Added Webhook Input Type Support

CONFIG.md

@@ -56,7 +56,7 @@ The `retention_check_interval` is the interval at which `grok_exporter` checks f
 Input Section
 -------------
 
-We currently support two input types: `file` and `stdin`. The following two sections describe the `file` input type and the `stdin` input type:
+We currently support three input types: `file`, `stdin`, and `webhook`. The following three sections describe the input types respectively:
 
 ### File Input Type
 
@@ -114,6 +114,50 @@ the exporter will terminate as soon as `sample.log` is processed,
 and we will not be able to access the result via HTTP(S) after that.
 Always use a command that keeps the output open (like `tail -f`) when testing the `grok_exporter` with the `stdin` input.
 
+### Webhook Input Type
+
+The grok_exporter is capable of receive log entries from webhook sources.  It supports webhook reception in various formats... plain-text or JSON, single entries or bulk entries.
+
+The following input configuration example which demonstrates how to configure grok_exporter to receive HTTP webhooks from the [Logstash HTTP Output Plugin](https://www.elastic.co/guide/en/logstash/current/plugins-outputs-http.html) configured in `json_batch` mode, which allows the transmission of multiple json log entries in a single webhook.
+
+```yaml
+input:
+
+    type: webhook
+
+    # HTTP Path to POST the webhook
+    # Default is `/webhook`
+    webhook_path: /webhook
+
+    # HTTP Body POST Format
+    # text_single: Webhook POST body is a single plain text log entry
+    # text_bulk: Webhook POST body contains multiple plain text log entries
+    #   separated by webhook_text_bulk_separator (default: \n\n)
+    # json_single: Webhook POST body is a single json log entry.  Log entry
+    #   text is selected from the value of a json key determined by
+    #   webhook_json_selector.
+    # json_bulk: Webhook POST body contains multiple json log entries.  The
+    #   POST body envelope must be a json array "[ <entry>, <entry> ]".  Log
+    #   entry text is selected from the value of a json key determined by
+    #   webhook_json_selector.
+    # Default is `text_single`
+    webhook_format: json_bulk
+
+    # JSON Path Selector
+    # Within an json log entry, text is selected from the value of this json selector
+    #   Example ".path.to.element"
+    # Default is `.message`
+    webhook_json_selector: .message
+
+    # Bulk Text Separator
+    # Separator for text_bulk log entries
+    # Default is `\n\n`
+    webhook_text_bulk_separator: "\n\n"
+```
+
+This configuration example may be found in the examples directory
+[here](example/config_logstash_http_input_ipv6.yml).
+
 Grok Section
 ------------
 
@@ -411,7 +455,7 @@ server:
 ```
 
 * `protocol` can be `http` or `https`. Default is `http`.
-* `host` can be a hostname or an IP address. If host is specified, `grok_exporter` will listen on the network interface with the given address. If host is omitted, `grok_exporter` will listen on all available network interfaces.
+* `host` can be a hostname or an IP address. If host is specified, `grok_exporter` will listen on the network interface with the given address. If host is omitted, `grok_exporter` will listen on all available network interfaces.  If `host` is set to `[::]`, `grok_exporter` will listen on all IPV6 addresses.
 * `port` is the TCP port to be used. Default is `9144`.
 * `path` is the path where the metrics are exposed. Default is `/metrics`, i.e. by default metrics will be exported on [http://localhost:9144/metrics].
 * `cert` is the path to the SSL certificate file for protocol `https`. It is optional. If omitted, a hard-coded default certificate will be used.

README.md

@@ -54,7 +54,7 @@ server:
     port: 9144
 ```
 
-[CONFIG.md] describes the `grok_exporter` configuration file and shows how to define Grok patterns, Prometheus metrics, and labels.
+[CONFIG.md] describes the `grok_exporter` configuration file and shows how to define Grok patterns, Prometheus metrics, and labels.  It also details how to configure file, stdin, and webhook inputs.
 
 Status
 ------

config/v2/configV2.go

@@ -27,6 +27,7 @@ const (
 	defaultRetentionCheckInterval = 53 * time.Second
 	inputTypeStdin                = "stdin"
 	inputTypeFile                 = "file"
+	inputTypeWebhook              = "webhook"
 )
 
 func Unmarshal(config []byte) (*Config, error) {
@@ -64,6 +65,10 @@ type InputConfig struct {
 	PollIntervalSeconds        string        `yaml:"poll_interval_seconds,omitempty"` // TODO: Use time.Duration directly
 	PollInterval               time.Duration `yaml:"-"`                               // parsed version of PollIntervalSeconds
 	MaxLinesInBuffer           int           `yaml:"max_lines_in_buffer,omitempty"`
+	WebhookPath                string        `yaml:"webhook_path,omitempty"`
+	WebhookFormat              string        `yaml:"webhook_format,omitempty"`
+	WebhookJsonSelector        string        `yaml:"webhook_json_selector,omitempty"`
+	WebhookTextBulkSeparator   string        `yaml:"webhook_text_bulk_separator,omitempty"`
 }
 
 type GrokConfig struct {
@@ -127,6 +132,20 @@ func (c *InputConfig) addDefaults() {
 	if c.Type == inputTypeFile && len(c.FailOnMissingLogfileString) == 0 {
 		c.FailOnMissingLogfileString = "true"
 	}
+	if c.Type == inputTypeWebhook {
+		if len(c.WebhookPath) == 0 {
+			c.WebhookPath = "/webhook"
+		}
+		if len(c.WebhookFormat) == 0 {
+			c.WebhookFormat = "text_single"
+		}
+		if len(c.WebhookJsonSelector) == 0 {
+			c.WebhookJsonSelector = ".message"
+		}
+		if len(c.WebhookTextBulkSeparator) == 0 {
+			c.WebhookTextBulkSeparator = "\n\n"
+		}
+	}
 }
 
 func (c *GrokConfig) addDefaults() {}
@@ -195,6 +214,23 @@ func (c *InputConfig) validate() error {
 				return fmt.Errorf("invalid input configuration: '%v' is not a valid boolean value in 'input.fail_on_missing_logfile'", c.FailOnMissingLogfileString)
 			}
 		}
+	case c.Type == inputTypeWebhook:
+		if c.WebhookPath == "" {
+			return fmt.Errorf("invalid input configuration: 'input.webhook_path' is required for input type \"webhook\"")
+		} else if c.WebhookPath[0] != '/' {
+			return fmt.Errorf("invalid input configuration: 'input.webhook_path' must start with \"/\"")
+		}
+		if c.WebhookFormat != "text_single" && c.WebhookFormat != "text_bulk" && c.WebhookFormat != "json_single" && c.WebhookFormat != "json_bulk" {
+			return fmt.Errorf("invalid input configuration: 'input.webhook_format' must be \"text_single|text_bulk|json_single|json_bulk\"")
+		}
+		if c.WebhookJsonSelector == "" {
+			return fmt.Errorf("invalid input configuration: 'input.webhook_json_selector' is required for input type \"webhook\"")
+		} else if c.WebhookJsonSelector[0] != '.' {
+			return fmt.Errorf("invalid input configuration: 'input.webhook_json_selector' must start with \".\"")
+		}
+		if c.WebhookFormat == "text_bulk" && c.WebhookTextBulkSeparator == "" {
+			return fmt.Errorf("invalid input configuration: 'input.webhook_text_bulk_separator' is required for input type \"webhook\" and webhook_format \"text_bulk\"")
+		}
 	default:
 		return fmt.Errorf("unsupported 'input.type': %v", c.Type)
 	}

example/config_logstash_http_input_ipv6.yml

@@ -0,0 +1,63 @@
+# The grok_exporter is capable of receive log entries from webhook sources.
+#
+# This input configuration example demonstrates how to configure grok_exporter
+#   to receive HTTP webhooks from the Logstash HTTP Output Plugin configured in
+#   "json_batch" mode, which allows the transmission of multiple json log
+#   entries in a single webhook.
+#   https://www.elastic.co/guide/en/logstash/current/plugins-outputs-http.html
+#
+# The grok_exporter supports webhook reception in various formats.  Plain-text
+#   or JSON, single entries or bulk entries.  To learn more, read the comments
+#   in this example, and review the webhookTeailer_test.go unit tests.
+
+global:
+    config_version: 2
+input:
+
+    type: webhook
+
+    # HTTP Path to POST the webhook
+    # Default is `/webhook`
+    webhook_path: /webhook
+
+    # HTTP Body POST Format
+    # text_single: Webhook POST body is a single plain text log entry
+    # text_bulk: Webhook POST body contains multiple plain text log entries
+    #   separated by webhook_text_bulk_separator (default: \n\n)
+    # json_single: Webhook POST body is a single json log entry.  Log entry
+    #   text is selected from the value of a json key determined by
+    #   webhook_json_selector.
+    # json_bulk: Webhook POST body contains multiple json log entries.  The
+    #   POST body envelope must be a json array "[ <entry>, <entry> ]".  Log
+    #   entry text is selected from the value of a json key determined by
+    #   webhook_json_selector.
+    # Default is `text_single`
+    webhook_format: json_bulk
+
+    # JSON Path Selector
+    # Within an json log entry, text is selected from the value of this json selector
+    #   Example ".path.to.element"
+    # Default is `.message`
+    webhook_json_selector: .message
+
+    # Bulk Text Separator
+    # Separator for text_bulk log entries
+    # Default is `\n\n`
+    webhook_text_bulk_separator: "\n\n"
+
+grok:
+    patterns_dir: ./logstash-patterns-core/patterns
+    additional_patterns:
+    - 'EXIM_MESSAGE [a-zA-Z ]*'
+metrics:
+    - type: counter
+      name: exim_rejected_rcpt_total
+      help: Total number of rejected recipients, partitioned by error message.
+      match: '%{EXIM_DATE} %{EXIM_REMOTE_HOST} F=<%{EMAILADDRESS}> rejected RCPT <%{EMAILADDRESS}>: %{EXIM_MESSAGE:message}'
+      labels:
+          error_message: '{{.message}}'
+server:
+    # For IPV4 localhost use "0.0.0.0"
+    # For IPV6 localhost use "[::]"
+    host: "[::]"
+    port: 9144

exporter/server.go

@@ -22,6 +22,11 @@ import (
 	"os"
 )
 
+type HttpServerPathHandler struct {
+	Path    string
+	Handler http.Handler
+}
+
 // cert and key created with openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -nodes
 
 const defaultCert = `-----BEGIN CERTIFICATE-----
@@ -77,7 +82,7 @@ XLgD9hrDBrTbnKBHHQ6MHpT6ILi4w/e4+5XEUUOBf44ZJE71uRr4ZUA=
 -----END RSA PRIVATE KEY-----
 `
 
-func RunHttpsServerWithDefaultKeys(host string, port int, path string, handler http.Handler) error {
+func RunHttpsServerWithDefaultKeys(host string, port int, httpHandlers []HttpServerPathHandler) error {
 	cert, err := createTempFile("cert", []byte(defaultCert))
 	if err != nil {
 		return err
@@ -88,24 +93,29 @@ func RunHttpsServerWithDefaultKeys(host string, port int, path string, handler h
 		return err
 	}
 	defer os.Remove(key)
-	return RunHttpsServer(host, port, cert, key, path, handler)
+	return RunHttpsServer(host, port, cert, key, httpHandlers)
 }
 
-func RunHttpsServer(host string, port int, cert, key, path string, handler http.Handler) error {
+func RunHttpsServer(host string, port int, cert string, key string, httpHandlers []HttpServerPathHandler) error {
 	err := tryOpenPort(host, port)
 	if err != nil {
 		return listenFailedError(host, port, err)
 	}
-	http.Handle(path, handler)
+	for _, httpHandler := range httpHandlers {
+		http.Handle(httpHandler.Path, httpHandler.Handler)
+	}
 	return http.ListenAndServeTLS(fmt.Sprintf(":%v", port), cert, key, nil)
 }
 
-func RunHttpServer(host string, port int, path string, handler http.Handler) error {
+func RunHttpServer(host string, port int, httpHandlers []HttpServerPathHandler) error {
 	err := tryOpenPort(host, port)
 	if err != nil {
 		return listenFailedError(host, port, err)
 	}
-	http.Handle(path, handler)
+	for _, httpHandler := range httpHandlers {
+		http.Handle(httpHandler.Path, httpHandler.Handler)
+	}
+
 	return http.ListenAndServe(fmt.Sprintf("%v:%v", host, port), nil)
 }
 

grok_exporter.go

@@ -26,8 +26,8 @@ import (
 	"github.com/fstab/grok_exporter/tailer/glob"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/sirupsen/logrus"
-	"net/http"
 	"os"
+	"strings"
 	"time"
 )
 
@@ -70,8 +70,20 @@ func main() {
 
 	tail, err := startTailer(cfg)
 	exitOnError(err)
-	fmt.Print(startMsg(cfg))
-	serverErrors := startServer(cfg.Server, prometheus.Handler())
+
+	// gather up the handlers with which to start the webserver
+	httpHandlers := []exporter.HttpServerPathHandler{}
+	httpHandlers = append(httpHandlers, exporter.HttpServerPathHandler{
+		Path:    cfg.Server.Path,
+		Handler: prometheus.Handler()})
+	if cfg.Input.Type == "webhook" {
+		httpHandlers = append(httpHandlers, exporter.HttpServerPathHandler{
+			Path:    cfg.Input.WebhookPath,
+			Handler: tailer.WebhookHandler()})
+	}
+
+	fmt.Print(startMsg(cfg, httpHandlers))
+	serverErrors := startServer(cfg.Server, httpHandlers)
 
 	retentionTicker := time.NewTicker(cfg.Global.RetentionCheckInterval)
 
@@ -126,7 +138,7 @@ func main() {
 	}
 }
 
-func startMsg(cfg *v2.Config) string {
+func startMsg(cfg *v2.Config, httpHandlers []exporter.HttpServerPathHandler) string {
 	host := "localhost"
 	if len(cfg.Server.Host) > 0 {
 		host = cfg.Server.Host
@@ -136,7 +148,15 @@ func startMsg(cfg *v2.Config) string {
 			host = hostname
 		}
 	}
-	return fmt.Sprintf("Starting server on %v://%v:%v%v\n", cfg.Server.Protocol, host, cfg.Server.Port, cfg.Server.Path)
+
+	var sb strings.Builder
+	baseUrl := fmt.Sprintf("%v://%v:%v", cfg.Server.Protocol, host, cfg.Server.Port)
+	sb.WriteString(fmt.Sprintf("Starting server on %v", baseUrl))
+	for _, httpHandler := range httpHandlers {
+		sb.WriteString(fmt.Sprintf("\n  %v%v", baseUrl, httpHandler.Path))
+	}
+	sb.WriteString("\n")
+	return sb.String()
 }
 
 func exitOnError(err error) {
@@ -251,17 +271,17 @@ func initSelfMonitoring(metrics []exporter.Metric) (*prometheus.CounterVec, *pro
 	return nLinesTotal, nMatchesByMetric, procTimeMicrosecondsByMetric, nErrorsByMetric
 }
 
-func startServer(cfg v2.ServerConfig, handler http.Handler) chan error {
+func startServer(cfg v2.ServerConfig, httpHandlers []exporter.HttpServerPathHandler) chan error {
 	serverErrors := make(chan error)
 	go func() {
 		switch {
 		case cfg.Protocol == "http":
-			serverErrors <- exporter.RunHttpServer(cfg.Host, cfg.Port, cfg.Path, handler)
+			serverErrors <- exporter.RunHttpServer(cfg.Host, cfg.Port, httpHandlers)
 		case cfg.Protocol == "https":
 			if cfg.Cert != "" && cfg.Key != "" {
-				serverErrors <- exporter.RunHttpsServer(cfg.Host, cfg.Port, cfg.Cert, cfg.Key, cfg.Path, handler)
+				serverErrors <- exporter.RunHttpsServer(cfg.Host, cfg.Port, cfg.Cert, cfg.Key, httpHandlers)
 			} else {
-				serverErrors <- exporter.RunHttpsServerWithDefaultKeys(cfg.Host, cfg.Port, cfg.Path, handler)
+				serverErrors <- exporter.RunHttpsServerWithDefaultKeys(cfg.Host, cfg.Port, httpHandlers)
 			}
 		default:
 			// This cannot happen, because cfg.validate() makes sure that protocol is either http or https.
@@ -288,6 +308,8 @@ func startTailer(cfg *v2.Config) (fswatcher.FileTailer, error) {
 		}
 	case cfg.Input.Type == "stdin":
 		tail = tailer.RunStdinTailer()
+	case cfg.Input.Type == "webhook":
+		tail = tailer.InitWebhookTailer(&cfg.Input)
 	default:
 		return nil, fmt.Errorf("Config error: Input type '%v' unknown.", cfg.Input.Type)
 	}