[Multi-Database Support] Introduce h2 postgre profile properties to let user config database config

[shoothzj]

Brief changelog

Introduce h2 postgre profile properties to let user config database config

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[codecov]

Codecov Report

Merging #4766 (9df198f) into master (9bed634) will decrease coverage by 0.05%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #4766      +/-   ##
============================================
- Coverage     47.26%   47.21%   -0.05%     
- Complexity     1657     1658       +1     
============================================
  Files           346      346              
  Lines         10683    10683              
  Branches       1063     1063              
============================================
- Hits           5049     5044       -5     
- Misses         5328     5331       +3     
- Partials        306      308       +2     

Impacted Files	Coverage Δ
...oServiceRegistryDeregisterApplicationListener.java	30.00% <0.00%> (-45.00%)	⬇️
...mework/apollo/openapi/service/ConsumerService.java	58.46% <0.00%> (+1.53%)	⬆️
...framework/apollo/openapi/entity/ConsumerAudit.java	48.48% <0.00%> (+6.06%)	⬆️

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[nobodyiam]

It looks like the content is the same among h2/postgres/mysql, I'm thinking if it's possible to leave the datasource config in application-github.properties and config database specific properties in application-mysql.properties/application-h2.properties/application-postgres.properties?

[shoothzj]

@nobodyiam Yes we can, But that would require udpated users add a mysql profile.
This is also a viable direction, I think we will eventually rename the github profile, give it a proper name.

• If we move database specific properties out, that's jpa
• If we keep database specific properties still in here, that's mysql

[nobodyiam]

I have given some thoughts on this and here are my suggestions.

1. Keep the github profile
   The github profile was designed to distinguish the internal version and the github version, the major difference is the datasource configuration part. So that's why the only configurations in the file are spring.datasource.*.
   Since Apollo is now widely deployed in many production sites, it's better we keep the github profile so that existing users could upgrade seamlessly, e.g. they could keep the previous startup scripts and only update the executables.

Another benefit is the current documentation could be reused, we don't need to modify the previous instructions.

2. Separate data source connection configuration and database specific configuration
   I suppose the data source connection configuration is the same for mysql/h2/postgres and since the user needs to change them, so we leave it in the application-github.properties.

# DataSource
spring.datasource.url = ${spring_datasource_url}
spring.datasource.username = ${spring_datasource_username}
spring.datasource.password = ${spring_datasource_password}

However, other configurations like init sql could be different for different databases and normally users don't need to change them, so we put them in database specific properties, e.g. application-mysql.properties

# Configurations for MySQL
spring.datasource.hikari.connection-init-sql = SET NAMES utf8mb4

3. Database default to MySQL
   It's important to make Apollo backward compatible and reduce the upgrading effort, so it's necessary to make the MySQL as the default database. To achieve this, we could configure the github profile default to include the mysql profile in the application.properties and document the steps about how to enable use h2 or postgres.

# You may change the following config to activate different database profiles like h2/postgres
spring.profiles.group.github = mysql

[shoothzj]

@nobodyiam spring.profiles.group.github is cool!!! Fixed

[shoothzj]

@nobodyiam Sorry, maybe I need a cup of coffee. The quality of the patch I was working on earlier was poor, and I was a bit distracted. But it's fixed now.

[nobodyiam]

LGTM