Put exec_platforms back on //:tars, use `--strategy=PackageTar=w…

…orker,sandboxed,local` to avoid it executing with docker or remote.

.github/workflows/bazel.yml

@@ -51,6 +51,8 @@ jobs:
       - uses: actions/checkout@v3
       - name: Work around https://github.com/actions/upload-artifact/issues/92
         run: echo "bazel_out=$(sudo runuser -u runner -g runner -G docker -- bazel info output_path)" >> $GITHUB_ENV
+      - name: Bazel Build
+        run: sudo runuser -u runner -g runner -G docker -- bazel build hellos tars rpms debs
       - name: Bazel Host Tests
         run: sudo runuser -u runner -g runner -G docker -- bazel test --strategy=TestRunner=sandboxed host-{hellos,tars}-test # We won't test the RPM and DEB tests on the host as they actually install the package.
       - uses: actions/upload-artifact@v3
@@ -79,6 +81,8 @@ jobs:
       - uses: actions/checkout@v3
       - name: Work around https://github.com/actions/upload-artifact/issues/92
         run: echo "bazel_out=$(bazel info output_path)" >> $GITHUB_ENV
+      - name: Bazel Build
+        run: bazel build hellos tars rpms debs
       - name: Bazel Test
         run: bazel test platform-{hello,tar,rpm,deb}-test-suite
       - uses: actions/upload-artifact@v3

BUILD.bazel

@@ -88,13 +88,13 @@ pkg_tar(
     srcs = [":pkg/hello"],
 )
 
-# Expand :tar to build for all platforms on the host platform! We can do this
-# because it's just tar. We do it by omitting the exec_platforms.
-# We have to do it for CentOS6 as it happens as its Python 3.4 is too old for
-# the pkg_tar rule and it fails.
+# Expand :tar to build for all platforms.
+# Theoretically we should just be able to remove the exec_platforms (or add
+# just @local_config_platform//:host) but there's wrong with it right now.
 platforms(
     name = "tars",
     actual = ":tar",
+    exec_platforms = _all_platforms,
     target_platforms = _all_platforms,
 )
 

README.md

@@ -137,6 +137,9 @@ Problems...
    declare that it is executable on the host: that seems to propagate to being
    instructions to compile `//:hello` for the host too.
 
+3. We avoided having to think about the difference between target and exec platform by
+   specifying both with the same values. TODO figure that out. I.e. we should be able
+   to specify that `//:tars` _targets_ all platforms, but can _execute_ on the host.
 ---
 
 References: