cultureamp/gostudy

gostudy

Some people learning Go.

Setup

Install Go:

brew install go

Make sure the Go bin directory is in your path (you'll probably want to put this in a shell startup script):

export PATH="$HOME/go/bin:$PATH"

Install some useful tools:

brew install httpie
go get golang.org/x/tools/cmd/goimports
go get golang.org/x/lint/golint

Install or enable Go support in your editor/IDE; I use https://github.com/fatih/vim-go

Clone this repo:

git clone https://github.com/cultureamp/gostudy

The master branch is empty, ready for you to proceed. You'll find various other branches with example code.

Session 01 — HTTP server & middleware

Initialize your codebase as a Go module: go mod init gostudy

This produces a go.mod that looks like this:

module gostudy

go 1.12

Create a basic HTTP server:

commit 29016c8b4efa07c5578a32dd468613f5ffbc565a
Author: Paul Annesley <paul@annesley.cc>
Date:   Thu Sep 5 14:39:17 2019 +1000

    hello world HTTP server

diff --git a/main.go b/main.go
new file mode 100644
index 0000000..a3eb9bf
--- /dev/null
+++ b/main.go
@@ -0,0 +1,21 @@
+package main
+
+import (
+	"io"
+	"net/http"
+	"os"
+)
+
+func main() {
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = "1234"
+	}
+
+	app := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		io.WriteString(w, "hello world")
+	})
+
+	http.ListenAndServe(":"+port, app)
+}

Add a basic logging middleware:

commit 19874cb54d6c008835e709f56e998aaf5ca202d2
Author: Paul Annesley <paul@annesley.cc>
Date:   Thu Sep 5 14:39:57 2019 +1000

    httplog middleware

diff --git a/main.go b/main.go
index a3eb9bf..0a98801 100644
--- a/main.go
+++ b/main.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"io"
+	"log"
 	"net/http"
 	"os"
 )
@@ -17,5 +18,12 @@ func main() {
 		io.WriteString(w, "hello world")
 	})
 
-	http.ListenAndServe(":"+port, app)
+	http.ListenAndServe(":"+port, httplog(app))
+}
+
+func httplog(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		log.Println(r.Method, r.URL.Path)
+		next.ServeHTTP(w, r)
+	})
 }

Add an authentication middleware:

commit a3cf02a1c291b72d58ea82bca717e9f3197842cb
Author: Paul Annesley <paul@annesley.cc>
Date:   Thu Sep 5 14:40:26 2019 +1000

    secure middleware for authentication

diff --git a/main.go b/main.go
index 0a98801..221ec07 100644
--- a/main.go
+++ b/main.go
@@ -18,7 +18,7 @@ func main() {
 		io.WriteString(w, "hello world")
 	})
 
-	http.ListenAndServe(":"+port, httplog(app))
+	http.ListenAndServe(":"+port, httplog(secure(app)))
 }
 
 func httplog(next http.Handler) http.Handler {
@@ -27,3 +27,15 @@ func httplog(next http.Handler) http.Handler {
 		next.ServeHTTP(w, r)
 	})
 }
+
+// secure verifies that all requests have an extremely strong password
+func secure(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// auth the request
+		if r.Header.Get("Authorization") != "hunter2" {
+			w.WriteHeader(401)
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}

Session 02 — JSON request & response

commit 9d023bce7b232df9942e6e6029e122ec57480ef3
Author: Paul Annesley <paul@annesley.cc>
Date:   Thu Sep 5 14:47:13 2019 +1000

    JSON request & response data

diff --git a/main.go b/main.go
index 221ec07..40bc586 100644
--- a/main.go
+++ b/main.go
@@ -1,12 +1,22 @@
 package main
 
 import (
-	"io"
+	"encoding/json"
+	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
 )
 
+type RequestThing struct {
+	Name string
+	Camp string
+}
+
+type ResponseThing struct {
+	Greeting string
+}
+
 func main() {
 	port := os.Getenv("PORT")
 	if port == "" {
@@ -14,8 +24,25 @@ func main() {
 	}
 
 	app := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		data, err := ioutil.ReadAll(r.Body)
+		if err != nil {
+			w.WriteHeader(500)
+			return
+		}
+		r.Body.Close()
+
+		var rt RequestThing
+		json.Unmarshal(data, &rt)
+
+		respBytes, err := json.Marshal(ResponseThing{Greeting: "hello " + rt.Name})
+		if err != nil {
+			w.WriteHeader(500)
+			return
+		}
+
+		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(200)
-		io.WriteString(w, "hello world")
+		w.Write(respBytes)
 	})
 
 	http.ListenAndServe(":"+port, httplog(secure(app)))

Session 03 — Miscellaneous

This was a more casual / exploration / Q&A session, with no permanent code.

We explored packages and their .go file layout, importing, exported vs unexported, pointers, adding methods to types to make “objects”, discussed what even is an object, etc.