[microservices] [configuration Center], [Service Discovery and Registration] who should rely on whom?

should [configuration Center] start first, and then [Service Discovery and Registration] read the configuration of [configuration Center]?
or should [Service Discovery and Registration] start first, and then [configuration Center] register itself?
or [configuration Center] and [Service Discovery and Registration] are combined into one service?

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b30cce-2bd39.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b30cce-2bd39.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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