moby--moby/docs/sources/articles/https.md

page_title: Running Docker with HTTPS page_description: How to setup and run Docker with HTTPS page_keywords: docker, docs, article, example, https, daemon, tls, ca, certificate

Running Docker with https

By default, Docker runs via a non-networked Unix socket. It can also optionally communicate using a HTTP socket.

If you need Docker to be reachable via the network in a safe manner, you can enable TLS by specifying the tlsverify flag and pointing Docker's tlscacert flag to a trusted CA certificate.

In the daemon mode, it will only allow connections from clients authenticated by a certificate signed by that CA. In the client mode, it will only connect to servers with a certificate signed by that CA.

Warning

: Using TLS and managing a CA is an advanced topic. Please familiarize yourself with OpenSSL, x509 and TLS before using it in production.

Warning

: These TLS commands will only generate a working set of certificates on Linux. Mac OS X comes with a version of OpenSSL that is incompatible with the certificates that Docker requires.

Create a CA, server and client keys with OpenSSL

First, initialize the CA serial file and generate CA private and public keys:

$ echo 01 > ca.srl
$ openssl genrsa -des3 -out ca-key.pem 2048
$ openssl req -new -x509 -days 365 -key ca-key.pem -out ca.pem

Now that we have a CA, you can create a server key and certificate signing request (CSR). Make sure that "Common Name" (i.e. server FQDN or YOUR name) matches the hostname you will use to connect to Docker:

$ openssl genrsa -des3 -out server-key.pem 2048
$ openssl req -subj '/CN=<Your Hostname Here>' -new -key server-key.pem -out server.csr

Next we're going to sign the key with our CA:

$ openssl x509 -req -days 365 -in server.csr -CA ca.pem -CAkey ca-key.pem \
  -out server-cert.pem

For client authentication, create a client key and certificate signing request:

$ openssl genrsa -des3 -out client-key.pem 2048
$ openssl req -subj '/CN=client' -new -key client-key.pem -out client.csr

To make the key suitable for client authentication, create an extensions config file:

$ echo extendedKeyUsage = clientAuth > extfile.cnf

Now sign the key:

$ openssl x509 -req -days 365 -in client.csr -CA ca.pem -CAkey ca-key.pem \
  -out client-cert.pem -extfile extfile.cnf

Finally, you need to remove the passphrase from the client and server key:

$ openssl rsa -in server-key.pem -out server-key.pem
$ openssl rsa -in client-key.pem -out client-key.pem

Now you can make the Docker daemon only accept connections from clients providing a certificate trusted by our CA:

$ sudo docker -d --tlsverify --tlscacert=ca.pem --tlscert=server-cert.pem --tlskey=server-key.pem \
  -H=0.0.0.0:2376

To be able to connect to Docker and validate its certificate, you now need to provide your client keys, certificates and trusted CA:

$ docker --tlsverify --tlscacert=ca.pem --tlscert=client-cert.pem --tlskey=client-key.pem \
  -H=dns-name-of-docker-host:2376

Note

: Docker over TLS should run on TCP port 2376.

Warning

: As shown in the example above, you don't have to run the docker client with sudo or the docker group when you use certificate authentication. That means anyone with the keys can give any instructions to your Docker daemon, giving them root access to the machine hosting the daemon. Guard these keys as you would a root password!

Secure by default

If you want to secure your Docker client connections by default, you can move the files to the .docker directory in your home directory - and set the DOCKER_HOST variable as well.

$ cp ca.pem ~/.docker/ca.pem
$ cp client-cert.pem ~/.docker/cert.pem
$ cp client-key.pem ~/.docker/key.pem
$ export DOCKER_HOST=tcp://:2376

Then you can just run Docker with the --tlsverify option.

$ docker --tlsverify ps

Other modes

If you don't want to have complete two-way authentication, you can run Docker in various other modes by mixing the flags.

Daemon modes

• tlsverify, tlscacert, tlscert, tlskey set: Authenticate clients
• tls, tlscert, tlskey: Do not authenticate clients

Client modes

• tls: Authenticate server based on public/default CA pool
• tlsverify, tlscacert: Authenticate server based on given CA
• tls, tlscert, tlskey: Authenticate with client certificate, do not authenticate server based on given CA
• tlsverify, tlscacert, tlscert, tlskey: Authenticate with client certificate and authenticate server based on given CA

If found, the client will send its client certificate, so you just need to drop your keys into ~/.docker/<ca, cert or key>.pem. Alternatively, if you want to store your keys in another location, you can specify that location using the environment variable DOCKER_CONFIG.

$ export DOCKER_CONFIG=${HOME}/.dockers/zone1/
$ docker --tlsverify ps