go – Page 3 – Tarik Billa

How to verify JWT signature with JWK in Go?

April 9, 2024 by Tarik

Below is an example of JWT decoding and verification. It uses both the jwt-go and jwk packages: package main import ( “errors” “fmt” “github.com/dgrijalva/jwt-go” “github.com/lestrrat-go/jwx/jwk” ) const token = `eyJhbGciOiJSUzI1NiIsImtpZCI6Ind5TXdLNEE2Q0w5UXcxMXVvZlZleVExMTlYeVgteHlreW1ra1h5Z1o1T00ifQ.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.OtVyCK0sE6Cuclg9VMD2AwLhqEyq2nv3a1bfxlzeS-bdu9KtYxcPSxJ6vxMcSSbMIIq9eEz9JFMU80zqgDPHBCjlOsC5SIPz7mm1Z3gCwq4zsFJ-2NIzYxA3p161ZRsPv_3bUyg9B_DPFyBoihgwWm6yrvrb4rmHXrDkjxpxCLPp3OeIpc_kb2t8r5HEQ5UBZPrsiScvuoVW13YwWpze59qBl_84n9xdmQ5pS7DklzkAVgqJT_NWBlb5uo6eW26HtJwHzss7xOIdQtcOtC1Gj3O82a55VJSQnsEEBeqG1ESb5Haq_hJgxYQnBssKydPCIxdZiye-0Ll9L8wWwpzwig` const jwksURL = `https://companyx.okta.com/oauth2/v1/keys` func getKey(token *jwt.Token) (interface{}, error) { // TODO: cache response so we don’t have to make a request every time // … Read more

How do struct{} and struct{}{} work in Go?

April 9, 2024 by Tarik

struct is a keyword in Go. It is used to define struct types, which is a sequence of named elements. For example: type Person struct { Name string Age int } The struct{} is a struct type with zero elements. It is often used when no information is to be stored. It has the benefit … Read more

Go: convert strings in array to integer

April 9, 2024 by Tarik

You will have to loop through the slice indeed. If the slice only contains integers, no need of ParseFloat, Atoi is sufficient. import “fmt” import “strconv” func main() { var t = []string{“1”, “2”, “3”} var t2 = []int{} for _, i := range t { j, err := strconv.Atoi(i) if err != nil { … Read more

Go language how detect file changing?

April 9, 2024 by Tarik

Here’s a simple cross-platform version: func watchFile(filePath string) error { initialStat, err := os.Stat(filePath) if err != nil { return err } for { stat, err := os.Stat(filePath) if err != nil { return err } if stat.Size() != initialStat.Size() || stat.ModTime() != initialStat.ModTime() { break } time.Sleep(1 * time.Second) } return nil } And … Read more

Generate random float64 numbers in specific range using Golang

April 9, 2024 by Tarik

Simply use rand.Float64() to get a random number in the range of [0..1), and you can map (project) that to the range of [min..max) like this: r := min + rand.Float64() * (max – min) And don’t create a new rand.Rand and / or rand.Source in your function, just create a global one or use … Read more

How to check if an object has a particular method?

April 9, 2024 by Tarik

A simple option is to declare an interface with just the method you want to check for and then do a type assert against your type like; i, ok := myInstance.(InterfaceImplementingThatOneMethodIcareAbout) // inline iface declaration example i, ok = myInstance.(interface{F()}) You likely want to use the reflect package if you plan to do anything too … Read more

golang cannot execute binary file: Exec format error

April 8, 2024 by Tarik

Since go 1.5, cross compiler has gotten pretty easy. Something like env GOOS=linux GOARCH=amd64 go build -v github.com/constabulary/gb/cmd/gb Refer to http://dave.cheney.net/2015/08/22/cross-compilation-with-go-1-5.

How to print the memory address of a slice in Golang?

April 8, 2024 by Tarik

http://golang.org/pkg/fmt/ fmt.Printf(“address of slice %p add of Arr %p \n”, &slice, &intarr) %p will print the address.

Setting timezone globally in golang

April 8, 2024 by Tarik

You can achieve what you want from inside your app using os.Setenv(“TZ”, “Africa/Cairo”), what matters is that you must call this before any other package uses anything from the time package. How to ensure that? Create a package that does nothing else except sets the timezone (later you may add other things to it, but … Read more

How to avoid indirect dependencies in go.mod file

April 8, 2024 by Tarik

Unfortunately, you can’t avoid them. Indirect dependency, is basically dependency that wasn’t listed in go.mod of your direct dependency, but is still required by it. In your case it happens, because you use github.com/gocolly/colly v1.2.0 as dependency and v1.2.0 of this package isn’t a module, because it doesn’t contain go.mod, so all it’s dependencies are … Read more