How to execute a target?

[Hilco Wijbenga]

Hi all,

I want to build a tool ("my_java_tool") and execute it to generate
code. I seem to be getting the syntax wrong.

def _my_java_tool_binary_impl(ctx):
<snip/>
ctx.actions.run(
<snip/>
executable = ctx.attr.the_executable_jar,
)

my_java_tool_binary = rule(
implementation = _my_java_tool_binary_impl,
attrs = {
"the_executable_jar": attr.label(
executable = True,
cfg = "exec",
allow_files = True,
default = "//my_java_tool:the_executable_jar",
),
},
)

This causes an error: got value of type 'Target', want 'File, string,
or FilesToRunProvider'.

Assuming I'm on the right track at all, what is the right syntax?

Cheers,
Hilco

[Austin Schuh]

I think you want cfg = "host" because the tool is going to run on your build machine, not on the target.

Drop the allow_files and see if that fixes it.

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[Gregg Reynolds]

On Wed, Feb 24, 2021 at 1:08 AM Hilco Wijbenga <hilco.w...@gmail.com> wrote:

Hi all,

I want to build a tool ("my_java_tool") and execute it to generate
code. I seem to be getting the syntax wrong.

def _my_java_tool_binary_impl(ctx):
    <snip/>
    ctx.actions.run(
        <snip/>
        executable = ctx.attr.the_executable_jar,
    )

Try

     executable = ctx.file.the_executable_jar,

 

[Gregg Reynolds]

And use allow_single_file = True

[John Cater]

This exact case (and many others) are covered in the examples repo, found at https://github.com/bazelbuild/examples/tree/master/rules

For this specific case, see actions_run/execute.bzl, which shows using `ctx.executable` instead of `ctx.attr` or `ctx.file`.

Also, the original use of `cfg = "exec"` is correct: the host platform is usually always available as an execution platform, but with remote execution there can be more execution platforms that are not the host platform. Using `cfg = "exec"` therefore has the same effect without remote execution, and avoids a number of potential problems with remote execution.

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[Gunnar Wagenknecht]

Hi Hilco,

> I want to build a tool ("my_java_tool") and execute it to generate
> code. I seem to be getting the syntax wrong.

If you are looking for a builder template I can highly recommend:
https://github.com/salesforce/bazel-java-builder-template

It does proper argument handling, supports workers and uses the executable from a java_binary.

See lines 32, 155 in mybuilder/defs.bzl
https://github.com/salesforce/bazel-java-builder-template/blob/0110f1d1023827d8b6f08fa7356485eb784d11f6/mybuilder/defs.bzl#L32
https://github.com/salesforce/bazel-java-builder-template/blob/0110f1d1023827d8b6f08fa7356485eb784d11f6/mybuilder/defs.bzl#L155

The java_binary is defined here:
https://github.com/salesforce/bazel-java-builder-template/blob/0110f1d1023827d8b6f08fa7356485eb784d11f6/src/main/java/com/salesforce/bazel/javabuilder/mybuilder/BUILD#L2


-Gunnar


--
Gunnar Wagenknecht
gun...@wagenknecht.org, http://guw.io/