fix: it's not necessary to download all platform versions of binary.

examples/WORKSPACE

@@ -153,12 +153,15 @@ go_repository(
     version = "v1.1.0",
 )
 
-http_archive(
+#http_archive(
+#    name = "io_bazel_rules_prometheus",
+#    sha256 = "f389ea769e8192a185c8f6216f8535a7eef3d64b619abcc61d56800f39ac62a3",
+#    urls = ["https://github.com/zacker330/rules_prometheus/releases/download/v0.0.2/rules_prometheus.tar.gz"],
+#)
+local_repository(
     name = "io_bazel_rules_prometheus",
-    sha256 = "f389ea769e8192a185c8f6216f8535a7eef3d64b619abcc61d56800f39ac62a3",
-    urls = ["https://github.com/zacker330/rules_prometheus/releases/download/v0.0.2/rules_prometheus.tar.gz"],
+    path = "../",
 )
-
 load("@io_bazel_rules_prometheus//:deps.bzl", "rules_prometheus_dependencies", "prometheus_register_toolchains", "alertmanager_register_toolchains")
 rules_prometheus_dependencies()
 prometheus_register_toolchains(version = "2.43.1")

internal/alertmanager/repos.bzl

@@ -57,7 +57,8 @@ def _format_url(version, platform, url):
     return whole_url
 
 def _alertmanager_download_rule_impl(ctx):
-    os, arch = ctx.attr.os, ctx.attr.arch
+    os, arch = detect_host_platform(ctx)
+#    os, arch = ctx.attr.os, ctx.attr.arch
     platform = os + "-" + arch
 
     version = ctx.attr.version

internal/prometheus/repos.bzl

@@ -6,7 +6,6 @@ load("@io_bazel_rules_prometheus//internal:platforms.bzl", "BAZEL_OS_CONSTRAINTS
 def _prometheus_build_file(ctx, platform, version):
     os, _, arch = platform.partition("-")
 
-
     constraints = [BAZEL_OS_CONSTRAINTS[os], BAZEL_ARCH_CONSTRAINTS[arch]]
 
     constraint_str = ",\n        ".join(['"%s"' % c for c in constraints])
@@ -60,14 +59,15 @@ def _format_url(version, platform, url):
     return whole_url
 
 def _prometheus_download_rule_impl(ctx):
-    if not ctx.attr.os and not ctx.attr.arch:
-        os, arch = detect_host_platform(ctx)
-    else:
-        if not ctx.attr.os:
-            fail("arch set but os not set")
-        if not ctx.attr.arch:
-            fail("os set but arch not set")
-    # os, arch = ctx.attr.os, ctx.attr.arch
+    os, arch = detect_host_platform(ctx)
+#    if not ctx.attr.os and not ctx.attr.arch:
+#        os, arch = detect_host_platform(ctx)
+#    else:
+#        if not ctx.attr.os:
+#            fail("arch set but os not set")
+#        if not ctx.attr.arch:
+#            fail("os set but arch not set")
+#    os, arch = ctx.attr.os, ctx.attr.arch
     platform = os + "-" + arch
 
     version = ctx.attr.version