cmd/coordinator: start of a Kubernetes buildlet pool

Updates golang/go#12546

Change-Id: Ia70baeb1df441509f70c77e7b94e7eb9fddccbf3
Reviewed-on: https://go-review.googlesource.com/14392
Reviewed-by: Evan Brown <evanbrown@google.com>

cmd/coordinator/coordinator.go

@@ -1070,6 +1070,9 @@ func poolForConf(conf dashboard.BuildConfig) BuildletPool {
 	if conf.VMImage != "" {
 		return gcePool
 	}
+	if conf.KubeImage != "" {
+		return kubePool // Kubernetes
+	}
 	return reversePool
 }
 

cmd/coordinator/kube.go

@@ -0,0 +1,43 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"sync"
+
+	"golang.org/x/build/buildlet"
+)
+
+/*
+This file implements the Kubernetes-based buildlet pool.
+*/
+
+var kubePool = &kubeBuildletPool{}
+
+// kubeBuildletPool is the Kubernetes buildlet pool.
+type kubeBuildletPool struct {
+	// ...
+	mu sync.Mutex
+}
+
+func (p *kubeBuildletPool) GetBuildlet(cancel Cancel, machineType, rev string, el eventTimeLogger) (*buildlet.Client, error) {
+	return nil, errors.New("TODO")
+}
+
+func (p *kubeBuildletPool) WriteHTMLStatus(w io.Writer) {
+	io.WriteString(w, "<b>Kubernetes pool summary</b><ul><li>(TODO)</li></ul>")
+}
+
+func (p *kubeBuildletPool) String() string {
+	p.mu.Lock()
+	inUse := 0
+	total := 0
+	// ...
+	p.mu.Unlock()
+	return fmt.Sprintf("Kubernetes pool capacity: %d/%d", inUse, total)
+}

cmd/coordinator/reverse.go

@@ -312,6 +312,7 @@ func (p *reverseBuildletPool) WriteHTMLStatus(w io.Writer) {
 func (p *reverseBuildletPool) String() string {
 	p.mu.Lock()
 	inUse := 0
+	total := len(p.buildlets)
 	for _, b := range p.buildlets {
 		if b.inUseAs != "" && b.inUseAs != "health" {
 			inUse++
@@ -319,7 +320,7 @@ func (p *reverseBuildletPool) String() string {
 	}
 	p.mu.Unlock()
 
-	return fmt.Sprintf("Reverse pool capacity: %d/%d %s", inUse, len(p.buildlets), p.Modes())
+	return fmt.Sprintf("Reverse pool capacity: %d/%d %s", inUse, total, p.Modes())
 }
 
 // Modes returns the a deduplicated list of buildlet modes curently supported

dashboard/builders.go

@@ -25,6 +25,7 @@ type BuildConfig struct {
 	Notes       string // notes for humans
 	Owner       string // e.g. "bradfitz@golang.org", empty means golang-dev
 	VMImage     string // e.g. "openbsd-amd64-56"
+	KubeImage   string // e.g. "linux-buildlet-std:latest" (suffix after "gcr.io/<PROJ>/")
 	machineType string // optional GCE instance type
 	Go14URL     string // URL to built Go 1.4 tar.gz
 	buildletURL string // optional override buildlet URL
@@ -613,5 +614,8 @@ func addBuilder(c BuildConfig) {
 	if c.VMImage == "" && !c.IsReverse {
 		panic("empty VMImage")
 	}
+	if c.VMImage != "" && c.KubeImage != "" {
+		panic("there can be only one of VMImage/KubeImage")
+	}
 	Builders[c.Name] = c
 }