adding alert templates support for AlertManager

pkg/alertmanager/alertmanager.go

@@ -149,18 +149,20 @@ func New(cfg *Config) (*Alertmanager, error) {
 }
 
 // ApplyConfig applies a new configuration to an Alertmanager.
-func (am *Alertmanager) ApplyConfig(conf *config.Config) error {
+func (am *Alertmanager) ApplyConfig(userID string, conf *config.Config) error {
 	var (
 		tmpl     *template.Template
 		pipeline notify.Stage
 	)
 
-	// TODO(cortex): How to support template files?
-	if len(conf.Templates) != 0 {
-		return fmt.Errorf("template files are not yet supported")
+	templateFiles := make([]string, len(conf.Templates), len(conf.Templates))
+	if len(conf.Templates) > 0 {
+		for i, t := range conf.Templates {
+			templateFiles[i] = filepath.Join(am.cfg.DataDir, "templates", userID, t)
+		}
 	}
 
-	tmpl, err := template.FromGlobs()
+	tmpl, err := template.FromGlobs(templateFiles...)
 	if err != nil {
 		return err
 	}

pkg/alertmanager/multitenant.go

@@ -9,6 +9,7 @@ import (
 	"net"
 	"net/http"
 	"os"
+	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"
@@ -421,12 +422,44 @@ func (am *MultitenantAlertmanager) transformConfig(userID string, amConfig *amco
 	return amConfig, nil
 }
 
+func (am *MultitenantAlertmanager) createTemplatesFile(userID, fn, content string) (bool, error) {
+	dir := filepath.Join(am.cfg.DataDir, "templates", userID, filepath.Dir(fn))
+	err := os.MkdirAll(dir, 0755)
+	if err != nil {
+		return false, fmt.Errorf("unable to create Alertmanager templates directory %q: %s", dir, err)
+	}
+
+	file := filepath.Join(dir, fn)
+	// Check if the template file already exists and if it has changed
+	if tmpl, err := ioutil.ReadFile(file); err == nil && string(tmpl) == content {
+		return false, nil
+	}
+
+	if err := ioutil.WriteFile(file, []byte(content), 0644); err != nil {
+		return false, fmt.Errorf("unable to create Alertmanager template file %q: %s", file, err)
+	}
+
+	return true, nil
+}
+
 // setConfig applies the given configuration to the alertmanager for `userID`,
 // creating an alertmanager if it doesn't already exist.
 func (am *MultitenantAlertmanager) setConfig(userID string, config configs.Config) error {
 	_, hasExisting := am.alertmanagers[userID]
 	var amConfig *amconfig.Config
 	var err error
+	var hasTemplateChanges bool
+
+	for fn, content := range config.TemplateFiles {
+		hasChanged, err := am.createTemplatesFile(userID, fn, content)
+		if err != nil {
+			return err
+		}
+
+		if hasChanged {
+			hasTemplateChanges = true
+		}
+	}
 
 	if config.AlertmanagerConfig == "" {
 		if am.fallbackConfig == "" {
@@ -462,9 +495,9 @@ func (am *MultitenantAlertmanager) setConfig(userID string, config configs.Confi
 		am.alertmanagersMtx.Lock()
 		am.alertmanagers[userID] = newAM
 		am.alertmanagersMtx.Unlock()
-	} else if am.cfgs[userID].AlertmanagerConfig != config.AlertmanagerConfig {
+	} else if am.cfgs[userID].AlertmanagerConfig != config.AlertmanagerConfig || hasTemplateChanges {
 		// If the config changed, apply the new one.
-		err := am.alertmanagers[userID].ApplyConfig(amConfig)
+		err := am.alertmanagers[userID].ApplyConfig(userID, amConfig)
 		if err != nil {
 			return fmt.Errorf("unable to apply Alertmanager config for user %v: %v", userID, err)
 		}
@@ -486,7 +519,7 @@ func (am *MultitenantAlertmanager) newAlertmanager(userID string, amConfig *amco
 		return nil, fmt.Errorf("unable to start Alertmanager for user %v: %v", userID, err)
 	}
 
-	if err := newAM.ApplyConfig(amConfig); err != nil {
+	if err := newAM.ApplyConfig(userID, amConfig); err != nil {
 		return nil, fmt.Errorf("unable to apply initial config for user %v: %v", userID, err)
 	}
 	return newAM, nil

pkg/configs/api/api.go

@@ -4,6 +4,7 @@ import (
 	"database/sql"
 	"encoding/json"
 	"fmt"
+	"html/template"
 	"io/ioutil"
 	"net/http"
 	"strconv"
@@ -57,6 +58,8 @@ func (a *API) RegisterRoutes(r *mux.Router) {
 		// be used.
 		{"get_rules", "GET", "/api/prom/configs/rules", a.getConfig},
 		{"set_rules", "POST", "/api/prom/configs/rules", a.setConfig},
+		{"get_templates", "GET", "/api/prom/configs/templates", a.getConfig},
+		{"set_templates", "POST", "/api/prom/configs/templates", a.setConfig},
 		{"get_alertmanager_config", "GET", "/api/prom/configs/alertmanager", a.getConfig},
 		{"set_alertmanager_config", "POST", "/api/prom/configs/alertmanager", a.setConfig},
 		{"validate_alertmanager_config", "POST", "/api/prom/configs/alertmanager/validate", a.validateAlertmanagerConfig},
@@ -124,6 +127,11 @@ func (a *API) setConfig(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, fmt.Sprintf("Invalid rules: %v", err), http.StatusBadRequest)
 		return
 	}
+	if err := validateTemplateFiles(cfg); err != nil {
+		level.Error(logger).Log("msg", "invalid templates", "err", err)
+		http.Error(w, fmt.Sprintf("Invalid templates: %v", err), http.StatusBadRequest)
+		return
+	}
 	if err := a.db.SetConfig(userID, cfg); err != nil {
 		// XXX: Untested
 		level.Error(logger).Log("msg", "error storing config", "err", err)
@@ -162,10 +170,6 @@ func validateAlertmanagerConfig(cfg string) error {
 		return err
 	}
 
-	if len(amCfg.Templates) != 0 {
-		return fmt.Errorf("template files are not supported in Cortex yet")
-	}
-
 	for _, recv := range amCfg.Receivers {
 		if len(recv.EmailConfigs) != 0 {
 			return fmt.Errorf("email notifications are not supported in Cortex yet")
@@ -180,6 +184,16 @@ func validateRulesFiles(c configs.Config) error {
 	return err
 }
 
+func validateTemplateFiles(c configs.Config) error {
+	for fn, content := range c.TemplateFiles {
+		if _, err := template.New(fn).Parse(content); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 // ConfigsView renders multiple configurations, mapping userID to configs.View.
 // Exposed only for tests.
 type ConfigsView struct {

pkg/configs/api/api_test.go

@@ -233,17 +233,6 @@ var amCfgValidationTests = []struct {
 		errContains: "yaml",
 	}, {
 		config: `
-        route:
-          receiver: noop
-        templates:
-        - "/path/to/file"
-
-        receivers:
-        - name: noop`,
-		shouldFail:  true,
-		errContains: "template files are not supported in Cortex yet",
-	}, {
-		config: `
         global:
           smtp_smarthost: localhost:25
           smtp_from: alertmanager@example.org

pkg/configs/configs.go

@@ -72,6 +72,7 @@ func (v *RuleFormatVersion) UnmarshalJSON(data []byte) error {
 type Config struct {
 	// RulesFiles maps from a rules filename to file contents.
 	RulesConfig        RulesConfig
+	TemplateFiles      map[string]string
 	AlertmanagerConfig string
 }
 
@@ -81,6 +82,7 @@ type Config struct {
 type configCompat struct {
 	RulesFiles         map[string]string `json:"rules_files"`
 	RuleFormatVersion  RuleFormatVersion `json:"rule_format_version"`
+	TemplateFiles      map[string]string `json:"template_files"`
 	AlertmanagerConfig string            `json:"alertmanager_config"`
 }
 
@@ -89,6 +91,7 @@ func (c Config) MarshalJSON() ([]byte, error) {
 	compat := &configCompat{
 		RulesFiles:         c.RulesConfig.Files,
 		RuleFormatVersion:  c.RulesConfig.FormatVersion,
+		TemplateFiles:      c.TemplateFiles,
 		AlertmanagerConfig: c.AlertmanagerConfig,
 	}
 
@@ -106,6 +109,7 @@ func (c *Config) UnmarshalJSON(data []byte) error {
 			Files:         compat.RulesFiles,
 			FormatVersion: compat.RuleFormatVersion,
 		},
+		TemplateFiles:      compat.TemplateFiles,
 		AlertmanagerConfig: compat.AlertmanagerConfig,
 	}
 	return nil