299 lines
12 KiB
Markdown
299 lines
12 KiB
Markdown
# lego
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Let's Encrypt client and ACME library written in Go
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[](https://godoc.org/github.com/xenolf/lego/acme)
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[](https://travis-ci.org/xenolf/lego)
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[](https://gitter.im/xenolf/lego)
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[](https://beerpay.io/xenolf/lego)
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## Installation
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lego supports both binary installs and install from source.
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To get the binary just download the latest release for your OS/Arch from [the release page](https://github.com/xenolf/lego/releases)
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and put the binary somewhere convenient. lego does not assume anything about the location you run it from.
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To install from source, just run:
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```bash
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go get -u github.com/xenolf/lego
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```
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To build lego inside a Docker container, just run
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```bash
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docker build -t lego .
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```
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That will build lego from the current source, if you want to build a different
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version, you can checkout the desired branch/tag/commit, and re-running the
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above mentioned command.
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If you want to tag the binary with the designated release, you can do so by
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passing the version identifier as a [`--build-arg`](https://docs.docker.com/engine/reference/commandline/build/#set-build-time-variables---build-arg)
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```bash
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docker build --build-arg LEGO_VERSION=v1.0.0 -t lego .
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```
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Otherwise the release will be tagged with the `dev` version identifier.
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### From the package manager
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- [ArchLinux (AUR)](https://aur.archlinux.org/packages/lego-git):
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```bash
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yaourt -S lego-git
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```
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## Features
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- Register with CA
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- Obtain certificates, both from scratch or with an existing CSR
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- Renew certificates
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- Revoke certificates
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- Robust implementation of all ACME challenges
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- HTTP (http-01)
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- DNS (dns-01)
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- TLS (tls-alpn-01)
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- SAN certificate support
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- Comes with multiple optional [DNS providers](https://github.com/xenolf/lego/tree/master/providers/dns)
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- [Custom challenge solvers](https://github.com/xenolf/lego/wiki/Writing-a-Challenge-Solver)
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- Certificate bundling
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- OCSP helper function
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Please keep in mind that CLI switches and APIs are still subject to change.
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When using the standard `--path` option, all certificates and account configurations are saved to a folder *.lego* in the current working directory.
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## Usage
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```text
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NAME:
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lego - Let's Encrypt client written in Go
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USAGE:
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lego [global options] command [command options] [arguments...]
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COMMANDS:
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run Register an account, then create and install a certificate
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revoke Revoke a certificate
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renew Renew a certificate
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dnshelp Shows additional help for the --dns global option
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help, h Shows a list of commands or help for one command
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GLOBAL OPTIONS:
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--domains value, -d value Add a domain to the process. Can be specified multiple times.
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--csr value, -c value Certificate signing request filename, if an external CSR is to be used
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--server value, -s value CA hostname (and optionally :port). The server certificate must be trusted in order to avoid further modifications to the client. (default: "https://acme-v02.api.letsencrypt.org/directory")
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--email value, -m value Email used for registration and recovery contact.
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--accept-tos, -a By setting this flag to true you indicate that you accept the current Let's Encrypt terms of service.
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--eab Use External Account Binding for account registration. Requires --kid and --hmac.
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--kid value Key identifier from External CA. Used for External Account Binding.
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--hmac value MAC key from External CA. Should be in Base64 URL Encoding without padding format. Used for External Account Binding.
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--key-type value, -k value Key type to use for private keys. Supported: rsa2048, rsa4096, rsa8192, ec256, ec384 (default: "rsa2048")
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--path value Directory to use for storing the data (default: "./.lego")
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--exclude value, -x value Explicitly disallow solvers by name from being used. Solvers: "http-01", "dns-01", "tls-alpn-01".
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--webroot value Set the webroot folder to use for HTTP based challenges to write directly in a file in .well-known/acme-challenge
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--memcached-host value Set the memcached host(s) to use for HTTP based challenges. Challenges will be written to all specified hosts.
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--http value Set the port and interface to use for HTTP based challenges to listen on. Supported: interface:port or :port
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--tls value Set the port and interface to use for TLS based challenges to listen on. Supported: interface:port or :port
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--dns value Solve a DNS challenge using the specified provider. Disables all other challenges. Run 'lego dnshelp' for help on usage.
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--http-timeout value Set the HTTP timeout value to a specific value in seconds. The default is 10 seconds. (default: 0)
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--dns-timeout value Set the DNS timeout value to a specific value in seconds. The default is 10 seconds. (default: 0)
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--dns-resolvers value Set the resolvers to use for performing recursive DNS queries. Supported: host:port. The default is to use the system resolvers, or Google's DNS resolvers if the system's cannot be determined.
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--pem Generate a .pem file by concatanating the .key and .crt files together.
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--help, -h show help
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--version, -v print the version
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```
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### Sudo
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The CLI does not require root permissions but needs to bind to port 80 and 443 for certain challenges.
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To run the CLI without sudo, you have four options:
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- Use setcap 'cap_net_bind_service=+ep' /path/to/program
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- Pass the `--http` or/and the `--tls` option and specify a custom port to bind to. In this case you have to forward port 80/443 to these custom ports (see [Port Usage](#port-usage)).
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- Pass the `--webroot` option and specify the path to your webroot folder. In this case the challenge will be written in a file in `.well-known/acme-challenge/` inside your webroot.
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- Pass the `--dns` option and specify a DNS provider.
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### Port Usage
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By default lego assumes it is able to bind to ports 80 and 443 to solve challenges.
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If this is not possible in your environment, you can use the `--http` and `--tls` options to instruct
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lego to listen on that interface:port for any incoming challenges.
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If you are using this option, make sure you proxy all of the following traffic to these ports.
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HTTP Port:
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- All plaintext HTTP requests to port 80 which begin with a request path of `/.well-known/acme-challenge/` for the HTTP challenge.
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TLS Port:
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- All TLS handshakes on port 443 for the TLS-ALPN challenge.
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This traffic redirection is only needed as long as lego solves challenges. As soon as you have received your certificates you can deactivate the forwarding.
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### CLI Example
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Assumes the `lego` binary has permission to bind to ports 80 and 443. You can get a pre-built binary from the [releases](https://github.com/xenolf/lego/releases) page.
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If your environment does not allow you to bind to these ports, please read [Port Usage](#port-usage).
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Obtain a certificate:
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```bash
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lego --email="foo@bar.com" --domains="example.com" run
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```
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(Find your certificate in the `.lego` folder of current working directory.)
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To renew the certificate:
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```bash
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lego --email="foo@bar.com" --domains="example.com" renew
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```
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To renew the certificate only if it expires within 30 days
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```bash
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lego --email="foo@bar.com" --domains="example.com" renew --days 30
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```
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Obtain a certificate using the DNS challenge and AWS Route 53:
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```bash
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AWS_REGION=us-east-1 AWS_ACCESS_KEY_ID=my_id AWS_SECRET_ACCESS_KEY=my_key lego --email="foo@bar.com" --domains="example.com" --dns="route53" run
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```
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Note that `--dns=foo` implies `--exclude=http-01`. lego will not attempt other challenges if you've told it to use DNS instead.
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Obtain a certificate given a certificate signing request (CSR) generated by something else:
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```bash
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lego --email="foo@bar.com" --csr=/path/to/csr.pem run
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```
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(lego will infer the domains to be validated based on the contents of the CSR, so make sure the CSR's Common Name and optional SubjectAltNames are set correctly.)
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lego defaults to communicating with the production Let's Encrypt ACME server. If you'd like to test something without issuing real certificates, consider using the staging endpoint instead:
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```bash
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lego --server=https://acme-staging-v02.api.letsencrypt.org/directory …
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```
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## DNS Challenge API Details
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### AWS Route 53
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The following AWS IAM policy document describes the permissions required for lego to complete the DNS challenge.
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Replace `<INSERT_YOUR_HOSTED_ZONE_ID_HERE>` with the Route 53 zone ID of the domain you are authorizing.
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```json
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{
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"Version": "2012-10-17",
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"Statement": [
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{
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"Effect": "Allow",
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"Action": [
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"route53:GetChange",
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"route53:ListHostedZonesByName"
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],
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"Resource": [
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"*"
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]
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},
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{
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"Effect": "Allow",
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"Action": [
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"route53:ChangeResourceRecordSets"
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],
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"Resource": [
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"arn:aws:route53:::hostedzone/<INSERT_YOUR_HOSTED_ZONE_ID_HERE>"
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]
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}
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]
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}
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```
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## ACME Library Usage
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A valid, but bare-bones example use of the acme package:
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```go
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// You'll need a user or account type that implements acme.User
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type MyUser struct {
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Email string
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Registration *acme.RegistrationResource
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key crypto.PrivateKey
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}
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func (u MyUser) GetEmail() string {
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return u.Email
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}
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func (u MyUser) GetRegistration() *acme.RegistrationResource {
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return u.Registration
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}
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func (u MyUser) GetPrivateKey() crypto.PrivateKey {
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return u.key
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}
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// Create a user. New accounts need an email and private key to start.
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const rsaKeySize = 2048
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privateKey, err := rsa.GenerateKey(rand.Reader, rsaKeySize)
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if err != nil {
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log.Fatal(err)
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}
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myUser := MyUser{
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Email: "you@yours.com",
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key: privateKey,
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}
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// A client facilitates communication with the CA server. This CA URL is
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// configured for a local dev instance of Boulder running in Docker in a VM.
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client, err := acme.NewClient("http://192.168.99.100:4000/directory", &myUser, acme.RSA2048)
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if err != nil {
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log.Fatal(err)
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}
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// We specify an http port of 5002 and an tls port of 5001 on all interfaces
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// because we aren't running as root and can't bind a listener to port 80 and 443
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// (used later when we attempt to pass challenges). Keep in mind that we still
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// need to proxy challenge traffic to port 5002 and 5001.
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client.SetHTTPAddress(":5002")
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client.SetTLSAddress(":5001")
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// New users will need to register
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reg, err := client.Register()
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if err != nil {
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log.Fatal(err)
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}
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myUser.Registration = reg
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// SAVE THE USER.
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// The client has a URL to the current Let's Encrypt Subscriber
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// Agreement. The user will need to agree to it.
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err = client.AgreeToTOS()
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if err != nil {
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log.Fatal(err)
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}
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// The acme library takes care of completing the challenges to obtain the certificate(s).
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// The domains must resolve to this machine or you have to use the DNS challenge.
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bundle := false
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certificates, failures := client.ObtainCertificate([]string{"mydomain.com"}, bundle, nil, false)
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if len(failures) > 0 {
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log.Fatal(failures)
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}
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// Each certificate comes back with the cert bytes, the bytes of the client's
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// private key, and a certificate URL. SAVE THESE TO DISK.
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fmt.Printf("%#v\n", certificates)
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// ... all done.
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```
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## ACME v1
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lego introduced support for ACME v2 in [v1.0.0](https://github.com/xenolf/lego/releases/tag/v1.0.0), if you still need to utilize ACME v1, you can do so by using the [v0.5.0](https://github.com/xenolf/lego/releases/tag/v0.5.0) version.
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