**Autocert** is a kubernetes add-on that automatically injects TLS/HTTPS certificates into your containers.
<palign="center"><imgsrc="demo.gif"style="max-width: 600px"alt="Animated terminal showing autocert in practice"></p>
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To request a certificate simply annotate your pods with a name. Certificates are issued by a private **internal certificate authority** that runs on your cluster and are mounted at `/var/run/autocert.step.sm` along with a corresponding private key and root certificate.
To get a certificate **simply annotate your pods** with a name. An X.509 (TLS/HTTPS) certificate is automatically created and mounted at `/var/run/autocert.step.sm/` along with a corresponding private key and root certificate (everything you need for [mTLS](#motivation)).
TLS (e.g., HTTPS) is the most widely deployed cryptographic protocol in the world. Mutual TLS (mTLS) provides end-to-end security for service-to-service communication and can **replace complex VPNs** to secure communication into, out of, and between kubernetes clusters. But **to use mTLS you need certificates issued by your own certificate authority (CA)**.
> *Note: this project is in **ALPHA**. DON'T use it for anything mission critical. EXPECT breaking changes in minor revisions with little or not warning. PLEASE provide feedback:*
Building and operating a CA, issuing certificates, and making sure they're renewed before they expire is tricky. Autocert does all of this for you.
TODO: Twitter, Slack, Issues (tagged with #autocert / special template)...
* [Getting a certificate locally](#local-certificate)
* [How it works](#how-it-works)
* [Uninstalling](#uninstalling)
* [Questions](#questions)
## Features
## Key Features
Autocert uses [`step certificates`](https://github.com/smallstep/certificates) to generate keys and issue certificates from your own **internal certificate authority**. This process is secure and automatic, all you have to do is [install autocert](#install) and [annotate your pods](#annotate-pods). Features include:
* A complete public key infrastructure that you control for your kubernetes clusters
* Certificate authority that's easy to initialize and install
* Automatic injection of certificates and keys in annotated containers
* Enable on a per-namespace basis
* Namespaced installation to restrict access to privileged CA and provisioner containers
* Ability to run subordinate to an existing public key infrastructure
* Supports federatation with other roots
* Short-lived certificates
* Automatic renewal
* Uses your own certificate authority -- you control who or what gets a certificate
* A complete **public key infrastructure** (PKI) for your kubernetes clusters
* A fully featured internal **certificate authority** (CA) that you control so you can **use mTLS to control access to services**
* Ability to run subnordinate to or federated with an existing PKI
* CA and PKI artifacts are installed in their own namespace (`step`) for easy access control
* Modern certificate best practices
* Automated certificate management (auto enrollment and renewal)
* Short-lived certificates
* Private keys are never transmitted across the network (and aren't stored in `etcd`)
* RFC5280 and CA/Browser Forum compliant certificates that work with browsers and other standard TLS implementations
* Builds on [`step certificates`](https://github.com/smallstep/certificates) so you can also issue certificates to servers, people, and code running in a different cluster and outside of kubernetes
## Motivation
TLS (e.g., HTTPS) is the most widely deployed cryptographic protocol in the world. Mutual TLS (mTLS) provides end-to-end security for service-to-service communication and can **replace complex VPNs** to secure communication into, out of, and between kubernetes clusters. But **to use mTLS to secure internal services you need certificates issued by your own certificate authority (CA)**.
Building and operating a CA, issuing certificates, and making sure they're renewed before they expire is tricky. Autocert does all of this for you.
## Getting Started
@ -29,15 +67,7 @@ These instructions will get `autocert` installed quickly on an existing kubernet
### Prerequisites
Make sure you've [`installed step`](https://github.com/smallstep/cli#installing) version `0.8.3` or later:
```bash
$ step version
Smallstep CLI/0.8.3 (darwin/amd64)
Release Date: 2019-01-16 01:46 UTC
```
You'll also need `kubectl` and a kubernetes cluster running version `1.9` or later with [webhook admission controllers](https://kubernetes.io/docs/reference/access-authn-authz/extensible-admission-controllers/#admission-webhooks) enabled:
You'll need `kubectl` and a kubernetes cluster running version `1.9` or later with [webhook admission controllers](https://kubernetes.io/docs/reference/access-authn-authz/extensible-admission-controllers/#admission-webhooks) enabled:
We'll be creating a new kubernetes namespace and setting up some RBAC rules during installation. You'll need appropriate permissions in your cluster (e.g., you may need to be cluster-admin).
```bash
TODO: Check whether you have cluster permissions..? GKE instructions here if you don't have them.
```
In order to grant these permissions you may need to give yourself cluster-admin rights in your cluster. GKE, in particular, does not give the cluster owner these rights by default. You can give yourself cluster-admin rights by running:
For [manual installation](INSTALL.md) you'll also need to [`install step`](https://github.com/smallstep/cli#installing) version `0.8.3` or later.
Feel free to [check out what the `autocert-init` container does](init/autocert.sh) if you're curious. You can also [install manually](INSTALL.md).
### Enable autocert
To enable `autocert` for a namespace the `autocert.step.sm=enabled` label (the `autocert` webhook will not affect namespaces for which it is not enabled). To enable `autocert` for the default namespace run:
To enable `autocert` for a namespace it must be labelled `autocert.step.sm=enabled`. To label the `default` namespace run:
In addition to enabling `autocert` for a namespace, pods must be annotated with their name for certificates to be injected. The annotated name will appear as the common name and SAN in the issued certificate.
To trigger certificate injection pods must be annotated at creation time. You can do this in your deployment YAMLs:
For `autocert` to inject a certificate pods must use the `autocert.step.sm/name` annotation to specify their name. The value of this annotation will appear as the name in the issued certificate (the X.509 common name and SAN).
The `autocert` admission webhook will intercept this pod creation request and inject an init container and sidecar to manage certificate issuance and renewal, respectively.
Once the pod has started we can check that our certificate, private key, and root certificate have been properly mounted in our container at `/var/run/autocert.step.sm`.
```bash
$ export SLEEP_POD=$(kubectl get pods -l app=sleep \
-o jsonpath={$.items[0].metadata.name})
$ kubectl exec -it $SLEEP_POD -c sleep -- ls /var/run/autocert.step.sm
root.crt site.crt site.key
```
> 🤔 **Tip:** The `autocert-renewer` sidecar also installs the [`step` CLI tool](https://github.com/smallstep/cli), which we can use to inspect the issued certificate.
With `autocert` issuing and rotating certificates we can start using mTLS between services. The [`examples/hello-mtls`](examples/hello-mtls) directory demonstrates the right way to do mTLS in several languages (contributions welcome :). Let's deploy one.
### Mutual TLS
Build and deploy the `hello-mtls` server for golang:
> curl: (60) SSL certificate problem: unable to get local issuer certificate
> More details here: https://curl.haxx.se/docs/sslcerts.html
>
> curl failed to verify the legitimacy of the server and therefore could not
> establish a secure connection to it. To learn more about this situation and
> how to fix it, please visit the web page mentioned above.
> ```
>
> You'll get similar errors from other tools, libraries, and applications if they're not properly configured to use the `autocert` certificates and keys. Minimally, for (non-mutual) TLS:
>
> * Clients must be configured to trust the `autocert` root certificate (`/var/run/autocert.step.sm/root.crt`) to authenticate a server
> * Servers must be configured to use the key and certificate issued by `autocert` (`/var/run/autocert.step.sm/site.crt` and `/var/run/autocert.step.sm/site.key`) to authenticate *to* a client
>
> If you're doing mTLS the inverse is also true: the server must trust the root certificate to authenticate client, and the client must be configured to use the `autocert`-issued key and certificate. In other words, for mTLS both the client and server should be configured to use `autocert`'s `root.crt`, `site.crt`, and `site.key`. With `curl` this is done using the `--cacert`, `--cert`, and `--key` flags, respectively.
### Exposing services using mTLS
With properly configured mTLS, services can be safely exposed directly to the public internet: **only clients that have a certificate issued by the internal certificate authority will be allowed to connect**. To demonstrate let's expose our `hello-mtls` service.
If you need a refresher, here's a rough approximation of how an mTLS handshake works:
* It's the signing of random numbers that proves we're talking to the right remote. It's the digital equivalent of asking someone to send you a photo of them with today's newspaper.
* The client and server need to have prior knowledge of the root certificate(s) used for signing other certificates.
* The client and server need to be configured to use the correct certificate and private key (the certificate must have been issued by a CA with a trusted root certificate)
#### Exposing `hello-mtls`
Because `hello-mtls` does proper mTLS itself we can expose it simply using a [service with type LoadBalancer](https://kubernetes.io/docs/concepts/services-networking/service/#loadbalancer).
The `autocert-renewer` sidecar also installs the `step` CLI tool, which we can use to inspect the issued certificate:
#### Obtaining a certificate locally
To connect to `hello-mtls` from outside kubernetes we need a certificate issued by our internal CA. Since `autocert` is built on `step certificates` we can securely issue certificates to users, devices, and workloads running in other environments.
> 🤯 **Note:** To follow along you'll need `step` [installed locally](https://github.com/smallstep/cli#installing).
First, port-forward from localhost to the `step-ca` pod:
```
$ export CA_POD=$(kubectl -n step get pods -l app=ca \
-o jsonpath={$.items[0].metadata.name})
$ kubectl -n step port-forward $CA_POD 4443:4443
```
Now we can use `step` to securely grab the CA's root certificate and obtain a certificate. You'll be prompted to select a provisioner and enter the correct password to continue:
> 🤔 **Tip:** If you want someone (or something) to have a certificate with a particular name, but don't want to give them the ability to provision arbitrary certificates, you can generate a bootstrap token for them:
>
> ```bash
> $ step ca token snarf.local.dev \
> --ca-url https://127.0.0.1:4443 \
> --root root.crt
> eyJhbG...
> ```
>
> They can use the token to obtain a certificate (once):
>
> ```bash
> $ step ca certificate snarf.local.dev snarf.crt snarf.key --token "eyJhbG..."
> ```
>
> Actually, this is exactly what the `autocert` mutating webhook is doing for your pods! Read [how it works](#how-it-works) for more info.
#### Connecting to `hello-mtls`
We're ready to securely connect to `hello-mtls`.
```
$ export HELLO_MTLS_IP=$(kubectl get svc hello-mtls-lb -ojsonpath={$.status.loadBalancer.ingress...?})
> 🤯 **Note:** HTTPS clients check that the name in the server's cerificate match the `authority` portion of the URL (e.g., `https://smallstep.com/` must present a certificate with the name `smallstep.com`). (See [RFC2818](https://tools.ietf.org/html/rfc2818#section-3).)
>
> Our `hello-mtls` service's certificate binds the name `hello-mtls.default.svc.cluster.local` so we *must* connect to it using that name. If we use a different authority we'll get an error:
>
> ```
> $ curl --cacert root.crt \
> --cert snarf.crt \
> --key snarf.key \
> https://127.0.0.1
> curl: (51) SSL: no alternative certificate subject name matches target host name '127.0.0.1'
> ```
>
> In a real production environment you'd address this by either:
>
> * using a properly registered domain name and configuring DNS either globally (e.g., using [ExternalDNS](https://github.com/kubernetes-incubator/external-dns/)), or
> * using internal names and configuring DNS locally in each environment (e.g., using an [ExternalName service](https://kubernetes.io/docs/concepts/services-networking/service/#externalname))
>
> In any case, `hello-mtls.default.svc.cluster.local` must resolve to the right IP.
>
> You could use `/etc/hosts`. Since we're testing with `curl` it's even easier to use the `--resolve` flag to override resolution for a single request.
## How it works
### Architecture
`Autocert` consists of a [webhook admission controllers](https://kubernetes.io/docs/reference/access-authn-authz/extensible-admission-controllers/#admission-webhooks) that injects one init container and one sidecar container to handle obtaining a certificate for the first time and renewing a certificate, respectively.
The `autocert` admission webhook will intercept this pod creation request and inject an [init container](bootstrapper/) and [sidecar](renewer/) to manage certificate issuance and renewal, respectively.
It integrates with [`step certificates`](https://github.com/smallstep/certificates) and uses the single-use token bootstrap protocol from that project to mutually authenticate a new pod with your certificate authority.
@ -227,10 +484,38 @@ Yes, but it's designed for use by the kubernetes control plane rather than by yo
It's harder and less secure.
#### Why not use kubernetes service accounts instead of bootstrap tokens?
#### Why does the mutating webhook have to create secrets / need cluster role bindings?
#### Why do I have to tell you the name to put in a certificate? Why can't you automatically bind service names?
#### What are `autocert` certificates good for?
Autocert certificates let you secure your data plane (service-to-service) communication using mutual TLS (mTLS). Services and proxies can limit access to clients that also have a certificate issued by your certificate authority (CA). Servers can identify which client is connecting improving visibility and enabling granular access control.
Once certificates are issued you can use mTLS to secure communication in to, out of, and between kubernetes clusters. Services can use mTLS to only allow connections from clients that have their own certificate issued from your CA.
It's like your own Let's Encrypt, but you control who gets a certificate.
It's like your own Let's Encrypt, but you control who gets a certificate.
#### How is this different than a service mesh?
Certificate management is a necessary building block for any service mesh that uses mutual TLS for authenticated encryption (e.g., istio, linkerd, consul connect). Typically, service mesh systems will provide their own certificate management solution. However, these systems
#### What about DaemonSets, ReplicaSets, StatefulSets, and all the other things that might need certificates?
...?
## Building
...
## Contributing
...
## License
Copyright 2019 Smallstep Labs
Licensed under [the Apache License, Version 2.0](https://github.com/smallstep/certificates/blob/master/LICENSE)
Mike Malone
5 years ago