When working with Bazel, you may come across a situation where you need to access the output directory of a genrule, even when it's an external. This can be a bit tricky, especially if you are new to Bazel. But don't worry, we are here to help you!
In this article, we will guide you through the steps to get the output directory of a genrule in Bazel, even when it's an external. Let's get started!
Understanding genrule in Bazel
Before we dive into the solution, let's quickly understand what genrule is in Bazel. Genrule is a rule in Bazel that allows you to run a command and generate files as output. It is commonly used when you need to generate files during the build process.
Genrule takes a set of inputs, runs a command, and produces a set of outputs. The command can be any executable or script that generates the desired output files. The outputs can be files or directories.
Accessing the output directory of a genrule
By default, genrule in Bazel generates its output files or directories in a temporary location. This location is not directly accessible from the build workspace. However, there is a way to access the output directory, even when it's an external. Here's how:
- First, you need to find the genrule target in your Bazel build file. The genrule target is defined using the
genrulerule in the BUILD file. - Once you have identified the genrule target, you can use the
bazel infocommand to get the output directory. Open your terminal or command prompt and navigate to the root directory of your Bazel workspace. - Run the following command to get the output directory of the genrule:
bazel info bazel-genfiles/path/to/genrule_target
Replace path/to/genrule_target with the actual path to your genrule target. This command will output the absolute path of the genrule's output directory.
Now that you have the output directory, you can use it in your build process or access the generated files as needed.
Example
Let's walk through an example to make things clearer. Suppose you have a genrule target defined in your BUILD file as follows:
genrule(
name = "my_genrule",
srcs = ["input_file.txt"],
outs = ["output_file.txt"],
cmd = "cp $< $@",
)
In this example, the genrule takes an input file input_file.txt and generates an output file output_file.txt by copying the input file. We want to access the output directory of this genrule.
To get the output directory, run the following command in your terminal:
bazel info bazel-genfiles/path/to/my_genrule
Replace path/to/my_genrule with the actual path to your genrule target. The command will output the absolute path of the genrule's output directory.
Getting the output directory of a genrule in Bazel, even when it's an external, is possible by using the bazel info command. By following the steps outlined in this article, you can easily access the output directory and use it in your build process or access the generated files.
We hope this article has been helpful in solving your query. If you have any further questions, feel free to reach out to our technical support team.
| Reference | Link |
|---|---|
| Bazel Documentation | https://docs.bazel.build |
| Bazel User Group | https://groups.google.com/forum/#!forum/bazel-discuss |