How to do a https request with bad certificate?

Say I want to get https://golang.org programatically. Currently golang.org (ssl) has a bad certificate which is issued to *.appspot.com So when I run this:

package main

import (
    "log"
    "net/http"
)

func main() {
    _, err := http.Get("https://golang.org/")
    if err != nil {
        log.Fatal(err)
    }
}

I get (as I expected)

Get https://golang.org/: certificate is valid for *.appspot.com, *.*.appspot.com, appspot.com, not golang.org

Now, I want to trust this certificate myself (imagine a self-issued certificate where I can validate fingerprint etc.): how can I make a request and validate/trust the certificate?

I probably need to use openssl to download the certificate, load it into my file and fill tls.Config struct !?

Security note: Disabling security checks is dangerous and should be avoided

You can disable security checks globally for all requests of the default client:

package main

import (
    "fmt"
    "net/http"
    "crypto/tls"
)

func main() {
    http.DefaultTransport.(*http.Transport).TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
    _, err := http.Get("https://golang.org/")
    if err != nil {
        fmt.Println(err)
    }
}

You can disable security check for a client:

package main

import (
    "fmt"
    "net/http"
    "crypto/tls"
)

func main() {
    tr := &http.Transport{
        TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
    }
    client := &http.Client{Transport: tr}
    _, err := client.Get("https://golang.org/")
    if err != nil {
        fmt.Println(err)
    }
}

Stack Overflow Q#12122159, score: 442