Setup TLS for Docker (Ubuntu 16.04)

docker_tls_ubuntu_16.04

- Create a CA, keys and certificates
- Source: https://docs.docker.com/engine/security/https/


# Create certs dir
mkdir ~/certs
cd ~/certs

# Ca key
openssl genrsa -aes256 -out ca-key.pem 4096

# Ca certificate
openssl req -new -x509 -days 9999 -key ca-key.pem -sha256 -out ca.pem

# Server key
openssl genrsa -out server-key.pem 4096

# Server certificate signing request
openssl req -subj "/CN=example.com" -sha256 -new -key server-key.pem -out server.csr

# Create configuration file
echo subjectAltName = DNS:example.com,IP:10.10.10.20,IP:127.0.0.1 >> extfile.cnf
echo extendedKeyUsage = serverAuth >> extfile.cnf

# Server cert
openssl x509 -req -days 9999 -sha256 -in server.csr -CA ca.pem -CAkey ca-key.pem \
  -CAcreateserial -out server-cert.pem -extfile extfile.cnf
  
# Client key
openssl genrsa -out key.pem 4096

# Client certificate signing request
openssl req -subj '/CN=client' -new -key key.pem -out client.csr

# Create configuration file
echo extendedKeyUsage = clientAuth >> extfile.client.cnf

# Client cert
openssl x509 -req -days 9999 -sha256 -in client.csr -CA ca.pem -CAkey ca-key.pem \
  -CAcreateserial -out cert.pem -extfile extfile.client.cnf
  
# Remove signing requests
rm -v *.csr

# Set permissions
chmod -v 0400 ca-key.pem key.pem server-key.pem
chmod -v 0444 ca.pem server-cert.pem cert.pem

# Copy ca cert and server key+cert to /etc/docker/certs.d/<domain name>:port
sudo mkdir -p /etc/docker/certs.d/example.com:2376
sudo cp ca.pem server-cert.pem server-key.pem /etc/docker/certs.d/example.com:2376


# Edit docker.service
sudo vi /lib/systemd/system/docker.service

	-> Remove '-H fd://' from 'ExecStart'

# Create /etc/docker/daemon.json
sudo tee /etc/docker/daemon.json << EOL
{
  "tlsverify": true,
  "tlscacert": "/etc/docker/certs.d/example.com:2376/ca.pem",
  "tlscert"  : "/etc/docker/certs.d/example.com:2376/server-cert.pem",
  "tlskey"   : "/etc/docker/certs.d/example.com:2376/server-key.pem",
  "hosts"    : ["fd://", "0.0.0.0:2376"]
}
EOL

# Reload and restart
sudo systemctl daemon-reload
sudo systemctl restart docker



# Test client connection from another server
# copy ca.pem, cert.pem and key.pem to another machine
docker --tlsverify --tlscacert=ca.pem --tlscert=cert.pem --tlskey=key.pem --host=example.com:2376 version