This is another FaaS project covered by this book. We quickly do hello world by installing the Fn CLI. Then use it to start a local Fn server, create an app, and then create a route that links to a pre-built Go function under the app. After that, we will use the curl command to test the deployed hello world function.

Here's the standard command to install the Fn client:

$ curl -LSs https://raw.githubusercontent.com/fnproject/cli/master/install | sudo sh

After that, we can use the fn command. Let's start an Fn server. Use --detach to make it run in the background:

$ fn start --detach

Well, if we see a container ID, it is good to go. Next, quickly create an Fn app and call it goapp:

$ fn apps create goapp

Then, we already have a pre-built image called chanwit/fn_ch1:0.0.2 on the Docker Hub. Just use it. We use the fn routes create command to link the new route to the image. The purpose of this step is to actually define a function:

$ fn routes create --image chanwit/fn_ch1:0.0.2 goapp /fn_ch1
/fn_ch1 created with chanwit/fn_ch1:0.0.2

OK, the route is ready. Now, we can use the curl command to just call our hello world program on Fn:

$ curl -v http://localhost:8080/r/goapp/fn_ch1
* Trying 127.0.0.1...
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET /r/goapp/fn_ch1 HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.47.0
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Length: 26
< Content-Type: application/json; charset=utf-8
< Fn_call_id: 01C99YJXCE47WG200000000000
< Xxx-Fxlb-Wait: 383.180124ms
< Date: Fri, 23 Mar 2018 17:30:34 GMT
< 
{"message":"Hello World"}
* Connection #0 to host localhost left intact

OK, it seems all things are working as well as expected for Fn. Let's remove the server after it has finished:

$ docker rm -f fnserver