Support port flag overrides (#44)

Author: dzbarsky

.bazelversion

@@ -1 +1 @@
-9.0.0rc5
+9.0.0

.bcr/presubmit.yml

@@ -2,7 +2,7 @@ bcr_test_module:
   module_path: "tests"
   matrix:
     platform: ["debian10", "macos", "ubuntu2004", "windows"]
-    bazel: [7.x, 8.x, rolling]
+    bazel: [7.x, 8.x, 9.x, rolling]
   tasks:
     run_tests:
       name: "Run tests"

cmd/svcinit/main.go

@@ -8,12 +8,12 @@ import (
 	"errors"
 	"fmt"
 	"log"
+	"maps"
 	"math"
 	"net"
 	"os"
 	"os/exec"
 	"os/signal"
-	"slices"
 	"strconv"
 	"strings"
 	"syscall"
@@ -360,15 +360,15 @@ func assignPorts(
 	ports := svclib.Ports{}
 
 	for label, spec := range serviceSpecs {
-		namedPorts := slices.Clone(spec.NamedPorts)
+		namedPorts := maps.Clone(spec.NamedPorts)
 		if spec.AutoassignPort {
-			namedPorts = append(namedPorts, "")
+			namedPorts[""] = spec.Port
 		}
 
 		// Note, this can cause collisions. So be careful!
 		// To avoid port collisions, set the `so_reuseport_aware` option on the service definition
 		// and use the SO_REUSEPORT socket option in your services.
-		for _, portName := range namedPorts {
+		for portName, port := range namedPorts {
 			// We do a bit of a dance here to set SO_LINGER to 0. For details, see
 			// https://stackoverflow.com/questions/71975992/what-really-is-the-linger-time-that-can-be-set-with-so-linger-on-sockets
 			lc := net.ListenConfig{
@@ -387,18 +387,18 @@ func assignPorts(
 				},
 			}
 
-			listener, err := lc.Listen(context.Background(), "tcp", "127.0.0.1:0")
+			listener, err := lc.Listen(context.Background(), "tcp", "127.0.0.1:"+port)
 			if err != nil {
 				return nil, err
 			}
-			_, port, err := net.SplitHostPort(listener.Addr().String())
+			_, port, err = net.SplitHostPort(listener.Addr().String())
 			if err != nil {
 				return nil, err
 			}
 
 			qualifiedPortName := label
 			if portName != "" {
-				qualifiedPortName += ":" + portName
+				qualifiedPortName += "." + portName
 			}
 
 			if !terseOutput {
@@ -407,6 +407,20 @@ func assignPorts(
 
 			ports.Set(qualifiedPortName, port)
 
+			{
+				// TODO(zbarsky): Clean this up after April 2026
+				qualifiedPortName := label
+				if portName != "" {
+					qualifiedPortName += ":" + portName
+				}
+
+				if !terseOutput {
+					log.Printf("Assigning port %s to %s\n", port, qualifiedPortName)
+				}
+
+				ports.Set(qualifiedPortName, port)
+			}
+
 			if !spec.SoReuseportAware {
 				toClose = append(toClose, listener)
 			}
@@ -424,10 +438,20 @@ func assignPorts(
 		for portName, aliasedTo := range spec.PortAliases {
 			qualifiedPortName := label
 			if portName != "" {
-				qualifiedPortName += ":" + portName
+				qualifiedPortName += "." + portName
 			}
 
 			ports.Set(qualifiedPortName, ports[aliasedTo])
+
+			{
+				// TODO(zbarsky): Clean this up after April 2026
+				qualifiedPortName := label
+				if portName != "" {
+					qualifiedPortName += ":" + portName
+				}
+
+				ports.Set(qualifiedPortName, ports[aliasedTo])
+			}
 		}
 	}
 
@@ -516,6 +540,7 @@ func augmentServiceSpecs(
 		Replacement{Old: "$${TMPDIR}", New: tmpDir},
 		Replacement{Old: "$${SOCKET_DIR}", New: socketDir},
 	)
+
 	for label, port := range ports {
 		replacements = append(replacements, Replacement{
 			Old: "$${" + label + "}",

docs/itest.md

@@ -1,5 +1,6 @@
 """ Rules for running services in integration tests. """
 
+load("@bazel_skylib//rules:common_settings.bzl", "int_flag")
 load(
     "//private:itest.bzl",
     _itest_service = "itest_service",
@@ -12,12 +13,32 @@ def port(label):
     return "$${%s}" % (str(native.package_relative_label(label)))
 
 def named_port(label, name):
-    return "$${%s:%s}" % (str(native.package_relative_label(label)), name)
+    return port(label + "." + name)
+
+def itest_service(name, tags = [], hygienic = True, named_ports = [], **kwargs):
+    if "port" in kwargs:
+        fail("Do not specify `port`, instead set it via the `%s` flag" % (name + ".port"))
+
+    int_flag(
+        name = name + ".port",
+        build_setting_default = 0,
+    )
+
+    named_ports_attr = {}
+    for named_port in named_ports:
+        named_port_label = name + "." + named_port
+        named_ports_attr[named_port_label] = named_port
+
+        int_flag(
+            name = named_port_label,
+            build_setting_default = 0,
+        )
 
-def itest_service(name, tags = [], hygienic = True, **kwargs):
     _itest_service(
         name = name,
         tags = tags + ["ibazel_notify_changes"],
+        port = name + ".port",
+        named_ports = named_ports_attr,
         **kwargs
     )
 

itest.bzl

@@ -204,10 +204,14 @@ def _itest_service_impl(ctx):
     extra_service_spec_kwargs = {
         "type": "service",
         "http_health_check_address": ctx.attr.http_health_check_address,
+        "port": str(ctx.attr.port[BuildSettingInfo].value),
         "autoassign_port": ctx.attr.autoassign_port,
         "so_reuseport_aware": ctx.attr.so_reuseport_aware,
         "deferred": ctx.attr.deferred,
-        "named_ports": ctx.attr.named_ports,
+        "named_ports": {
+            name: str(port_flag[BuildSettingInfo].value)
+            for port_flag, name in ctx.attr.named_ports.items()
+        },
         "hot_reloadable": ctx.attr.hot_reloadable,
         "expected_start_duration": ctx.attr.expected_start_duration,
         "health_check_interval": ctx.attr.health_check_interval,
@@ -249,10 +253,11 @@ _itest_service_attrs = _itest_binary_attrs | {
         For example, the following Bash command:
         `PORT=$($GET_ASSIGNED_PORT_BIN @@//label/for:service)`""",
     ),
-    "named_ports": attr.string_list(
+    "port": attr.label(doc="Internal"),
+    "named_ports": attr.label_keyed_string_dict(
         doc = """For each element of the list, the service manager will pick a free port and assign it to the service.
         The port's fully-qualified name is the service's fully-qualified label and the port name, separated by a colon.
-        For example, a port assigned with `named_ports = ["http_port"]` will be assigned a fully-qualified name of `@@//label/for:service:http_port`.
+        For example, a port assigned with `named_ports = ["http_port"]` will be assigned a fully-qualified name of `@@//label/for:service.http_port`.
 
         Named ports are accessible through the service-port mapping. For more details, see `autoassign_port`.""",
     ),

private/itest.bzl

@@ -19,9 +19,10 @@ type ServiceSpec struct {
 	HealthCheckTimeout      string            `json:"health_check_timeout"`
 	VersionFile             string            `json:"version_file"`
 	Deps                    []string          `json:"deps"`
+	Port                    string            `json:"port"`
 	AutoassignPort          bool              `json:"autoassign_port"`
 	SoReuseportAware        bool              `json:"so_reuseport_aware"`
-	NamedPorts              []string          `json:"named_ports"`
+	NamedPorts              map[string]string `json:"named_ports"`
 	HotReloadable           bool              `json:"hot_reloadable"`
 	PortAliases             map[string]string `json:"port_aliases"`
 	ShutdownSignal          string            `json:"shutdown_signal"`