add tiup no-sudo doc

TOC.md

@@ -432,6 +432,7 @@
     - TiUP Components
       - [tiup-playground](/tiup/tiup-playground.md)
       - [tiup-cluster](/tiup/tiup-cluster.md)
+      - [tiup-cluster no-sudo mode](/tiup/tiup-cluster-no-sudo-mode.md)
       - [tiup-mirror](/tiup/tiup-mirror.md)
       - [tiup-bench](/tiup/tiup-bench.md)
   - [TiDB Operator](/tidb-operator-overview.md)

tiup/tiup-cluster-no-sudo-mode.md

@@ -0,0 +1,204 @@
+---
+title: Deploy and Maintain an Online TiDB Cluster Using TiUP No-sudo Mode
+summary: Learns how to deploy and maintain an online TiDB cluster using TiUP no-sudo mode.
+---
+
+# Deploy and Maintain an Online TiDB Cluster Using TiUP No-sudo Mode
+
+This document describes how to use the TiUP no-sudo mode to deploy a cluster.
+
+> **Note:**
+>
+> For CentOS, only CentOS 8 or later versions are supported.
+
+## Prepare the user and configure the SSH mutual trust
+
+1. Log in to all deployment target machines in sequence, and use the `root` user to create a user named `tidb` with the following command. In no-sudo mode, there is no need to configure password-free sudo for the `tidb` user, that is, you do not need to add the `tidb` user to sudoers.
+
+    ```shell
+    adduser tidb
+    ```
+
+2. Start the `systemd` user mode for the `tidb` user on every deployment target machine. This step is required and do not skip it.
+
+    1. Use the `tidb` user to set the `XDG_RUNTIME_DIR` environment variable.
+
+        ```shell
+        mkdir -p ~/.bashrc.d
+        echo "export XDG_RUNTIME_DIR=/run/user/$(id -u)" > ~/.bashrc.d/systemd
+        source ~/.bashrc.d/systemd
+        ```
+
+    2. Use `root` user to start user service.
+
+        ```shell
+        $ systemctl start [email protected] # `1000` is the ID of the tidb user. You can get the user ID by executing the `id` command.
+        $ systemctl status [email protected]
+        [email protected] - User Manager for UID 1000
+        Loaded: loaded (/usr/lib/systemd/system/[email protected]; static; vendor preset>
+        Active: active (running) since Mon 2024-01-29 03:30:51 EST; 1min 7s ago
+        Main PID: 3328 (systemd)
+        Status: "Startup finished in 420ms."
+        Tasks: 6
+        Memory: 6.1M
+        CGroup: /user.slice/user-1000.slice/[email protected]
+                ├─dbus.service
+                │ └─3442 /usr/bin/dbus-daemon --session --address=systemd: --nofork >
+                ├─init.scope
+                │ ├─3328 /usr/lib/systemd/systemd --user
+                │ └─3335 (sd-pam)
+                └─pulseaudio.service
+                  └─3358 /usr/bin/pulseaudio --daemonize=no --log-target=journal
+        ```
+
+    Execute `systemctl --user` in the terminal. If no errors are reported, it indicates that it has started normally.
+
+3. Use ssh-keygen in the central control computer to generate a key and copy the public key to other deployment machines.
+
+## Prepare the topology file
+
+1. Use the following command to generate topology file.
+
+    ```shell
+    tiup cluster template > topology.yaml
+    ```
+
+2. Edit the topology file.
+
+    Compared with the previous mode, TiUP in no-sudo mode requires adding `systemd_mode: "user"` in the global block of `topology.yaml`. The `systemd_mode` parameter specifies whether to use systemd's user mode. If this parameter is not set, the default value is `system`, meaning sudo permissions are required. 
+
+    Additionally, in no-sudo mode, because the non-root user `tidb` has no required permissions, `/data` cannot be used as the `deploy_dir` or `data_dir`. You must select a path accessible to non-root users. The following example uses relative paths and the final paths used are `/home/tidb/data/tidb-deploy` and `/home/tidb/data/tidb-data`. The rest is the same as the old version.
+
+    ```yaml
+    global:
+      user: "tidb"
+      systemd_mode: "user"
+      ssh_port: 22
+      deploy_dir: "data/tidb-deploy"
+      data_dir: "data/tidb-data"
+      arch: "amd64"
+      ...
+    ```
+
+## Manually repair failed check items
+
+Executing `tiup cluster check topology.yaml --user tidb` will generate some failed check items. The following is an example.
+
+```shell
+Node            Check         Result  Message
+----            -----         ------  -------
+192.168.124.27  thp           Fail    THP is enabled, please disable it for best performance
+192.168.124.27  command       Pass    numactl: policy: default
+192.168.124.27  os-version    Pass    OS is CentOS Stream 8 
+192.168.124.27  network       Pass    network speed of ens160 is 10000MB
+192.168.124.27  disk          Warn    mount point / does not have 'noatime' option set
+192.168.124.27  disk          Fail    multiple components tikv:/home/blackcat/data/tidb-deploy/tikv-20160/data/tidb-data,tikv:/home/blackcat/data/tidb-deploy/tikv-20161/data/tidb-data are using the same partition 192.168.124.27:/ as data dir
+192.168.124.27  selinux       Pass    SELinux is disabled
+192.168.124.27  cpu-cores     Pass    number of CPU cores / threads: 16
+192.168.124.27  cpu-governor  Warn    Unable to determine current CPU frequency governor policy
+192.168.124.27  swap          Warn    swap is enabled, please disable it for best performance
+192.168.124.27  memory        Pass    memory size is 9681MB
+192.168.124.27  service       Fail    service firewalld is running but should be stopped
+```
+
+In no-sudo mode, the `tidb` user lacks sudo permissions, so running `tiup cluster check topology.yaml --apply --user tidb` can cause failed check items that cannot be automatically fixed due to insufficient permissions. You need to perform operations manually on the deployment machines using the `root` user.
+
+1. Install the numactl tool.
+
+    ```shell
+    sudo yum -y install numactl
+    ```
+
+2. Close swap.
+
+    ```shell
+    swapoff -a || exit 0
+    ```
+
+3. Disable transparent huge pages.
+
+    ```shell
+    echo never > /sys/kernel/mm/transparent_hugepage/enabled
+    ```
+
+4. Start the `irqbalance` service.
+
+    ```shell
+   systemctl start irqbalance
+    ```
+
+5. Disable the firewall and disable firewall auto-start.
+
+    ```shell
+    systemctl stop firewalld.service
+    systemctl disable firewalld.service
+    ```
+
+6. Modify sysctl parameters.
+
+    ```shell
+    echo "fs.file-max = 1000000">> /etc/sysctl.conf
+    echo "net.core.somaxconn = 32768">> /etc/sysctl.conf
+    echo "net.ipv4.tcp_tw_recycle = 0">> /etc/sysctl.conf
+    echo "net.ipv4.tcp_syncookies = 0">> /etc/sysctl.conf
+    echo "vm.overcommit_memory = 1">> /etc/sysctl.conf
+    echo "vm.swappiness = 0">> /etc/sysctl.conf
+    sysctl -p
+    ```
+
+7. Configure the user's `limits.conf` file.
+
+    ```shell
+    cat << EOF >>/etc/security/limits.conf
+    tidb           soft    nofile          1000000
+    tidb           hard    nofile          1000000
+    tidb           soft    stack           32768
+    tidb           hard    stack           32768
+    tidb           soft    core            unlimited
+    tidb           hard    core            unlimited
+    EOF
+    ```
+
+## Deploy the cluster
+
+To use the `tidb` user created in the previous steps and avoid creating a new one, add `--user tidb` when running the `deploy` command.
+
+```shell
+tiup cluster deploy mycluster v8.1.0 topology.yaml --user tidb
+```
+
+Start the cluster:
+
+```shell
+tiup cluster start mycluster
+```
+
+Scale out the cluster:
+
+```shell
+tiup cluster scale-out mycluster scale.yaml --user tidb
+```
+
+Scale in the cluster:
+
+```shell
+tiup cluster scale-in mycluster -N 192.168.124.27:20160
+```
+
+Upgrade the cluster:
+
+```shell
+tiup cluster upgrade mycluster v8.2.0
+```
+
+## FAQ
+
+### When you start [email protected], the following error occurs: `Failed to fully start up daemon: Permission denied`
+
+This issue might be caused by the absence of `pam_systemd.so` in your `/etc/pam.d/system-auth.ued` file.
+
+To resolve this issue, use the following command to check if the `/etc/pam.d/system-auth.ued` file contains the `pam_systemd.so` module. If not, append `session optional pam_systemd.so` to the end of the file.
+
+```shell
+grep 'pam_systemd.so' /etc/pam.d/system-auth.ued || echo 'session     optional      pam_systemd.so' >> /etc/pam.d/system-auth.ued
+```

tiup/tiup-cluster-topology-reference.md

@@ -42,6 +42,8 @@ The `global` section corresponds to the cluster's global configuration and has t
 
 - `group`: The user group to which a user belongs. It is specified when the user is created. The value defaults to that of the `<user>` field. If the specified group does not exist, it is automatically created.
 
+- `systemd_mode`: Specifies the `systemd` mode used on the target machine during cluster deployment. The default value is `system`. If set to `user`, sudo permissions are not required on the target machine, meaning [TiUP no-sudo mode](/tiup/tiup-cluster-no-sudo-mode.md) is used.
+
 - `ssh_port`: Specifies the SSH port to connect to the target machine for operations. The default value is `22`.
 
 - `enable_tls`: Specifies whether to enable TLS for the cluster. After TLS is enabled, the generated TLS certificate must be used for connections between components or between the client and the component. The default value is `false`.