examples

Author: wybiral

examples/certstream/main.go

@@ -0,0 +1,69 @@
+// Example of using hookah to create an input stream from the CertStream
+// WebSocket API (https://certstream.calidog.io/).
+// The cert updates are filtered to remove heartbeat messages and processed by
+// restricting the JSON fields and adding indentation.
+// These updates are then written to stdout.
+package main
+
+import (
+	"encoding/json"
+	"io"
+	"log"
+
+	"github.com/wybiral/hookah"
+)
+
+// CertStream JSON struct
+type certUpdate struct {
+	MessageType string `json:"message_type"`
+	Data        struct {
+		UpdateType string `json:"update_type"`
+		LeafCert   struct {
+			AllDomains  []string `json:"all_domains"`
+			Fingerprint string   `json:"fingerprint"`
+		} `json:"leaf_cert"`
+		Source struct {
+			URL  string `json:"url"`
+			Name string `json:"name"`
+		}
+	} `json:"data"`
+}
+
+func main() {
+	// Create hookah input (certstream WebSocket API)
+	r, err := hookah.NewInput("wss://certstream.calidog.io")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer r.Close()
+	// Create hookah output (stdout)
+	w, err := hookah.NewOutput("stdout")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer w.Close()
+	// Start stream
+	stream(w, r)
+}
+
+// Copy from reader to writer
+// Drops heartbeat messages, restricts fields, and formats JSON
+func stream(w io.Writer, r io.Reader) {
+	var u certUpdate
+	d := json.NewDecoder(r)
+	e := json.NewEncoder(w)
+	e.SetIndent("", "  ")
+	for {
+		err := d.Decode(&u)
+		if err != nil {
+			log.Fatal(err)
+		}
+		if u.MessageType == "heartbeat" {
+			continue
+		}
+		err = e.Encode(u.Data)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+}

examples_test.go

@@ -17,6 +17,16 @@ func ExampleNewInput_stdin() {
 	r, err = hookah.NewInput("stdin")
 }
 
+// Create file input from absolute path.
+func ExampleNewInput_fileAbsolute() {
+	r, err = hookah.NewInput("file:///relative/path")
+}
+
+// Create file input from relative path.
+func ExampleNewInput_fileRelative() {
+	r, err = hookah.NewInput("file://relative/path")
+}
+
 // Create HTTP client input.
 func ExampleNewInput_httpClient() {
 	r, err = hookah.NewInput("http://localhost:8080")
@@ -69,6 +79,16 @@ func ExampleNewOutput_stderr() {
 	w, err = hookah.NewOutput("stderr")
 }
 
+// Create file output from absolute path (opens in append mode).
+func ExampleNewOutput_fileAbsolute() {
+	w, err = hookah.NewOutput("file:///relative/path")
+}
+
+// Create file output from relative path (opens in append mode).
+func ExampleNewOutput_fileRelative() {
+	w, err = hookah.NewOutput("file://relative/path")
+}
+
 // Create HTTP client output.
 func ExampleNewOutput_httpClient() {
 	w, err = hookah.NewOutput("http://localhost:8080")

pkg/input/file.go

@@ -5,6 +5,7 @@ import (
 	"os"
 )
 
+// Create a file input and return as ReadCloser
 func file(path string) (io.ReadCloser, error) {
 	return os.Open(path)
 }

pkg/output/file.go

@@ -5,6 +5,7 @@ import (
 	"os"
 )
 
+// Create a file output (in append mode) and return as WriteCloser
 func file(path string) (io.WriteCloser, error) {
 	flags := os.O_APPEND | os.O_WRONLY | os.O_CREATE
 	return os.OpenFile(path, flags, 0600)