feat: support use database as a registry

[Anilople]

What's the purpose of this PR

Use database as a registry.

less dependency, config, startup fail,

maybe more reliability,

Which issue(s) this PR fixes:

Fixes #4583

Brief changelog

A simple try to implement a registry by database.

Eureka is still default registry, this feature is active by spring boot's profile.

Write the main code in apollo-biz module with spring boot auto configuration for configservice and adminservice.

Create a new table Registry in configdb to save the service instance's information.

There 4 column with table Registry:

• ServiceName: the name of service. i.e apollo-configservice or apollo-adminservice.
• Uri: instead of host and port, use an uri like http://127.0.0.1:8080/ directly, maybe it's more simple.
• Cluster: mainly use for only discover same network region's instances.
• Metadata: for the extension in the feature, like manually register, disable health check with instance.

Here are some concept:

• register: save self's instance to database if it doesn't exist, update instance's dataChangeLastModifiedTime if it exists.
• heartbeat: do register every 10s.
• deregister: remove self's instance from database when shutdown.
• scheduled clear policy: if an instance has no heartbeat 10 minutes, delete it from database.

Unit test, changelog and document will be added when this pr's direction is correct.

Follow this checklist to help us incorporate your contribution quickly and easily:

• Read the Contributing Guide before making this pull request.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit tests to verify the code.
• Run mvn clean test to make sure this pull request doesn't break anything.
• Update the CHANGES log.

[codecov]

Codecov Report

Merging #4595 (1d1d77e) into master (f8d35bd) will increase coverage by 0.75%.
The diff coverage is 76.89%.

@@             Coverage Diff              @@
##             master    #4595      +/-   ##
============================================
+ Coverage     46.48%   47.23%   +0.75%     
- Complexity     1568     1649      +81     
============================================
  Files           332      347      +15     
  Lines         10367    10631     +264     
  Branches       1043     1053      +10     
============================================
+ Hits           4819     5022     +203     
- Misses         5252     5306      +54     
- Partials        296      303       +7     

Impacted Files	Coverage Δ
...llo/metaservice/controller/HomePageController.java	100.00% <ø> (ø)
.../metaservice/service/DatabaseDiscoveryService.java	0.00% <0.00%> (ø)
...o/metaservice/service/DefaultDiscoveryService.java	100.00% <ø> (ø)
...oServiceRegistryDeregisterApplicationListener.java	30.00% <30.00%> (ø)
...tion/support/ApolloServiceDiscoveryProperties.java	66.66% <66.66%> (ø)
...p/framework/apollo/biz/entity/ServiceRegistry.java	67.85% <67.85%> (ø)
...ation/support/ApolloServiceRegistryProperties.java	75.86% <75.86%> (ø)
...t/ApolloServiceRegistryClearApplicationRunner.java	81.25% <81.25%> (ø)
...tabaseDiscoveryClientMemoryCacheDecoratorImpl.java	84.61% <84.61%> (ø)
...olloServiceRegistryHeartbeatApplicationRunner.java	90.00% <90.00%> (ø)
... and 7 more

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[nobodyiam]

BTW, the program failed to start by running com.ctrip.framework.apollo.assembly.ApolloApplication, see the error message below.
However, it works after I removed the class ApolloRegistryAutoConfiguration. What's the use of this class?

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of method registryService in com.ctrip.framework.apollo.biz.registry.configuration.ApolloRegistryClientAutoConfiguration required a bean of type 'com.ctrip.framework.apollo.biz.repository.RegistryRepository' that could not be found.


Action:

Consider defining a bean of type 'com.ctrip.framework.apollo.biz.repository.RegistryRepository' in your configuration.

[Anilople]

BTW, the program failed to start by running com.ctrip.framework.apollo.assembly.ApolloApplication, see the error message below. However, it works after I removed the class ApolloRegistryAutoConfiguration. What's the use of this class?

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of method registryService in com.ctrip.framework.apollo.biz.registry.configuration.ApolloRegistryClientAutoConfiguration required a bean of type 'com.ctrip.framework.apollo.biz.repository.RegistryRepository' that could not be found.


Action:

Consider defining a bean of type 'com.ctrip.framework.apollo.biz.repository.RegistryRepository' in your configuration.

ApolloRegistryAutoConfiguration is used to forbid component didn't scan by springboot, see Creating a Custom Starter with Spring Boot. Write it in apollo-biz module, and conbine with conditional config, then configservice and adminservice can use it by different config.

'com.ctrip.framework.apollo.biz.repository.RegistryRepository' that could not be found

This error log still occur in my machine, I will try to fix it.

[nobodyiam]

BTW, the program failed to start by running com.ctrip.framework.apollo.assembly.ApolloApplication, see the error message below. However, it works after I removed the class ApolloRegistryAutoConfiguration. What's the use of this class?

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of method registryService in com.ctrip.framework.apollo.biz.registry.configuration.ApolloRegistryClientAutoConfiguration required a bean of type 'com.ctrip.framework.apollo.biz.repository.RegistryRepository' that could not be found.


Action:

Consider defining a bean of type 'com.ctrip.framework.apollo.biz.repository.RegistryRepository' in your configuration.

ApolloRegistryAutoConfiguration is used to forbid component didn't scan by springboot, see Creating a Custom Starter with Spring Boot. Write it in apollo-biz module, and conbine with conditional config, then configservice and adminservice can use it by different config.

'com.ctrip.framework.apollo.biz.repository.RegistryRepository' that could not be found

This error log still occur in my machine, I will try to fix it.

I think ApolloRegistryAutoConfiguration is not necessary here as the ApolloRegistryClientAutoConfiguration and ApolloRegistryDiscoveryAutoConfiguration are already in the Component Scan path, which is different from a normal spring boot starter.

[Anilople]

Should let user can manual register an instance that always be healthy?
i.e this instance won't remove when it cannot send heartbeat to database.

Or we just keep registry simple without the manual register function?

[nobodyiam]

Should let user can manual register an instance that always be healthy? i.e this instance won't remove when it cannot send heartbeat to database.

Or we just keep registry simple without the manual register function?

I don't whether this use case is valid, is there an actual scenario?

[Anilople]

Should let user can manual register an instance that always be healthy? i.e this instance won't remove when it cannot send heartbeat to database.
Or we just keep registry simple without the manual register function?

I don't whether this use case is valid, is there an actual scenario?

like profile custom-defined-discovery, register a domain, a nginx ip or a k8s service domain to database.

Some instances can be clearup, but other instances always exists whenever they have heartbeat or not.

[Anilople]

Ok~.

I add a table column Metadata with default value {}.

if someone add config

apollo.service.registry.metadata.a=1
apollo.service.registry.metadata.isAutoRegister=true

then will generate value

{"a":"1","isAutoRegister":"true"} in database

in table's column Metadata.

Is it ok?

[nobodyiam]

This looks good to me now. Please help to update the CHANGES.md and add some documentation.

[Anilople]

This looks good to me now. Please help to update the CHANGES.md and add some documentation.

When I write document, I notice that the file application-database-discovery.properties will be packaged in to .jar file.

If someone want to change

apollo.service.registry.cluster=default

to

apollo.service.registry.cluster=beijing-1

Is there another way to do it without rebuild the whole project?

Can we add it to config/application-database-discovery.properties in .zip file?

[nobodyiam]

This looks good to me now. Please help to update the CHANGES.md and add some documentation.

When I write document, I notice that the file application-database-discovery.properties will be packaged in to .jar file.

If someone want to change

apollo.service.registry.cluster=default

to

apollo.service.registry.cluster=beijing-1

Is there another way to do it without rebuild the whole project?

Can we add it to config/application-database-discovery.properties in .zip file?

The assembly-descriptor.xml could be used to achieve this. However, I think we may simply tell the user to config apollo.service.registry.cluster in config/application-github.properties, as it's not a common use case.
And there are also many other profile-specific configs, it would look messy if we copy all of them to config/ folder.

[Anilople]

This looks good to me now. Please help to update the CHANGES.md and add some documentation.

When I write document, I notice that the file application-database-discovery.properties will be packaged in to .jar file.
If someone want to change

apollo.service.registry.cluster=default

to

apollo.service.registry.cluster=beijing-1

Is there another way to do it without rebuild the whole project?
Can we add it to config/application-database-discovery.properties in .zip file?

The assembly-descriptor.xml could be used to achieve this. However, I think we may simply tell the user to config apollo.service.registry.cluster in config/application-github.properties, as it's not a common use case. And there are also many other profile-specific configs, it would look messy if we copy all of them to config/ folder.

Agree that.

it would look messy if we copy all of them to config/ folder.

And there is another thing about spring.profiles.active, I opened a discussion #4610

[Anilople]

There are some feature need to support later:

• use jvm memory as cache to decrease the read of database.
• when database happened failure, config service can run well.

left them in another pr?

[nobodyiam]

1. use jvm memory as cache to decrease the read of database.
2. when database happened failure, config service can run well.

I think we could use the first feature to enable the second feature, e.g. when the database failed, we could still use the service instance in the memory cache.
This could be enhanced with another pr.

[nobodyiam]

LGTM