Apache Nutch README

For the latest information about Nutch, please visit our website at:

https://nutch.apache.org/

and our wiki, at:

https://cwiki.apache.org/confluence/display/NUTCH/Home

To get started using Nutch read Tutorial:

https://cwiki.apache.org/confluence/display/NUTCH/NutchTutorial

Contributing

To contribute a patch, follow these instructions (note that installing Hub is not strictly required, but is recommended).

0. Download and install hub.github.com
1. File JIRA issue for your fix at https://issues.apache.org/jira/projects/NUTCH/issues
   • you will get issue id NUTCH-xxxx where xxxx is the issue ID.
2. git clone https://github.com/apache/nutch.git
3. cd nutch
4. git checkout -b NUTCH-xxxx
5. edit files (please try and include a test case if possible)
6. git status (make sure it shows what files you expected to edit)
7. Make sure that your code complies with the Nutch codeformatting template, which is basically two space indents
8. git add <files>
9. git commit -m "fix for NUTCH-xxx contributed by <your username>"
10. hub fork (if hub is not installed, fork using the "fork" button on the Nutch Github project page)
11. git push -u <your git username> NUTCH-xxxx
12. hub pull-request (if hub is not installed, please follow the instructions to create a pull-request from a fork)

Pre-commit / Apache Yetus

Pull requests run Apache Yetus test-patch for automated checks (style, reporting). See Basic Precommit and Usage Introduction. CI uses Java 17. To run test-patch locally (e.g. before opening a PR):

test-patch --basedir=/path/to/clean/repo --build-tool=nobuild \
  --plugins=all,-jira,-gitlab,-unit,-compile [patchfile]

Exclude patterns can be added in .yetus/excludes.txt (regex, one per line).

IDE setup

Eclipse

Generate Eclipse project files

ant eclipse

and follow the instructions in Importing existing projects.

You must configure the nutch-site.xml before running. Make sure you have added http.agent.name and plugin.folders properties. The plugin.folders normally points to <project_root>/build/plugins.

Now create a Java Application Configuration, choose org.apache.nutch.crawl.Injector, add two paths as arguments: first the crawldb directory, second the URL directory where the injector can read urls. Then run your configuration.

If we still see "No plugins found on paths of property plugin.folders=plugins", update the plugin.folders in the nutch-default.xml; this is a quick fix, but should not be used.

Intellij IDEA

First install the IvyIDEA Plugin. Then run ant eclipse. This creates the .classpath and .project files so Intellij can import the project.

In Intellij IDEA, select File > New > Project from Existing Sources. Select the nutch home directory and click "Open".

On the "Import Project" screen select the "Import project from external model" radio button and select "Eclipse". Click "Create". On the next screen the "Eclipse projects directory" should be already set to the nutch folder. Leave the "Create module files near .classpath files" radio button selected.

Click "Next" on the next screens. On the project SDK screen select Java 11 and click "Create". N.B. On Mac with homebrew openjdk, use the directory under libexec: <openjdk11_directory>/libexec/openjdk.jdk/Contents/Home.

Once the project is imported, you will see a popup saying "Ant build scripts found", "Frameworks detected - IvyIDEA Framework detected". Click "Import". If you don't get the pop-up, go through the steps again as this happens from time to time. There is another Ant popup that asks you to configure the project. Do NOT click "Configure".

To import the code-style: Intellij IDEA > Preferences > Editor > Code Style > Java. For the Scheme dropdown select "Project". Click the gear icon and select "Import Scheme" > "Eclipse XML file". Select the eclipse-format.xml file and click "Open". On the next screen check the "Current Scheme" checkbox and hit OK.

Running in Intellij IDEA

Running in Intellij

• Open Run/Debug Configurations
• Select "+" to create a new configuration and select "Application"
• For "Main Class" enter a class with a main function (e.g. org.apache.nutch.indexer.IndexingJob)
• For "Program Arguments" add the arguments needed for the class. You can get these by running the crawl executable for your job. Use full-qualified paths (e.g. crawldb and segments paths plus -deleteGone)
• For "Working Directory" enter your nutch runtime/local path
• Select "Modify options" > "Modify Classpath" and add the config directory for that Working Directory (e.g. runtime/local/conf)
• Select "Modify options" > "Add VM Options" and add the VM options from running the crawl executable (e.g. -Xmx4096m -Dhadoop.log.dir=... etc.)

Note: You will need to manually trigger a build through ANT to get latest updated changes when running, because the ant build system is separate from the Intellij one.