chore: import upstream snapshot with attribution

home/docs/en/help/redis_sentinel.md

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+---
+id: redis_sentinel
+title: Monitoring Redis Sentinel
+sidebar_label: Redis Sentinel
+keywords: [open-source monitoring system, open-source database monitoring, Redis Sentinel monitoring]
+---
+
+> Collect and monitor Redis Sentinel instances for key performance metrics.
+
+## Pre-monitoring Requirements
+
+> Before adding the Redis Sentinel monitor, please ensure the following:
+
+1. The Redis Sentinel service is running and the sentinel port (default **26379**) is accessible from the HertzBeat server.
+2. If authentication is configured on the Sentinel instance, prepare the username and password.
+3. No firewall rules are blocking the sentinel port between HertzBeat and the target host.
+
+## Configuration Parameters
+
+| Parameter | Parameter Help Description |
+| --------- | -------------------------- |
+| Target Host | The IPv4, IPv6 address or domain name of the host being monitored. Note: do not include protocol headers, e.g. `192.168.0.1`. |
+| Port | The listening port of the Redis Sentinel instance. Default: **26379**. |
+| Timeout | Timeout value for the connection, in milliseconds. Default: `3000`. |
+| Username | The username used to authenticate with the Redis Sentinel instance. Optional. |
+| Password | The password used to authenticate with the Redis Sentinel instance. Optional. |
+| Collection Interval | How often HertzBeat polls this monitor, in seconds. Minimum value: 30s. |
+| Description/Remarks | Additional notes and descriptions for this monitor. |
+
+## Collection Metrics
+
+### Metric Set: sentinel
+
+> Sentinel overview metrics collected via `INFO sentinel`.
+
+| Metric Name | Metric Unit | Metric Help Description |
+| ----------- | ----------- | ----------------------- |
+| sentinel_masters | None | Total number of Redis master nodes monitored by this Sentinel instance. |
+| sentinel_tilt | None | Whether the Sentinel is currently in TILT mode (time-skew safety mode). `1` means TILT is active, `0` means normal. |
+| sentinel_running_scripts | None | Number of Lua scripts currently being executed by the Sentinel. |
+| sentinel_timedout_scripts | None | Number of scripts that have timed out. |
+| sentinel_scripts_queue_length | None | Number of scripts currently waiting in the execution queue. |
+| sentinel_simulate_failure_flags | None | Bitmask flags used for failure simulation testing (via `SENTINEL SIMULATE-FAILURE`). |
+
+### Metric Set: master_status
+
+> Status information for each monitored Redis master node.
+
+| Metric Name | Metric Unit | Metric Help Description |
+| ----------- | ----------- | ----------------------- |
+| master0 | None | Status string for the first monitored master, e.g. `name=mymaster,status=ok,address=127.0.0.1:6379,slaves=1,sentinels=3`. |
+| master1 | None | Status string for the second monitored master (if present). |
+| master2 | None | Status string for the third monitored master (if present). |
+
+### Metric Set: server
+
+> Server-level information for the Sentinel process, collected via `INFO server`.
+
+| Metric Name | Metric Unit | Metric Help Description |
+| ----------- | ----------- | ----------------------- |
+| redis_version | None | Version string of the Redis (Sentinel) binary. |
+| os | None | Operating system on which the Sentinel is running. |
+| arch_bits | None | CPU architecture (32 or 64 bits). |
+| process_id | None | PID of the Sentinel server process. |
+| tcp_port | None | The TCP port on which the Sentinel is listening. |
+| uptime_in_seconds | s | Number of seconds since the Sentinel process started. |
+| uptime_in_days | d | Number of days since the Sentinel process started. |
+| hz | None | Frequency of the server's background event loop (calls per second). |
+| executable | None | Absolute path to the server executable. |
+| config_file | None | Absolute path to the sentinel configuration file. |
+
+### Metric Set: clients
+
+> Client connection statistics, collected via `INFO clients`.
+
+| Metric Name | Metric Unit | Metric Help Description |
+| ----------- | ----------- | ----------------------- |
+| connected_clients | None | Number of client connections currently open (excluding connections from replicas). |
+| blocked_clients | None | Number of clients blocked waiting on a blocking command (e.g. BLPOP, WAIT). |
+| maxclients | None | The configured maximum number of client connections allowed. |
+| client_recent_max_input_buffer | None | Largest input buffer size (in bytes) seen across all current client connections. |
+| client_recent_max_output_buffer | None | Largest output buffer size (in bytes) seen across all current client connections. |
+
+### Metric Set: stats
+
+> General statistics, collected via `INFO stats`.
+
+| Metric Name | Metric Unit | Metric Help Description |
+| ----------- | ----------- | ----------------------- |
+| total_connections_received | None | Total number of connections accepted by the server since startup. |
+| total_commands_processed | None | Total number of commands processed by the server since startup. |
+| instantaneous_ops_per_sec | None | Number of commands processed per second (real-time snapshot). |
+| rejected_connections | None | Number of connections rejected because the `maxclients` limit was reached. |
+| total_net_input_bytes | None | Total bytes of data received from clients since startup. |
+| total_net_output_bytes | None | Total bytes of data sent to clients since startup. |
+
+### Metric Set: cpu
+
+> CPU consumption statistics, collected via `INFO cpu`.
+
+| Metric Name | Metric Unit | Metric Help Description |
+| ----------- | ----------- | ----------------------- |
+| used_cpu_sys | None | System CPU time consumed by the Sentinel server process (kernel mode). |
+| used_cpu_user | None | User CPU time consumed by the Sentinel server process (user mode). |
+| used_cpu_sys_children | None | System CPU time consumed by the background child processes (kernel mode). |
+| used_cpu_user_children | None | User CPU time consumed by the background child processes (user mode). |