env/linux-x86-buster: add Debian Buster builder

This change adds a Debian Buster builder.

Fixes golang/go#42410

Change-Id: If11ebe6df3bad88aac40b0a6f841edc5fb3a5b4a
Reviewed-on: https://go-review.googlesource.com/c/build/+/267937
Trust: Carlos Amedee <carlos@golang.org>
Run-TryBot: Carlos Amedee <carlos@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Alexander Rakoczy <alex@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/dashboard/builders.go b/dashboard/builders.go
index 95bd0d7..8fce694 100644
--- a/dashboard/builders.go
+++ b/dashboard/builders.go
@@ -106,6 +106,13 @@
 // Hosts contains the names and configs of all the types of
 // buildlets. They can be VMs, containers, or dedicated machines.
 var Hosts = map[string]*HostConfig{
+	"host-linux-buster": &HostConfig{
+		Notes:           "Debian Buster",
+		ContainerImage:  "linux-x86-buster:latest",
+		buildletURLTmpl: "https://storage.googleapis.com/$BUCKET/buildlet.linux-amd64",
+		env:             []string{"GOROOT_BOOTSTRAP=/go1.4"},
+		SSHUsername:     "root",
+	},
 	"host-linux-jessie": &HostConfig{
 		Notes:           "Debian Jessie, our standard Linux container image.",
 		ContainerImage:  "linux-x86-jessie:latest",
@@ -1776,6 +1783,15 @@
 		},
 	})
 	addBuilder(BuildConfig{
+		Name:     "linux-amd64-buster",
+		HostType: "host-linux-buster",
+		Notes:    "Debian Buster.",
+		env: []string{
+			"GO_DISABLE_OUTBOUND_NETWORK=1",
+		},
+		KnownIssue: 42750,
+	})
+	addBuilder(BuildConfig{
 		Name:     "linux-amd64-longtest",
 		HostType: "host-linux-stretch-morecpu",
 		Notes:    "Debian Stretch with go test -short=false",