The project does not enforce the use of a specific IDE, but rather suggest the use of IntelliJ IDEA community edition which is free.
The following examples and documentation focus on IntelliJ IDEA. For other IDEs, developers should consult the documentation for the IDE of choice for specific configuration steps.
To get the best development experience for ONOS, the team suggests using IntelliJ 2019.2 with the Bazel plugin installed.
You can find and download IntelliJ versions here: https://www.jetbrains.com/idea/download/previous.html
If you have no idea where to start, here are some instructions on how to install IntelliJ.
Bazel plugin Installation
After having downloaded and installed IntelliJ, ONOS requires the Bazel plugin to be installed.
- Go into IntelliJ IDEA > Preferences > Plugins and search for Bazel
- Click on Install
- Wait for download and installation
- Restart IntelliJ
More information on how to install the Bazel plugin can be found here: https://ij.bazel.build/docs/bazel-plugin.html
Using more recent versions of IntelliJ
IMPORTANT! After a new version of IntelliJ is released, you might need to wait a few weeks since a compatible version of the Bazel plugin is released as well. Before updating IntelliJ or choosing to download a newer version, check the version requirements for the Bazel plugin: https://plugins.jetbrains.com/plugin/8609-bazel. Alternatively, if you can't wait using the latest shiny features of IntelliJ, you might try building the Bazel plugin yourself without waiting for an official release: https://github.com/bazelbuild/intellij
Importing the ONOS source
Assuming you have obtained the source code already and Installed the Bazel plugin form the previous section, the following steps can be followed to import ONOS into IntelliJ:
- To import the ONOS project, simply open IntelliJ and select Import Bazel Project from the welcome screen if it's your first time using Intellij. Otherwise select File > Import Bazel Project.
- The next window asks you for the Bazel Workspace, click on the three dots (...) on the right, navigate to the ONOS folder and select it, the path should appear in the widows' box. Press Next.
- The next window asks you to Select a project view. Here you need to select a .bazelproject file, see the next section to create one, then press Next.
- Select Finish to import the ONOS project.
More information on how to import a Bazel project can be found here: https://ij.bazel.build/docs/import-project.html
Creating a .bazelproject file
ONOS is not shipped with an existing .bazelproject file, for this reason, we will need to create one. This file defines which part of the source tree IntelliJ needs to be aware of and how. When importing a project in IntelliJ, you can choose the option Create from scratch, which will generate a generic configuration that looks like this:
Essentially, here we tell IntelliJ to import ALL directories and ALL Bazel targets (
//...). Since ONOS is quite a big project, importing all targets for the first time can take more than 20 minutes depending on your configuration. Unfortunately, this .bazelproject configuration will make the IDE build and import many targets that are not needed for development (such as OSGi and test coverage artifacts).
Generate a minimal .bazelproject file (recommended)
To reduce the number of imported targets and to speed up the import process we have created a tool to auto-generate a minimal .bazelproject file for ONOS that imports only the targets needed for Java development. To auto-generate a .bazelproject file when importing ONOS for the first time in IntelliJ:
Auto-generate a temporary project file:
- In the Select Project View window when importing the project in IntelliJ, select Copy external and insert the location of the generated file:
With this option, it should take around 10 minutes to import the project for the first time.
Update an existing .bazelproject file
This tool creates a project file that imports the relevant targets available in ONOS at the time the tool is executed. If you create a new app/library in ONOS, or if you check out a different branch with different targets, you might want to update your existing .bazelproject file to reflect the changes:
This will replace the project file previosuly created during the import process.
To load the new .bazelproject file and re-sync your project, in the top menu select Bazel > Sync > Sync project with BUILD files. It should take only a few seconds to re-sync the project after the first import.
If your import fails with the error Error:Cannot run program "bazel" (in directory ): error=2, No such file or directory, it means IntelliJ did not properly pick-up the location of the Bazel binary and we need to change it.
- Go into Intellij IDEA > Preferences > Bazel Settings
- Under Bazel Binary Location click on the three dots (...) on the right and select the location you installed Bazel in ( e.g. /usr/local/bin/bazel). You can also type the Bazel path.
- Re-start the import process by re-syncing the project, in the top menu select Bazel > Sync > Sync project with BUILD files
More information on this error can be found here: https://github.com/bazelbuild/intellij/issues/230
Importing the settings
While the project is being processed, we can go ahead and import the recommended IntelliJ settings. We do this by selecting File… Import Settings… and then navigating to the ONOStools/dev directory and selecting the idea-settings.jar file. We can complete the process by pressing the OK button.
These settings have the JDK home setup for OS X (
/Library/Java/JavaVirtualMachines/<JDK-VERSION>/Contents/Home). For Linux, select File... Project Structure... SDKs... then edit the JDK home path for to be
/usr/lib/jvm/<JDK-VERSION>. If IntelliJ is throwing errors such as "cannot resolve symbol string", the JDK home is likely incorrect.
If IntelliJ is throwing errors like "The package 'org.onosproject.cluster' is not exported by the bundle dependencies," go to IntelliJ IDEA->Preferences. On the sidebar, under the Editor dropdown section, select Inspections. From there, search OSGi and under the OSGi dropdown, uncheck Package accessibility inspections and press OK.
Importing the Copyright header
Since ONOS is licensed under Apache 2 license, we need to make sure that all source files are properly decorated with the Apache 2 license header file.
To configure IntelliJ appropriately, we will locate the header.txt file under ONOS tools/dev directory and copy its contents. Then, from IntelliJ preferences, we will select Copyright section and add a new new copyright profile. We will call this profile ONOS and paste in the previously copied header text.
Then we will make sure that the newly created ONOS copyright profile is the default and we are done.
The ONOS Screencasts page provides helpful videos on importing, debugging, and developing ONOS with IntelliJ.