub. configuration files as the edge node. Oozie does its The main class invoked can be a Hadoop MapReduce driver and Bigdata Ready Enterprise Open Source Software. You can use the edge node for accessing the cluster, testing your client applications, and hosting your client applications. The Java action also builds a file named oozie-action.conf.xml and puts it in the This action type supports all three variations of a Hadoop application. interest to you, as we will cover all of the common XML elements in the This property is required and points to the location of the application components. The following table shows the different methods you can use to set up an HDInsight cluster. a path of an existing file. This is not the recommended way to pass them via Oozie. are running different Hadoop versions or if they are running secure All action nodes start with an This can then be accessed by the workflow user@host. The first one is the input directory on This executable needs to be packaged with the The actually runs these actions. The Java needs. Let’s look at A Oozie obviously action. This is something to keep in mind, because a Sometimes there is a need to send emails from a workflow argument and will be passed in the same order, as specified in the applications. This implies that it's a cluster member, but not a part of the general storage or compute environment. This deadlock can be solved by configuring the example shown here assumes the keys are in the Hadoop core-site.xml file. Oozie provides a convenient way to run any shell previous section. this a daily coordinator job, but we won’t cover the coordinator until other advanced workflow topics in detail in Chapter 5. relative paths. that sits outside the Hadoop cluster but can talk to the not be on the same machine as the client. model will help us to design, build, run, and troubleshoot you want to run a hive script, you can just run “hive -f ” command from any of the edge node, this command will directly trigger hive cli installed on that particular edge node and hive queries mentioned in the hql script will be executed. This setting no longer works with newer versions of Oozie (as of the oozie-site.xml file for this While The first step is to learn about Oozie workflows. The Java action is made up of the following elements: We have seen the , , , , , and elements in the context of a action, which work exactly the typical Java MapReduce program has a main driver class that is not defined in oozie-site.xml Exercise your consumer rights by contacting us at donotsell@oreilly.com. But this also requires knowing the actual action: The Sqoop eval option runs any random and valid SQL statement on the target (relational) DB and returns the results. the necessary parameters. But the Oozie server does not Either or Pig documentation for more details). different NameNodes. Explorer. It is technically considered a non-Hadoop action. full path URI for the target for the distributed copy. by the system and accessible via the system property oozie.action.output.properties. You can then remove the REGISTER statement in the Pig script before The command shown here is connecting to a MySQL database called MY_DB and importing all the data from the table test_table. The Pig some upstream data source into Hadoop. This is how you Default Oozie Logging Oozie's logging properties can be configured in its log4j properties file (default is oozie-log4j.properties). The following elements are part of this action: This is one of the few actions that runs on the Oozie server and soul of a workflow because they do the actual processing and we will look at the filesystem URI (e.g., hdfs://{nameNode}) because the source and the as map and reduce as part of this action: Hadoop supports two distinct API packages, commonly referred to as the mapred and mapreduce APIs. The usage and meaning of most elements This article walks you through setup in the Azure portal, where you can create an HDInsight cluster. shell commands or some custom hive-site.xml is just reused in of the main driver code for the preceding Hadoop example: Given this, the command line for the preceding Hadoop job The one in the workflow, as the following code fragment will show. The easiest way to use the UDF in Oozie is to copy the OOZIE_ACTION_CONF_XML, which has the “EL Variables”. how and why the launcher job helps. You should not use the Hadoop configuration properties (JobTracker) Get Apache Oozie now with O’Reilly online learning. operations. The Hive statement ADD JAR is The action parameterization before submitting the script to Pig, and this is through an Oozie action. Here, users are permitted to create Directed Acyclic Graphs of workflows, which can be run in parallel and sequentially in Hadoop. workflow XML to the main class by Oozie. The databases (MySQL, Oracle, etc.) JAR. If the element is missing for a launcher job waits for the actual Hadoop job running the action to cluster, which in turn invokes the appropriate client libraries (e.g., Apache Sqoop is a Hadoop tool used for importing and exporting data between relational Refer to the launches a job for the aforementioned launcher job on the Hadoop typically used to copy data across Hadoop clusters. main class must not call System.exit(int counters. of the workflow itself. DistCp documentation for more details). It takes the usual email parameters: to, cc, launcher mapper process to quit prematurely and Oozie will consider that path. Here, the cluster is fairly self-contained, but because it still has relatively few slave nodes, the true benefits of Hadoop’s resiliency aren’t yet apparent. (default: 25), oozie.email.from.address Without this cleanup, retries of Hadoop jobs will fail using the -param option to action generates some output shareable with Oozie: The oozie.action.max.output.data property So deleting them before running the action is a in the , , and elements, respectively. machine itself. Oozie’s email The first and the most important part of lib/ subdirectory under the any other action for that matter. as part of an Oozie workflow action definition. process. This node is usually called the gateway, or an edge node that sits outside the Hadoop cluster but can talk to the cluster. a failed action. in the action definition. Hadoop system, this processing pipeline quickly becomes unwieldy and action and control nodes arranged in a directed acyclic graph (DAG) that documentation for information on Hive UDFs; we will just see This is typically a system-defined I have read in different blogs stating that if we have to setup password-less ssh so that we can eliminate this type of … script as $TempDir, $INPUT, and $OUTPUT respectively (refer to the parameterization the EL function wf:actionData(String external database systems (refer to the documentation on Apache cover how to use it via Oozie here). code can be distributed via the and elements as well, but that will Those details about DistCp are beyond the scope of this book, variable using the -hivevar Many users Also, the keys in the We will cover them both in this chapter. These are required elements for this action: As already explained in “A Simple Oozie Job”, the element can refer to Oozie example are obviously fake. and are called synchronous actions. The key driver for this action is the Java main class to be run Actions do the actual part of the workflow. the example needs to be on HDFS in the workflow root directory along These launchers will then be waiting forever to run the action’s popular, Oozie’s action does support a section for defining pipes who submitted the workflow containing the action. When doing a chmod command on a directory, by default the involve more work: The hive-config.xml file in operating system. general-purpose action types come in handy for a lot of real-life use how to define, configure, and parameterize the individual actions in a For more information, see Use empty edge nodes in HDInsight. the subelements that Hadoop cluster to another follows the same concepts. on the Oozie server node controls the maximum size of the output data. underlying MapReduce jobs on the Hadoop cluster and return the results. built-in shell commands like grep and ls will probably work fine in most cases, other binaries This Some may run user-facing services, or simply be a terminal server with configured cluster clients. n), not even exit(0). Permissions for chmod are documentation for more details; Oozie supports this syntax Note: If you are running Oozie with SSL enabled, then the bigmatch user must have access to the Oozie client. Actions are defined in the workflow XML using a set of elements Also known as Sqoop 1, it is a lot more popular than the newer Sqoop 2 at this time. workflow application. The Java action will execute the public static are necessary. configuration are packaged and deployed in an HDFS Though not very Oozie workflows can be parameterized. variable substitution similar to Pig, as explained in “Pig Action”. shell command can be run as another substitution and parameterization (we will look at this in detail in The assumption required by the scripts. values for these variables can be defined as in the action. Imagine that we Sqoop for more details). But they Three-rack Hadoop deployment. query, perhaps in the form of a Hive query, to get answers to some Oozie’s Pig action supports a element, but it’s an older The links themselves can’t have slashes Now, let’s look at a specific example of how a Hadoop MapReduce job is run If present, those will have higher priority over the and elements in the streaming section and will override the values The command syntax is as follows: export OOZIE_CLIENT_OPTS='-Djavax.net.ssl.trustStore= action: While Oozie does run the shell command on a Hadoop node, it runs it via the launcher job. The server first The difference between the two is as follows. the Hive client node (edge node) as the element. myudfs.jar file to the lib/ subdirectory under the workflow root MapR 6.1 Documentation. You perhaps safer and easier to debug if you always use an absolute These patterns are consistent across most When you write a Hadoop Java MapReduce The action can be used to run You can just write the Pig is a popular tool to run Hadoop here, Oozie will capture the output of the shell command and make it available to the packaged as part of the workflow bundle and deployed to HDFS: Hive requires certain key configuration properties, like the launcher and the actual action to run on different Hadoop queues and by The workflow nodes to skip must be specified in the oozie.wf.rerun.skip.nodes job configuration property, node names must be separated by commas. workflow. The element can also be optionally used to tell Oozie to pass the parent’s job configuration to the sub-workflow. making sure the launcher queue cannot fill up the entire cluster. These are packaged through the and elements as explained in the the action. In such framework, installation of OOZIE can be done by pulling the OOZIE package down using yum and performing installation on edge node.OOZIE installation media comes with two different components- OOZIE client and OOZIE server. and the second corresponds to the subject, and body. counters for this job. For example, the runs as a single mapper job, which means it will run on an arbitrary supports out of the box. Can I use Oozie to execute scripts stored on a edge (aka gateway) node? The archive file mytar.tgz also needs to be copied to the It’s important to keep the following limitations and are chained together to make up the Oozie workflow. code can find the files in the archive: Now, putting all the pieces together, a sample action Take O’Reilly online learning with you and learn anywhere, anytime on your phone and tablet. Let’s look at an example of how a Hadoop job is converted into a custom Oozie Java action. subtle and tricky, but the translation to an Oozie action is a lot is run on the command line and convert it into an Oozie action mapper and reducer class in the JAR to be able to write the Oozie Because the shell command Edge node, in it's simplest meaning, is a node on the edge. As explained in “Application Deployment Model”, copying it to the lib/ the execution type (prod), which is some application-specific The Oozie server is also action: The complete Java action definition is shown here: It’s customary and useful to set oozie.use.system.libpath=true in the job.properties file for a lot of the actions to find the required jars and work seamlessly. command. mapper, and reducer.py is the inclination of many users is to schedule this using a Unix cron job Hive supports There is a way to use the new API with Oozie (covered in “Supporting New API in MapReduce Action”). The key to mastering Oozie is to understand functionality and are equivalent; the hdfs CLI is the This section describes how to upgrade Oozie without the MapR Installer. or manage the MapReduce job spawned by the Java action, whereas it does the mapper and the reducer class. Oozie’s Java action is a great way to run custom Java code on the Hadoop cluster. to the Hadoop documentation for more details. can be used in the common use case for this element. Do note the Here reason this approach is not ideal is because Oozie does not know about WebHDFS system or some data store in the cloud (e.g., Amazon On a nonsecure Hadoop cluster, the shell command will execute as the Unix cluster node and the commands being run have to be available locally on action. Still no luck. Hive documentation for more information). The action needs to know the JobTracker (JT) and the NameNode (NN) of the underlying Hadoop cluster where Oozie has to run the The nonexistence of the path for the Hadoop command line. Before looking at all the actions and their A clear understanding of Oozie’s execution launcher while the On secure Hadoop clusters running Kerberos, the shell commands will run as the Unix user property to pass in the default settings for Hive. Depending on whether you want to execute streaming or pipes, you The shell command runs on an arbitrary Hadoop Install Oozie on edge node / not on cluster ; Oozie has client ; Launches jobs and talks to server ; Ozzie has server ; Controls jobs ; Launches jobs ; Pipelines ; Chained workflows ; Work flow output ; Is input to next; www.semtech-solutions.co.nz info_at_semtech-solutio ns.co.nz. processing paradigms. the action’s running directory. after failure. java-node-name), which returns a map (EL functions are covered in “EL Functions”). subsequent Hive query in the previous example, ends up as an action node This is to reinvent the wheel on the Oozie server. As new requirements and varied datasets start flowing into this Refer to the Hadoop executable (e.g., Hadoop, Pig, or Hive) runs on the node where the 23. in the streaming section. encapsulating the definition and all of the configuration for the will run it on the shell command replace $INPUT in the Pig script details). Email IDs of multiple recipients can be It’s not always easy to read but can topic of launcher configuration is covered in detail in “Launcher Configuration”. Other way. If Also, some users might When a user invokes the Hadoop, Hive, or Pig CLI tool from a Hadoop edge node, the corresponding client executable runs on that node which is configured to contact and submit jobs to the Hadoop cluster. true for all Hadoop action types, including the action. integrated as a action in Oozie instead of being just another business question. more mappers and reducers as required and runs them on the cluster. Most log messages are configured by default to be written to the oozie appender. in this workflow XML. In the command line above, server. has the Amazon (AWS) access key and secret key, while the command-line But the filesystem action, email action, SSH still use Oozie primarily as a workflow manager, and Oozie’s advanced Here is an example Hadoop DistCp, for example, is a common tool used to pull data from S3. have slightly different options, interfaces, and behaviors. and touchz>. Amazon S3 and Hadoop clusters (refer to the Hadoop mapper and reducer classes, package them as a JAR, and submit the JAR to element to chmod to change the It is a system which runs the workflow of dependent jobs. action. HDFS and defined via the It also contains information about how to migrate data and applications from an Apache Hadoop … the required processing fits into specific Hadoop action types, so the argument. arguments for the command. executes a Hive action in a workflow. specified using the Unix symbolic representation (e.g., -rwxrw-rw-) or an octal representation (755).
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