Container Infrastructure Management Service for OpenStack
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Transport Layer Security

Magnum uses TLS to secure communication between a Bay's services and the outside world. This includes not only Magnum itself, but also the end-user when they choose to use native client libraries to interact with the Bay. Magnum also uses TLS certificates for client authentication, which means each client needs a valid certificate to communicate with a Bay.

TLS is a complex subject, and many guides on it exist already. This guide will not attempt to fully describe TLS, only the necessary pieces to get a client set up to talk to a Bay with TLS. A more indepth guide on TLS can be found in the OpenSSL Cookbook by Ivan Ristić.

Deploy a secure bay

Magnum supports secure communication between the Magnum service and the Kubernetes service using TLS. This document explains how to use this feature.

Below is the detailed step for deploying a secure bay and using kubectl to run Kubernetes commands that uses SSL certificates to communicate with Kubernetes services running on secure bay.

Create a baymodel, by default TLS is enabled in Magnum:

magnum baymodel-create --name secure-kubernetes \
                       --keypair-id default \
                       --external-network-id public \
                       --image-id fedora-atomic \
                       --flavor-id m1.small \
                       --docker-volume-size 1 \
                       --coe kubernetes \
                       --network-driver flannel

+---------------------+--------------------------------------+
| Property            | Value                                |
+---------------------+--------------------------------------+
| http_proxy          | None                                 |
| updated_at          | None                                 |
| master_flavor_id    | None                                 |
| fixed_network       | None                                 |
| uuid                | 668a5e97-ba92-4b84-bdc3-e2388e0462ea |
| no_proxy            | None                                 |
| https_proxy         | None                                 |
| tls_disabled        | False                                |
| keypair_id          | default                              |
| public              | False                                |
| labels              | {}                                   |
| docker_volume_size  | 1                                    |
| external_network_id | public                               |
| cluster_distro      | fedora-atomic                        |
| image_id            | fedora-atomic                        |
| registry_enabled    | False                                |
| apiserver_port      | None                                 |
| name                | secure-kubernetes                    |
| created_at          | 2015-10-08T05:05:10+00:00            |
| network_driver      | flannel                              |
| coe                 | kubernetes                           |
| flavor_id           | m1.small                             |
| dns_nameserver      | 8.8.8.8                              |
+---------------------+--------------------------------------+

To disable TLS in magnum use option '--tls-disabled'. Please note it is not recommended to disable TLS due to security reasons.

Now create a bay. Use the baymodel name as a template for bay creation:

magnum bay-create --name secure-k8sbay \
                  --baymodel secure-kubernetes \
                  --node-count 1

+--------------------+------------------------------------------------------------+
| Property           | Value                                                      |
+--------------------+------------------------------------------------------------+
| status             | None                                                       |
| uuid               | 04952c60-a338-437f-a7e7-d016d1d00e65                       |
| status_reason      | None                                                       |
| created_at         | 2015-10-08T04:19:14+00:00                                  |
| updated_at         | None                                                       |
| bay_create_timeout | 0                                                          |
| api_address        | None                                                       |
| baymodel_id        | da2825a0-6d09-4208-b39e-b2db666f1118                       |
| node_count         | 1                                                          |
| node_addresses     | None                                                       |
| master_count       | 1                                                          |
| discovery_url      | https://discovery.etcd.io/3b7fb09733429d16679484673ba3bfd5 |
| name               | secure-k8sbay                                              |
+--------------------+------------------------------------------------------------+

Now run bay-show command to get the IP of the bay host:

magnum bay-show secure-k8sbay
+--------------------+------------------------------------------------------------+
| Property           | Value                                                      |
+--------------------+------------------------------------------------------------+
| status             | CREATE_COMPLETE                                            |
| uuid               | 04952c60-a338-437f-a7e7-d016d1d00e65                       |
| status_reason      | Stack CREATE completed successfully                        |
| created_at         | 2015-10-08T04:19:14+00:00                                  |
| updated_at         | 2015-10-08T04:21:00+00:00                                  |
| bay_create_timeout | 0                                                          |
| api_address        | https://192.168.19.86:6443                                 |
| baymodel_id        | da2825a0-6d09-4208-b39e-b2db666f1118                       |
| node_count         | 1                                                          |
| node_addresses     | [u'192.168.19.88']                                         |
| master_count       | 1                                                          |
| discovery_url      | https://discovery.etcd.io/3b7fb09733429d16679484673ba3bfd5 |
| name               | secure-k8sbay                                              |
+--------------------+------------------------------------------------------------+

You can see the api_address contains https in URL that denotes the Kubernetes services are configured securely with SSL certificates and now any communication to kube-apiserver will be over https making it secure.

Generating a Client Key and Certificate Signing Request

The first step to setting up a client is to generate your personal private key. This is essentially a cryptographically generated string of bytes. It should be protected as a password. To generate an RSA key, you will use the 'genrsa' command of the 'openssl' tool.

openssl genrsa -out client.key 4096

This command generates a 4096 byte RSA key at client.key.

Next, you will need to generate a certificate signing request (CSR). This will be used by Magnum to generate a signed certificate you will use to communicate with the Bay. It is used by the Bay to secure the connection and validate you are you who say you are.

To generate a CSR for client authentication, openssl requires a config file that specifies a few values. Below is a simple template, just fill in the 'CN' value with your name and save it as client.conf

$ cat > client.conf << END
[req]
distinguished_name = req_distinguished_name
req_extensions     = req_ext
prompt = no
[req_distinguished_name]
CN = Your Name
[req_ext]
extendedKeyUsage = clientAuth
END

Once you have client.conf, you can run the openssl 'req' command to generate the CSR.

openssl req -new -days 365 \
    -config client.conf \
    -key client.key \
    -out client.csr

Now that you have your client CSR, you can use the Magnum CLI to send it off to Magnum to get it signed.

magnum ca-sign --bay secure-k8sbay --csr client.csr > client.crt

The final piece you need to retrieve is the CA certificate for the bay. This is used by your native client to ensure you're only communicating with hosts that Magnum set up.

magnum ca-show --bay secure-k8sbay > ca.crt

You need to get kubectl, a kubernetes CLI tool, to communicate with the bay

wget https://github.com/kubernetes/kubernetes/releases/download/v1.0.4/kubernetes.tar.gz
tar -xzvf kubernetes.tar.gz
sudo cp -a kubernetes/platforms/linux/amd64/kubectl /usr/bin/kubectl

Now let's run some kubectl commands to check secure communication:

KUBERNETES_URL=$(magnum bay-show secure-k8sbay |
                 awk '/ api_address /{print $4}')
kubectl version --certificate-authority=ca.crt \
                --client-key=client.key \
                --client-certificate=client.crt -s $KUBERNETES_URL

Client Version: version.Info{Major:"1", Minor:"0", GitVersion:"v1.0.4", GitCommit:"65d28d5fd12345592405714c81cd03b9c41d41d9", GitTreeState:"clean"}
Server Version: version.Info{Major:"1", Minor:"0", GitVersion:"v1.0.4", GitCommit:"65d28d5fd12345592405714c81cd03b9c41d41d9", GitTreeState:"clean"}

kubectl create -f redis-master.yaml --certificate-authority=ca.crt \
                                    --client-key=client.key \
                                    --client-certificate=client.crt -s $KUBERNETES_URL

pods/test2

kubectl get pods --certificate-authority=ca.crt \
                 --client-key=client.key \
                 --client-certificate=client.crt -s $KUBERNETES_URL
NAME           READY     STATUS    RESTARTS   AGE
redis-master   2/2       Running   0          1m

You can create kubectl configuration for these flags:

kubectl config set-cluster secure-k8sbay --server=${KUBERNETES_URL} \
    --certificate-authority=${PWD}/ca.crt
kubectl config set-credentials client --certificate-authority=${PWD}/ca.crt \
    --client-key=${PWD}/client.key --client-certificate=${PWD}/client.crt
kubectl config set-context secure-k8sbay --cluster=secure-k8sbay --user=client
kubectl config use-context secure-k8sbay

Now you can use kubectl commands without extra flags:

kubectl get pods
NAME           READY     STATUS    RESTARTS   AGE
redis-master   2/2       Running   0          1m

Access to Kubernetes User Interface:

curl -L ${KUBERNETES_URL}/ui --cacert ca.crt --key client.key \
    --cert client.crt

You may also set up kubectl proxy which will use your client certificate to allow you to
browse to a local address to use the UI without installing a certificate in your browser.

kubectl proxy --api-prefix=/ --certificate-authority=ca.crt --client-key=client.key \
              --client-certificate=client.crt -s $KUBERNETES_URL

Open http://localhost:8001/ui in your browser

Once you have all of these pieces, you can configure your native client. Below is an example for Docker.

docker -H tcp://192.168.19.86:2376 --tlsverify \
    --tlscacert ca.crt \
    --tlskey client.key \
    --tlscert client.crt \
    info