Add kubernetes native service discovery support and helm chart templates

[nobodyiam]

What's the purpose of this PR

Add kubernetes native service discovery support to simplify the deployment complexity of apollo and enable the possibliity to integrate with other kubernetes tooling ,such as Istio.

Which issue(s) this PR fixes:

Fixes #3054

Brief changelog

1. Add KubernetesDiscoveryService implementation that skips any service discovery and just return what is configured
2. Add helm charts for configservice, adminservice and portal which leverage the kubernetes native service discovery

Helm Chart Quick Start

1. Add Apollo Helm Chart Repository

$ helm repo add apollo http://ctripcorp.github.io/apollo/charts
$ helm search repo apollo

2. Install apollo-configservice and apollo-adminservice

Suppose the address of ApolloConfigDB is 1.2.3.4, user name/password is apollo, then

$ helm install apollo-service-dev \
    --set configdb.host=1.2.3.4 \
    --set configdb.userName=apollo \
    --set configdb.password=apollo \
    --set configdb.service.enabled=true \
    --set configService.replicaCount=1 \
    --set adminService.replicaCount=1 \
    apollo/apollo-service

3. Install apollo-portal

Suppose the address of ApolloPortalDB is 1.2.3.4, user name/password is apollo, the service name of apollo-configservice is apollo-service-dev-apollo-configservice, then

$ helm install apollo-portal \
    --set portaldb.host=1.2.3.4 \
    --set portaldb.userName=apollo \
    --set portaldb.password=apollo \
    --set portaldb.service.enabled=true \
    --set config.envs="dev" \
    --set config.metaServers.dev=http://apollo-service-dev-apollo-configservice:8080 \
    --set replicaCount=1 \
    apollo/apollo-portal

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• Read the Contributing Guide before making this pull request.
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[codecov-io]

Codecov Report

Merging #3055 into master will increase coverage by 0.23%.
The diff coverage is 94.54%.

@@             Coverage Diff              @@
##             master    #3055      +/-   ##
============================================
+ Coverage     51.32%   51.55%   +0.23%     
- Complexity     2235     2249      +14     
============================================
  Files           432      433       +1     
  Lines         13385    13404      +19     
  Branches       1375     1372       -3     
============================================
+ Hits           6870     6911      +41     
+ Misses         6041     6017      -24     
- Partials        474      476       +2     

Impacted Files	Coverage Δ	Complexity Δ
...k/apollo/adminservice/AdminServiceApplication.java	0.00% <ø> (ø)	0.00 <0.00> (ø)
...apollo/configservice/ConfigServiceApplication.java	0.00% <ø> (ø)	0.00 <0.00> (ø)
...k/apollo/portal/component/config/PortalConfig.java	25.30% <0.00%> (ø)	9.00 <0.00> (ø)
...lo/portal/spi/configuration/AuthConfiguration.java	6.39% <33.33%> (+0.54%)	2.00 <1.00> (+1.00)
...rvice/controller/KubernetesHomePageController.java	100.00% <100.00%> (ø)	2.00 <2.00> (?)
...ollo/metaservice/controller/ServiceController.java	100.00% <100.00%> (+77.77%)	4.00 <3.00> (+2.00)
...o/metaservice/service/DefaultDiscoveryService.java	100.00% <100.00%> (ø)	6.00 <6.00> (?)
...etaservice/service/KubernetesDiscoveryService.java	100.00% <100.00%> (ø)	7.00 <7.00> (?)
...ip/framework/apollo/mockserver/EmbeddedApollo.java	90.12% <0.00%> (-2.65%)	18.00% <0.00%> (-1.00%)
.../apollo/internals/RemoteConfigLongPollService.java	79.51% <0.00%> (-1.21%)	28.00% <0.00%> (-1.00%)
... and 3 more

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[codecov-commenter]

Codecov Report

Merging #3055 into master will increase coverage by 0.28%.
The diff coverage is 94.54%.

@@             Coverage Diff              @@
##             master    #3055      +/-   ##
============================================
+ Coverage     51.22%   51.50%   +0.28%     
- Complexity     2234     2251      +17     
============================================
  Files           432      433       +1     
  Lines         13427    13448      +21     
  Branches       1382     1379       -3     
============================================
+ Hits           6878     6927      +49     
+ Misses         6069     6042      -27     
+ Partials        480      479       -1     

Impacted Files	Coverage Δ	Complexity Δ
...k/apollo/adminservice/AdminServiceApplication.java	0.00% <ø> (ø)	0.00 <0.00> (ø)
...apollo/configservice/ConfigServiceApplication.java	0.00% <ø> (ø)	0.00 <0.00> (ø)
...k/apollo/portal/component/config/PortalConfig.java	25.30% <0.00%> (ø)	9.00 <0.00> (ø)
...lo/portal/spi/configuration/AuthConfiguration.java	6.39% <33.33%> (+0.54%)	2.00 <1.00> (+1.00)
...rvice/controller/KubernetesHomePageController.java	100.00% <100.00%> (ø)	2.00 <2.00> (?)
...ollo/metaservice/controller/ServiceController.java	100.00% <100.00%> (+77.77%)	4.00 <3.00> (+2.00)
...o/metaservice/service/DefaultDiscoveryService.java	100.00% <100.00%> (ø)	6.00 <6.00> (?)
...etaservice/service/KubernetesDiscoveryService.java	100.00% <100.00%> (ø)	7.00 <7.00> (?)
... and 2 more

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update df6cb39...7ac6bd2. Read the comment docs.

[stheart]

$ helm repo add apollo http://ctripcorp.github.io/apollo/charts
$ helm search repo apollo
执行完上述命令后显示为：No results found
http://ctripcorp.github.io/apollo/charts 这个地址是正确的吗

[nobodyiam]

@stheart 地址是正确的，看下是否是你本地的网络访问有问题？可以尝试下载下面的文件试试
http://ctripcorp.github.io/apollo/charts/index.yaml

[stheart]

@stheart 地址是正确的，看下是否是你本地的网络访问有问题？可以尝试下载下面的文件试试
http://ctripcorp.github.io/apollo/charts/index.yaml

地址没问题，是我helm版本低了，不支持helm search repo