metropolis: unify utility packages
One last sweeping rename / reshuffle.
We get rid of //metropolis/node/common and //golibs, unifying them into
a single //metropolis/pkg meta-package.
This is to be documented somwhere properly, but here's the new logic
behind selecting where to place a new library package:
- if it's specific to k8s-on-metropolis, put it in
//metropolis/node/kubernetes/*. This is a self-contained tree that
other paths cannot import from.
- if it's a big new subsystem of the metropolis core, put it in
//metropolis/node/core. This can be imported by anything in
//m/n (eg the Kubernetes code at //m/n/kubernetes
- otherwise, treat it as generic library that's part of the metropolis
project, and put it in //metropolis/pkg. This can be imported by
anything within //metropolis.
This will be followed up by a diff that updates visibility rules.
Test Plan: Pure refactor, CI only.
X-Origin-Diff: phab/D683
GitOrigin-RevId: 883e7f09a7d22d64e966d07bbe839454ed081c79
diff --git a/metropolis/pkg/freeport/BUILD.bazel b/metropolis/pkg/freeport/BUILD.bazel
new file mode 100644
index 0000000..8ac6daf
--- /dev/null
+++ b/metropolis/pkg/freeport/BUILD.bazel
@@ -0,0 +1,8 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+ name = "go_default_library",
+ srcs = ["freeport.go"],
+ importpath = "git.monogon.dev/source/nexantic.git/metropolis/pkg/freeport",
+ visibility = ["//visibility:public"],
+)
diff --git a/metropolis/pkg/freeport/freeport.go b/metropolis/pkg/freeport/freeport.go
new file mode 100644
index 0000000..bd047b5
--- /dev/null
+++ b/metropolis/pkg/freeport/freeport.go
@@ -0,0 +1,51 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package freeport
+
+import (
+ "io"
+ "net"
+)
+
+// AllocateTCPPort allocates a TCP port on the looopback address, and starts a temporary listener on it. That listener
+// is returned to the caller alongside with the allocated port number. The listener must be closed right before
+// the port is used by the caller. This naturally still leaves a race condition window where that port number
+// might be snatched up by some other process, but there doesn't seem to be a better way to do this.
+func AllocateTCPPort() (uint16, io.Closer, error) {
+ addr, err := net.ResolveTCPAddr("tcp", "127.0.0.1:0")
+ if err != nil {
+ return 0, nil, err
+ }
+
+ l, err := net.ListenTCP("tcp", addr)
+ if err != nil {
+ return 0, nil, err
+ }
+ return uint16(l.Addr().(*net.TCPAddr).Port), l, nil
+}
+
+// MustConsume takes the result of AllocateTCPPort, closes the listener and returns the allocated port.
+// If anything goes wrong (port could not be allocated or closed) it will panic.
+func MustConsume(port uint16, lis io.Closer, err error) int {
+ if err != nil {
+ panic(err)
+ }
+ if err := lis.Close(); err != nil {
+ panic(err)
+ }
+ return int(port)
+}