How to enable TLS1.2 only in Nginx web server

LVM management mainly includes extending, reducing, deleting, renaming logical volumes and viewing structures. 1. To expand the logical volume, you need to confirm the remaining space of VG, and then use lvextend to expand and adjust the file system; 2. Before shrinking the logical volume, you must back up, uninstall, check, and shrink the file system and the logical volume in turn; 3. Delete the logical volume first uninstall and then use the lvremove command, rename and use lvrename and update fstab; 4. You can use pvdisplay, vgdisplay, lvdisplay or simplified commands lvs and vgs to view the structure. Be careful when operating to avoid data loss.

The steps to install Kubernetes include: 1. Prepare the system environment and dependencies, such as using Ubuntu or CentOS, close swap, install Docker/containerd, kubeadm, kubelet, and kubectl; 2. Use kubeadm to initialize the master node and configure user permissions; 3. Run the kubeadmjoin command on the worker node to join the cluster; 4. Install CNI network plug-ins such as Flannel to ensure the interoperability of Pod networks. The entire process requires attention to details such as firewall, swap settings and network plug-in selection, and problems can be checked through kubelet logs.

Steps to build a local development environment using Vagrant: 1. Install VirtualBox and Vagrant; 2. Execute vagrantinit initialization environment and generate Vagrantfile; 3. Configure virtual machine parameters such as system image, network, and shared folders; 4. Run vagrantup to start the virtual machine and automatically deploy dependencies; 5. Log in to the virtual machine through vagrantssh for service installation and debugging. Common considerations include solving shared folder permission issues, optimizing performance configuration, and rationally managing Vagrantfiles for multiple projects.

The key to system update monitoring is to establish a mechanism to promptly understand updates. First, use the system's own tools to check and update regularly, such as Linux's apt/yum/dnf, Windows Update and macOS's softwareupdate commands; second, configure the automatic notification mechanism, and implement daily reminders by writing scripts combined with cron timing tasks and email or message push services; finally, for multi-device management scenarios, third-party tools such as Lynis, SaltStack, Ansible, Nagios or Zabbix can be used to centrally monitor and alarm to ensure that system security patches are updated in a timely manner.

THP problem troubleshooting needs to be carried out in accordance with the steps. 1. Confirm whether THP is enabled. Check the /sys/kernel/mm/transparent_hugepage/enabled status. If it is always or madvise, it is recommended to set it to never for delay-sensitive applications; 2. Check whether there is delay caused by THP or the CPU is too high, observe the activity of kcompactd0 or khugepaged process, and monitor the growth of related indicators through /proc/vmstat; 3. Analyze the relationship between the application layer performance and THP. For example, applications such as Redis, PostgreSQL and other applications may cause fork delay or performance degradation due to THP. You can turn it off.

To enable and check the AppArmor status, execute systemctlstatusapparm. If it is not started, use sudosystemctlstartapparmor and set the power-on and then execute aa-status to view the policy loading status. To create a configuration file, you need to manually store it in the /etc/apparmor.d/ directory or use aa-genprof to generate the basic configuration and then load it through apparmor_parser. During debugging, you can check logs in combination with dmesg or journalctl to find permission problems. You can temporarily switch the complain mode to adjust the policy and then restore the enforce mode. Notes include avoiding direct copying

To troubleshoot high load average, you must first confirm the load status and then analyze the resource bottlenecks. First, use uptime or top to view the loadaverage value. If it continues to be higher than the number of CPU cores, the system may be under pressure; then run htop, free-h, df-h and iostat-x1 to check the CPU usage, memory, disk space and IO conditions respectively; further use vmstat1 or sar to observe the overall trend, and locate the specific process behavior through pidstat-pPID; judge it as CPU-intensive, IO-intensive, insufficient memory or abnormal processes based on the load type; take measures such as limiting resources, optimizing code, upgrading hardware or releasing caches for different situations; at the same time, you can use

Using an SSH key is more secure and convenient than a password because it has high encryption strength, prevents brute force cracking, and enables password-free login through configuration. 1. The SSH key pair consists of a private key and a public key. The private key is protected with a password, and cannot be used directly even if it is leaked; 2. Use the ssh-keygen-trsa-b4096 command to generate the key, and save the default path, and it is recommended to create independent keys for different purposes; 3. Add the public key to the server to use the ssh-copy-iduser@hostname command or manually copy and paste it in the ~/.ssh/authorized_keys file. Note that the directory permission is set to 700 and the file permission is 600; 4. When using multiple keys, you can use the ~/.ssh/conf