Alibaba cloud CDN practice

Mainstream CDN Service providers include Alibaba cloud 、 Hua Wei Yun 、 Tencent cloud 、 Web host technology 、 LAN xunyun, etc .

1、 Alibaba cloud CDN brief introduction

         Alibaba cloud has 2800+ node . In mainland China （ mainland ） Have 2300+ node , Cover 31 A provincial region , A large number of nodes are located in the provincial capital and other first tier cities . overseas 、 Hong Kong, China, 、 Macao, China and Taiwan, China, China have 500+ node , Cover 70 Multiple countries and regions . meanwhile , All Alibaba cloud nodes are connected to 10 Gigabit network cards , The storage capacity of a single node is up to 40TB~1.5PB, Bandwidth load reaches 40Gbps~200Gbps, Have 130Tbps Bandwidth reserve .

（1） Alibaba cloud CDN The main application scenarios include ：

• Picture small file ： If your website or application App Our main business is downloading pictures and small files , Including all kinds of pictures 、html、css、js Small papers, etc .
• Big file download ： Website or app App Our main business is downloading large files , The average single file size is 20M above , As the game 、 Various client downloads and App Download stores, etc .
• Video and audio on demand ： Website or app App Our main business is video on demand or short video . Support MP4、FLV And other mainstream video formats .
• Speed up the whole station ： Whole site acceleration is an independent product of Alibaba cloud , Mainly used for dynamic content acceleration , It can also realize the acceleration of dynamic and static separation .
• Safe acceleration ： If your website is vulnerable to attack and must take into account the accelerated business scenario , You need to use the safe acceleration function , Improve the safety of the whole station .

（2） Alibaba cloud CDN working principle

         Suppose the acceleration domain name is www.a.com , Access CDN The Internet , After you start using the accelerator , When the end user （ Beijing ） launch HTTP When asked , The processing flow is shown in the figure below .

1. When the end user （ Beijing ） towards www.a.com When a request is initiated by the specified resource under , First of all to LDNS（ Local DNS） Initiate domain name resolution request .
2. LDNS Check the cache for www.a.com Of IP Address record . If there is , It is returned directly to the end user ; without , To authorize DNS Inquire about .
3. When authorizing DNS analysis www.a.com when , Return to domain name CNAME www.a.tbcdn.com Corresponding IP Address .
4. The domain name resolution request is sent to alicloud DNS Scheduling system , And assign the best node... To the request IP Address .
5. LDNS obtain DNS Parsing returned IP Address .
6. User get resolution IP Address . 
7. Users get from IP Address initiates an access request to the resource .
   • If it's time to IP The node corresponding to the address has already cached the resource , The data will be returned directly to the user , for example , The steps in the picture 7 and 8, End of request .
   • If it's time to IP The node corresponding to the address does not cache the resource , Then the node sends a request for the resource to the source station . After obtaining resources , Combined with user-defined configuration of the cache strategy , Cache resources to nodes , for example , The Beijing node in the picture , And return to the user , End of request .

2、 Use CDN

2.1、 Opening CDN service  

（1） Prerequisite ： 

Before performing this article , Please ensure that you have completed Alibaba cloud account registration and real name authentication .

（2） Operation steps ：

Log in to alicloud CDN platform .
Click open now .
Choose the billing type that suits you , And select the service agreement .

Click open now . 

Successfully opened CDN After service , You can click management console , Get into CDN Console .

2.2、 Add acceleration domain name  

         If needed CDN Accelerate business on designated websites , You need to use the website as the source site , Create an accelerated domain name for it .CDN Cache resources on the origin site to by accelerating the domain name CDN The acceleration node of , Accelerate resource access .

（1） Operation steps ：

• Sign in CDN Console .
• On the left navigation bar , Click domain name management .
• On the domain name management page , Click Add domain name .
• Configure accelerated domain name 、 Resource grouping 、 Business types 、 Origin information 、 Ports and acceleration areas .

Description of source station information parameter values ：
# IP： Support multiple server extranets IP, Alibaba cloud ECS Of IP Audit exemption
# Origin domain name ： Support multiple origin domain names
# OSS domain name ： Alibaba cloud OSS Bucket Internet domain name
# Function to calculate the domain name ： Select function calculation area and domain name
Port parameter value description ：
# 80 port CDN Return to the source of the request 80 port .
# 443 port CDN Return to the source of the request 443 port . 

Click next  

When you speed up the domain name approval , It will appear in the domain name list of domain name management . The status is normal operation , Indicates successful addition . 

2.3、 To configure CNAME

         After the domain name is added successfully , Alibaba cloud CDN Will assign the corresponding CNAME Address . If enabled CDN Accelerated Service , You need to point the accelerated domain name to CNAME Address , Requests for access to accelerated domain names can only be forwarded to CDN Node , Achieve acceleration effect .

Get the CNAME Address .

（1） Get the CNAME Address .

• Sign in CDN Console .
• On the left navigation bar , Click domain name management .
• Enter the domain name management page , Copy the acceleration domain name CNAME value .

（2） add to CNAME Record . 

         This step is used to resolve in Alibaba cloud DNS The console adds CNAME Record as an example , Let me introduce you to CNAME Configuration process of . If you are in DNSPod、 New network 、Godaddy Domain name resolution set by other domain name resolution service providers , Please go to the corresponding domain name resolution service provider to add CNAME Record , The addition method is similar to the method introduced in this article .

1. Log in to alicloud to resolve DNS Console .
2. Enter the domain name resolution page , After the domain name you need to set up , Click resolve settings .
3. Click Add record , add to CNAME Record .

explain  

• Record type ： choice CNAME .
• Host record ： Accelerate the prefix of domain name . 

• Analytic circuit ： The default value is .
• Record value ： Enter the... Corresponding to the accelerated domain name CNAME Address .
• TTL： The default value is . 

Click OK .

• Successfully configured CNAME And after it takes effect , The acceleration service will take effect immediately .

（3） verification CNAME Whether the configuration is effective .

• open Windows Of CMD Command line program .
• On the command line ping Accelerate domain name , If the returned parsing result is the same as CDN On the console, the domain name should be accelerated CNAME Value consistent , said CDN The acceleration has taken effect .

 

3、 Service management

         If monitoring is required 、 Statistical analysis 、 Usage query 、 Refresh preheating 、 Log analysis, etc CDN Manage resources , You can use Alibaba cloud CDN The service management function provided by the console . Through this function, you can analyze in real time and effectively CDN Health , And make business decisions in time .

Alibaba cloud CDN List of service management functions ：

Refresh preheating  

        CDN Provide the function of refreshing and preheating resources . Through the refresh function , You can force CDN The node returns to the source and gets the latest file ; Through the preheating function, hot resources can be preheated during business peak , Improve resource access efficiency . 

CDN The concept of the refresh and warm-up functions of the resources provided is as follows ：

• The refresh function refers to submitting URL After refresh or directory refresh request ,CDN The cached content of the node will be forced to expire , Direction CDN When a node requests a resource ,CDN It will go back to the source station directly to get the corresponding resources and return them to you , And cache it . The refresh function will reduce the cache hit rate . Use scenarios ： Usually, static resources are updated in the source site . Take the initiative to load the latest resources from the edge node .
• The warm-up function refers to submitting URL After warm-up request , The origin will actively cache the corresponding resources to CDN node , When first requested , You can go straight from CDN Get the latest request resource from the node cache , There is no need to go back to the source station to get . The cache warm-up function will improve the cache hit rate .

Operation steps ：

1. Sign in CDN Console .
2. On the left navigation bar , Click refresh preheating .
3. In the refresh cache tab , You can do as you need , Configure refresh or warm-up information .
4. Click Submit
5. Click operation record
6. On the operation record tab , Configure query time 、 Operation type 、 Domain name or URL, Click query .

The detailed description of the refresh and warm-up functions is shown in the following table . 

 

4、 Domain name management

4.1、 Back to source configuration

         When requesting access to resources through the client , If CDN The resource is not cached on the node , You will go to the source station to get , Cache to CDN node . You can configure the related functions of returning to the source according to your needs , Improve resource access efficiency .

function	explain
Configure back to source HOST	When you need to customize CDN When the node returns to the source, it needs to access the specific server domain name , Need to configure back to source HOST Type of domain name .
Configure the back to source protocol	When requesting access to resources through the client , If CDN The resource is not cached on the node , Then it will follow the rules to the source station to obtain resources according to the configured Protocol , Cache to CDN node .
Open private Bucket Back to source authorization	When the origin is OSS（ Alibaba cloud cloud storage ） when , You can open accelerated domain name access private OSS Bucket Resource permissions , Effectively prevent resource theft .
Close private Bucket Back to source authorization	Can pass RAM Console , Cancel the authorization of the corresponding role name , Close private Bucket Back to source function .
Configure back to source SNI	If the origin IP Bound multiple domain names , When CDN Node to HTTPS When the protocol accesses your origin , You can set back to the source SNI, Specify the specific access domain name .SNI（Server Name Indication） yes TLS An extension of , To solve a The server has multiple domain names .
Configure custom back to source HTTP head	HTTP When requesting a return to the source , You can add or delete back to the source HTTP head .
Configure the timeout of the request back to the source	CDN The timeout waiting time of the back to source request of the acceleration node defaults to 30 second , It can be set according to actual needs CDN The longest waiting time for a request back to the source . When the waiting time of the request back to the source exceeds the configured timeout ,CDN The connection between the node and the source station is disconnected .

4.2、 Cache configuration

        CDN When accelerating static resources , Cache the resources on the origin to the nearest to the client CDN Node . When accessing the static resource , Get directly from the cache , Avoid going back to the source over a long link , Improve access efficiency .

function	explain
Configure cache expiration time	You can specify the cache expiration time of directory and file suffix for static resource configuration , And priority , Make it CDN Cache according to cache rules .
Configure the expiration time of the status code	You can configure the expiration time of the status code of the specified directory or file suffix of the resource .
To configure HTTP head	You can configure the resource cache to expire HTTP The message header .
Custom error page	You can customize it according to your needs HTTP perhaps HTTPS The response return code jumps completely URL Address .
Configuration override	You can respond to the requested URI Make modifications and 302 Redirect to target URI.

4.3、 Access control  

         Can be set by Referer、IP、UsageAgent Blacklist and whitelist , as well as URL authentication , To realize the identification and filtering of visitor identity , To restrict access to CDN Users of resources , promote CDN The security of .

function	explain
To configure Refer Anti theft chain	You can access through configuration Referer Black list and white list to identify and filter the identity of visitors , Limit access to CDN Users of resources .
To configure URL authentication	You can configure URL The authentication function protects the resources of the user site from being downloaded and misappropriated by illegal sites .URL Authentication ratio Referer The security of anti-theft chain is higher .
To configure IP Black and white list	You can configure IP Black list and white list to identify and filter the identity of visitors , Limit access to CDN Users of resources .
To configure UA Black and white list	You can configure UsageAgent Black list and white list to identify and filter the identity of visitors , Limit access to CDN Users of resources .

4.4、 performance optimization

Set the performance optimization function of accelerating the domain name , Reduce the size of access files , Improve the efficiency of accelerating business and page readability .

Carry a pair of 11 Flow peak ： With the national acceleration node 、 Intelligent flexible scheduling system and security protection capability , Perfectly support billions QPS Peak value , Ensure that hundreds of millions of buyers around the world can quickly browse high-definition pictures and videos , Order smoothly . Through the performance optimization function , Perform the following operations on the domain name .

function	explain
Page optimization	When you turn on the page optimization function ,CDN Automatic removal of HTML Redundant comments and repeated white space characters on the page , Reduce file size , Improve page readability .
Intelligent compression	When you turn on the intelligent compression function ,CDN The static file is automatically Gzip Compress . Through intelligence Gzip Compression way , It can effectively reduce the size of the transfer file , Improve the efficiency of accelerating business .
Brotli Compress	When you need to compress static text files , You can turn on this function , Effectively reduce the size of transmission content , Speed up the distribution effect .
Filter Parameters	When your URL The request carries a question mark （?） And parameters ,CDN Node is receiving URL After the request , Judge whether it is necessary to carry parameters URL Return to the origin .

4.5、 Video related  

Can be set by Range Back to source and drag and drop play function , Reduce the consumption of return flow , And improve the playback effect of video and audio .

Through video related functions , Perform the following operations on the domain name .

function	explain
Range Back to the source	Turn on Range Back to source function , It can reduce the consumption of back to source traffic , And improve resource response time .
Drag play	After the drag and play function is enabled , When playing video and audio , Drag and drop the playback progress at will , Without affecting the playback effect of video and audio .