유레카 모듈 추가

discovery/build.gradle

@@ -0,0 +1,14 @@
+ext {
+    set('springCloudVersion', "2021.0.1")
+}
+
+dependencies {
+    implementation 'org.springframework.cloud:spring-cloud-starter-netflix-eureka-server'
+    testImplementation 'org.springframework.boot:spring-boot-starter-test'
+}
+
+dependencyManagement {
+    imports {
+        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
+    }
+}

discovery/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'discovery'

discovery/src/main/java/com/roy/springcloud/discovery/DiscoveryApplication.java

@@ -0,0 +1,15 @@
+package com.roy.springcloud.discovery;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
+
+@EnableEurekaServer
+@SpringBootApplication
+public class DiscoveryApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(DiscoveryApplication.class, args);
+    }
+
+}

discovery/src/main/resources/application.yml

@@ -0,0 +1,11 @@
+server:
+  port: 8761
+
+spring:
+  application:
+    name: discovery
+
+eureka:
+  client:
+    register-with-eureka: false
+    fetch-registry: false

discovery/src/test/java/com/roy/springcloud/discovery/DiscoveryApplicationTests.java

@@ -1,10 +1,10 @@
-package com.roy.users;
+package com.roy.springcloud.discovery;
 
 import org.junit.jupiter.api.Test;
 import org.springframework.boot.test.context.SpringBootTest;
 
 @SpringBootTest
-class UsersApplicationTests {
+class DiscoveryApplicationTests {
 
     @Test
     void contextLoads() {

document/discovery/eureka_practice.md

@@ -0,0 +1,79 @@
+이번 장에서는 [Spring Cloud Netflix Eureka - 이론]()에 이어 직접 디스커버리(유레카) 서버를 구축해본다.
+모든 소스 코드는 [깃허브 (링크)](https://github.com/roy-zz/spring-cloud) 에 올려두었다.
+
+---
+
+### 기본 프로젝트 구성
+
+마이크로서비스의 특성상 한 번에 많은 프로젝트를 실행시켜야한다.
+수많은 프로젝트를 위해 IDE를 여러개 실행시키기에는 무리가 있으므로 멀티 모듈로 구성하여 진행하도록 한다.
+멀티 모듈 프로젝트 구성은 필자가 이전에 작성해놓은 [글 (링크)](https://imprint.tistory.com/206?category=1069520) 를 참고하도록 한다.
+
+---
+
+**1. 의존성 추가.**
+
+유레카 서버를 구축하기 위해 필요한 의존성이므로 전부 추가하도록 한다.
+
+```bash
+ext {
+    set('springCloudVersion', "2021.0.1")
+}
+
+dependencies {
+    implementation 'org.springframework.cloud:spring-cloud-starter-netflix-eureka-server'
+    testImplementation 'org.springframework.boot:spring-boot-starter-test'
+}
+
+dependencyManagement {
+    imports {
+        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
+    }
+}
+```
+
+**2. MainClass 수정**
+
+main 메서드가 있는 클래스에 @EnableEurekaServer 애노테이션을 작성해준다.
+
+```java
+@EnableEurekaServer
+@SpringBootApplication
+public class DiscoveryApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(DiscoveryApplication.class, args);
+    }
+}
+```
+
+**3. application.yml 수정**
+
+서버가 사용할 포트를 8761로 지정하였다.
+애플리케이션의 이름을 discovery로 지정하였다.
+eureka.client.register-with-eureka(유레카 서버에 등록이 될 것인지)와 eureka.client.fetch-registry(유레카 서버의 registry와 동기화 여부)는 기본값이 true다.
+유레카 서버의 경우 두 기능이 필요없으므로 false 처리한다.
+
+```yaml
+server:
+  port: 8761
+
+spring:
+  application:
+    name: discovery
+
+eureka:
+  client:
+    register-with-eureka: false
+    fetch-registry: false
+```
+
+**4. 정상작동 확인**
+
+애플리케이션을 실행시키고 브라우저로 이동하여 localhost:8761으로 접속한다.
+아래의 이미지와 같은 화면이 나온다면 정상적으로 유레카 서버 구축이 완료된 것이다.
+
+![](image/eureka-page.png)
+
+---
+
+참고한 강의: https://www.inflearn.com/course/%EC%8A%A4%ED%94%84%EB%A7%81-%ED%81%B4%EB%9D%BC%EC%9A%B0%EB%93%9C-%EB%A7%88%EC%9D%B4%ED%81%AC%EB%A1%9C%EC%84%9C%EB%B9%84%EC%8A%A4

document/discovery/eureka_theory.md

@@ -0,0 +1,40 @@
+이번 장에서는 Spring Cloud Netflix Eureka(이하 유레카)에 대해서 알아보고 직접 유레카 서버를 구축해본다.
+
+### Spring Cloud Netflix Eureka
+
+마이크로서비스 아키텍처에서 유레카란 client-side service discovery라고 할 수 있다.
+시스템은 트래픽에 따라 동적으로 늘어날 수도 줄어들 수도 있다. 
+이러한 환경에서 서비스의 host와 port가 동적으로 변하더라도 서비스 인스턴스를 호출할 수 있도록 해주는 Service Registry를 제공 및 관리해준다.
+
+#### 설계 목적
+
+유레카는 middle-tier load balancer로 정의된다.
+middle-tier load balancer는 로드밸런싱과 장애복구(failover)가 가능한 middle-tier 서비스 환경을 구성 했을 때 클라이언트(추후에 살펴볼 API Gateway 또는 서비스간 통신)에게 사용 가능한 서비스의 위치 정보를 동적으로 제공할 수 있어야 한다.
+전통적인 로드밸런싱의 경우 서비스의 위치가 고정되어 있었지만 AWS와 같은 클라우드 환경에서는 서버의 위치가 동적으로 변동되기 때문에 개발자가 직접 이를 컨트롤 하기는 쉽지 않다.
+AWS에서는 middle-tier load balancer를 제공하지 않기 때문에 유레카는 더 많은 관심을 받고 있다.
+
+#### 잘 설계된 유레카 서버 구조
+
+![](image/eureka-server-architecture.png)
+
+AWS 기준으로 가용지역마다 유레카 서버가 복제되어 있다.
+서버가 복제되어 있기 때문에 일부 유레카 서버가 중지되더라도 서비스 전체가 중지되는 현상은 발생하지 않는다.
+
+#### 용어 정리
+
+* Service Registration: Client(마이크로서비스)가 자신의 정보를 유레카에 등록하는 행동을 의미한다.
+
+* Service Registry: Client의 정보들(목록, 가용 Client의 위치)을 저장하는 위치를 의미한다.
+
+* Service Discovery: 클라이언트가 Service Registry에서 요청을 보내야하는 대상을 찾는 과정을 의미한다.
+
+
+
+
+
+
+---
+
+Spring Cloud Netflix Eureka에 대한 설명의 아래의 글을 재해석 하였음.
+
+- 참고한 자료: https://coe.gitbook.io/guide/

settings.gradle

@@ -1,2 +1,3 @@
 rootProject.name = 'springcloud'
-include("users")
+include("discovery")
+include("zuul-gateway")

users/build.gradle

@@ -1,4 +0,0 @@
-dependencies {
-    api("org.springframework.boot:spring-boot-starter")
-    testImplementation("org.springframework.boot:spring-boot-starter-test")
-}

users/settings.gradle

@@ -1 +0,0 @@
-rootProject.name = 'users'

zuul-gateway/build.gradle

@@ -0,0 +1,8 @@
+plugins {
+    id 'org.springframework.boot' version '2.3.9'
+}
+
+dependencies {
+    implementation 'org.springframework.boot:spring-boot-starter'
+    testImplementation 'org.springframework.boot:spring-boot-starter-test'
+}

zuul-gateway/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.4.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

zuul-gateway/gradlew

@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

zuul-gateway/gradlew.bat

@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

zuul-gateway/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'zuul-gateway'

zuul-gateway/src/main/java/com/roy/springcloud/zuulgateway/ZuulGatewayApplication.java

@@ -1,13 +1,13 @@
-package com.roy.users;
+package com.roy.springcloud.zuulgateway;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 
 @SpringBootApplication
-public class UsersApplication {
+public class ZuulGatewayApplication {
 
     public static void main(String[] args) {
-        SpringApplication.run(UsersApplication.class, args);
+        SpringApplication.run(ZuulGatewayApplication.class, args);
     }
 
 }

zuul-gateway/src/test/java/com/roy/springcloud/zuulgateway/ZuulGatewayApplicationTests.java

@@ -0,0 +1,13 @@
+package com.roy.springcloud.zuulgateway;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class ZuulGatewayApplicationTests {
+
+    @Test
+    void contextLoads() {
+    }
+
+}