tiup: add kvcdc server topylogy example

tiup/tiup-cluster-topology-reference.md

@@ -24,6 +24,7 @@ A topology configuration file for TiDB deployment using TiUP might contain the f
 - [tikv_servers](#tikv_servers): The configuration of the TiKV instance. This configuration specifies the machines to which the TiKV component is deployed.
 - [tiflash_servers](#tiflash_servers): The configuration of the TiFlash instance. This configuration specifies the machines to which the TiFlash component is deployed.
 - [tiproxy_servers](#tiproxy_servers): The configuration of the TiProxy instance. This configuration specifies the machines to which the TiProxy component is deployed.
+- [kvcdc_servers](#kvcdc_servers): The configuration of the [TiKV-CDC](https://tikv.org/docs/7.1/concepts/explore-tikv-features/cdc/cdc/) instance. This configuration specifies the machines to which the TiKV-CDC component is deployed.
 - [cdc_servers](#cdc_servers): The configuration of the TiCDC instance. This configuration specifies the machines to which the TiCDC component is deployed.
 - [tispark_masters](#tispark_masters): The configuration of the TiSpark master instance. This configuration specifies the machines to which the TiSpark master component is deployed. Only one node of TiSpark master can be deployed.
 - [tispark_workers](#tispark_workers): The configuration of the TiSpark worker instance. This configuration specifies the machines to which the TiSpark worker component is deployed.
@@ -463,6 +464,50 @@ tiproxy_servers:
   - host: 10.0.1.22
 ```
 
+### `kvcdc_servers`
+
+`kvcdc_servers` specifies the machines to which the [TiKV-CDC](https://tikv.org/docs/7.1/concepts/explore-tikv-features/cdc/cdc/) services are deployed. It also specifies the service configuration on each machine. `kvcdc_servers` is an array. Each array element contains the following fields:
+
+- `addr`: The listening address of TiKV-CDC, the HTTP API address, and the Prometheus address of the TiKV-CDC service. The default value is `127.0.0.1:8600`.
+
+- `advertise-addr`: The advertised address via which clients access TiKV-CDC. If not specified, the value is the same as that of `addr`.
+
+- `pd`: A comma-separated list of PD endpoints.
+
+- `config`: The address of the configuration file that TiKV-CDC uses (optional).
+
+- `data-dir`: The directory that TiKV-CDC uses to store temporary files for sorting. It is recommended to ensure that the free disk space for this directory is greater than or equal to 500 GiB (optional).
+
+- `gc-ttl`: The TTL (Time to Live, in seconds) of the service-level GC safepoint in PD set by TiKV-CDC (optional). It is the duration that replication tasks can be suspended, defaulting to `86400`, which is 24 hours. Note that suspending replication tasks affects the progress of TiKV garbage collection. The longer the `gc-ttl`, the longer changefeeds can be paused, but at the same time, more obsolete data will be kept and occupy more space. Vice versa.
+
+- `log-file`: The path to which logs are output when the TiKV-CDC process is running (optional). If not specified, logs are written to the standard output (stdout).
+
+- `log-level`: The log level when the TiKV-CDC process is running (optional). The default value is `"info"`.
+
+- `ca`: The path of the CA certificate file in PEM format for TLS connection (optional).
+
+- `cert`: The path of the certificate file in PEM format for TLS connection (optional).
+
+- `key`: The path of the private key file in PEM format for TLS connection (optional).
+
+- `cert-allowed-cn`: The allowed caller identities (certificate Common Name, optional). Use commas to separate multiple CNs.
+
+For the above fields, you cannot modify these configured fields after the deployment:
+
+- `host`
+- `port`
+- `deploy_dir`
+- `data_dir`
+- `log_dir`
+
+A `kvcdc_servers` configuration example is as follows:
+
+```yaml
+kvcdc_servers:
+  - host: 10.0.1.21
+  - host: 10.0.1.22
+```
+
 ### `cdc_servers`
 
 `cdc_servers` specifies the machines to which the TiCDC services are deployed. It also specifies the service configuration on each machine. `cdc_servers` is an array. Each array element contains the following fields: