[Improvement] Specify backup/restore PORT by name

[shanshanying]

Descriptions

When a backup job is created, some built-in ENVs will be injected into the backup JOB to perform a BACKUP task. Such envs are not not limited to:

- name: DP_DB_HOST
  value: mycluster-mysql-comp-0.mycluster-mysql-comp-headless
- name: DP_DB_PORT
  value: "3306"

The full list of ENVs can be found in :

kubeblocks/pkg/dataprotection/types/constant.go

Line 82 in 6ef3c13

const (

These ENVs are inferred from target cluster (say on which cluster to do backup).
e.g.

• DP_DB_HOST is inferred from target instance
• DP_DB_PORT is inferred from contaienrs[0].ports[0], if not specified.

Since release 0.9, ConnectionCredential is deprecated. we'd better as as useer to

1. explicitly specifiy the PROT
2. specify by either port number of port name (there are cases PORT Nubmer is not fixed, e.g. svc.spec.ports[].targePort is of type 'intorstring')

[YTGhost]

Hi, I'm interested in this issue. Please assign it to me. Thanks.

[YTGhost]

@shanshanying Hi, I am trying to solve this issue, but I still have some unclear points about it, such as where should the user specify the PORT?