Adding 'greet', a replacement for socat

Author: beautifulentropy

greet/cmd/greet.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+
+	"gopkg.in/yaml.v3"
+)
+
+// config represents to contents of our YAML configuration file. It's fields are
+// exported for this purpose.
+type config struct {
+	Name string
+	Port int
+}
+
+func main() {
+	// Declare and parse our CLI flags.
+	configFile := flag.String("c", "", "Path to the YAML config file")
+	flag.Parse()
+
+	// Ensure that the '-c' flag was passed.
+	if *configFile == "" {
+		log.Fatal("Flag '-c' is required, use '-help' for more info")
+	}
+
+	// Load the contents of the config file into memory.
+	configData, err := os.ReadFile(*configFile)
+	if err != nil {
+		log.Fatalf("While loading the config file at %q: %s", *configFile, err)
+	}
+
+	// Unmarshal our config file.
+	var conf config
+	err = yaml.Unmarshal(configData, &conf)
+	if err != nil {
+		log.Fatalf("While unmarshaling the config file at %q: %s", *configFile, err)
+	}
+
+	// Declare our request handler.
+	http.HandleFunc(
+		"/",
+		func(w http.ResponseWriter, r *http.Request) {
+			fmt.Fprintf(w, "Hello, %s", conf.Name)
+		},
+	)
+
+	// Start our web server. If an error is encountered it will log and exit
+	// immediately.
+	log.Fatal(http.ListenAndServe(fmt.Sprintf(":%d", conf.Port), nil))
+}

greet/example/config.yml

@@ -0,0 +1,3 @@
+---
+name: Samantha
+port: 1234

greet/go.mod

@@ -0,0 +1,5 @@
+module github.com/letsencrypt/hashicorp-lessons/greet
+
+go 1.17
+
+require gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b

greet/go.sum

@@ -0,0 +1,4 @@
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=