bootcfg/version: Add version package and HTTP version output

* bootcfg/version package provides the linker's GIT SHA based
version to bootcfg components
* Display the bootcfg version via the HTTP server / path for
convenience and for validating a deployed version easily
* Log requests to the / rooted subtree paths to surface machines
which are making requests containing typos and mistakes that do
not match HTTP API endpoints

Documentation/config.md

@@ -20,7 +20,7 @@ Configuration arguments can be provided as flags or as environment variables.
 | data      | /var/lib/bootcfg/{profiles,groups,ignition,cloud} |
 | assets    | /var/lib/bootcfg/assets |
 
-## Check Version
+## Version
 
     ./bin/bootcfg -version
     sudo rkt --insecure-options=image run quay.io/coreos/bootcfg:latest -- -version

bootcfg/http/handlers.go

@@ -1,12 +1,14 @@
 package http
 
 import (
+	"fmt"
 	"net/http"
 
 	"golang.org/x/net/context"
 
 	"github.com/coreos/coreos-baremetal/bootcfg/server"
 	pb "github.com/coreos/coreos-baremetal/bootcfg/server/serverpb"
+	"github.com/coreos/coreos-baremetal/bootcfg/version"
 )
 
 // requireGET requires requests to be an HTTP GET. Otherwise, it responds with
@@ -31,6 +33,19 @@ func logRequests(next http.Handler) http.Handler {
 	return http.HandlerFunc(fn)
 }
 
+// versionHandler shows the server name and version for root requests.
+// Otherwise, a 404 is returned.
+func versionHandler() http.Handler {
+	fn := func(w http.ResponseWriter, req *http.Request) {
+		if req.URL.Path != "/" {
+			http.NotFound(w, req)
+			return
+		}
+		fmt.Fprintf(w, "bootcfg version: %s", version.Version)
+	}
+	return http.HandlerFunc(fn)
+}
+
 // selectGroup selects the Group whose selectors match the query parameters,
 // adds the Group to the ctx, and calls the next handler. The next handler
 // should handle a missing Group.

bootcfg/http/server.go

@@ -46,6 +46,8 @@ func (s *Server) HTTPHandler() http.Handler {
 	mux := http.NewServeMux()
 	srv := server.NewServer(&server.Config{s.store})
 
+	// bootcfg version
+	mux.Handle("/", logRequests(versionHandler()))
 	// Boot via GRUB
 	mux.Handle("/grub", logRequests(NewHandler(selectProfile(srv, grubHandler()))))
 	// Boot via iPXE

bootcfg/version/version.go

@@ -0,0 +1,5 @@
+// Package version provides the bootcfg version.
+package version
+
+// Version provided by compile time -ldflags.
+var Version = "was not built properly"

build

@@ -1,6 +1,6 @@
 #!/bin/bash -e
 
-LD_FLAGS="-w -X main.version=$(./git-version)"
+LD_FLAGS="-w -X github.com/coreos/coreos-baremetal/bootcfg/version.Version=$(./git-version)"
 CGO_ENABLED=0 go build -o bin/bootcfg -ldflags "$LD_FLAGS" -a -tags netgo github.com/coreos/coreos-baremetal/cmd/bootcfg
 
 # bootcmd CLI binary

cmd/bootcfg/main.go

@@ -17,12 +17,11 @@ import (
 	"github.com/coreos/coreos-baremetal/bootcfg/server"
 	"github.com/coreos/coreos-baremetal/bootcfg/sign"
 	"github.com/coreos/coreos-baremetal/bootcfg/storage"
+	"github.com/coreos/coreos-baremetal/bootcfg/version"
 )
 
 var (
-	// version provided by compile time flag: -ldflags "-X main.version $GIT_SHA"
-	version = "was not built properly"
-	log     = capnslog.NewPackageLogger("github.com/coreos/coreos-baremetal/cmd/bootcfg", "main")
+	log = capnslog.NewPackageLogger("github.com/coreos/coreos-baremetal/cmd/bootcfg", "main")
 )
 
 func main() {
@@ -56,7 +55,7 @@ func main() {
 	passphrase := os.Getenv("BOOTCFG_PASSPHRASE")
 
 	if flags.version {
-		fmt.Println(version)
+		fmt.Println(version.Version)
 		return
 	}