Add etcd notifier

config/config.go

@@ -458,6 +458,7 @@ type Receiver struct {
 	HipchatConfigs   []*HipchatConfig   `yaml:"hipchat_configs,omitempty" json:"hipchat_configs,omitempty"`
 	SlackConfigs     []*SlackConfig     `yaml:"slack_configs,omitempty" json:"slack_configs,omitempty"`
 	WebhookConfigs   []*WebhookConfig   `yaml:"webhook_configs,omitempty" json:"webhook_configs,omitempty"`
+	EtcdConfigs      []*EtcdConfig      `yaml:"etcd_configs,omitempty" json:"etcd_configs,omitempty"`
 	OpsGenieConfigs  []*OpsGenieConfig  `yaml:"opsgenie_configs,omitempty" json:"opsgenie_configs,omitempty"`
 	PushoverConfigs  []*PushoverConfig  `yaml:"pushover_configs,omitempty" json:"pushover_configs,omitempty"`
 	VictorOpsConfigs []*VictorOpsConfig `yaml:"victorops_configs,omitempty" json:"victorops_configs,omitempty"`

config/notifiers.go

@@ -27,6 +27,23 @@ var (
 		},
 	}
 
+	// DefaultEtcdConfig defines default values for Etcd configurations.
+	DefaultEtcdConfig = EtcdConfig{
+		NotifierConfig: NotifierConfig{
+			VSendResolved: true,
+		},
+		Firing: EtcdPostConf{
+			URL:             "",
+			KeyAnnotation:   "etcd_key",
+			ValueAnnotation: "etcd_value",
+		},
+		Resolved: EtcdPostConf{
+			URL:             "",
+			KeyAnnotation:   "etcd_key",
+			ValueAnnotation: "etcd_value",
+		},
+	}
+
 	// DefaultEmailConfig defines default values for Email configurations.
 	DefaultEmailConfig = EmailConfig{
 		NotifierConfig: NotifierConfig{
@@ -291,6 +308,40 @@ func (c *WebhookConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	return checkOverflow(c.XXX, "webhook config")
 }
 
+// EtcdAlertConf holds information needed to push alerts to etcd
+type EtcdPostConf struct {
+	URL             string `yaml:"url" json:"url"`
+	KeyAnnotation   string `yaml:"key_annotation" json:"key_annotation"`
+	ValueAnnotation string `yaml:"value_annotation" json:"value_annotation"`
+}
+
+// EtcdConfig configures notifications to an etcd KV store.
+type EtcdConfig struct {
+	NotifierConfig `yaml:",inline" json:",inline"`
+
+	Firing   EtcdPostConf `yaml:"firing" json:"firing"`
+	Resolved EtcdPostConf `yaml:"resolved" json:"resolved"`
+
+	// Catches all undefined fields and must be empty after parsing.
+	XXX map[string]interface{} `yaml:",inline" json:"-"`
+}
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface.
+func (c *EtcdConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	*c = DefaultEtcdConfig
+	type plain EtcdConfig
+	if err := unmarshal((*plain)(c)); err != nil {
+		return err
+	}
+	if c.Firing.URL == "" {
+		return fmt.Errorf("missing firing URL in etcd config")
+	}
+	if c.Resolved.URL == "" {
+		return fmt.Errorf("missing resolved URL in etcd config")
+	}
+	return checkOverflow(c.XXX, "etcd config")
+}
+
 // OpsGenieConfig configures notifications via OpsGenie.
 type OpsGenieConfig struct {
 	NotifierConfig `yaml:",inline" json:",inline"`

notify/impl.go

@@ -104,6 +104,10 @@ func BuildReceiverIntegrations(nc *config.Receiver, tmpl *template.Template) []I
 		n := NewWebhook(c, tmpl)
 		add("webhook", i, n, c)
 	}
+	for i, c := range nc.EtcdConfigs {
+		n := NewEtcd(c, tmpl)
+		add("etcd", i, n, c)
+	}
 	for i, c := range nc.EmailConfigs {
 		n := NewEmail(c, tmpl)
 		add("email", i, n, c)
@@ -206,6 +210,99 @@ func (w *Webhook) retry(statusCode int) (bool, error) {
 	return false, nil
 }
 
+// EtcdAlertConf holds information needed to push alerts to etcd
+type EtcdAlertConf struct {
+	URL             string // etcd instance to post to
+	KeyAnnotation   string // annotation holding the etcd key to put/delete
+	ValueAnnotation string // annotation holding the value to put
+}
+
+// Etcd implements a Notifier for setting etcd keys
+type Etcd struct {
+	// map "firing" or "resolved" status to conf
+	confs map[model.AlertStatus]EtcdAlertConf
+	tmpl  *template.Template
+}
+
+// NewEtcd returns a new Etcd notifier.
+func NewEtcd(conf *config.EtcdConfig, t *template.Template) *Etcd {
+	return &Etcd{
+		confs: map[model.AlertStatus]EtcdAlertConf{
+			model.AlertFiring: EtcdAlertConf{
+				URL:             conf.Firing.URL,
+				KeyAnnotation:   conf.Firing.KeyAnnotation,
+				ValueAnnotation: conf.Firing.ValueAnnotation,
+			},
+			model.AlertResolved: EtcdAlertConf{
+				URL:             conf.Resolved.URL,
+				KeyAnnotation:   conf.Resolved.KeyAnnotation,
+				ValueAnnotation: conf.Resolved.ValueAnnotation,
+			},
+		},
+		tmpl: t,
+	}
+}
+
+// EtcdMessage defines the JSON object to send to etcd.
+type EtcdMessage struct {
+	Key   []byte `json:"key"`
+	Value []byte `json:"value"`
+}
+
+// Notify implements the Notifier interface.
+func (n *Etcd) Notify(ctx context.Context, alerts ...*types.Alert) (bool, error) {
+	data := n.tmpl.Data(receiverName(ctx), groupLabels(ctx), alerts...)
+
+	conf, ok := n.confs[types.Alerts(alerts...).Status()]
+	if !ok {
+		return false, fmt.Errorf("missing etcd conf for status '%v'", data.Status)
+	}
+
+	key, ok := data.CommonAnnotations[conf.KeyAnnotation]
+	if !ok {
+		return false, fmt.Errorf("etcd key annotation '%v' missing", conf.KeyAnnotation)
+	}
+	value, ok := data.CommonAnnotations[conf.ValueAnnotation]
+	if !ok {
+		return false, fmt.Errorf("etcd value annotation '%v' missing", conf.ValueAnnotation)
+	}
+
+	msg := &EtcdMessage{
+		Key:   []byte(key),
+		Value: []byte(value),
+	}
+
+	var buf bytes.Buffer
+	if err := json.NewEncoder(&buf).Encode(msg); err != nil {
+		return false, err
+	}
+
+	req, err := http.NewRequest("POST", conf.URL, &buf)
+	if err != nil {
+		return true, err
+	}
+	req.Header.Set("Content-Type", contentTypeJSON)
+	req.Header.Set("User-Agent", userAgentHeader)
+
+	resp, err := ctxhttp.Do(ctx, http.DefaultClient, req)
+	if err != nil {
+		return true, err
+	}
+	resp.Body.Close()
+
+	return n.retry(resp.StatusCode)
+}
+
+func (n *Etcd) retry(statusCode int) (bool, error) {
+	// Etcd is assumed to respond with 2xx response codes on a successful
+	// request and 5xx response codes are assumed to be recoverable.
+	if statusCode/100 != 2 {
+		return (statusCode/100 == 5), fmt.Errorf("unexpected status code %v", statusCode)
+	}
+
+	return false, nil
+}
+
 // Email implements a Notifier for email notifications.
 type Email struct {
 	conf *config.EmailConfig