我们经常会利用Portainer来管理docker环境，也经常会用Jenkins来自动构建和部署docker，远程管理都会使用到Docker API，通常我们只是开启了没有安全保护的2375（通常）端口，这个比较危险，会导致远程劫持攻击。那么我们就需要配置TLS认证的2376（通常）端口。

下面我们针对CoreOS系统进行配置：

一、利用系统自带的openssl生成相应的服务端和客户端证书

我们利用脚本自动生成，这样非常便捷，脚本（auto-tls-certs.sh）如下：

#!/bin/bash
# 
# -------------------------------------------------------------
# 自动创建 Docker TLS 证书
# -------------------------------------------------------------

# 以下是配置信息
# --[BEGIN]------------------------------

CODE="dp"
IP="docker服务器ip"
PASSWORD="证书密码"
COUNTRY="CN"
STATE="BEIJING"
CITY="BEIJING"
ORGANIZATION="公司"
ORGANIZATIONAL_UNIT="Dev"
COMMON_NAME="$IP"
EMAIL="邮箱"

# --[END]--

# Generate CA key
openssl genrsa -aes256 -passout "pass:$PASSWORD" -out "ca-key-$CODE.pem" 4096
# Generate CA
openssl req -new -x509 -days 365 -key "ca-key-$CODE.pem" -sha256 -out "ca-$CODE.pem" -passin "pass:$PASSWORD" -subj "/C=$COUNTRY/ST=$STATE/L=$CITY/O=$ORGANIZATION/OU=$ORGANIZATIONAL_UNIT/CN=$COMMON_NAME/emailAddress=$EMAIL"
# Generate Server key
openssl genrsa -out "server-key-$CODE.pem" 4096

# Generate Server Certs.
openssl req -subj "/CN=$COMMON_NAME" -sha256 -new -key "server-key-$CODE.pem" -out server.csr

echo "subjectAltName = IP:$IP,IP:127.0.0.1" >> extfile.cnf
echo "extendedKeyUsage = serverAuth" >> extfile.cnf

openssl x509 -req -days 365 -sha256 -in server.csr -passin "pass:$PASSWORD" -CA "ca-$CODE.pem" -CAkey "ca-key-$CODE.pem" -CAcreateserial -out "server-cert-$CODE.pem" -extfile extfile.cnf


# Generate Client Certs.
rm -f extfile.cnf

openssl genrsa -out "key-$CODE.pem" 4096
openssl req -subj '/CN=client' -new -key "key-$CODE.pem" -out client.csr
echo extendedKeyUsage = clientAuth >> extfile.cnf
openssl x509 -req -days 365 -sha256 -in client.csr -passin "pass:$PASSWORD" -CA "ca-$CODE.pem" -CAkey "ca-key-$CODE.pem" -CAcreateserial -out "cert-$CODE.pem" -extfile extfile.cnf

rm -vf client.csr server.csr

chmod -v 0400 "ca-key-$CODE.pem" "key-$CODE.pem" "server-key-$CODE.pem"
chmod -v 0444 "ca-$CODE.pem" "server-cert-$CODE.pem" "cert-$CODE.pem"

# 打包客户端证书
mkdir -p "tls-client-certs-$CODE"
cp -f "ca-$CODE.pem" "cert-$CODE.pem" "key-$CODE.pem" "tls-client-certs-$CODE/"
cd "tls-client-certs-$CODE"
tar zcf "tls-client-certs-$CODE.tar.gz" *
mv "tls-client-certs-$CODE.tar.gz" ../
cd ..
rm -rf "tls-client-certs-$CODE"

# 拷贝服务端证书
mkdir -p /etc/docker/certs.d
cp "ca-$CODE.pem" "server-cert-$CODE.pem" "server-key-$CODE.pem" /etc/docker/certs.d/

对脚本中的变量进行修改后运行，自动会创建好tls证书，服务器的证书在/etc/docker/certs.d/目录下:

客户端的证书在运行脚本的目录下，同时还自动打好了一个.tar.gz的包，很方便。

二、配置Docker服务（官方说明）

注意修改证书路径。

Enable the secure remote API on a new socket

Create a file called /etc/systemd/system/docker-tls-tcp.socket to make Docker available on a secured TCP socket on port 2376.

[Unit]
Description=Docker Secured Socket for the API

[Socket]
ListenStream=2376
BindIPv6Only=both
Service=docker.service

[Install]
WantedBy=sockets.target

Then enable this new socket:

systemctl enable docker-tls-tcp.socket
systemctl stop docker
systemctl start docker-tls-tcp.socket

Drop-in configuration

Create /etc/systemd/system/docker.service.d/10-tls-verify.conf drop-in for systemd Docker service:

[Service]
Environment="DOCKER_OPTS=--tlsverify --tlscacert=/etc/docker/ca.pem --tlscert=/etc/docker/server.pem --tlskey=/etc/docker/server-key.pem"

Reload systemd config files and restart docker service:

sudo systemctl daemon-reload
sudo systemctl restart docker.service

三、配置Portainer远程TLS连接

证书对应选择：

1. ca.pem
2. cert.pem
3. key.pem

这样就完成了。注意如果之前开启了未认证的2375端口，请关闭并禁用，重启docker服务。

# 停止不安全的2375端口
systemctl stop docker-tcp.socket

# 禁用该端口
systemctl disable docker-tcp.socket

# 重启docker服务
systemctl restart docker.service