Add support for 'port_aliases' to service_group

cmd/svcinit/main.go

@@ -384,6 +384,17 @@ func assignPorts(
 		}
 	}
 
+	for label, spec := range serviceSpecs {
+		for portName, aliasedTo := range spec.PortAliases {
+			qualifiedPortName := label
+			if portName != "" {
+				qualifiedPortName += ":" + portName
+			}
+
+			ports.Set(qualifiedPortName, ports[aliasedTo])
+		}
+	}
+
 	// Complete hack - we have observed that the ports may not be ready immediately after closing, even with SO_LINGER set to 0.
 	// Give the kernel a bit of time to figure out what we've done.
 	time.Sleep(10 * time.Millisecond)

docs/itest.md

@@ -78,7 +78,7 @@ All [common binary attributes](https://bazel.build/reference/be/common-definitio
 ## itest_service_group
 
 <pre>
-itest_service_group(<a href="#itest_service_group-name">name</a>, <a href="#itest_service_group-autoassign_port">autoassign_port</a>, <a href="#itest_service_group-named_ports">named_ports</a>, <a href="#itest_service_group-services">services</a>, <a href="#itest_service_group-so_reuseport_aware">so_reuseport_aware</a>)
+itest_service_group(<a href="#itest_service_group-name">name</a>, <a href="#itest_service_group-port_aliases">port_aliases</a>, <a href="#itest_service_group-services">services</a>)
 </pre>
 
 A service group is a collection of services/tasks.
@@ -94,10 +94,8 @@ It can bring up multiple services with a single `bazel run` command, which is us
 | Name  | Description | Type | Mandatory | Default |
 | :------------- | :------------- | :------------- | :------------- | :------------- |
 | <a id="itest_service_group-name"></a>name |  A unique name for this target.   | <a href="https://bazel.build/concepts/labels#target-names">Name</a> | required |  |
-| <a id="itest_service_group-autoassign_port"></a>autoassign_port |  If true, the service manager will pick a free port and assign it to the service.         The port will be interpolated into <code>$${PORT}</code> in the service's <code>http_health_check_address</code> and <code>args</code>.         It will also be exported under the target's fully qualified label in the service-port mapping.<br><br>        The assigned ports for all services are available for substitution in <code>http_health_check_address</code> and <code>args</code> (in case one service needs the address for another one.)         For example, the following substitution: <code>args = ["-client-addr", "127.0.0.1:$${@@//label/for:service}"]</code><br><br>        The service-port mapping is a JSON string -&gt; int map propagated through the <code>ASSIGNED_PORTS</code> env var.         For example, a port can be retrieved with the following JS code:         <code>JSON.parse(process.env["ASSIGNED_PORTS"])["@@//label/for:service"]</code>.<br><br>        Alternately, the env will also contain the location of a binary that can return the port, for contexts without a readily-accessible JSON parser.         For example, the following Bash command:         <code>PORT=$($GET_ASSIGNED_PORT_BIN @@//label/for:service)</code>   | Boolean | optional | <code>False</code> |
-| <a id="itest_service_group-named_ports"></a>named_ports |  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 <code>named_ports = ["http_port"]</code> will be assigned a fully-qualified name of <code>@@//label/for:service:http_port</code>.<br><br>        Named ports are accessible through the service-port mapping. For more details, see <code>autoassign_port</code>.   | List of strings | optional | <code>[]</code> |
+| <a id="itest_service_group-port_aliases"></a>port_aliases |  Port aliases allow you to 're-export' another service's port as belonging to this service group. This can be used to create abstractions (such as an itest_service combined with an itest_task) but not leak their implementation through how client code accesses port names.   | <a href="https://bazel.build/rules/lib/dict">Dictionary: String -> String</a> | optional | <code>{}</code> |
 | <a id="itest_service_group-services"></a>services |  Services/tasks that comprise this group. Can be <code>itest_service</code>, <code>itest_task</code>, or <code>itest_service_group</code>.   | <a href="https://bazel.build/concepts/labels">List of labels</a> | optional | <code>[]</code> |
-| <a id="itest_service_group-so_reuseport_aware"></a>so_reuseport_aware |  If set, the service manager will not release the autoassigned port. The service binary must use SO_REUSEPORT when binding it.         This reduces the possibility of port collisions when running many service_tests in parallel, or when code binds port 0 without being         aware of the port assignment mechanism.<br><br>        Must only be set when <code>autoassign_port</code> is enabled or <code>named_ports</code> are used.   | Boolean | optional | <code>False</code> |
 
 
 <a id="itest_task"></a>
@@ -130,7 +128,7 @@ All [common binary attributes](https://bazel.build/reference/be/common-definitio
 ## service_test
 
 <pre>
-service_test(<a href="#service_test-name">name</a>, <a href="#service_test-autoassign_port">autoassign_port</a>, <a href="#service_test-data">data</a>, <a href="#service_test-env">env</a>, <a href="#service_test-named_ports">named_ports</a>, <a href="#service_test-services">services</a>, <a href="#service_test-so_reuseport_aware">so_reuseport_aware</a>, <a href="#service_test-test">test</a>)
+service_test(<a href="#service_test-name">name</a>, <a href="#service_test-data">data</a>, <a href="#service_test-env">env</a>, <a href="#service_test-port_aliases">port_aliases</a>, <a href="#service_test-services">services</a>, <a href="#service_test-test">test</a>)
 </pre>
 
 Brings up a set of services/tasks and runs a test target against them.
@@ -165,12 +163,10 @@ All [common binary attributes](https://bazel.build/reference/be/common-definitio
 | Name  | Description | Type | Mandatory | Default |
 | :------------- | :------------- | :------------- | :------------- | :------------- |
 | <a id="service_test-name"></a>name |  A unique name for this target.   | <a href="https://bazel.build/concepts/labels#target-names">Name</a> | required |  |
-| <a id="service_test-autoassign_port"></a>autoassign_port |  If true, the service manager will pick a free port and assign it to the service.         The port will be interpolated into <code>$${PORT}</code> in the service's <code>http_health_check_address</code> and <code>args</code>.         It will also be exported under the target's fully qualified label in the service-port mapping.<br><br>        The assigned ports for all services are available for substitution in <code>http_health_check_address</code> and <code>args</code> (in case one service needs the address for another one.)         For example, the following substitution: <code>args = ["-client-addr", "127.0.0.1:$${@@//label/for:service}"]</code><br><br>        The service-port mapping is a JSON string -&gt; int map propagated through the <code>ASSIGNED_PORTS</code> env var.         For example, a port can be retrieved with the following JS code:         <code>JSON.parse(process.env["ASSIGNED_PORTS"])["@@//label/for:service"]</code>.<br><br>        Alternately, the env will also contain the location of a binary that can return the port, for contexts without a readily-accessible JSON parser.         For example, the following Bash command:         <code>PORT=$($GET_ASSIGNED_PORT_BIN @@//label/for:service)</code>   | Boolean | optional | <code>False</code> |
 | <a id="service_test-data"></a>data |  -   | <a href="https://bazel.build/concepts/labels">List of labels</a> | optional | <code>[]</code> |
 | <a id="service_test-env"></a>env |  The service manager will merge these variables into the environment when spawning the underlying binary.   | <a href="https://bazel.build/rules/lib/dict">Dictionary: String -> String</a> | optional | <code>{}</code> |
-| <a id="service_test-named_ports"></a>named_ports |  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 <code>named_ports = ["http_port"]</code> will be assigned a fully-qualified name of <code>@@//label/for:service:http_port</code>.<br><br>        Named ports are accessible through the service-port mapping. For more details, see <code>autoassign_port</code>.   | List of strings | optional | <code>[]</code> |
+| <a id="service_test-port_aliases"></a>port_aliases |  Port aliases allow you to 're-export' another service's port as belonging to this service group. This can be used to create abstractions (such as an itest_service combined with an itest_task) but not leak their implementation through how client code accesses port names.   | <a href="https://bazel.build/rules/lib/dict">Dictionary: String -> String</a> | optional | <code>{}</code> |
 | <a id="service_test-services"></a>services |  Services/tasks that comprise this group. Can be <code>itest_service</code>, <code>itest_task</code>, or <code>itest_service_group</code>.   | <a href="https://bazel.build/concepts/labels">List of labels</a> | optional | <code>[]</code> |
-| <a id="service_test-so_reuseport_aware"></a>so_reuseport_aware |  If set, the service manager will not release the autoassigned port. The service binary must use SO_REUSEPORT when binding it.         This reduces the possibility of port collisions when running many service_tests in parallel, or when code binds port 0 without being         aware of the port assignment mechanism.<br><br>        Must only be set when <code>autoassign_port</code> is enabled or <code>named_ports</code> are used.   | Boolean | optional | <code>False</code> |
 | <a id="service_test-test"></a>test |  The underlying test target to execute once the services have been brought up and healthchecked.   | <a href="https://bazel.build/concepts/labels">Label</a> | optional | <code>None</code> |
 
 

private/itest.bzl

@@ -217,8 +217,8 @@ def _itest_service_impl(ctx):
 
     return _itest_binary_impl(ctx, extra_service_spec_kwargs, extra_exe_runfiles)
 
-_port_assignment_attrs = {
-  # Note, autoassigning a port is a little racy. If you can stick to hardcoded ports and network namespace, you should prefer that.
+_itest_service_attrs = _itest_binary_attrs | {
+    # Note, autoassigning a port is a little racy. If you can stick to hardcoded ports and network namespace, you should prefer that.
     "autoassign_port": attr.bool(
         doc = """If true, the service manager will pick a free port and assign it to the service.
         The port will be interpolated into `$${PORT}` in the service's `http_health_check_address` and `args`.
@@ -249,9 +249,10 @@ _port_assignment_attrs = {
 
         Must only be set when `autoassign_port` is enabled or `named_ports` are used.""",
     ),
-}
-
-_itest_service_attrs = _itest_binary_attrs | _port_assignment_attrs | {
+    "expected_start_duration": attr.string(
+        default = "0s",
+        doc = "How long the service expected to take before passing a healthcheck. Any failing health checks before this duration elapses will not be logged.",
+    ),
     "health_check": attr.label(
         cfg = "target",
         mandatory = False,
@@ -263,10 +264,6 @@ _itest_service_attrs = _itest_binary_attrs | _port_assignment_attrs | {
     "health_check_args": attr.string_list(
         doc = """Arguments to pass to the health_check binary. The various defined ports will be substituted prior to being given to the health_check binary.""",
     ),
-    "expected_start_duration": attr.string(
-        default = "0s",
-        doc = "How long the service expected to take before passing a healthcheck. Any failing health checks before this duration elapses will not be logged.",
-    ),
     "health_check_interval": attr.string(
         default = "200ms",
         doc = "The duration between each health check. The syntax is based on common time duration with a number, followed by the time unit. For example, `200ms`, `1s`, `2m`, `3h`, `4d`.",
@@ -313,16 +310,11 @@ All [common binary attributes](https://bazel.build/reference/be/common-definitio
 def _itest_service_group_impl(ctx):
     services = _collect_services(ctx.attr.services)
 
-    if ctx.attr.so_reuseport_aware and not (ctx.attr.autoassign_port or ctx.attr.named_ports):
-        fail("SO_REUSEPORT awareness only makes sense when using port autoassignment")
-
     service = struct(
         type = "group",
         label = str(ctx.label),
         deps = [str(service.label) for service in ctx.attr.services],
-        autoassign_port = ctx.attr.autoassign_port,
-        so_reuseport_aware = ctx.attr.so_reuseport_aware,
-        named_ports = ctx.attr.named_ports,
+        port_aliases = ctx.attr.port_aliases
     )
     services[service.label] = service
 
@@ -337,7 +329,12 @@ def _itest_service_group_impl(ctx):
         _ServiceGroupInfo(services = services),
     ]
 
-_itest_service_group_attrs = _port_assignment_attrs | _svcinit_attrs | {
+_itest_service_group_attrs = _svcinit_attrs | {
+    "port_aliases": attr.string_dict(
+        doc = """Port aliases allow you to 're-export' another service's port as belonging to this service group.
+This can be used to create abstractions (such as an itest_service combined with an itest_task) but not leak
+their implementation through how client code accesses port names.""",
+    ),
     "services": attr.label_list(
         providers = [_ServiceGroupInfo],
         doc = "Services/tasks that comprise this group. Can be `itest_service`, `itest_task`, or `itest_service_group`.",

svclib/types.go

@@ -23,6 +23,7 @@ type ServiceSpec struct {
 	SoReuseportAware       bool              `json:"so_reuseport_aware"`
 	NamedPorts             []string          `json:"named_ports"`
 	HotReloadable          bool              `json:"hot_reloadable"`
+	PortAliases            map[string]string `json:"port_aliases"`
 }
 
 // Our internal representation.

tests/BUILD.bazel

@@ -113,13 +113,14 @@ itest_service(
     http_health_check_address = "http://127.0.0.1:$${PORT}",
 )
 
-# Test port assignment through a group
+# Test port aliases
 itest_service(
     name = "_speedy_service2",
     args = [
         "-port",
-        "$${@@//:speedy_service2:port}",
+        "$${@@//:speedy_service2}",
     ],
+    autoassign_port = True,
     env = {"foo": "bar"},
     exe = "//go_service",
     http_health_check_address = "http://127.0.0.1:$${@@//:speedy_service2:port}",
@@ -128,6 +129,9 @@ itest_service(
 
 itest_service_group(
     name = "speedy_service2",
-    services = [":_speedy_service"],
-    named_ports = ["port"],
+    services = [":_speedy_service2"],
+    port_aliases = {
+        "": "@@//:_speedy_service2",
+        "port": "@@//:_speedy_service2",
+    },
 )