Merge "Add script to enable Docker Remote API by updating Docker Daemon configuration"

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+Encrypt the docker remote API via TLS for Ubuntu and CentOS

+

+[Introduction]

+The Docker daemon can listen to Docker Remote API requests via three types of

+Socket: unix, tcp and fd. By default, a unix domain socket (or IPC socket) is

+created at /var/run/docker.sock, requiring either root permission, or docker

+group membership.

+

+Port 2375 is conventionally used for un-encrypted communition with Docker daemon

+remotely, where docker server can be accessed by any docker client via tcp socket

+in local area network. You can listen to port 2375 on all network interfaces with

+-H tcp://0.0.0.0:2375, where 0.0.0.0 means any available IP address on host, and

+tcp://0.0.0.0:2375 indicates that port 2375 is listened on any IP of daemon host.

+If we want to make docker server open on the Internet via TCP port, and only trusted

+clients have the right to access the docker server in a safe manner, port 2376 for

+encrypted communication with the daemon should be listened. It can be achieved to

+create certificate and distribute it to the trusted clients.

+

+Through creating self-signed certificate, and using --tlsverify command when running

+Docker daemon, Docker daemon opens the TLS authentication. Thus only the clients

+with related private key files can have access to the Docker daemon's server. As

+long as the key files for encryption are secure between docker server and client,

+the Docker daemon can keep secure.

+In summary,

+Firstly we should create docker server certificate and related key files, which

+are distributed to the trusted clients.

+Then the clients with related key files can access docker server.

+

+[Steps]

+1.0. Create a CA, server and client keys with OpenSSL.

+    OpenSSL is used to generate certificate, and can be installed as follows.

+    apt-get install openssl openssl-devel

+

+1.1 First generate CA private and public keys.

+    openssl genrsa -aes256 -out ca-key.pem 4096

+    openssl req -new -x509 -days 365 -key ca-key.pem -sha256 -out ca.pem

+

+    You are about to be asked to enter information that will be incorporated

+    into your certificate request, where the instance of $HOST should be replaced

+    with the DNS name of your Docker daemon's host, here the DNS name of my Docker

+    daemon is ly.

+       Common Name (e.g. server FQDN or YOUR name) []:$HOST

+

+1.2 Now we have a CA (ca-key.pem and ca.pem), you can create a server key and

+certificate signing request.

+    openssl genrsa -out server-key.pem 4096

+    openssl req -subj "/CN=$HOST" -sha256 -new -key server-key.pem -out server.csr

+

+1.3 Sign the public key with our CA.

+    TLS connections can be made via IP address as well as DNS name, they need to be

+    specified when creating the certificate.

+

+    echo subjectAltName = IP:172.16.10.121,IP:127.0.0.1 > extfile.cnf

+    openssl x509 -req -days 365 -sha256 -in server.csr -CA ca.pem -CAkey ca-key.pem \

+    -CAcreateserial -out server-cert.pem -extfile extfile.cnf

+

+1.4 For client authentication, create a client key and certificate signing request.

+    openssl genrsa -out key.pem 4096

+    openssl req -subj '/CN=client' -new -key key.pem -out client.csr

+

+1.5 To make the key suitable for client authentication, create an extensions config file.

+    echo extendedKeyUsage = clientAuth > extfile.cnf

+

+1.6 Sign the public key and after generating cert.pem and server-cert.pem, two certificate

+    signing requests can be removed.

+    openssl x509 -req -days 365 -sha256 -in client.csr -CA ca.pem -CAkey ca-key.pem \

+    -CAcreateserial -out cert.pem -extfile extfile.cnf

+

+1.7 In order to protect your keys from accidental damage, you may change file modes to

+    be only readable.

+    chmod -v 0400 ca-key.pem key.pem server-key.pem

+    chmod -v 0444 ca.pem server-cert.pem cert.pem

+

+1.8 Build docker server

+    dockerd --tlsverify --tlscacert=ca.pem --tlscert=server-cert.pem --tlskey=server-key.pem \

+    -H=0.0.0.0:2376

+    Then, it can be seen from the command 'netstat -ntlp' that port 2376 has been listened

+    and the Docker daemon only accept connections from clients providing a certificate

+    trusted by our CA.

+

+1.9 Distribute the keys to the client

+    scp /etc/docker/ca.pem wwl@172.16.10.121:/etc/docker

+    scp /etc/docker/cert.pem wwl@172.16.10.121:/etc/docker

+    scp /etc/docker/key.pem wwl@172.16.10.121:/etc/docker

+    Where, wwl and 172.16.10.121 is the username and IP of the client respectively.

+    And the password of the client is needed when you distribute the keys to the client.

+

+1.10 To access Docker daemon from the client via keys.

+    docker --tlsverify --tlscacert=ca.pem --tlscert=cert.pem --tlskey=key.pem \

+    -H=$HOST:2376 version

+

+    Then we can operate docker in the Docker daemon from the client vis keys, for example:

+    1) create container from the client

+    docker --tlsverify --tlscacert=ca.pem --tlscert=cert.pem --tlskey=key.pem -H=ly:2376 run -d \

+    -it --name w1 grafana/grafana

+    2) list containers from the client

+    docker --tlsverify --tlscacert=ca.pem --tlscert=cert.pem --tlskey=key.pem -H=ly:2376 pa -a

+    3) stop/start containers from the client

+    docker --tlsverify --tlscacert=ca.pem --tlscert=cert.pem --tlskey=key.pem -H=ly:2376 stop w1

+    docker --tlsverify --tlscacert=ca.pem --tlscert=cert.pem --tlskey=key.pem -H=ly:2376 start w1

+

+

+

+

+

+

+