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
Generating RSA private key, 2048 bit long modulus
......+++
...............+++
e is 65537 (0x10001)
Enter pass phrase for ca-key.pem:
Verifying - Enter pass phrase for ca-key.pem:
$ openssl req -new -x509 -days 365 -key ca-key.pem -out ca.pem
Enter pass phrase for ca-key.pem:
 You are about to be asked to enter information that will be incorporated
 into your certificate request.
 What you are about to enter is what is called a Distinguished Name or a DN.
 There are quite a few fields but you can leave some blank
 For some fields there will be a default value,
 If you enter '.', the field will be left blank.
 -----
 Country Name (2 letter code) [AU]:
 State or Province Name (full name) [Some-State]:Queensland
 Locality Name (eg, city) []:Brisbane
 Organization Name (eg, company) [Internet Widgits Pty Ltd]:Docker Inc
 Organizational Unit Name (eg, section) []:Boot2Docker
 Common Name (e.g. server FQDN or YOUR name) []:your.host.com
 Email Address []:Sven@home.org.au

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
Generating RSA private key, 2048 bit long modulus
......................................................+++
............................................+++
e is 65537 (0x10001)
Enter pass phrase for server-key.pem:
Verifying - Enter pass phrase for server-key.pem:
$ openssl req -subj '/CN=<Your Hostname Here>' -new -key server-key.pem -out server.csr
Enter pass phrase for server-key.pem:

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
Signature ok
subject=/CN=your.host.com
Getting CA Private Key
Enter pass phrase for ca-key.pem:

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

$ openssl genrsa -des3 -out key.pem 2048
Generating RSA private key, 2048 bit long modulus
...............................................+++
...............................................................+++
e is 65537 (0x10001)
Enter pass phrase for key.pem:
Verifying - Enter pass phrase for key.pem:
$ openssl req -subj '/CN=client' -new -key key.pem -out client.csr
Enter pass phrase for key.pem:

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 cert.pem -extfile extfile.cnf
Signature ok
subject=/CN=client
Getting CA Private Key
Enter pass phrase for ca-key.pem:

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

$ openssl rsa -in server-key.pem -out server-key.pem
Enter pass phrase for server-key.pem:
writing RSA key
$ openssl rsa -in key.pem -out key.pem
Enter pass phrase for key.pem:
writing RSA key

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=cert.pem --tlskey=key.pem \
  -H=dns-name-of-docker-host:2376 version

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

Then you can 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_CERT_PATH.

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