Go Template
This template allows you to code Functions using Golang 1.19. The handle function
defines the HTTP request handler logic. This function must implement the logic that
the Function should execute each time it is
invoked
package function
import (
"io/ioutil"
"net/http"
)
func Handle(w http.ResponseWriter, r *http.Request) {
var body []byte
if r.body !=nil {
defer r.Body.Close()
body, _= ioutil.ReadAll(r.Body)
}
w.WriteHeader(http.StatusOK)
w.Write(body)
The Handle function is the HTTP Handler in which your code will
run. You can use other Functions in your code to make it cleaner, but the Handle
function is the entry point of your serverless function. Check these sources for
further information about Go handlers:
Libraries
Adding third-party dependencies is not allowed at the moment. For now, you can use
the following pre-installed dependencies (this list will grow):
- resty: A simple HTTP and REST client library for Go.
- eclipse/paho.mqtt.golang: The Eclipse Paho MQTT Go client.
- gopkg.in/yaml.v3: Allows you to encode and decode YAML values.
SWX Package
The function/SWX package allows you to obtain and revoke access tokens for the Altair IoT Studio REST API
- Get an access token.Note: This package is in a very early stage of development. More features will be added in the future.
Secrets
You can access your Secrets using the two built-in Functions in the function/secrets
package:
- func Get(secretName string) string
- Returns the value of the given secret. If the secret is not found, an empty string will be returned.
- func Exists(secretName string) bool
- Returns a boolean value indicating if the given secret is found.
Example:
package function
import (
"function/secrets"
"net/http"
)
func Handle(w http.ResponseWriter, r *http.Request) {
// ...
if secrets.Exists("my_password") {
mySecret := secrets.Get("my_password")
// ...
}
// ...
}
Logging
Anything you write to
stderr
will be saved as a log entry. You can
use the log
package for
that:package function
import (
"log"
"net/http"
)
func Handle(w http.ResponseWriter, r *http.Request) {
// ...
log.Println("My log entry!")
// ...
}
Examples
Here are some simple examples to illustrate how you can write your own functions using Go.
- Adder
- This is a really simple function that gets a comma-separated list of
numbers in the request body and return the sum of them (or an error if
the input format is invalid).
package function import ( "fmt" "io/ioutil" "net/http" "strconv" "strings" ) func Handle(w http.ResponseWriter, r *http.Request) { var body []byte var sum float64 = 0 //Gets function input if r.Body != nil { defer r.Body.Close() body, _=ioutil.ReadAll(r.Body) } // Parses input as a comma-separated list of numbers numbers := strings.Split(string(body), ",") //Tries to convert all values to numbers for _, number :=range numbers { number = strings.TrimSpace(number) if value, err :=strconv.ParserFloat(number, 32); err != nil { //Throws an error if something is not a number w.WriteHeader(http.StatusBadRequest) w.Write([]byte("Invalid input format!")) return } else { sum += value } } w.WriterHeader(http.StatusOK) w.Write([]byte(fmt.Sprintf("%f", sum))) }
- MQTT Publisher
- The following example shows how to set up an MQTT client to publish the
payload of the request to the
functions/go
topic. - Update a Thing's Property
- The following example shows how to update a Thing's Property using the
swx
package to deal with token request and revocation.