Add websocket with configurable boost (#3050)

Closes #3045

---

Please note that with `boost.asio`, only Bazel 7.x is supported. With
Bazel 6, I ran into [this
error](https://buildkite.com/bazel/bcr-presubmit/builds/8436#0192dd4c-016a-4d23-8724-30cdc578f223):
`Error computing the main repository mapping: in module dependency chain
<root> -> websocketpp@0.8.2.bcr.2 -> boost.asio@1.83.0 ->
boringssl@0.20240913.0 -> googletest@1.15.2: error executing
MODULE.bazel file for googletest@1.15.2`. [The googletest
version](https://github.com/bazelbuild/bazel-central-registry/blob/main/modules/googletest/1.15.2/presubmit.yml)
only supports Bazel 7.x in CI, so I do the same.

modules/websocketpp/0.8.2.bcr.2/MODULE.bazel

@@ -0,0 +1,11 @@
+module(
+    name = "websocketpp",
+    version = "0.8.2.bcr.2",
+    compatibility_level = 1,
+)
+bazel_dep(name = "asio", version = "1.28.2")
+bazel_dep(name = "bazel_skylib", version = "1.7.1")
+bazel_dep(name = "boost.asio", version = "1.83.0")
+bazel_dep(name = "platforms", version = "0.0.10")
+bazel_dep(name = "rules_cc", version = "0.0.9")
+bazel_dep(name = "zlib", version = "1.3")

modules/websocketpp/0.8.2.bcr.2/overlay/BUILD.bazel

@@ -0,0 +1,41 @@
+load("@bazel_skylib//rules:common_settings.bzl", "bool_flag")
+load("@rules_cc//cc:defs.bzl", "cc_library")
+
+bool_flag(
+    name = "use_boost",
+    build_setting_default = False,
+)
+
+config_setting(
+    name = "use_boost_setting",
+    flag_values = {":use_boost": "True"},
+)
+
+cc_library(
+    name = "websocketpp",
+    hdrs = glob(["websocketpp/**/*.hpp"]),
+    defines = select({
+        ":use_boost_setting": ["_WEBSOCKETPP_CPP11_STL_"],
+        "//conditions:default": [
+            "_WEBSOCKETPP_CPP11_STL_",
+            "ASIO_STANDALONE",
+        ],
+    }),
+    includes = ["."],
+    linkopts = select({
+        "@platforms//os:osx": [
+            "-lpthread",
+        ],
+        "//conditions:default": [
+            "-lpthread",
+            "-lrt",
+        ],
+    }),
+    visibility = ["//visibility:public"],
+    deps = [
+        "@zlib",
+    ] + select({
+        ":use_boost_setting": ["@boost.asio"],
+        "//conditions:default": ["@asio"],
+    }),
+)

modules/websocketpp/0.8.2.bcr.2/overlay/MODULE.bazel

@@ -0,0 +1 @@
+../MODULE.bazel

modules/websocketpp/0.8.2.bcr.2/presubmit.yml

@@ -0,0 +1,23 @@
+matrix:
+  platform:
+    - debian10
+    - ubuntu2004
+    - macos
+    - macos_arm64
+  bazel:
+    - 7.x
+tasks:
+  verify_targets:
+    name: Verify build targets
+    platform: ${{ platform }}
+    bazel: ${{ bazel }}
+    build_targets:
+      - "@websocketpp"
+  verify_targets_boost:
+    name: Verify build targets using boost asio
+    platform: ${{ platform }}
+    bazel: ${{ bazel }}
+    build_targets:
+      - "@websocketpp"
+    build_flags:
+    - '--@websocketpp//:use_boost=true'

modules/websocketpp/0.8.2.bcr.2/source.json

@@ -0,0 +1,10 @@
+{
+    "url": "https://github.com/zaphoyd/websocketpp/archive/refs/tags/0.8.2.tar.gz",
+    "integrity": "sha256-bOiJ2F7Nwtj6B0CNZ4fnNSUQdQ2qZrWtRKrLR76nZ1U=",
+    "strip_prefix": "websocketpp-0.8.2",
+    "overlay": {
+        "MODULE.bazel": "sha256-MmqOQI1EtRqoMO42ogfsACw86/eLQ7dq6TInLEp0sgk=",
+        "BUILD.bazel": "sha256-Awc0CFGb0fJhuWFn/zl7DUM/95rnuXc+k8YN7D5QQWE="
+    },
+    "patch_strip": 0
+}

modules/websocketpp/metadata.json

@@ -11,7 +11,8 @@
   ],
   "versions": [
     "0.8.2",
-    "0.8.2.bcr.1"
+    "0.8.2.bcr.1",
+    "0.8.2.bcr.2"
   ],
   "yanked_versions": {}
 }