lego/README.md

lego

Let's Encrypt client and library in go!

This is a work in progress. Please do NOT run this on a production server.

Current Status

The code in this repository is currently quite raw. You are currently able to register an account with the ACME server as well as request certificates through the CLI.

Please keep in mind that CLI switches and APIs are still subject to change.

When using the standard --path option, all certificates and account configurations are saved to a folder .lego in the current working directory.

Sudo

I tried to not need sudo apart from challenges where binding to a privileged port is necessary. To run the CLI without sudo, you have two options:

• Use setcap 'cap_net_bind_service=+ep' /path/to/program
• Pass the --port option and specify a custom port to bind to. In this case you have to forward port 443 to this custom port.

Usage

NAME:
   lego - Let's encrypt client to go!

USAGE:
   lego [global options] command [command options] [arguments...]

VERSION:
   0.0.2

COMMANDS:
   run      Register an account, then create and install a certificate
   auth     Create a certificate - must already have an account
   revoke   Revoke a certificate
   help, h  Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --domains, -d [--domains option --domains option]     Add domains to the process
   --server, -s "https://acme-staging.api.letsencrypt.org/" CA hostname (and optionally :port). The server certificate must be trusted in order to avoid further modifications to the client.
   --email, -m                      Email used for registration and recovery contact.
   --rsa-key-size, -B "2048"              Size of the RSA key.
   --path "CWD"       Directory to use for storing the data
   --port                     Challenges will use this port to listen on. Please make sure to forward port 443 to this port on your machine. Otherwise use setcap on the binary
   --help, -h                    show help
   --version, -v                 print the version

ACME Library Usage

A valid, but bare-bones example use of the acme package:

// You'll need a user or account type that implements acme.User
type MyUser struct {
	Email        string
	Registration *acme.RegistrationResource
	key          *rsa.PrivateKey
}
func (u MyUser) GetEmail() string {
	return u.Email
}
func (u MyUser) GetRegistration() *acme.RegistrationResource {
	return u.Registration
}
func (u MyUser) GetPrivateKey() *rsa.PrivateKey {
	return u.key
}

// Create a user. New accounts need an email and private key to start.
const rsaKeySize = 2048
privateKey, err := rsa.GenerateKey(rand.Reader, rsaKeySize)
if err != nil {
	log.Fatal(err)
}
myUser := MyUser{
	Email: "you@yours.com",
	key: privateKey,
}

// A client facilitates communication with the CA server. This CA URL is
// configured for a local dev instance of Boulder running in Docker in a VM.
// We specify an optPort of 5001 because we aren't running as root and can't
// bind a listener to port 443 (used later when we attempt to pass challenge).
client := acme.NewClient("http://192.168.99.100:4000", &myUser, rsaKeySize, "5001")

// New users will need to register; be sure to save it
reg, err := client.Register()
if err != nil {
	log.Fatal(err)
}
myUser.Registration = reg

// The client has a URL to the current Let's Encrypt Subscriber
// Agreement. The user will need to agree to it.
err = client.AgreeToTos()
if err != nil {
	log.Fatal(err)
}

// The acme library takes care of completing the challenges to obtain the certificate(s).
// Of course, the hostnames must resolve to this machine or it will fail.
certificates, err := client.ObtainCertificates([]string{"mydomain.com"})
if err != nil {
	log.Fatal(err)
}

// Each certificate comes back with the cert bytes, the bytes of the client's
// private key, and a certificate URL. This is where you should save them to files!
fmt.Printf("%#v\n", certificates)

// ... all done.