Let's Encrypt client and ACME library written in Go
This is a work in progress. Please do NOT run this on a production server.
Please report any bugs you find!
The code in this repository is under development.
Current features:
- Registering with a CA
- Requesting Certificates
- Renewing Certificates
- Revoking Certificates
- Initiating account recovery
- Identifier validation challenges
- SimpleHTTP Challenge
- DVSNI Challenge
- Proof of Possession of a Prior Key
- DNS Challenge
- Certificate bundling
- Library support for OCSP
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.
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.
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
renew Renew 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
--devMode If set to true, all client side challenge pre-tests are skipped.
--help, -h show help
--version, -v print the version
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.