CDN+ user guide

Available in Classic and VPC

Introduction to CDN+ service

This section describe the concept and basic structure of the NAVER Cloud Platform CDN+ service.

NAVER Cloud Platform CDN+

CDN+ platform is an improved CDN platform that provides more stable and diverse features than the existing domestic CDN services. CDN is a service that delivers various content to Internet users in a fast and secure manner. You can easily apply for CDN service through a web-based console and support large traffic through the configured CDN. It is utilized for services that require large amounts of images or large content downloads, and smoothly transfers content even when usage increases sharply.

Introduction to the main features of CDN+ service

1. Large content transfer

   It provides web caching and download services for various large contents such as images, game installation files, and media images. Even if there is a sharp increase in content usage, it can stably transmit content to maintain service continuity.

2. Support for various source servers

   To transmit content through CDN+, it is necessary to access the source server to cache and transmit content.

   CDN+ supports content integration with various source servers via HTTP/HTTPS protocols. Customers can set up various web servers they possess, as well as NAVER Cloud Platform's Object Storage and Servers, as source servers, and can freely specify ports for connectivity.

3. Strong security for content transmission

   If the web service is provided via HTTPS, many web browsers display security warning messages if content is called via HTTP. CDN+ allows content to be transmitted via HTTPS protocol. HTTP can also be used, and it is possible to mix the two or utilize HTTPS only by limiting HTTP.

   If you select the HTTPS protocol, you can also communicate with the source server via HTTPS to enhance security in the path of overall content transmission.

   It provides domain-based access permission registered as a referrer and can restrict access to content to Secure-Token-based secure URLs.

4. Can be integrated with other services provided by NAVER Cloud Platform

   It provides convenient integration setup with other services on the NAVER Cloud Platform. You can easily connect your content source to Object Storage or Server, and by using Live Station, you can utilize live streaming services by automatically integrating with CDN.

Summary of CDN+ related glossary

Requesting subscription to CDN+

Request subscription to CDN+

1. Access Console and go to Services > Content Delivery > CDN+ menu.

2. Click [Request subscription to CDN] button.

Service settings

Configure the service name, service protocol, and service domain.
Before the configuration, click the [?] button for each item for help.

① Enter the name of the CDN+ service you want to request subscription to.

② Select the service protocol. ALL supports both HTTP and HTTPS protocols.

• Note for selecting HTTPS or HTTP/HTTPS protocol

  

③ Select the service domain.

• If you use a CDN domain, it is automatically set to [random ID].cdn.ntruss.com by default.
• If you choose "CDN domain > Enter manually", it is set to a domain in the form of [input string].cdn.ntruss.com.
• If you are using your own domain, manually enter the domain you own.
• Up to 10 customer-owned domains are supported.

④ If you use your own domain and select HTTPS or HTTP/HTTPS as the service protocol, you need to register a certificate. You can use an existing registered certificate or register a new certificate. The feature of registering a new SSL certificate has been transferred to Certificate Manager.

• If you want to use a certificate issued by Let's Encrypt, enter the Full Chain path in Certificate Manager.

⑤ Select whether to save the access log.

• You can save the logs requested in CDN+ in your Object Storage. To save logs, you need to create a storage for each type of storage. You need to create a bucket in Object Storage.

• Log data requested at hourly intervals is saved in compressed format (gz). If you save logs, you can check the logs of the previous time period after 50 minutes each hour. For CDNs with high usage, it may take time to collect logs, and logs may be transmitted after 2 hours.

• The format of the saved log is as follows, and each item is separated by a space. If there is no data, it is displayed as "-".

  Example)
  2018-02-08 22:08:06 183.111.24.145 GET /cdn/test.png - 8080 - 218.55.184.71+183.111.24.145 Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_12_6)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/63.0.3239.132+Safari/537.36 200 57287 0 http://logformat.example.com/ - - TCP_HIT gzip+deflate 155999646 57018 0 c -
  

⑥ Enter a description.

• You can enter descriptions related to CDN+. You do not need to enter it because it is not a required value.

Source settings

You can configure the source location, host header passed to the source, cache key hostname, and whether Gzip compression is supported.

① Specify the location of the source to be used for CDN+ service.

• If you are using NAVER Cloud Platform's Object Storage, you must create a bucket in advance to use it. When using Object Storage as the source, the network transfer fees between CDN+ <-> and Object Storage are free of charge.

• You can enter the source protocol regardless of the service protocol. The default protocol is selected based on the service protocol, but it may be changed. Each port number is set to the default value of 80 for HTTP and 443 for HTTPS.

• Caution Please note that if you choose to use "source path (optional)" option as your source, the service path will be specified as follows:

  Example) When using the source path (optional) option: if the /example/ path is set as the vhost root path on the source server
  * Source path: http://origin.naver.com/example/logo.gif
  * CDN+ service path: http://example.cdn.ntruss.com/logo.gif (he source path entered is excluded)
  

• If you want to enter it manually, enter the IP address or domain name of the source server, and we recommend setting it to a domain rather than an IP address.

• If the source server uses a port other than the default port (80) for HTTP protocol, specify the port number.

• If it is source and cannot be entered

  |* Private IP addresses cannot be entered: 127.0.0.1, 10.x.x.x, 172.1[6-9]|2[0-9]|3[0-1].x.x, 192.168.x.x range cannot be entered|

  • If there is no record A for the source domain name: it cannot be entered when querying the domain and there is no record A (IP information)

    Example) When querying the domain origin.example.com, and if the response is "NXDOMAIN", it cannot be entered

② Specify an additional directory location where the source files to be served as the actual service are located, in addition to the source location.

③ Choose the host header information that is passed on to the source server when a request is made from CDN+.

• When setting up virtual host on the source server, you can control the response content by referring to the host header information. The incoming host header is used to pass the host information from the user's request to the source request. Typically for web browsers, the service domain becomes the host header (example: ex.cdn.ntruss.com is the host header when requested for ex.cdn.ntruss.com/img.jpg).
• Select the origin hostname setting if you want the source server to have a virtual host setting as origin hostname and allow only this domain.
• The default setting uses the "Incoming Host Header" value of the service domain.

④ Choose a cache key to uniquely identify CDN+ content.

• Recommend using "Cache Key > Incoming Host Header": use it when the source responds with different content based on the virtual host

The contents are distinguished by individual cache keys depending on the service domain. If the contents transmitted differ according to the service domain, select the incoming host header value.

Example)
The cache key for http://sample.cdn.ntruss.com/logo.gif is "sample.cdn.ntruss.com",
and the cache key for http://example.cdn.ntruss.com/logo.gif is "example.cdn.ntruss.com", with logo.gif cached as other content.

• Recommend using "Cache Key > Origin Hostname": used when responding with the same file from the source to the URL regardless of virtual host. Recommended for improved cache hit rate

Different service domains are consolidated into one source cache key. If the source server and the content being transmitted are the same, it is recommended to set the cache key to "Origin hostname".

Example)
The cache key of http://sample.cdn.ntruss.com/logo.gif is "origin.cdn.ntruss.com",
and the cache key for http://example.cdn.ntruss.com/logo.gif is "origin.cdn.ntruss.com", with logo.gif cached as one content

• If you select a CDN+ held domain or use a single domain for your own domain, you can only choose "incoming host header" as the cache key.

⑤ Select whether to enable compression for the source.

• Enabling compression can reduce the traffic to the source server and improve response times.
• You can receive compressed content by requesting "Accept-Encodgin: gzip" with the source in CDN+. Select "Use" if the source supports Gzip compression in responses.

⑥ You can add/change or delete headers in the source request.

• The following strings cannot be entered as header names or values: "(),/:;<=>?@[]{}", non-alphanumeric characters, spaces
• The maximum length of header value that can be entered is 256 bytes.
• Example) Action: Add, Header Name : NCP-Custom-Header, Header Value : ncp => NCP-Custom-Header: ncp

Caching settings

This setting configures the caching expiration time and cache-related options in CDN+.

① Choose the default caching policy of CDN+.

• By default, the length of time kept on the cache server should follow the same policy as "Cache-Control: max-age=..." or "Expires" header values on the source server.
• If the header for adjusting the cache is not responded from the source, the cache server will apply the "Cache Expiry" setting value to determine how long to retain it.
• When selecting cache, the maximum caching period is applied to the value set in "Cache Expiry" on the cache server.
• The No-store/Bypass Cache setting is an option that disables caching on the CDN+ server, and it is not recommended as all requests are served through the source without using the cache.

② Select how CDN+ operates if communication with the source is difficult.

• If communication with the source server fails, it can provide users content that is stored on the cache server. It may not be up to date and valid content, but it can be serviced in the event of a failure of the source server.
• If the service is impacted by being served invalid content in the event of a source server failure, choose to always serve the most recent and valid content compared to the content on the source server.

③ Configure cache expiry.

• Specify the cycle for checking whether the content cached on the CDN+ cache server has been changed on the source server. However, if Cache-Control: max-age exists in the response header of the source server, that setting takes precedence. When updating the content often, set it to be short. However, use this with caution since setting it short increases the load of the source.

④ Select the cache policy for when query string is used for service requests.

• You can choose whether to include the user's request query string when requesting the source server. If the source server responds with different content depending on the query string, select "Disable" option.
• If the source server responds with the same content regardless of the query string, selecting "Enable" can improve caching efficiency, reduce source requests and load.

⑤ Select the cache policy for the Vary header response from the source.

• If the source server responds with a "Vary" header, but the content is the same, it is recommended to remove it for caching efficiency. Even if the source server responds with a Vary header, you can exclude it from caching to recognize it as the same content.
• If the content has various versions and the response content varies depending on the Vary request headers such as User-Agent, Referer, and Cookie, select "Enable".

⑥ Select the optimized transfer option for caching efficiency when serving large files.

• When transferring large files, they are cached in chunks of 2 MB, and if you don't complete the download and a certain amount of data remains, it doesn’t make any more requests to the source, reducing the load on the source. To apply this, range response setting is required in the source. When using the option, if you update the content without changing the content name, it is essential to perform a purge operation for content integrity.
• The target file extensions are "exe, bz2, dmz, gz, iso, mov, pkg, tar, tgz, wmv, wma, zip, webp, jxr, hhdp, wdp", and they can be applied to content ranging from 100 MB to 16 GB in size.

Viewer transfer settings

Set control options when content is sent to users from CDN+.

① Select whether to enable compression when delivering content from CDN+ to users.

• If the user's User-Agent (browser or device) supports Gzip/Unzip, the content is compressed and transmitted to the user. Compressing content before transmitting it to users with low network quality can improve response times.
  It is effective to apply to HTML, JavaScript, or text-based contents that are over 10KB.

• To apply compressed/uncompressed response flexibly according to the content extension or request header on the source server, select "Apply the same compression settings as source".

• It is not recommended to apply additional compression to images (jpg, png, etc.), videos (mp4, flv, etc.), or contents that have already been compressed. Select Disable if you are only serving content that has already been compressed.

• When using compressed transfer, the following MIME type is applied to the target content.
  

  Text/html*, text/css*, application/x-javascript*, application/javascript*
  

② Set access control based on the referrer when a user requests content.

• You can set access control for requests with or without referrers from the specified domain. As it is a domain-based setting, special characters such as "*", "-", "_" are allowed, and when using a wildcard (*), access control settings are applied to sub-domains as well.
• By default, content is allowed even if there is no referrer. To allow access only to registered referrers, choose "Disallow".

③ Select when using a secure token to respond only to allowed requests with content.

• When an access token for one-time use is created and used to request content, the secure token responds, with content, only to requests that have passed authentication.
• Secure token supports query string and the cookie header in the header within the URL.

• The SDK that creates secure tokens is provided for each programming language. You can create secure tokens by making selections based on the programming language used.

  1. Python: https://github.com/akamai/EdgeAuth-Token-Python
  2. Java: https://github.com/akamai/EdgeAuth-Token-Java
  3. Ruby: https://github.com/akamai/EdgeAuth-Token-Ruby
  4. NodeJS: https://github.com/akamai/EdgeAuth-Token-Node
  5. Golang : https://github.com/mobilerider/EdgeAuth-Token-Golang
  6. C# : https://github.com/BookBeat/EdgeAuth-Token-CSharp

• The following is an example of settings in which the start time (st), expiration time (exp), and ACL (URL path condition) of the token valid time are used to create an authentication token, which is then sent as a query string and cookie header.

• How to create an authentication token using the Java language

  1. Write code that utilizes the Java SDK to generate a token. (Sample Code)

  package com.akamai.edgeauth;
  
  public class ExampleEdgeAuth {
      public static void main(String[] args) {
        String hostname = "example.cdn.ntruss.com";   // service domain name
        String ET_ENCRYPTION_KEY = "b2b1";            // key to generate token
        String tokenName = "token";                   // set token name to "token"
        long duration = 3600L;                        // 3600 seconds = 1 hour
  
        try {
            EdgeAuth ea = new EdgeAuthBuilder()
                    .key(ET_ENCRYPTION_KEY)
                    .startTime(EdgeAuth.NOW)
                    .windowSeconds(duration)
                    .tokenName(tokenName)
                    .escapeEarly(false)
                    .build();
  
            String acl = "/sample.pdf*"; //*/
            String file_url = "/sample.pdf";
            String token = ea.generateACLToken(acl);
            String url = String.format("http://%s%s?%s=%s", hostname, file_url, tokenName, token);
  
            System.out.println(url);
  
        } catch (EdgeAuthException e) {
            e.printStackTrace();
        }
      }
  }
  

  2. This is an example of creating a request URL by running Java.

  http://example.cdn.ntruss.com/sample.pdf?token=st=1592202370~exp=1592205970~acl=/sample.pdf*~hmac=d422a548ae769bbaddc1d27f03fe6e096a4ba492928f3eb9c09824f93d78f507
  

  3. This is an example request that includes the generated token in the cookie header.

  - URL : http://example.cdn.ntruss.com/sample.pdf
  - Header information to include on request 
  Cookie:  token=st=1628596072~exp=1628682472~acl=/sample.pdf*~hmac=8094467ff875e72e8fccc2e579a0cfd002f680cda7acd10b820c193f671952d8
  

• How to create an authentication token using the Python language

  1. Create a token with the file provided on Git. (Sample Code)

  $ python cms_edgeauth.py -k b2b1 -n token -s now -w 3600 -a /sample.pdf* enter the input command as shown in the example
  => Results in the following output
  token=st=1592204787~exp=1592208387~acl=/sample.pdf*~hmac=79872098f16596c8c40ebab649ae2aac8cce3e3bece204b641c99b6cfac42779
  

  2. This is an example of creating a final request URL that includes the tokens created.

  http://example.cdn.ntruss.com/sample.pdf?token=st=1592204787~exp=1592208387~acl=/sample.pdf*~hmac=79872098f16596c8c40ebab649ae2aac8cce3e3bece204b641c99b6cfac42779
  

  3. This is an example request that includes the generated token in the cookie header.

  - URL : http://example.cdn.ntruss.com/sample.pdf
  - Header information to include on request 
  Cookie:  token=st=1628596072~exp=1628682472~acl=/sample.pdf*~hmac=8094467ff875e72e8fccc2e579a0cfd002f680cda7acd10b820c193f671952d8
  

• How to create an authentication token using the C# language

  1. Write the code to generate a token from the file provided by Git. (Sample Code)

  using BookBeat.Akamai.EdgeAuthToken;
  namespace MyNameSpace {
      public class MyTokenGenerator {
          public string GenerateMyToken(long window, string acl, string key) {
              var tokenConfig = new AkamaiTokenConfig
              {
                  Window = window, // Time to live (in seconds)
                  Acl = /sample.pdf*, // Access control list containing token permissions
                  Key = b2b1, // Encryption key
                  StartTime = DateTimeOffset.Now.ToUnixTimeSeconds() // Time to Start Timing(From Now)
              };
  
              var tokenGenerator = new AkamaiTokenGenerator();
              var token = tokenGenerator.GenerateToken(tokenConfig);
  
              return token;
          }
      }
  }
  

  2. This is an example of creating a final request URL that includes the tokens created.

  http://example.cdn.ntruss.com/sample.pdf? token=st=1628596072~exp=1628682472~acl=/sample.pdf*~hmac=8094467ff875e72e8fccc2e579a0cfd002f680cda7acd10b820c193f671952d8
  

  3. This is an example request that includes the generated token in the cookie header.

  - URL : http://example.cdn.ntruss.com/sample.pdf
  - Header information to include on request 
  Cookie:  token=st=1628596072~exp=1628682472~acl=/sample.pdf*~hmac=8094467ff875e72e8fccc2e579a0cfd002f680cda7acd10b820c193f671952d8
  

• Note about the st (startTime) value: if the time of the customer's token creation server is faster than the time of the CDN+ Edge server by 2 to 4 seconds, then the token's start time (st value) may be recognized as "too early" on the edge server and cause a failure in authentication. To prevent this, it is recommended that you set the start_time value 10 seconds faster than the current time, and the end_time value 10 seconds slower, when calling the method for creating tokens. Above all, it is important to accurately sync the time of the web server for creating tokens to NTP.

④ When a user responds, you can respond by adding/changing or deleting headers.

• The following strings cannot be entered as header names or values: "(),/:;<=>?@[]{}", non-alphanumeric characters, spaces
• The maximum length of header value that can be entered is 256 bytes.
• Example) Action: Add, Header Name : Access-Control-Allow-Origin, Header Value : => you can set the CORS header of "Access-Control-Allow-Origin:" to be responded to by the edge.

Confirm and apply CDN+ settings

Confirm CDN+ settings

Confirm the information of the settings you entered. After confirming, click the [Request subscription to CDN] button.

• If you want to edit the input settings, click the [Previous] button.
• The CDN setup begins with clicking the [Request subscription to CDN] button and the status changes from "Requesting" to "Operational" once the configuration is complete.

Register domain for using CDN+

• This is not applicable when used as a domain provided by the NAVER Cloud Platform.
• If you have requested for your own domain as a service domain, you can verify your CDN+ domain by requesting subscription to CDN+.
• In order to use NAVER Cloud Platform domain, it is necessary to set CNAME for it in the DNS system or hosting company that is being used.

Example)

• Your domain: sample.example.com

• NAVER Cloud Platform domain: example.cdn.ntruss.com

  sample.example.com	600	IN CNAME	example.cdn.ntruss.com.
  

Managing CDN+

Change settings

You can change the settings you configured when request subscription to CDN+.

① Select the CDN+ service for which you want to change the settings.

② Click the [Change settings] button.

③ You can change all settings except for the service name and CDN domain. When you have finished entering or selecting the changes, click the [Next] button.

• How to change the domain according to the impossibility of changing the service domain

Create a new CDN and change the CDN domain in the customer service to the newly created domain.
Check the usage statistics of the existing CDN for the transmission and request counts, and if there is no usage, it means that the service domain transfer has been completed, so please return it.

④ Changes made in the existing settings are highlighted and upon confirmation, clicking the [Change settings] button will apply the changes to the CDN service settings. The changes to the settings may take a few minutes to reflect, and the status will change from "Changing" to "Operational" when the changes are complete.

Purge

It is a feature that deletes content saved on the cache server.

① All files: purge all files corresponding to the domain.

② Directory: purge files in a specific directory path (including sub-directories) within the domain.

③ Manually enter file: purge only specific content entered. You can enter only 100 files at a time.

• If you are using a single CDN+ service for multiple domains and the cache key is set to incoming host header, select the specific domain to apply the purge to. You can select one or multiple domains using multi-select.

• Please use with caution when performing a "Full File"or "Directory" purge as it will clear caching and may increase requests to the source.

• You can utilize the purge feature through APIs in addition to the GUI.
  
  For a detailed guide, refer to CDN+ Purge API reference.

Purge log

You can see the history of the purge.

① Select the CDN+ service to see the purge history.

② Click the [Purge log] button.

③ You can see the history of the last 5 purges applied. However, even if the file name is entered incorrectly, the purge will be marked as successful.

Suspend CDN

You can temporarily stop CDN+ content delivery.

① Select the CDN+ service to suspend.

② Click the [Suspend] button.

Restart/Cancel subscription to CDN

You can restart or cancel the CDN+ service that was temporarily suspended.

This action is only available when the status is Stopped.

① Select the CDN+ service you want to restart or cancel subscription to from a Stopped status.

② Click the [Restart] or [Cancel subscription to CDN] button.

③ After the restart is complete, the status in the list will change from Stopped to Operational. Once the cancellation is complete, it will disappear from the list.

Manage certificate

The feature of registering and managing certificates in CDN+ has been transferred to Certificate Manager.

You can easily manage certificates using Certificate Manager.

Monitoring

Select monitoring

You can select the target service name and period to view statistical graphs of the transfer volume, number of requests, cache hit rate, and response codes.

There is a delay of about 20 minutes in collecting/processing data due to statistical delays from collecting data from the CDN cache server.

You can select a period for viewing monitoring data ranging from a minimum of 2 days to a maximum of 3 months, and future dates cannot be selected.

The data analysis cycle according to the viewing period is as follows:

• Within 2 days: 5 minutes
• More than 2 days - within 1 week: 30 minutes
• More than 1 week - within 1 month: 2 hours
• More than 1 month - within 3 months: 6 hours

Monitored items

① Traffic (Mbps): network bandwidth of data transmitted through CDN

② Transfer amount (Bytes): amount of data transmitted through CDN (basis for calculating service usage fees)

③ Number of requests: number of service requests incoming through CDN (basis for calculating service usage fees)

④ Cache hit rate (%): the ratio of the number of requests through CDN to the number of requests incoming to the source server, and the higher the hit rate, the higher the reuse of cached content within the cache server, and the lower the requests to the source server and the source server load.

⑤ Response codes (count): number of responses (2xx, 3xx, 4xx, 5xx) from CDN to users

⑥ Source server traffic (Mbps): network bandwidth of data received from the source server as measured by CDN

⑦ Source responses (count): number of responses (2xx, 3xx, 4xx, 5xx) received from the source server as measured by CDN

Statistics

Select statistics

You can select the target service name and period to view statistical graphs of the transfer volume and number of requests.

You can select a period for viewing statistical data ranging from a minimum of 2 days to a maximum of 1 year, and statistics can be viewed in daily data units.

When selecting the data viewing date, future dates cannot be selected based on the current date.
You can compare periods, and the viewing period (2 days, 1 week, 1 month, etc.) must be the same for comparison.

Statistics items

① Traffic (bps): network bandwidth of data transmitted through CDN

② Transfer amount (Bytes): amount of data transmitted through CDN (basis for calculating service usage fees)

③ Number of requests: number of service requests incoming through CDN (basis for calculating service usage fees)

Go to related information

You can see related information in the guides listed below.

• CDN+ Purge API start guide