Secure services with TLS¶
After deploying a layer 7 routing solution, you have two options for securing your services with TLS:
Let the proxy terminate the TLS connection. All traffic between end-users and the proxy is encrypted, but the traffic going between the proxy and your Swarm service is not secured.
Let your Swarm service terminate the TLS connection. The end-to-end traffic is encrypted and the proxy service allows TLS traffic to passthrough unchanged.
Regardless of the option selected to secure Swarm services, there are two steps required to route traffic with TLS:
Create Docker secrets to manage from a central place the private key and certificate used for TLS.
Add labels to your Swarm service for MKE to reconfigure the proxy service.
Let the proxy handle TLS¶
The following example deploys a Swarm service and lets the proxy service handle the TLS connection. All traffic between the proxy and the swarm service is not secured, so use this option only if you trust that no one can monitor traffic inside services running in your datacenter.
Start by getting a private key and certificate for the TLS connection. Make sure the Common Name in the certificate matches the name where your service is going to be available.
You can generate a self-signed certificate for
openssl req \ -new \ -newkey rsa:4096 \ -days 3650 \ -nodes \ -x509 \ -subj "/C=US/ST=CA/L=SF/O=Docker-demo/CN=app.example.org" \ -keyout app.example.org.key \ -out app.example.org.cert
Then, create a docker-compose.yml file with the following content:
version: "3.2" services: demo: image: ehazlett/docker-demo deploy: replicas: 1 labels: com.docker.lb.hosts: app.example.org com.docker.lb.network: demo-network com.docker.lb.port: 8080 com.docker.lb.ssl_cert: demo_app.example.org.cert com.docker.lb.ssl_key: demo_app.example.org.key environment: METADATA: proxy-handles-tls networks: - demo-network networks: demo-network: driver: overlay secrets: app.example.org.cert: file: ./app.example.org.cert app.example.org.key: file: ./app.example.org.key
Notice that the demo service has labels specifying that the proxy service
app.example.org traffic to this service. All traffic between
the service and proxy takes place using the
demo-network network. The
service also has labels specifying the Docker secrets to use on the proxy
service for terminating the TLS connection.
Because the private key and certificate are stored as Docker secrets, you can easily scale the number of replicas used for running the proxy service. Docker distributes the secrets to the replicas.
Set up your CLI client with a MKE client bundle and deploy the service:
docker stack deploy --compose-file docker-compose.yml demo
The service is now running. To test that everything is working correctly,
/etc/hosts file to map
app.example.org to the IP address of
a MKE node.
In a production deployment, you must create a DNS entry so that users can access the service using the domain name of your choice. After creating the DNS entry, you can access your service:
For this example:
hostnameis the name you specified with the
https-portis the port you configured in the MKE settings.
Because this example uses self-sign certificates, client tools like browsers display a warning that the connection is insecure.
You can also test from the CLI:
curl --insecure \ --resolve <hostname>:<https-port>:<mke-ip-address> \ https://<hostname>:<https-port>/ping
If everything is properly configured, you should get a JSON payload:
Because the proxy uses SNI to decide where to route traffic, make sure you are
using a version of
curl that includes the SNI header with insecure
curl displays an error saying that the SSL handshake
Currently there is no way to update expired certificates using this method. The proper way is to create a new secret then update the corresponding service.
Let your service handle TLS¶
The second option for securing with TLS involves encrypting traffic from end users to your swarm service.
To do that, deploy your swarm service using the following
version: "3.2" services: demo: image: ehazlett/docker-demo command: --tls-cert=/run/secrets/cert.pem --tls-key=/run/secrets/key.pem deploy: replicas: 1 labels: com.docker.lb.hosts: app.example.org com.docker.lb.network: demo-network com.docker.lb.port: 8080 com.docker.lb.ssl_passthrough: "true" environment: METADATA: end-to-end-TLS networks: - demo-network secrets: - source: app.example.org.cert target: /run/secrets/cert.pem - source: app.example.org.key target: /run/secrets/key.pem networks: demo-network: driver: overlay secrets: app.example.org.cert: file: ./app.example.org.cert app.example.org.key: file: ./app.example.org.key
The service is updated to start using the secrets with the private key and
certificate. The service is also labeled with
true, signaling MKE to configure the proxy service such that TLS traffic for
app.example.org is passed to the service.
Since the connection is fully encrypted from end-to-end, the proxy service cannot add metadata such as version information or request ID to the response headers.