Ktor no netty_transport_native_epoll_x86_64 in java.library.path

Hi all

During starting Ktor application, I've got the following logs:

```
java.lang.UnsatisfiedLinkError: no netty_transport_native_epoll_x86_64 in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1871)
at java.lang.Runtime.loadLibrary0(Runtime.java:872)
at java.lang.System.loadLibrary(System.java:1124)
at io.netty.util.internal.NativeLibraryUtil.loadLibrary(NativeLibraryUtil.java:38)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at io.netty.util.internal.NativeLibraryLoader$1.run(NativeLibraryLoader.java:369)
at java.security.AccessController.doPrivileged(Native Method)
at io.netty.util.internal.NativeLibraryLoader.loadLibraryByHelper(NativeLibraryLoader.java:361)
at io.netty.util.internal.NativeLibraryLoader.loadLibrary(NativeLibraryLoader.java:339)
at io.netty.util.internal.NativeLibraryLoader.load(NativeLibraryLoader.java:136)
at io.netty.channel.epoll.Native.loadNativeLibrary(Native.java:231)
at io.netty.channel.epoll.Native.(Native.java:58)
at io.netty.channel.epoll.Epoll.(Epoll.java:39)
at io.ktor.server.netty.EventLoopGroupProxy$Companion.create(NettyApplicationEngine.kt:189)
at io.ktor.server.netty.NettyApplicationEngine.(NettyApplicationEngine.kt:74)
at io.ktor.server.netty.EngineMain.main(EngineMain.kt:22)
22:56:07.760 [main] DEBUG io.netty.util.internal.NativeLibraryLoader - netty_transport_native_epoll_x86_64 cannot be loaded from java.library.path, now trying export to -Dio.netty.native.workdir: /tmp
java.lang.UnsatisfiedLinkError: no netty_transport_native_epoll_x86_64 in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1871)
at java.lang.Runtime.loadLibrary0(Runtime.java:872)
at java.lang.System.loadLibrary(System.java:1124)
at io.netty.util.internal.NativeLibraryUtil.loadLibrary(NativeLibraryUtil.java:38)
at io.netty.util.internal.NativeLibraryLoader.loadLibrary(NativeLibraryLoader.java:349)
at io.netty.util.internal.NativeLibraryLoader.load(NativeLibraryLoader.java:136)
at io.netty.channel.epoll.Native.loadNativeLibrary(Native.java:231)
at io.netty.channel.epoll.Native.(Native.java:58)
at io.netty.channel.epoll.Epoll.(Epoll.java:39)
at io.ktor.server.netty.EventLoopGroupProxy$Companion.create(NettyApplicationEngine.kt:189)
at io.ktor.server.netty.NettyApplicationEngine.(NettyApplicationEngine.kt:74)
at io.ktor.server.netty.EngineMain.main(EngineMain.kt:22)
Suppressed: java.lang.UnsatisfiedLinkError: no netty_transport_native_epoll_x86_64 in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1871)
at java.lang.Runtime.loadLibrary0(Runtime.java:872)
at java.lang.System.loadLibrary(System.java:1124)
at io.netty.util.internal.NativeLibraryUtil.loadLibrary(NativeLibraryUtil.java:38)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at io.netty.util.internal.NativeLibraryLoader$1.run(NativeLibraryLoader.java:369)
at java.security.AccessController.doPrivileged(Native Method)
at io.netty.util.internal.NativeLibraryLoader.loadLibraryByHelper(NativeLibraryLoader.java:361)
at io.netty.util.internal.NativeLibraryLoader.loadLibrary(NativeLibraryLoader.java:339)
... 7 common frames omitted
22:56:07.761 [main] DEBUG io.netty.util.internal.NativeLibraryLoader - Unable to load the library 'netty_transport_native_epoll', trying other loading mechanism.
java.lang.UnsatisfiedLinkError: no netty_transport_native_epoll in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1871)
at java.lang.Runtime.loadLibrary0(Runtime.java:872)
at java.lang.System.loadLibrary(System.java:1124)
at io.netty.util.internal.NativeLibraryUtil.loadLibrary(NativeLibraryUtil.java:38)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at io.netty.util.internal.NativeLibraryLoader$1.run(NativeLibraryLoader.java:369)
at java.security.AccessController.doPrivileged(Native Method)
at io.netty.util.internal.NativeLibraryLoader.loadLibraryByHelper(NativeLibraryLoader.java:361)
at io.netty.util.internal.NativeLibraryLoader.loadLibrary(NativeLibraryLoader.java:339)
at io.netty.util.internal.NativeLibraryLoader.load(NativeLibraryLoader.java:136)
at io.netty.channel.epoll.Native.loadNativeLibrary(Native.java:234)
at io.netty.channel.epoll.Native.(Native.java:58)
at io.netty.channel.epoll.Epoll.(Epoll.java:39)
at io.ktor.server.netty.EventLoopGroupProxy$Companion.create(NettyApplicationEngine.kt:189)
at io.ktor.server.netty.NettyApplicationEngine.(NettyApplicationEngine.kt:74)
at io.ktor.server.netty.EngineMain.main(EngineMain.kt:22)
22:56:07.761 [main] DEBUG io.netty.util.internal.NativeLibraryLoader - netty_transport_native_epoll cannot be loaded from java.library.path, now trying export to -Dio.netty.native.workdir: /tmp
java.lang.UnsatisfiedLinkError: no netty_transport_native_epoll in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1871)
at java.lang.Runtime.loadLibrary0(Runtime.java:872)
at java.lang.System.loadLibrary(System.java:1124)
at io.netty.util.internal.NativeLibraryUtil.loadLibrary(NativeLibraryUtil.java:38)
at io.netty.util.internal.NativeLibraryLoader.loadLibrary(NativeLibraryLoader.java:349)
at io.netty.util.internal.NativeLibraryLoader.load(NativeLibraryLoader.java:136)
at io.netty.channel.epoll.Native.loadNativeLibrary(Native.java:234)
at io.netty.channel.epoll.Native.(Native.java:58)
at io.netty.channel.epoll.Epoll.(Epoll.java:39)
at io.ktor.server.netty.EventLoopGroupProxy$Companion.create(NettyApplicationEngine.kt:189)
at io.ktor.server.netty.NettyApplicationEngine.(NettyApplicationEngine.kt:74)
at io.ktor.server.netty.EngineMain.main(EngineMain.kt:22)
Suppressed: java.lang.UnsatisfiedLinkError: no netty_transport_native_epoll in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1871)
at java.lang.Runtime.loadLibrary0(Runtime.java:872)
at java.lang.System.loadLibrary(System.java:1124)
at io.netty.util.internal.NativeLibraryUtil.loadLibrary(NativeLibraryUtil.java:38)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at io.netty.util.internal.NativeLibraryLoader$1.run(NativeLibraryLoader.java:369)
at java.security.AccessController.doPrivileged(Native Method)
at io.netty.util.internal.NativeLibraryLoader.loadLibraryByHelper(NativeLibraryLoader.java:361)
at io.netty.util.internal.NativeLibraryLoader.loadLibrary(NativeLibraryLoader.java:339)
... 7 common frames omitted
```
the build file

```
plugins {
application
kotlin("jvm") version "1.3.61"
}

group = "io.oceanstack"
version = "1.0-SNAPSHOT"

val ktor_version = "1.3.1"

repositories {
mavenCentral()
jcenter()
}

dependencies {
implementation(kotlin("stdlib-jdk8"))
compile("io.ktor:ktor-server-core:$ktor_version")
compile("io.ktor:ktor-server-netty:$ktor_version")
compile("ch.qos.logback:logback-classic:1.2.3")
testCompile(group = "junit", name = "junit", version = "4.12")
}

tasks {
compileKotlin {
kotlinOptions.jvmTarget = "1.8"
}
compileTestKotlin {
kotlinOptions.jvmTarget = "1.8"
}
}

application {
mainClassName = "io.ktor.server.netty.EngineMain"
}
```
What am I doing wrong?

The Java runtime:

```
java -version
openjdk version "1.8.0_242"
OpenJDK Runtime Environment (Zulu 8.44.0.11-CA-linux64) (build 1.8.0_242-b20)
OpenJDK 64-Bit Server VM (Zulu 8.44.0.11-CA-linux64) (build 25.242-b20, mixed mode)
```

Thanks

Start with the dependency and application configuration in the shown build file, then trace startup through io.ktor.server.netty.EventLoopGroupProxy, NettyApplicationEngine, and EngineMain. Reproduce the application launch and determine why the native epoll library is unavailable; done means the reported UnsatisfiedLinkError is resolved or the required configuration is documented.

Written by the indexing model from the issue text.