# 2021-09-17-16:38:42+0800 Fix db-discovery uready

- Cause: `https://pingcap.pagerduty.com/incidents/PO0DN98?utm_source=slack&utm_campaign=channel`
- Operation:
1. update kube-schedule version match with kubectl version,
show k8s version
```bash
[ 08:44:31 ] ❯ KUBECONFIG=445f9b59.kubeconfig kubectl version
Client Version: version.Info{Major:"1", Minor:"20", GitVersion:"v1.20.5", GitCommit:"6b1d87acf3c8253c123756b9e61dac642678305f", GitTreeState:"clean", BuildDate:"2021-03-18T01:10:43Z", GoVersion:"go1.15.8", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"16", GitVersion:"v1.16.9", GitCommit:"a17149e1a189050796ced469dbd78d380f2ed5ef", GitTreeState:"clean", BuildDate:"2020-04-16T11:36:15Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}
```

update schedule version from v1.20.0 to v1.16.9
```bash
kubectl edit deploy tidb-scheduler -n tidb-admin
``` 

2. update tc hostnetwork field, global hostnetwork set to false, tidb and pd set to true

```bash
kubectl patch tc db -p '{"spec": {
        "hostNetwork": false,
        "pd": {
            "hostNetwork": true
        },
        "tidb": {
            "hostNetwork": true
        }
    }
}' --type=merge
```

- Impact: `db-discovery will recreate`
- Recovery operation: `NONE`
- Time window: `2021-09-17-16 ~ 2021-09-17-17`