Feature: Add support for body templates

alerts/handler.go

@@ -79,10 +79,13 @@ type ReceiverHandler struct {
 
 	// titleTmpl is used to format the title of the new issue.
 	titleTmpl *template.Template
+
+	// alertTmpl is used to format the context of the new issue.
+	alertTmpl *template.Template
 }
 
 // NewReceiver creates a new ReceiverHandler.
-func NewReceiver(client ReceiverClient, githubRepo string, autoClose bool, resolvedLabel string, extraLabels []string, titleTmplStr string) (*ReceiverHandler, error) {
+func NewReceiver(client ReceiverClient, githubRepo string, autoClose bool, resolvedLabel string, extraLabels []string, titleTmplStr string, alertTmplStr string) (*ReceiverHandler, error) {
 	rh := ReceiverHandler{
 		Client:        client,
 		DefaultRepo:   githubRepo,
@@ -97,6 +100,11 @@ func NewReceiver(client ReceiverClient, githubRepo string, autoClose bool, resol
 		return nil, err
 	}
 
+	rh.alertTmpl, err = template.New("alert").Parse(alertTmplStr)
+	if err != nil {
+		return nil, err
+	}
+
 	return &rh, nil
 }
 
@@ -171,7 +179,10 @@ func (rh *ReceiverHandler) processAlert(msg *webhook.Message) error {
 	// issue from github, so create a new issue.
 	if msg.Data.Status == "firing" {
 		if foundIssue == nil {
-			msgBody := formatIssueBody(msg)
+			msgBody, err := rh.formatIssueBody(msg)
+			if err != nil {
+				return fmt.Errorf("format body for %q: %s", msg.GroupKey, err)
+			}
 			_, err = rh.Client.CreateIssue(rh.getTargetRepo(msg), msgTitle, msgBody, rh.ExtraLabels)
 			if err == nil {
 				createdIssues.WithLabelValues(alertName).Inc()

alerts/handler_test.go

@@ -4,14 +4,14 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//     http://www.apache.org/licenses/LICENSE-2.0
+//	http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-//////////////////////////////////////////////////////////////////////////////
+// ////////////////////////////////////////////////////////////////////////////
 package alerts
 
 import (
@@ -125,6 +125,7 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 		msgRepo           string
 		fakeClient        *fakeClient
 		titleTmpl         string
+		alertTmpl         string
 		httpStatus        int
 		expectReceiverErr bool
 		wantMessageErr    bool
@@ -140,6 +141,8 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 					createIssue("DiskRunningFull", "body1", ""),
 				},
 			},
+			titleTmpl:  DefaultTitleTmpl,
+			alertTmpl:  DefaultAlertTmpl,
 			httpStatus: http.StatusOK,
 		},
 		{
@@ -148,6 +151,8 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 			msgAlert:       "DiskRunningFull",
 			msgAlertStatus: "resolved",
 			fakeClient:     &fakeClient{},
+			titleTmpl:      DefaultTitleTmpl,
+			alertTmpl:      DefaultAlertTmpl,
 			httpStatus:     http.StatusOK,
 		},
 		{
@@ -156,6 +161,8 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 			msgAlert:       "DiskRunningFull",
 			msgAlertStatus: "firing",
 			fakeClient:     &fakeClient{},
+			titleTmpl:      DefaultTitleTmpl,
+			alertTmpl:      DefaultAlertTmpl,
 			httpStatus:     http.StatusOK,
 		},
 		{
@@ -165,6 +172,8 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 			msgAlertStatus: "firing",
 			msgRepo:        "custom-repo",
 			fakeClient:     &fakeClient{},
+			titleTmpl:      DefaultTitleTmpl,
+			alertTmpl:      DefaultAlertTmpl,
 			httpStatus:     http.StatusOK,
 		},
 		{
@@ -177,6 +186,8 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 					createIssue("DiskRunningFull", "body1", ""),
 				},
 			},
+			titleTmpl:  DefaultTitleTmpl,
+			alertTmpl:  DefaultAlertTmpl,
 			httpStatus: http.StatusOK,
 		},
 		{
@@ -190,6 +201,7 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 				},
 			},
 			titleTmpl:  `{{ (index .Data.Alerts 0).Labels.alertname }}`,
+			alertTmpl:  `Disk is running full on {{ (index .Data.Alerts 0).Labels.instance }}`,
 			httpStatus: http.StatusOK,
 		},
 		{
@@ -203,6 +215,8 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 				},
 				labelError: errors.New("No such label"),
 			},
+			titleTmpl:  DefaultTitleTmpl,
+			alertTmpl:  DefaultAlertTmpl,
 			httpStatus: http.StatusInternalServerError,
 		},
 		{
@@ -216,6 +230,7 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 				},
 			},
 			titleTmpl:  `{{ (index .Data.Alerts 1).Status }}`,
+			alertTmpl:  DefaultAlertTmpl,
 			httpStatus: http.StatusInternalServerError,
 		},
 		{
@@ -229,18 +244,38 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 				},
 			},
 			titleTmpl:         `{{ x }}`,
+			alertTmpl:         DefaultAlertTmpl,
+			expectReceiverErr: true,
+			httpStatus:        http.StatusInternalServerError,
+		},
+		{
+			name:           "failure-alert-template-bad-syntax",
+			method:         http.MethodPost,
+			msgAlert:       "DiskRunningFull",
+			msgAlertStatus: "firing",
+			fakeClient: &fakeClient{
+				listIssues: []*github.Issue{
+					createIssue("DiskRunningFull", "body1", ""),
+				},
+			},
+			titleTmpl:         `{{ (index .Data.Alerts 1).Status }}`,
+			alertTmpl:         `{{ x }}`,
 			expectReceiverErr: true,
 			httpStatus:        http.StatusInternalServerError,
 		},
 		{
 			name:           "failure-unmarshal-error",
 			method:         http.MethodPost,
+			titleTmpl:      DefaultTitleTmpl,
+			alertTmpl:      DefaultAlertTmpl,
 			httpStatus:     http.StatusBadRequest,
 			wantMessageErr: true,
 		},
 		{
 			name:        "failure-reader-error",
 			method:      http.MethodPost,
+			titleTmpl:   DefaultTitleTmpl,
+			alertTmpl:   DefaultAlertTmpl,
 			httpStatus:  http.StatusInternalServerError,
 			wantReadErr: true,
 		},
@@ -250,13 +285,27 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 			fakeClient: &fakeClient{
 				listError: fmt.Errorf("Fake error listing current issues"),
 			},
+			titleTmpl:  DefaultTitleTmpl,
+			alertTmpl:  DefaultAlertTmpl,
 			httpStatus: http.StatusInternalServerError,
 		},
 		{
 			name:       "failure-wrong-method",
 			method:     http.MethodGet,
+			titleTmpl:  DefaultTitleTmpl,
+			alertTmpl:  DefaultAlertTmpl,
 			httpStatus: http.StatusMethodNotAllowed,
 		},
+		{
+			name:           "failure-body-template",
+			method:         http.MethodPost,
+			msgAlert:       "DiskRunningFull",
+			msgAlertStatus: "firing",
+			fakeClient:     &fakeClient{},
+			titleTmpl:      DefaultTitleTmpl,
+			alertTmpl:      `{{ .NOTAREAL_FIELD }}`,
+			httpStatus:     http.StatusInternalServerError,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -284,11 +333,7 @@ func TestReceiverHandler_ServeHTTP(t *testing.T) {
 				return
 			}
 
-			titleTmpl := tt.titleTmpl
-			if titleTmpl == "" {
-				titleTmpl = DefaultTitleTmpl
-			}
-			rh, err := NewReceiver(tt.fakeClient, "default", true, "", nil, titleTmpl)
+			rh, err := NewReceiver(tt.fakeClient, "default", true, "", nil, tt.titleTmpl, tt.alertTmpl)
 			if tt.expectReceiverErr {
 				if err == nil {
 					t.Fatal()

alerts/template.go

@@ -18,14 +18,12 @@ package alerts
 import (
 	"bytes"
 	"fmt"
-	"html/template"
-	"log"
 
 	"github.com/prometheus/alertmanager/notify/webhook"
 )
 
 const (
-	// alertMD reports all alert labels and annotations in a markdown format
+	// DefaultAlertTmpl reports all alert labels and annotations in a markdown format
 	// that renders correctly in github issues.
 	//
 	// Example:
@@ -51,7 +49,7 @@ const (
 	//	 - alertname = DiskRunningFull
 	//	 - dev = sda2
 	//   - instance = example2
-	alertMD = `
+	DefaultAlertTmpl = `
 Alertmanager URL: {{.Data.ExternalURL}}
 {{range .Data.Alerts}}
   * {{.Status}} {{.GeneratorURL}}
@@ -77,10 +75,6 @@ TODO: add graph url from annotations.
 	DefaultTitleTmpl = `{{ .Data.GroupLabels.alertname }}`
 )
 
-var (
-	alertTemplate = template.Must(template.New("alert").Parse(alertMD))
-)
-
 func id(msg *webhook.Message) string {
 	return fmt.Sprintf("0x%x", msg.GroupKey)
 }
@@ -95,13 +89,10 @@ func (rh *ReceiverHandler) formatTitle(msg *webhook.Message) (string, error) {
 }
 
 // formatIssueBody constructs an issue body from a webhook message.
-func formatIssueBody(msg *webhook.Message) string {
+func (rh *ReceiverHandler) formatIssueBody(msg *webhook.Message) (string, error) {
 	var buf bytes.Buffer
-	err := alertTemplate.Execute(&buf, msg)
-	if err != nil {
-		log.Printf("Error executing template: %s", err)
-		return ""
+	if err := rh.alertTmpl.Execute(&buf, msg); err != nil {
+		return "", err
 	}
-	s := buf.String()
-	return fmt.Sprintf("<!-- ID: %s -->\n%s", id(msg), s)
+	return buf.String(), nil
 }

alerts/template_test.go

@@ -16,24 +16,74 @@
 package alerts
 
 import (
-	"html/template"
 	"testing"
 
 	"github.com/prometheus/alertmanager/notify/webhook"
 	amtmpl "github.com/prometheus/alertmanager/template"
 )
 
 func Test_formatIssueBody(t *testing.T) {
-	wh := createWebhookMessage("FakeAlertName", "firing", "")
-	brokenTemplate := `
-{{range .NOT_REAL_FIELD}}
-    * {{.Status}}
-{{end}}
-	`
-	alertTemplate = template.Must(template.New("alert").Parse(brokenTemplate))
-	got := formatIssueBody(wh)
-	if got != "" {
-		t.Errorf("formatIssueBody() = %q, want empty string", got)
+	msg := webhook.Message{
+		Data: &amtmpl.Data{
+			Status: "firing",
+			Alerts: []amtmpl.Alert{
+				{
+					Annotations: amtmpl.KV{"env": "prod", "svc": "foo"},
+				},
+				{
+					Annotations: amtmpl.KV{"env": "stage", "svc": "foo"},
+				},
+			},
+		},
+	}
+	tests := []struct {
+		name     string
+		template string
+		want     string
+		wantErr  bool
+	}{
+		{
+			name:     "success",
+			template: "foo",
+			want:     "foo",
+		},
+		{
+			name:     "success-data-status",
+			template: "{{ .Data.Status }}",
+			want:     "firing",
+		},
+		{
+			name:     "success-status",
+			template: "{{ .Status }}",
+			want:     "firing",
+		},
+		{
+			name:     "error-template",
+			template: "{{ range .NOT_REAL_FIELD }}\n* {{.Status}}\n{{end}}",
+			wantErr:  true,
+		},
+		{
+			name:     "error-template-no-field",
+			template: "{{ .Foo }}",
+			wantErr:  true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			rh, err := NewReceiver(&fakeClient{}, "default", false, "", nil, "", tt.template)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			got, err := rh.formatIssueBody(&msg)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("formatIssueBody() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("formatIssueBody() = %v, want %v", got, tt.want)
+			}
+		})
 	}
 }
 
@@ -80,7 +130,7 @@ func TestReceiverHandler_formatTitle(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			rh, err := NewReceiver(&fakeClient{}, "default", false, "", nil, tt.template)
+			rh, err := NewReceiver(&fakeClient{}, "default", false, "", nil, tt.template, "")
 			if err != nil {
 				t.Fatal(err)
 			}

cmd/github_receiver/main.go

@@ -51,6 +51,7 @@ var (
 	alertLabel      = flag.String("alertlabel", "alert:boom:", "The default label applied to all alerts. Also used to search the repo to discover exisitng alerts.")
 	extraLabels     = flagx.StringArray{}
 	titleTmplFile   = flagx.FileBytes(alerts.DefaultTitleTmpl)
+	alertTmplFile   = flagx.FileBytes(alerts.DefaultAlertTmpl)
 )
 
 // Metrics.
@@ -89,8 +90,9 @@ func init() {
 	flag.Var(&extraLabels, "label", "Extra labels to add to issues at creation time.")
 	flag.Var(&authtokenFile, "authtoken-file", "Oauth2 token file for access to github API. When provided it takes precedence over authtoken.")
 	flag.Var(&titleTmplFile, "title-template-file", "File containing a template to generate issue titles.")
+	flag.Var(&alertTmplFile, "alert-template-file", "File containing Markdown template to generate issue context.")
 	flag.Usage = func() {
-		fmt.Fprintf(flag.CommandLine.Output(), usage)
+		fmt.Fprint(flag.CommandLine.Output(), usage)
 		flag.PrintDefaults()
 	}
 }
@@ -141,7 +143,7 @@ func main() {
 	promSrv := prometheusx.MustServeMetrics()
 	defer promSrv.Close()
 
-	receiver, err := alerts.NewReceiver(client, *githubRepo, *enableAutoClose, *labelOnResolved, extraLabels, string(titleTmplFile))
+	receiver, err := alerts.NewReceiver(client, *githubRepo, *enableAutoClose, *labelOnResolved, extraLabels, string(titleTmplFile), string(alertTmplFile))
 	if err != nil {
 		fmt.Print(err)
 		osExit(1)