Nginx ultra detailed notes from theory to practice

2021-08-09 16:40:52

nginx ultra detailed notes theory

Recently, I spent some time summarizing nginx Common skills and knowledge points , Through some common practical cases to nginx Many small points of knowledge are connected .

The first is to enter nginx Directory for script startup , Ready to initialize environment ：

[root@idea-centos nginx]# cd ./sbin/
[root@idea-centos sbin]# ll
total 3528
-rwxr-xr-x. 1 root root 3611160 Dec 26 16:43 nginx
[root@idea-centos sbin]# ps -ef|grep nginx
root 7270 7194 0 10:42 pts/1 00:00:00 grep --color=auto nginx
[root@idea-centos sbin]# ./nginx 
[root@idea-centos sbin]# ps -ef|grep nginx
root 7272 1 0 10:42 ? 00:00:00 nginx: master process ./nginx
nobody 7273 7272 0 10:42 ? 00:00:00 nginx: master process ./nginx
root 7275 7194 0 10:42 pts/1 00:00:00 grep --color=auto nginx

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After successful startup , adopt curl Access tests can be performed

First, through ip add To view the address information （ I am using a virtual machine ）：

[root@idea-centos sbin]# ip add
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 00:0c:29:ea:63:63 brd ff:ff:ff:ff:ff:ff
inet 192.168.43.235/24 brd 192.168.43.255 scope global noprefixroute dynamic ens33
valid_lft 2922sec preferred_lft 2922sec
inet6 2409:8955:3048:50d5:e7e8:636d:bdf1:7033/64 scope global noprefixroute dynamic
valid_lft 2964sec preferred_lft 2964sec
inet6 fe80::8a65:608b:505e:fe4/64 scope link noprefixroute
valid_lft forever preferred_lft forever

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And then through curl Test on this virtual machine ：

[root@idea-centos sbin]# curl http://192.168.43.235/
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
width: 35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>

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If the access fails , Please check whether the firewall is on first , If it's on , You can close it first , Facilitate subsequent demo practice ：

[root@idea-centos sbin]# firewall-cmd --state
running
[root@idea-centos sbin]# systemctl stop firewalld.service
[root@idea-centos sbin]# firewall-cmd --state
not running

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After successful access , Will see nginx Home page ：

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nginx Summary of common basic commands

# Start by default ：
./sbin/nginx
# Specify profile startup 
./sbing/nginx -c /tmp/nginx.conf
# Appoint nginx Program directory startup 
./sbin/nginx -p /usr/local/nginx/
# Stop quickly 
./sbin/nginx -s stop
# Elegant stop ( Will wait until the current request is processed before killing )
./sbin/nginx -s quit
# Hot mount profile 
./sbin/nginx -s reload
# Reopen the log file 
./sbin/nginx -s reopen
# Verify that the configuration is correct 
./sbin/nginx -t

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start-up nginx after , You can view the process related information through the log

[root@idea-centos nginx]# ./sbin/nginx
[root@idea-centos nginx]# ps -ef|grep nginx
root 11059 1 0 16:34 ? 00:00:00 nginx: master process ./sbin/nginx
nobody 11060 11059 0 16:34 ? 00:00:00 nginx: worker process
root 11062 8193 0 16:34 pts/1 00:00:00 grep --color=auto nginx

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master process It is mainly responsible for updating logs , Hot loading The main process
worker process Working process Handle client connections , Processing requests

nginx Log

stay nginx Of log Under the folder , After we revisit the server , Corresponding access The log will add new attribute content .

Look for the logs here , It is actually based on the object handle to find the specified file .

About nginx Understanding of processing mechanism

nginx The high performance of the is mainly attributed to its corresponding unique io Multiplexing . Whenever a request is sent , All requests are put into a select Inside the queue , Dedicated storage client http Link information , Polling is then handled through a special selector , Monitor whether the client sends the requested data （ Always polling , Congestion will not occur until data is sent ）, Once the transmitted data is received ,selector The specified processing will be made .

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When we start nginx after , There are two types of processes , Namely master The process and worker process , The request sent by the client is usually just and master Process communication ,master The process is responsible for receiving these requests , And then distribute it to different worker Process to process .

In essence ,worker The process is from master Process side fork Coming out , stay master In the process of , You need to establish the monitored socket after , Again fork More than one worker process , Multiple worker process （ Multicore cpu In the environment ） Will fight accept_mutex The mutex , The process that successfully grabs the lock will register the corresponding event to process the task . The advantage of this independent process handling events is that it avoids the original locking overhead , At the same time, when something happens in the process bug When out of the ordinary , It won't affect other processes , Reduced risk .

nginx How to deal with high concurrency ？ When multiple worker To handle the request , Every worker There is only one main thread in it , But the number of concurrency is very limited , When the number of concurrent is large , Do you need to create thousands of threads to process requests ？

nginx The design of is brilliant at this point , Its mechanism is a bit similar to linux Inside epoll Such system scheduling . Response thread processed （ Tentatively named A） only one , When the requested event is processed , Will inform you A , There is no waiting operation for blocked requests . This design avoids A Event consumption caused by actively polling and waiting for event processing .

Compared to traditional apache The server , Every connection ,apache It creates a process , Single thread per process ,apache You can create at most 256 A process . For a website with a relatively high load ,256 The process of , That is to say 256 Threads , Because when a thread processes a request , It's synchronous blocking mode , After receiving the request , Will always wait for the request to read the program file （IO）（ Sync ）, Execute business logic , Back to the client , All operations are completed before the next request can be processed （ Blocking ） If the server has reached 256 The limits of , Then the next access needs to be queued, which is why the load of some servers is not high .

Summary

Every worker Processes are single threaded
Every io Links are built based on asynchronous non blocking models .
worker The number of processes is combined with the number of servers cpu Quantity to set , It can achieve the effect of tuning

nginx The basic modules inside

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nginx When processing a request , More importantly, these requests will form a request chain , Each module on the chain will handle different functions . For example, for request decompression and compression processing , about ssl Processing module, etc . in general ,nginx I summarize the basic modules for the following ：

event module Event handling mechanism module , It provides a specific processing framework for various events .nginx What kind of events are used to handle , Depending on the operating system and compilation settings , for example ngx_event_core_module and ngx_epoll_module.

phase handler Mainly responsible for processing client requests and generating content to be responded ,ngx_http_static_module Is one of them , The module Mainly is to nginx The request goes to read some data on the disk , Then make an output response , For example, ：uri In order to / ending , Will be left to index Module to link the complete path name, and then call this module through internal call .

output filter The module can make specified modifications to the output content of the response , For example, some specific to the page url Carry out replacement operations .

upstream This module is the first mock exam. , This module mainly does the work of reverse proxy .

load-balancer This module is mainly responsible for the load balancing function , Select any server in the cluster to process the request .

nginx Explanation of common configuration cases

First, let's take a look at the most basic nginx Basic configuration ：

events {
worker_connections 1024;
}
http {
include mime.types;
default_type application/octet-stream;
sendfile on; # Identity uses zero copy 
keepalive_timeout 65; # The identification adopts long connection 
server {
listen 80;
server_name localhost;
location / {
root html;
index index.html index.htm;
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}
}
}

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ps: This configuration is divided into many configuration blocks , A space is required between each configuration block and braces , Otherwise, the failure will be identified

To configure location The redirection of

For example, we are /usr/local/www/ A copy is created under the folder html page , And then you need to go through nginx To visit ,nginx It's matching server Of location In the path , Will follow the full path first , From left to right , Then match from right to left .

Be careful , Inside root The configuration is inherited ,location Inside root Will inherit location Outside root Information . If location It says root, Will follow location Inside root To judge .server Outside >server Inside >location Inside .

Configure dynamic and static separation

The so-called dynamic static separation essentially refers to our understanding of nginx The dynamic request and static file in the configuration are separated to some extent . For example, the following configuration information ：

server {
listen 80;
server_name www.idea.com *.idea.com idea.*;
root /usr/local/www;
# Add mapping here static The record of 
location /static {
root /usr/local/static/;
}
location / {
root /usr/local/www/;
index idea.html;
}
}

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ps: Configuration content in this , I introduced it host File modification

The actual storage location of the picture is ：

/usr/local/static/img/logo.jpg

According to the above configuration , The way to access is ：

http://www.idea.com/static/img/logo.jpg

But in this case , We go through nginx The way to access pictures won't succeed , The reason is that this address will be deleted nginx Process as ：

Go to root Address +static Query the final address of ：

/usr/local/static/static

To avoid that , Aliases are usually used alias To match , The specific configuration is as follows ：

server {
listen 80;
server_name www.idea.com *.idea.com idea.*;
root /usr/local/www;
location /static {
alias /usr/local/static/;
}
location / {
root /usr/local/www/;
index idea.html;
}
}

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This is the time , We'll visit again http://www.idea.com/static/img/logo.jpg The visit will be successful .

Similarly, we can carry out more complex logical operation cases for aliases ：

Suppose we need to visit static Contents of the file below , At this time, you don't need to carry the corresponding name , Direct access through
http://www.idea.com/static/css/test.css You can access /usr/local/www/static/css/ The content below

that , If there are many types of static files that need to be mapped, how to configure them ？ At this time, the configuration of regular expressions can be introduced ：

 server {
listen 80;
server_name www.idea.com *.idea.com idea.*;
root /usr/local/www;
location /static {
alias /usr/local/static/;
}
# there ~ This means that case is ignored 
location ~* \.(gif|png|jpg|css|js) {
root /usr/local/static/;
}
location / {
root /usr/local/www/;
index idea.html;
}
}

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After adding the configuration of this regular expression （~* .(gif|png|css|js)$） By accessing the path ：
http://www.idea.com/css/test.css We can visit /usr/local/static/css/ The contents of the file below .

Proxy access mechanism

nginx It also provides a very flexible proxy access mechanism , For us to access by proxy location

adopt nginx Configure the exact matching agent for page Jump ：

 server {
listen 80;
server_name www.idea.com *.idea.com idea.*;
root /usr/local/www;
location /static {
alias /usr/local/static/;
}
location ~* \.(gif|png|jpg|css|js) {
alias /usr/local/static/;
}
location =/idea-serach {
proxy_pass http://www.baidu.com
}
location / {
root /usr/local/www/;
index idea.html;
}
}

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adopt proxy_pass Configure to provide proxy request forwarding , When we visit http://www.idea.com/idea-serach When , It will match the page visiting Baidu .

Summary

nginx Common configurations for access support the following ：

Full path access location
By keyword static Match to access location
Access through regular expressions location
Access through reverse proxy location

Anti theft chain matching

Set some links to allow access only on fixed websites , Prevent some special domain names from changing ip After visiting, steal the resource files of this website , Therefore, the function of the anti-theft chain can be set . The specific configuration is as follows ：

server {
listen 80;
server_name www.idea.com *.idea.com idea.*;
root /usr/local/www/;
location /static {
alias /usr/local/static/;
}
# Anti theft chain configuration 
location ~* \.(gif|png|jpg|css|js) {
valid_referers none blocked *.idea.com;
if ($invalid_referer) {
return 403;
}
root /usr/local/static/;
}
location =/idea-serach {
proxy_pass http://www.baidu.com;
}
location / {
root /usr/local/www/;
}
}

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Website blacklist

The configuration of blacklist is relatively simple , Just create the blacklist file first , And then in http Just introduce it into the block

Remember to make the configuration successful nginx reload once , At the same time, check whether it is 203, If so, it indicates that it is a cache request .

nginx Log configuration for

When we need to view some details of the data sent by the client , Need to be right nginx Keep a log , The corresponding optional parameters are as follows ：

log_format Format variable ：
$remote_addr # Record the address of the client visiting the website 
$remote_user # Remote client user name 
$time_local # Record access time and time zone 
$request # User http Request start line information 
$status #http Status code , Record the status code returned by the request , for example ：200、301、404 etc. 
$body_bytes_sent # The response sent by the server to the client body Number of bytes 
$http_referer # Record the connection from which the request is accessed , The anti-theft chain can be set according to this parameter .
$http_user_agent # Record client access information , for example ： browser 、 Mobile clients, etc 
$http_x_forwarded_for # When there is a proxy server at the current end , Set up web The node records the configuration of the client address , The precondition for this parameter to take effect is that the proxy server also needs to carry out relevant x_forwarded_for Set up 

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Place log configuration in http Just inside the block .

Usually, we will place the log configuration in http Modules , For example, the following group of cases ：

events {
worker_connections 1024;
}
http {
include mime.types;
default_type application/octet-stream;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log logs/access.log main;
sendfile on;
keepalive_timeout 65;
server {
listen 80;
server_name localhost;
#charset koi8-r;
#access_log logs/host.access.log main;
location / {
root html;
index index.html index.htm;
}
#error_page 404 /404.html;
# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}
}
}

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ngixn Agent configuration inside

Forward agency

Add a layer between the client and the server proxy Agent machine , When a request occurs , Request by proxy server server End . The most common forward agency cases are ：***, Internet client tools in LAN .

For example, a chestnut ：

When we need to match to $host: $port /baidu.html When , Proxy request Baidu page , The following configurations can be performed ：

Reverse proxy

When the client requests the server , In fact, there is a proxy machine in the access layer of the server to forward requests , The forwarding of requests in this layer is transparent to the client .

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The reverse proxy requests the internal server , Although the configuration is similar , But the function is different , The configuration case is as follows ：

Proxy related parameters

proxy_pass # Agency service 
proxy_redirect off; # Whether to allow redirection 
proxy_set_header Host $host; # Pass on header Parameters to backend services 
proxy_set_header X-Forwarded-For $remote_addr; # Set up request header The client side IP Address 
proxy_connect_timeout 90; # Connection agent service timeout 
proxy_send_timeout 90; # Maximum time to send a request 
proxy_read_timeout 90; # Maximum read time 
proxy_buffer_size 4k;
proxy_buffers 4 32k;
proxy_busy_buffers_size 64k;
proxy_temp_file_write_size 64k;

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ngixn Load balancing inside

nginx There's one called upstream Module , Content dedicated to configuring load balancing ,upstream The following related parameters are provided ：

service Reverse service address Add ports
weight The weight
max_fails How many times have you failed If you think the host is down , Kicked out
fail_timeout remove server Time after re request When the service hangs up , Reconnect during this time
backup Standby service （ When all the services hang up , Then you will request the service here ）
max_conns Maximum connections allowed
slow_start When the node recovers , Don't join immediately , But wait slow_start Add service pair column after .

The specific configuration of corresponding parameters is as follows: ：

ngixn The default supported load balancing strategy is polling and weighting , besides ,nginx It also supports a variety of additional load balancing strategies ：

ll+weight： Polling weighted weight ( Default )
Prone to weightlessness , For example, access to a machine is too slow , It is easy to cause request accumulation .

ip_hash : be based on Hash Calculation , Often used to keep session Oneness
be based on hash When calculating , According to ip Conduct hash Calculate the request to the specified server .
（ Usually session The best way to deal with consistency in distributed is to session Stored in a third-party storage center ）

First of all, ip Conduct hash After calculation , Modulo the value and the number of servers .

url_hash: Static resource cache , Save storage , Speed up
According to the picture url Request to the specified server , It's easy to understand .

least_conn : Minimum number of links
Each request will only request to the server with the minimum number of client connections .

least_time ： Minimum response time
Calculate the average response time of nodes , And then take the fastest response , Higher assignment weight

Configuration case

By using ip Request the back-end server by hashing

 upstream backend {
ip_hash;
server 192.168.43.191:8080 weight=1;
server 192.168.43.191:8089 weight=8 fail_timeout=10s;
}
location / {
#root html;
index index.html index.htm;
proxy_pass http://backend;
}

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Of course nginx In addition to these common functions , It also provides a very rich configuration of other functions , Please refer to nginx Official document configuration information for http://nginx.org/en/docs/

After reading this article, there are gains ？ Please forward to share with more people

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