bazel，python 规则，创建的文件如何获取它们

Question

如何访问我的 python 正在创建的文件？
所以在python里面我得到了类似的东西：

from pathlib import Path
p = Path('my_file.txt')
p.write_text('testing')
print("Testing done")

然后，当我执行bazel run my_file 时，我可以在终端文本中看到一切顺利以及打印信息，但是当我试图找到 my_file.txt 时，什么也没有。那么我需要对我的规则做些什么才能在 bazel 运行完成后访问该文件？

Answer 1

如果您能提供更多详细信息可能会有所帮助：

1. python 代码是如何运行的？它是作为一个动作运行的吗？
2. my_file 目标是什么？
3. 你提到你有一些规则。这些 Starlark 规则是你写的吗？

但要直接回答：当使用bazel run 运行二进制文件时，它会在包含二进制文件所有依赖项的符号链接的“运行文件树”中执行。所以你的文件将被放在二进制文件的 runfiles 目录中。

my_program.py:

import os
from pathlib import Path

print("current working directory: " + os.getcwd())

p = Path('my_file.txt')
p.write_text('testing')
print("Testing done")

BUILD:

py_binary(
  name = "my_program",
  srcs = ["my_program.py"],
)

$ bazel run my_program
INFO: Analyzed target //:my_program (18 packages loaded, 90 targets configured).
INFO: Found 1 target...
Target //:my_program up-to-date:
  bazel-bin/my_program
INFO: Elapsed time: 0.226s, Critical Path: 0.01s
INFO: 5 processes: 5 internal.
INFO: Build completed successfully, 5 total actions
INFO: Build completed successfully, 5 total actions
current working directory: /home/ahumesky/.cache/bazel/_bazel_ahumesky/5123c9882cdbb6c5e34f583431173549/execroot/__main__/bazel-out/k8-fastbuild/bin/my_program.runfiles/__main__
Testing done

$ ls /home/ahumesky/.cache/bazel/_bazel_ahumesky/5123c9882cdbb6c5e34f583431173549/execroot/__main__/bazel-out/k8-fastbuild/bin/my_program.runfiles/__main__
external  my_file.txt  my_program  my_program.py

$ cat /home/ahumesky/.cache/bazel/_bazel_ahumesky/5123c9882cdbb6c5e34f583431173549/execroot/__main__/bazel-out/k8-fastbuild/bin/my_program.runfiles/__main__/my_file.txt 
testing

如果可能，最好将输出文件路径作为参数传递给程序，以便文件位于某个已知位置：

import sys
from pathlib import Path

p = Path(sys.argv[1])
p.write_text('testing')
print("Testing done")

$ bazel run my_program -- /tmp/output.txt
INFO: Analyzed target //:my_program (0 packages loaded, 0 targets configured).
INFO: Found 1 target...
Target //:my_program up-to-date:
  bazel-bin/my_program
INFO: Elapsed time: 0.040s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action
INFO: Build completed successfully, 1 total action
Testing done

$ cat /tmp/output.txt
testing

或者，如果你直接运行程序，那么文件将在当前工作目录中：

$ bazel build my_program
INFO: Analyzed target //:my_program (18 packages loaded, 90 targets configured).
INFO: Found 1 target...
Target //:my_program up-to-date:
  bazel-bin/my_program
INFO: Elapsed time: 0.219s, Critical Path: 0.01s
INFO: 5 processes: 5 internal.
INFO: Build completed successfully, 5 total actions

$ bazel-bin/my_program
current working directory: /home/ahumesky/test
Testing done

$ cat my_file.txt
testing

Answer 2

看script：你可以使用BUILD_WORKING_DIRECTORY env 变量在工作目录中创建文件路径

Answer 3

write_text() 返回写入文本文件的字符数，也许你可以检查一下。或者，试试print(p.read_text())