Support new base64 encoding for pushing to the Pushgateway

This should only be released after PGW 0.9 is released.

Signed-off-by: beorn7 <beorn@grafana.com>

prometheus/push/push.go

@@ -36,6 +36,7 @@ package push
 
 import (
 	"bytes"
+	"encoding/base64"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -48,7 +49,12 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
-const contentTypeHeader = "Content-Type"
+const (
+	contentTypeHeader = "Content-Type"
+	// base64Suffix is appended to a label name in the request URL path to
+	// mark the following label value as base64 encoded.
+	base64Suffix = "@base64"
+)
 
 // HTTPDoer is an interface for the one method of http.Client that is used by Pusher
 type HTTPDoer interface {
@@ -77,9 +83,6 @@ type Pusher struct {
 // name. You can use just host:port or ip:port as url, in which case “http://”
 // is added automatically. Alternatively, include the schema in the
 // URL. However, do not include the “/metrics/jobs/…” part.
-//
-// Note that until https://github.com/prometheus/pushgateway/issues/97 is
-// resolved, a “/” character in the job name is prohibited.
 func New(url, job string) *Pusher {
 	var (
 		reg = prometheus.NewRegistry()
@@ -91,9 +94,6 @@ func New(url, job string) *Pusher {
 	if strings.HasSuffix(url, "/") {
 		url = url[:len(url)-1]
 	}
-	if strings.Contains(job, "/") {
-		err = fmt.Errorf("job contains '/': %s", job)
-	}
 
 	return &Pusher{
 		error:      err,
@@ -155,19 +155,12 @@ func (p *Pusher) Collector(c prometheus.Collector) *Pusher {
 // will lead to an error.
 //
 // For convenience, this method returns a pointer to the Pusher itself.
-//
-// Note that until https://github.com/prometheus/pushgateway/issues/97 is
-// resolved, this method does not allow a “/” character in the label value.
 func (p *Pusher) Grouping(name, value string) *Pusher {
 	if p.error == nil {
 		if !model.LabelName(name).IsValid() {
 			p.error = fmt.Errorf("grouping label has invalid name: %s", name)
 			return p
 		}
-		if strings.Contains(value, "/") {
-			p.error = fmt.Errorf("value of grouping label %s contains '/': %s", name, value)
-			return p
-		}
 		p.grouping[name] = value
 	}
 	return p
@@ -215,13 +208,7 @@ func (p *Pusher) Delete() error {
 	if p.error != nil {
 		return p.error
 	}
-	urlComponents := []string{url.QueryEscape(p.job)}
-	for ln, lv := range p.grouping {
-		urlComponents = append(urlComponents, ln, lv)
-	}
-	deleteURL := fmt.Sprintf("%s/metrics/job/%s", p.url, strings.Join(urlComponents, "/"))
-
-	req, err := http.NewRequest(http.MethodDelete, deleteURL, nil)
+	req, err := http.NewRequest(http.MethodDelete, p.fullURL(), nil)
 	if err != nil {
 		return err
 	}
@@ -235,7 +222,7 @@ func (p *Pusher) Delete() error {
 	defer resp.Body.Close()
 	if resp.StatusCode != 202 {
 		body, _ := ioutil.ReadAll(resp.Body) // Ignore any further error as this is for an error message only.
-		return fmt.Errorf("unexpected status code %d while deleting %s: %s", resp.StatusCode, deleteURL, body)
+		return fmt.Errorf("unexpected status code %d while deleting %s: %s", resp.StatusCode, p.fullURL(), body)
 	}
 	return nil
 }
@@ -244,12 +231,6 @@ func (p *Pusher) push(method string) error {
 	if p.error != nil {
 		return p.error
 	}
-	urlComponents := []string{url.QueryEscape(p.job)}
-	for ln, lv := range p.grouping {
-		urlComponents = append(urlComponents, ln, lv)
-	}
-	pushURL := fmt.Sprintf("%s/metrics/job/%s", p.url, strings.Join(urlComponents, "/"))
-
 	mfs, err := p.gatherers.Gather()
 	if err != nil {
 		return err
@@ -273,7 +254,7 @@ func (p *Pusher) push(method string) error {
 		}
 		enc.Encode(mf)
 	}
-	req, err := http.NewRequest(method, pushURL, buf)
+	req, err := http.NewRequest(method, p.fullURL(), buf)
 	if err != nil {
 		return err
 	}
@@ -288,7 +269,40 @@ func (p *Pusher) push(method string) error {
 	defer resp.Body.Close()
 	if resp.StatusCode != 202 {
 		body, _ := ioutil.ReadAll(resp.Body) // Ignore any further error as this is for an error message only.
-		return fmt.Errorf("unexpected status code %d while pushing to %s: %s", resp.StatusCode, pushURL, body)
+		return fmt.Errorf("unexpected status code %d while pushing to %s: %s", resp.StatusCode, p.fullURL(), body)
 	}
 	return nil
 }
+
+// fullURL assembles the URL used to push/delete metrics and returns it as a
+// string. The job name and any grouping label values containing a '/' will
+// trigger a base64 encoding of the affected component and proper suffixing of
+// the preceding component. If the component does not contain a '/' but other
+// special character, the usual url.QueryEscape is used for compatibility with
+// older versions of the Pushgateway and for better readability.
+func (p *Pusher) fullURL() string {
+	urlComponents := []string{}
+	if encodedJob, base64 := encodeComponent(p.job); base64 {
+		urlComponents = append(urlComponents, "job"+base64Suffix, encodedJob)
+	} else {
+		urlComponents = append(urlComponents, "job", encodedJob)
+	}
+	for ln, lv := range p.grouping {
+		if encodedLV, base64 := encodeComponent(lv); base64 {
+			urlComponents = append(urlComponents, ln+base64Suffix, encodedLV)
+		} else {
+			urlComponents = append(urlComponents, ln, encodedLV)
+		}
+	}
+	return fmt.Sprintf("%s/metrics/%s", p.url, strings.Join(urlComponents, "/"))
+}
+
+// encodeComponent encodes the provided string with base64.RawURLEncoding in
+// case it contains '/'. If not, it uses url.QueryEscape instead. It returns
+// true in the former case.
+func encodeComponent(s string) (string, bool) {
+	if strings.Contains(s, "/") {
+		return base64.RawURLEncoding.EncodeToString([]byte(s)), true
+	}
+	return url.QueryEscape(s), false
+}

prometheus/push/push_test.go

@@ -120,6 +120,57 @@ func TestPush(t *testing.T) {
 		t.Error("unexpected path:", lastPath)
 	}
 
+	// Pushes that require base64 encoding.
+	if err := New(pgwOK.URL, "test/job").
+		Collector(metric1).
+		Collector(metric2).
+		Push(); err != nil {
+		t.Fatal(err)
+	}
+	if lastMethod != http.MethodPut {
+		t.Errorf("got method %q for Push, want %q", lastMethod, http.MethodPut)
+	}
+	if !bytes.Equal(lastBody, wantBody) {
+		t.Errorf("got body %v, want %v", lastBody, wantBody)
+	}
+	if lastPath != "/metrics/job@base64/dGVzdC9qb2I" {
+		t.Error("unexpected path:", lastPath)
+	}
+	if err := New(pgwOK.URL, "testjob").
+		Grouping("foobar", "bu/ms").
+		Collector(metric1).
+		Collector(metric2).
+		Push(); err != nil {
+		t.Fatal(err)
+	}
+	if lastMethod != http.MethodPut {
+		t.Errorf("got method %q for Push, want %q", lastMethod, http.MethodPut)
+	}
+	if !bytes.Equal(lastBody, wantBody) {
+		t.Errorf("got body %v, want %v", lastBody, wantBody)
+	}
+	if lastPath != "/metrics/job/testjob/foobar@base64/YnUvbXM" {
+		t.Error("unexpected path:", lastPath)
+	}
+
+	// Push that requires URL encoding.
+	if err := New(pgwOK.URL, "testjob").
+		Grouping("titan", "Προμηθεύς").
+		Collector(metric1).
+		Collector(metric2).
+		Push(); err != nil {
+		t.Fatal(err)
+	}
+	if lastMethod != http.MethodPut {
+		t.Errorf("got method %q for Push, want %q", lastMethod, http.MethodPut)
+	}
+	if !bytes.Equal(lastBody, wantBody) {
+		t.Errorf("got body %v, want %v", lastBody, wantBody)
+	}
+	if lastPath != "/metrics/job/testjob/titan/%CE%A0%CF%81%CE%BF%CE%BC%CE%B7%CE%B8%CE%B5%CF%8D%CF%82" {
+		t.Error("unexpected path:", lastPath)
+	}
+
 	// Push some Collectors with a broken PGW.
 	if err := New(pgwErr.URL, "testjob").
 		Collector(metric1).
@@ -140,19 +191,6 @@ func TestPush(t *testing.T) {
 		Push(); err == nil {
 		t.Error("push with grouping contained in metrics succeeded")
 	}
-	if err := New(pgwOK.URL, "test/job").
-		Collector(metric1).
-		Collector(metric2).
-		Push(); err == nil {
-		t.Error("push with invalid job value succeeded")
-	}
-	if err := New(pgwOK.URL, "testjob").
-		Grouping("foobar", "bu/ms").
-		Collector(metric1).
-		Collector(metric2).
-		Push(); err == nil {
-		t.Error("push with invalid grouping succeeded")
-	}
 	if err := New(pgwOK.URL, "testjob").
 		Grouping("foo-bar", "bums").
 		Collector(metric1).