cd /usr/local/elasticsearch/bin/
./elasticsearch-certgen
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Please enter the desired output file [certificate-bundle.zip]: cert.zip （生成的壓縮包名稱，輸入或者保持默認，直接回車）
Enter instance name: my-application (實例名)
Enter name for directories and files [my-application]: elasticsearch（存儲實例證書的文件夾名，可以隨意指定或保持默認）
Enter IP Addresses for instance (comma-separated if more than one) []: 127.0.0.1(實例ip，多個ip用逗號隔開)
Enter DNS names for instance (comma-separated if more than one) []: node-1（節點名，多個節點用逗號隔開）
Would you like to specify another instance? Press 'y' to continue entering instance information: (到達這一步,不需要按y重新設置,按空格鍵就完成了)
Certificates written to /usr/local/elasticsearch/bin/cert.zip（這個是生成的文件存放地址，不用填寫）
解壓cert.zip文件會得到
creating: ca/
inflating: ca/ca.crt
inflating: ca/ca.key
creating: my-applicaiton/
inflating: my-applicaiton/my-applicaiton.crt
inflating: my-applicaiton/my-applicaiton.key
es配置文件中使用如下：
xpack.security.transport.ssl.enabled: true
xpack.ssl.key: my-applicaiton.key
xpack.ssl.certificate: my-applicaiton.crt
xpack.ssl.certificate_authorities: ca.crt