Skywalking Illegal character in hostname at index

ERROR 2020-07-02 14:04:09:379 SkywalkingAgent-5-GRPCChannelManager-0 GRPCChannelManager : Create channel to apm-skywalking_oap:11800 fail. 
java.lang.IllegalArgumentException: Invalid host or port: apm-skywalking_oap 11800
        at org.apache.skywalking.apm.dependencies.io.grpc.internal.GrpcUtil.authorityFromHostAndPort(GrpcUtil.java:488)
        at org.apache.skywalking.apm.dependencies.io.grpc.netty.NettyChannelBuilder.<init>(NettyChannelBuilder.java:133)
        at org.apache.skywalking.apm.dependencies.io.grpc.netty.NettyChannelBuilder.forAddress(NettyChannelBuilder.java:119)
        at org.apache.skywalking.apm.agent.core.remote.GRPCChannel.<init>(GRPCChannel.java:38)
        at org.apache.skywalking.apm.agent.core.remote.GRPCChannel.<init>(GRPCChannel.java:29)
        at org.apache.skywalking.apm.agent.core.remote.GRPCChannel$Builder.build(GRPCChannel.java:101)
        at org.apache.skywalking.apm.agent.core.remote.GRPCChannelManager.run(GRPCChannelManager.java:115)
        at org.apache.skywalking.apm.util.RunnableWithExceptionProtection.run(RunnableWithExceptionProtection.java:33)
        at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
        at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305)
        at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.net.URISyntaxException: Illegal character in hostname at index 16: //apm-skywalking_oap:11800
        at java.base/java.net.URI$Parser.fail(URI.java:2913)
        at java.base/java.net.URI$Parser.parseHostname(URI.java:3448)
        at java.base/java.net.URI$Parser.parseServer(URI.java:3297)
        at java.base/java.net.URI$Parser.parseAuthority(URI.java:3216)
        at java.base/java.net.URI$Parser.parseHierarchical(URI.java:3158)
        at java.base/java.net.URI$Parser.parse(URI.java:3125)
        at java.base/java.net.URI.<init>(URI.java:685)
        at org.apache.skywalking.apm.dependencies.io.grpc.internal.GrpcUtil.authorityFromHostAndPort(GrpcUtil.java:486)
        ... 13 more

該問題是由於Skywalking agent連接到 oap-server，對於oap-server的主機名或者域名不能帶有 _ 下劃線，比較扯，docker swarm中生成的全名爲 stack_servicename，對於swarm service直接使用servicename即可，總之skywalking不支持 _ 下劃線的服務地址。需要避免該問題