How to find files in runfiles dir?

[pa...@lucidchart.com]

I have some jars that must be loaded with a non-system classloader.

I can add these jars as data to java_binary, but there's no way to know where they will wind up in the JAVA_RUNFILES directory, yets?

It seems they are saved in the directory as the unaliased identify, which can change.

(bind() is used, so that users can either use an external dependency, or provide their own local version.)

I can search through all run files and do content detection but the whole things seems very messy.

If I write

java_binary(
name = "example",
main_class = "Main",
visibility = ["//visibility:public"],
deps = [
":deps",
],
data = [
"//external:myjar"
],
)

Of all the runfiles, how I can I identify //external:myjar ?

[Alex Humesky]

Two solutions come to mind:

1. Use the args attribute to tell the binary where the jars are. Something like this:

JARS = [

    "//external:myjar",

]

java_binary(

  name = "Test",

  srcs = glob(["java/**"]),

  args = ["--jar=$(location %s)" % j for j in JARS],

  data = JARS,

)

This only works if you run the binary through bazel run though, and requires that the binary understands these flags.

2. Create a "jar manifest" using a genrule that contains the paths of the jars you want. The jar manifest will be at a known location so you can read that at runtime. Something like:

JARS = [

    "//external:myjar",

]

java_binary(

  name = "Test",

  srcs = glob(["java/**"]),

  data = [

    ":jar_manifest",

  ] + JARS,

)

genrule(

  name = "gen_jar_manifest",

  outs = ["jar_manifest"],

  srcs = JARS,

  cmd = " && ".join(["echo '$(location %s)' >> $@" % j for j in JARS]),

)

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[Alex Humesky]

(You could also get fancy with #2 and instead of generating a file to manually read at runtime, you could generate a java file that has the file paths in a list, and then it's just available as a part of your application, but I don't know if I'd actually recommend this.)

[pa...@lucidchart.com]

Good to know the location trick.

I was using genquery to obtain the bound actual. Location is much better.

[ittai zeidman]

I’m fairly certain what you want is $execpath and not $location since the former is for runtime and the latter is for build times

[Marcel Hlopko]

+László Csomor 

Laszlo recently shared https://docs.google.com/document/d/e/2PACX-1vSDIrFnFvEYhKsCMdGdD40wZRBX3m3aZ5HhVj4CtHPmiXKDCxioTUbYsDydjKtFDAzER5eg7OjJWs3V/pub, would that solve your problem?

On Fri, Apr 6, 2018 at 8:13 AM ittai zeidman <itt...@gmail.com> wrote:

I’m fairly certain what you want is $execpath and not $location since the former is for runtime and the latter is for build times

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Marcel Hlopko | Software Engineer | hlo...@google.com | 

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