Parameters for Environment Detection
Take a CentOS 7.9 server as an example
User
Description: The user when running the script
Requirement: To root a user or a user with root permissions is required because docker is in use.
Selinux
Description: The security system of Linux
Requirement: Selinux should be disabled because docker is in use.
Temporarily disabled: `setenforce 0
Permanently disabled: modify SELINUX=enforcing or SELINUX=permissive to SELINUX=disabled in /etc/selinux/config
Firewalld
Note: It is a self-contained firewall tool. It is recommended to disable the firewall as it tends to conflict with iptables rules. Cloud servers can rely on security group rules for network control.
Temporarily disabled: systemctl stop firewalld (you need to restart the docker service after shutting down the firewall, otherwise the rules may be lost and lead to network anomalies)
Permanently disabled: systemctl disable firewalld
CPU
Description: Processor
Requirements: Minimum 4 cores
Memory
Description: Memory
Requirement: Minimum 32G memory capacity
docker
Description: The docker command must be available in the environment variable and can be executed successfully.
Requirement: It will be added to the PATH environment variable automatically after installation via RPM. If it is a binary installation, you need to add it to the environment variable manually.
dockerd
Note: The dockerd command must be available in the environment variable and can be executed successfully.
Requirement: It will be added to the PATH environment variable automatically after installation via RPM. If it is a binary installation, you need to add it to the environment variable manually.
MaxMapCount
Description: It limits the number of VMAs (Virtual Memory Areas) that a process can have, and the built-in Elasticsearch needs to be adjusted to start successfully.
Temporary adjustment: sysctl -w vm.max_map_count=262144
Permanent adjustment: add the file vm.max_map_count=262144 to /etc/sysctl.conf
SysFileNr
Description: OS-level file descriptor limit
Temporary adjustment: sysctl -w fs.file-max=2048000
Permanent adjustment: add the file fs.file-max=2048000 to /etc/sysctl.conf
IPv4Forward
Note: It needs to be enabled for docker to provide external services.
Temporary adjustment: sysctl -w net.ipv4.ip_forward=1
Permanent adjustment: add the file net.ipv4.ip_forward=1 to /etc/sysctl.conf
DockerCgroupDrive
Description: The limit of Cgroup file descriptors in docker containers. If docker version is 20.10.16 or newer, it defaults to cgroupfs; if it is systemd, there may be insufficient file descriptors; if dockerd is not running, you need to start dockerd (systemctl start docker).
Permanent adjustment:
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Upgrade Docker to version 20.10.16 or newer
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If the check environment is still systemd after upgrade, you need to modify or add the configuration item "exec-opts": ["native.cgroupdriver=cgroupfs"] in /etc/docker/daemon.json
DockerdFileNr
Description: The number of file descriptors in docker. If dockerd is not running, you need to start dockerd (systemctl start docker).
Permanent adjustment: For example, if you start the docker service via systemd, set LimitNOFILE=102400 in the file docker.service.