Travis PPC64le: Move Docker Work-Around

Move the control of the work-around for docker on ppc64le on travis
into the `docker_container` logic and do not expose as interface.

cibuildwheel/docker_container.py

@@ -1,6 +1,7 @@
 import io
 import json
 import os
+import platform
 import shlex
 import subprocess
 import sys
@@ -9,6 +10,8 @@
 from types import TracebackType
 from typing import IO, Dict, List, Optional, Sequence, Type, cast
 
+from cibuildwheel.util import CIProvider, detect_ci_provider
+
 from .typing import PathOrStr, PopenBytes
 
 
@@ -35,22 +38,28 @@ def __init__(
         *,
         docker_image: str,
         simulate_32_bit: bool = False,
-        network_host: bool = False,
         cwd: Optional[PathOrStr] = None,
     ):
         if not docker_image:
             raise ValueError("Must have a non-empty docker image to run.")
 
         self.docker_image = docker_image
         self.simulate_32_bit = simulate_32_bit
-        self.network_host = network_host
         self.cwd = cwd
         self.name: Optional[str] = None
 
     def __enter__(self) -> "DockerContainer":
         self.name = f"cibuildwheel-{uuid.uuid4()}"
         cwd_args = ["-w", str(self.cwd)] if self.cwd else []
-        network_args = ["--network=host"] if self.network_host else []
+
+        # work-around for Travis-CI PPC64le Docker runs since 2021:
+        # this avoids network splits
+        # https://github.com/pypa/cibuildwheel/issues/904
+        # https://github.com/conda-forge/conda-smithy/pull/1520
+        network_args = []
+        if detect_ci_provider() == CIProvider.travis_ci and platform.machine() == "ppc64le":
+            network_args = ["--network=host"]
+
         shell_args = ["linux32", "/bin/bash"] if self.simulate_32_bit else ["/bin/bash"]
         subprocess.run(
             [
@@ -60,7 +69,7 @@ def __enter__(self) -> "DockerContainer":
                 f"--name={self.name}",
                 "--interactive",
                 "--volume=/:/host",  # ignored on CircleCI
-                *network_args,  # mainly for TravisCI PPC64le
+                *network_args,
                 *cwd_args,
                 self.docker_image,
                 *shell_args,

cibuildwheel/linux.py

@@ -338,7 +338,6 @@ def build(options: Options) -> None:
             with DockerContainer(
                 docker_image=build_step.docker_image,
                 simulate_32_bit=build_step.platform_tag.endswith("i686"),
-                network_host=build_step.platform_tag.endswith("ppc64le"),
                 cwd=container_project_path,
             ) as docker: