This page will guide you to set up Gobblin, and run a quick and simple first job.
git clone https://github.com/linkedin/gobblin.git
cd gobblin ./gradlew clean build
To build against Hadoop 2, add
-PuseHadoop2. To skip unit tests, add
Here we illustrate how to run a simple job. This job will pull the five latest revisions of each of the four Wikipedia pages: NASA, Linkedin, Parris_Cues and Barbara_Corcoran. A total of 20 records, each corresponding to one revision, should be pulled if the job is successfully run. The records will be stored as Avro files.
Gobblin can run either in standalone mode or on MapReduce. In this example we will run Gobblin in standalone mode.
This page explains how to run the job from the terminal. You may also run this job from your favorite IDE (IntelliJ is recommended).
Each Gobblin job minimally involves several constructs, e.g. Source, Extractor, DataWriter and [DataPublisher] (https://github.com/linkedin/gobblin/blob/master/gobblin-api/src/main/java/gobblin/publisher/DataPublisher.java). As the names suggest, Source defines the source to pull data from, Extractor implements the logic to extract data records, DataWriter defines the way the extracted records are output, and DataPublisher publishes the data to the final output location. A job may optionally have one or more Converters, which transform the extracted records, as well as one or more PolicyCheckers that check the quality of the extracted records and determine whether they conform to certain policies.
Some of the classes relevant to this example include WikipediaSource, WikipediaExtractor, WikipediaConverter, AvroHdfsDataWriter and [BaseDataPublisher] (https://github.com/linkedin/gobblin/blob/master/gobblin-core/src/main/java/gobblin/publisher/BaseDataPublisher.java).
To run Gobblin in standalone mode we need a Gobblin configuration file (such as uses gobblin-standalone.properties). And for each job we wish to run, we also need a job configuration file (such as wikipedia.pull). The Gobblin configuration file, which is passed to Gobblin as a command line argument, should contain a property
jobconf.dir which specifies where the job configuration files are located. By default,
jobconf.dir points to environment variable
GOBBLIN_JOB_CONFIG_DIR. Each file in
jobconf.dir with extension
.pull is considered a job configuration file, and Gobblin will launch a job for each such file. For more information on Gobblin deployment in standalone mode, refer to the Standalone Deployment page.
A list of commonly used configuration properties can be found here: Configuration Properties Glossary.
Create a folder to store the job configuration file. Put wikipedia.pull in this folder, and set environment variable
GOBBLIN_JOB_CONFIG_DIR to point to this folder. Also, make sure that the environment variable
JAVA_HOME is set correctly.
Create a folder as Gobblin's working directory. Gobblin will write job output as well as other information there, such as locks and state-store (for more information, see the Standalone Deployment page). Set environment variable
GOBBLIN_WORK_DIR to point to that folder.
tar -zxvf gobblin-dist.tar.gz cd gobblin-dist
This script will launch Gobblin and pass the Gobblin configuration file (gobblin-standalone.properties) as an argument.
The job log, which contains the progress and status of the job, will be written into
logs/gobblin-current.log (to change where the log is written, modify the Log4j configuration file
conf/log4j-standalone.xml). Stdout will be written into
Among the job logs there should be the following information:
INFO JobScheduler - Loaded 1 job configuration INFO AbstractJobLauncher - Starting job job_PullFromWikipedia_1422040355678 INFO TaskExecutor - Starting the task executor INFO LocalTaskStateTracker2 - Starting the local task state tracker INFO AbstractJobLauncher - Submitting task task_PullFromWikipedia_1422040355678_0 to run INFO TaskExecutor - Submitting task task_PullFromWikipedia_1422040355678_0 INFO AbstractJobLauncher - Waiting for submitted tasks of job job_PullFromWikipedia_1422040355678 to complete... to complete... INFO AbstractJobLauncher - 1 out of 1 tasks of job job_PullFromWikipedia_1422040355678 are running INFO WikipediaExtractor - 5 record(s) retrieved for title NASA INFO WikipediaExtractor - 5 record(s) retrieved for title LinkedIn INFO WikipediaExtractor - 5 record(s) retrieved for title Parris_Cues INFO WikipediaExtractor - 5 record(s) retrieved for title Barbara_Corcoran INFO Task - Extracted 20 data records INFO Fork-0 - Committing data of branch 0 of task task_PullFromWikipedia_1422040355678_0 INFO LocalTaskStateTracker2 - Task task_PullFromWikipedia_1422040355678_0 completed in 2334ms with state SUCCESSFUL INFO AbstractJobLauncher - All tasks of job job_PullFromWikipedia_1422040355678 have completed INFO TaskExecutor - Stopping the task executor INFO LocalTaskStateTracker2 - Stopping the local task state tracker INFO AbstractJobLauncher - Publishing job data of job job_PullFromWikipedia_1422040355678 with commit policy COMMIT_ON_FULL_SUCCESS INFO AbstractJobLauncher - Persisting job/task states of job job_PullFromWikipedia_1422040355678
The job output is written in
GOBBLIN_WORK_DIR/job-output folder as an Avro file.
To see the content of the job output, use the Avro tools to convert Avro to JSON. Download the latest version of Avro tools (e.g. avro-tools-1.7.7.jar):
curl -O http://central.maven.org/maven2/org/apache/avro/avro-tools/1.7.7/avro-tools-1.7.7.jar
java -jar avro-tools-1.7.7.jar tojson --pretty [job_output].avro > output.json `
output.json will contain all retrieved records in JSON format.
Note that since this job configuration file we used (wikipedia.pull) doesn't specify a job schedule, the job will run immediately and will run only once. To schedule a job to run at a certain time and/or repeatedly, set the
job.schedule property with a cron-based syntax. For example,
job.schedule=0 0/2 * * * ? will run the job every two minutes. See this link (Quartz CronTrigger) for more details.
Besides the Wikipedia example, we have another example job SimpleJson, which extracts records from JSON files and store them in Avro files.
To create your own jobs, simply implement the relevant interfaces such as Source, Extractor, Converter and DataWriter. In the job configuration file, set properties such as
converter.class to point to these classes.
On a side note: while users are free to directly implement the Extractor interface (e.g., WikipediaExtractor), Gobblin also provides several extractor implementations based on commonly used protocols, e.g., RestApiExtractor, JdbcExtractor, SftpExtractor, etc. Users are encouraged to extend these classes to take advantage of existing implementations.