使用 Kafka 和 ELK 搭建测试日志系统（1）
本文仅供自己学习，不合适转载。这是两篇文章的第一部分。
1. 安装 ELK
1.1 安装 ElasticSearch
在海航云上创建一个 Ubutu 16.4 虚机，2核4GB内存。
（1）执行以下命令，更新系统
sudo apt-get update -y
sudo apt-get upgrade -y
（2）安装 Java
sudo add-apt-repository -y ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java8-installer -y
（3）安装ES
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-5.2.2.deb
sudo dpkg -i elasticsearch-5.2.2.deb
修改/etc/elasticsearch/elasticsearch.yml:
[*]将 network.host 修改为本机 ip 即 192.168.10.102
[*]将 http.port 修改为 9200
[*]将 cluster.name 修改为 elk-test
重启 ES并检查服务状态：
root@elk:/home/ubuntu# service elasticsearch restart
root@elk:/home/ubuntu# service elasticsearch status
● elasticsearch.service - Elasticsearch
Loaded: loaded (/usr/lib/systemd/system/elasticsearch.service; disabled; vendor preset: enab
Active: active (running) since Sat 2017-09-30 11:23:17 CST; 3s ago
Docs: http://www.elastic.co
Process: 3861 ExecStartPre=/usr/share/elasticsearch/bin/elasticsearch-systemd-pre-exec (code=
Main PID: 3864 (java)
Tasks: 15
Memory: 2.1G
CPU: 4.511s
1.2 安装 Nginx 和 Logstash
创建另一台虚机，安装 Nginx 和 Logstash。
1.2.1 安装 Nginx
apt-get install nginx
Ubuntu安装之后的文件结构大致为：
[*]所有的配置文件都在/etc/nginx下，并且每个虚拟主机已经安排在了/etc/nginx/sites-available下
[*]程序文件在/usr/sbin/nginx
[*]日志放在了/var/log/nginx中
[*]并已经在/etc/init.d/下创建了启动脚本nginx
[*]默认的虚拟主机的目录设置在了/var/www/nginx-default (有的版本 默认的虚拟主机的目录设置在了/var/www, 请参考/etc/nginx/sites-available里的配置)
启动并查看服务状态：
root@elk:/home/ubuntu# /etc/init.d/nginx start
[ ok ] Starting nginx (via systemctl): nginx.service.
root@elk:/home/ubuntu# /etc/init.d/nginx status
● nginx.service - A high performance web server and a reverse proxy server
Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
Active: active (running) since Sat 2017-09-30 11:40:59 CST; 1min 8s ago
Main PID: 4320 (nginx)
CGroup: /system.slice/nginx.service
├─4320 nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
├─4321 nginx: worker process
└─4322 nginx: worker process
Sep 30 11:40:59 elk systemd: Starting A high performance web server and a reverse pro...r...
Sep 30 11:40:59 elk systemd: Started A high performance web server and a reverse prox...ver.
Sep 30 11:42:06 elk systemd: Started A high performance web server and a reverse prox...ver.
Hint: Some lines were ellipsized, use -l to show in full.
为了测试起见，将端口修改为 88.修改文件/etc/nginx/sites-available/default，并重启 Nginx 服务：
server {
listen 88 default_server;
listen [::]:88 default_server;
鉴于该服务器没有设置公网IP，在其路由器上设置端口转发规则，使得可以通过路由器的EIP的88端口访问到它上面的Nginx服务：
在浏览器上测试，Nginx 可用：
1.2.2 安装和配置 Logstash
wget https://artifacts.elastic.co/downloads/logstash/logstash-5.2.2.tar.gz
tar zxvf logstash-5.2.2.tar.gz
ln -s logstash-5.2.2 logstash
创建文件 nginxlog2es.conf，内容如下。它会将 Nginx 的日志文件 /var/log/nginx/access.log_json 中的日志发到 ES 服务器 192.168.10.102:9200：
input {
file {
path => "/var/log/nginx/access.log_json"
codec => "json"
}
}
filter {
mutate {
split => [ "upstreamtime", "," ]
}
mutate {
convert => [ "upstreamtime", "float" ]
}
}
output {
stdout { codec => rubydebug }
elasticsearch {
hosts => ["192.168.10.102:9200"]
index => "logstash-%{type}-%{+YYYY.MM.dd}"
document_type => "%{type}"
flush_size => 20000
idle_flush_time => 10
sniffing => true
template_overwrite => true
}
}
修改 /etc/nginx/nginx.conf，添加：
##
# Logging Settings
##
log_format json '{"@timestamp":"$time_iso8601",'
'"host":"$server_addr",'
'"clientip":"$remote_addr",'
'"size":$body_bytes_sent,'
'"responsetime":$request_time,'
'"upstreamtime":"$upstream_response_time",'
'"upstreamhost":"$upstream_addr",'
'"http_host":"$host",'
'"url":"$uri",'
'"xff":"$http_x_forwarded_for",'
'"referer":"$http_referer",'
'"agent":"$http_user_agent",'
'"status":"$status"}';
access_log /var/log/nginx/access.log_json json;
重启 Nginx 服务，在浏览器上刷新页面，查看 Nginx 日志，
{"@timestamp":"2017-09-30T12:44:19+08:00","host":"192.168.10.104","clientip":"140.206.84.10","size":0,"responsetime":0.000,"upstreamtime":"-","upstreamhost":"-","http_host":"120.132.124.103","url":"/index.nginx-debian.html","xff":"-","referer":"-","agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.101 Safari/537.36","status":"304"}
启动logstash，
nohup logstash/bin/logstash -f nginxlog2es.conf > /tmp/logstash.log 2>&1 &
刷新 Nginx 页面，能看到 logstash 收集到的 Nginx 日志：
{
"referer" => "-",
"agent" => "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.101 Safari/537.36",
"http_host" => "120.132.124.103",
"url" => "/index.nginx-debian.html",
"path" => "/var/log/nginx/access.log_json",
"upstreamhost" => "-",
"@timestamp" => 2017-09-30T04:48:23.000Z,
"size" => 0,
"clientip" => "140.206.84.10",
"host" => "192.168.10.104",
"@version" => "1",
"responsetime" => 0.0,
"xff" => "-",
"upstreamtime" => [
0.0
],
"status" => "304"
}
1.3 安装 Kibana
wget https://artifacts.elastic.co/downloads/kibana/kibana-5.2.2-linux-x86_64.tar.gz
ln -s kibana-5.2.2-linux-x86_64 kibana
修改配置文件 kibana/config/kibana.yml，
server.host: "192.168.10.102"
elasticsearch.url: "http://192.168.10.102:9200"
启动 kibana，
nohup kibana/bin/kibana > /tmp/kibana.log 2>&1 &
在浏览器里面输入 http://120.132.124.103:5601/ 就可以打开 kibana 页面了。可以看到Nginx 的日志：
1.4 小结
从上面的步骤可以看出，ELK 的结构相对简单：
[*]Logstack 负责收集日志，并推送到 ES 中
[*]ES 负责存储
[*]Kibana 负责界面展示
ELK 的总体架构如下：
但是，这种架构有不少问题，其中问题之一是处理能力问题。bol.com 公司有如下的ELK架构演进路线：
（1）初始架构（2013年）
问题是单实例的 logstash 有性能瓶颈。
（2）使用 redis 缓存以及多个 logstash 实例（2014年）
使用 redis 作为消息缓存，使用多实例 Logstash 增加处理性能。
参考链接：
https://devops.profitbricks.com/tutorials/install-and-configure-apache-kafka-on-ubuntu-1604-1/
http://www.cnblogs.com/xiaoqi/p/elk-part1.html
https://www.slideshare.net/TinLe1/elk-atlinked-in
https://www.slideshare.net/renzotoma39/scaling-an-elk-stack-at-bolcom-39412550
https://www.elastic.co/blog/logstash-kafka-intro
https://www.elastic.co/blog/just-enough-kafka-for-the-elastic-stack-part2
https://www.elastic.co/blog/just-enough-kafka-for-the-elastic-stack-part1
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