Day 7: Project setup

src/blog/posts/2024/5/learning-go-day-7.md

@@ -0,0 +1,90 @@
+---
+title: "Learning Go: Day Seven"
+date: 2024-05-07T08:00:00.0Z
+tags:
+    - learning
+    - go
+excerpt: "Kicking off the project by starting to build out an HTTP server"
+---
+
+So, yesterday I [decided I was going to build an uptime monitor and status page](/post/learning-go-day-six.md). To recap, here's the list of things I need to figure out how to do:
+
+* Run a web server
+* Render web pages with some dynamic content
+* Store & read data from/to a database
+* Send requets to a server & handle the responses
+* Do all of the above on a periodic schedule
+
+I've decided to call the project Oopsie, because that's what I'll say when things go red, and have setup the repo on [my git server](https://git.lewisdale.dev/lewis/oopsie). Like on [day one](https://lewisdale.dev/post/learning-go-day-one), I initialised my Go module:
+
+```bash
+go mod init lewisdale.dev/oopsie
+```
+
+And then created my `main.go` file.
+
+## Creating a web server and handling my first request
+
+Once again, Go's standard library comes to the rescue, as there are libraries for dealing with HTTP requests built right into the runtime. The [net/http package](https://pkg.go.dev/net/http) has functions for creating a server, listening for requests, and even serving static assets, which is really useful.
+
+My first server, and request handler, is the ever-original "Hello, world":
+
+```go
+package main
+
+import (
+	"net/http"
+)
+
+func main() {
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("Hello, World!"))
+	})
+	http.ListenAndServe(":8000", nil)
+}
+```
+
+It's fairly straightforward. The `http.HandleFunc` call registers a handler on the root URL, and `http.ResponseWriter.Write` outputs a string, which is converted to a slice of bytes. Then I start the actual server on port 8000 with `http.ListenAndServe`. Truly, riveting stuff.
+
+
+## Pattern-matching handlers
+
+The pattern syntax for `HandleFunc` is something called ServeMux, which I don't fully understand but fortunately the syntax is well-documented on the [package docs](https://pkg.go.dev/net/http#hdr-Patterns). It's not too dissimilar to most other URL pattern-matching libraries[^1]. Generally the syntax is:
+
+1. `/` - match the root 
+2. `/something` - explictly match a URL
+3. `/something-else/` - matching any URL where the path starts with `/something-else/`
+4. `/route/{param}` - match a URL that starts with `/route/` and then has an arbitrary parameter in the second block of the path
+
+You can also prefix the paths with either the request method, host name, or both. For example:
+
+```go
+http.HandleFunc("GET /", func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("This was a GET request!"))
+	})
+http.HandleFunc("POST /", func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("This was a POST request!"))
+	})
+```
+
+So then if I perform a POST request:
+
+```bash
+curl -X POST http://localhost:8000
+> This was a POST request!%  
+```
+
+And then just a GET request:
+
+```bash
+curl http://localhost:8000
+This was a GET request!%  
+```
+
+That's a pretty powerful pattern-matcher to have straight out of the box. The only thing I'm less keen on is the `w.Write` syntax, but that's extremely minor. It'll be interesting to see how I get on.
+
+[^1]: I still prefer Express-style pattern matching because inertia
+
+
+
+