Consolidate external reachability flags into one.

Besides fixing prometheus#805 by making the entire externally reachable server URL configurable, this adds tests for the "globalURL" template function and makes it easier to test other such functions in the future. This breaks the `web.Hostname` flag (and introduces `web.external-url`). This flag is likely only used by few users, so I hope that's justifiable. Fixes prometheus#805
riccardolorenzon · Jul 3, 2015 · fcff35b · fcff35b
1 parent 8510076
commit fcff35b
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Showing 6 changed files with 122 additions and 90 deletions.
diff --git a/cmd/prometheus/config.go b/cmd/prometheus/config.go
@@ -17,6 +17,7 @@ import (
 	"flag"
 	"fmt"
 	"net"
+	"net/url"
 	"os"
 	"strings"
 	"text/template"
@@ -68,17 +69,13 @@ func init() {
 	)
 
 	// Web.
-	cfg.fs.StringVar(
-		&cfg.web.PathPrefix, "web.path-prefix", "",
-		"Prefix for all web paths.",
-	)
 	cfg.fs.StringVar(
 		&cfg.web.ListenAddress, "web.listen-address", ":9090",
 		"Address to listen on for the web interface, API, and telemetry.",
 	)
 	cfg.fs.StringVar(
-		&cfg.web.Hostname, "web.hostname", "",
-		"Hostname on which the server is available.",
+		&cfg.prometheusURL, "web.external-url", "",
+		"The URL under which Prometheus is externally reachable (for example, if Prometheus is served via a reverse proxy). Used for generating relative and absolute links back to Prometheus itself. If omitted, relevant URL components will be derived automatically.",
 	)
 	cfg.fs.StringVar(
 		&cfg.web.MetricsPath, "web.telemetry-path", "/metrics",
@@ -98,7 +95,7 @@ func init() {
 	)
 	cfg.fs.StringVar(
 		&cfg.web.ConsoleTemplatesPath, "web.console.templates", "consoles",
-		"Path to the console template directory, available at /console.",
+		"Path to the console template directory, available at /consoles.",
 	)
 	cfg.fs.StringVar(
 		&cfg.web.ConsoleLibrariesPath, "web.console.libraries", "console_libraries",
@@ -224,24 +221,29 @@ func parse(args []string) error {
 		return err
 	}
 
-	ppref := strings.TrimRight(cfg.web.PathPrefix, "/")
-	if ppref != "" && !strings.HasPrefix(ppref, "/") {
-		ppref = "/" + ppref
-	}
-	cfg.web.PathPrefix = ppref
-
-	if cfg.web.Hostname == "" {
-		cfg.web.Hostname, err = os.Hostname()
+	if cfg.prometheusURL == "" {
+		hostname, err := os.Hostname()
 		if err != nil {
 			return err
 		}
+		_, port, err := net.SplitHostPort(cfg.web.ListenAddress)
+		if err != nil {
+			return err
+		}
+		cfg.prometheusURL = fmt.Sprintf("http://%s:%s/", hostname, port)
 	}
 
-	_, port, err := net.SplitHostPort(cfg.web.ListenAddress)
+	promURL, err := url.Parse(cfg.prometheusURL)
 	if err != nil {
 		return err
 	}
-	cfg.prometheusURL = fmt.Sprintf("http://%s:%s%s/", cfg.web.Hostname, port, cfg.web.PathPrefix)
+	cfg.web.ExternalURL = promURL
+
+	ppref := strings.TrimRight(cfg.web.ExternalURL.Path, "/")
+	if ppref != "" && !strings.HasPrefix(ppref, "/") {
+		ppref = "/" + ppref
+	}
+	cfg.web.ExternalURL.Path = ppref
 
 	return nil
 }

diff --git a/cmd/prometheus/main.go b/cmd/prometheus/main.go
@@ -75,8 +75,7 @@ func Main() int {
 		SampleAppender:      sampleAppender,
 		NotificationHandler: notificationHandler,
 		QueryEngine:         queryEngine,
-		PrometheusURL:       cfg.prometheusURL,
-		PathPrefix:          cfg.web.PathPrefix,
+		ExternalURL:         cfg.web.ExternalURL,
 	})
 
 	flags := map[string]string{}

diff --git a/rules/manager.go b/rules/manager.go
@@ -16,8 +16,8 @@ package rules
 import (
 	"fmt"
 	"io/ioutil"
+	"net/url"
 	"path/filepath"
-	"strings"
 	"sync"
 	"time"
 
@@ -103,8 +103,7 @@ type Manager struct {
 	sampleAppender      storage.SampleAppender
 	notificationHandler *notification.NotificationHandler
 
-	prometheusURL string
-	pathPrefix    string
+	externalURL *url.URL
 }
 
 // ManagerOptions bundles options for the Manager.
@@ -115,8 +114,7 @@ type ManagerOptions struct {
 	NotificationHandler *notification.NotificationHandler
 	SampleAppender      storage.SampleAppender
 
-	PrometheusURL string
-	PathPrefix    string
+	ExternalURL *url.URL
 }
 
 // NewManager returns an implementation of Manager, ready to be started
@@ -130,7 +128,7 @@ func NewManager(o *ManagerOptions) *Manager {
 		sampleAppender:      o.SampleAppender,
 		queryEngine:         o.QueryEngine,
 		notificationHandler: o.NotificationHandler,
-		prometheusURL:       o.PrometheusURL,
+		externalURL:         o.ExternalURL,
 	}
 	return manager
 }
@@ -211,7 +209,7 @@ func (m *Manager) queueAlertNotifications(rule *AlertingRule, timestamp clientmo
 		defs := "{{$labels := .Labels}}{{$value := .Value}}"
 
 		expand := func(text string) string {
-			tmpl := template.NewTemplateExpander(defs+text, "__alert_"+rule.Name(), tmplData, timestamp, m.queryEngine, m.pathPrefix)
+			tmpl := template.NewTemplateExpander(defs+text, "__alert_"+rule.Name(), tmplData, timestamp, m.queryEngine, m.externalURL.Path)
 			result, err := tmpl.Expand()
 			if err != nil {
 				result = err.Error()
@@ -230,7 +228,7 @@ func (m *Manager) queueAlertNotifications(rule *AlertingRule, timestamp clientmo
 			Value:        aa.Value,
 			ActiveSince:  aa.ActiveSince.Time(),
 			RuleString:   rule.String(),
-			GeneratorURL: m.prometheusURL + strings.TrimLeft(strutil.GraphLinkForExpression(rule.vector.String()), "/"),
+			GeneratorURL: m.externalURL.String() + strutil.GraphLinkForExpression(rule.vector.String()),
 		})
 	}
 	m.notificationHandler.SubmitReqs(notifications)