Generate docker TLS certs for secure remote access

Makefile

# host name of your docker server
HOST=host.net
# ip of your docker server
IP=0.0.0.0
# days of validity for cert
DAYS=365

default:
	openssl genrsa -aes256 -out ca-key.pem 4096
	openssl req -new -x509 -days ${DAYS} -key ca-key.pem -sha256 -out ca.pem
	openssl genrsa -out server-key.pem 4096
	openssl req -subj '/CN=${HOST}' -new -key server-key.pem -out server.csr
	echo subjectAltName = IP:${IP},IP:127.0.0.1 > extfile.cnf
	openssl x509 -req -days ${DAYS} -sha256 -in server.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out server-cert.pem -extfile extfile.cnf
	openssl genrsa -out key.pem 4096
	openssl req -subj '/CN=client' -new -key key.pem -out client.csr
	echo extendedKeyUsage = clientAuth > extfile.cnf
	openssl x509 -req -days ${DAYS} -sha256 -in client.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out cert.pem -extfile extfile.cnf
	rm -v client.csr server.csr
	chmod -v 0400 ca-key.pem key.pem server-key.pem
	chmod -v 0444 ca.pem server-cert.pem cert.pem

# daemon flags: docker -d --tlsverify --tlscacert=ca.pem --tlscert=server-cert.pem --tlskey=server-key.pem -H=0.0.0.0:2376
# client flags: docker --tlsverify --tlscacert=ca.pem --tlscert=cert.pem --tlskey=key.pem -H=$HOST:2376 version
# reference page: https://docs.docker.com/engine/security/https/

Docs: https://docs.docker.com/articles/https/