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    Custom Headers

    Last updated: 2024-05-06 09:46:39
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      Feature Overview

      An HTTP header (metadata header) of an object is a string sent by the server over HTTP before it sends HTML data to the browser. By modifying HTTP headers (metadata headers), you can modify how the webpage responds as well as certain configurations, such as caching time. Modifying an object's HTTP headers does not modify the object itself.
      Note:
      For objects of ARCHIVE and DEEP ARCHIVE, custom headers can only be set during upload. Setting custom headers for objects that have already been uploaded is not supported.

      How It Works

      1. Log in to the COS console.
      2. Click Bucket List on the left sidebar.
      3. Locate the bucket where the object resides and click the bucket name.
      4. Click File List on the left sidebar.
      5. Locate the object for which a header is to be customized and click More > Custom Header in the operation column on the right. To customize headers for multiple objects, select multiple objects and click More Actions > Custom Header on the top.
      6. In the pop-up window, select the parameter type of the metadata header to be set, enter the metadata value, and click OK. COS provides the following six types of object HTTP headers for configuration:
      HTTP Header
      Description
      Example
      Content-Type
      MIME information of the file
      image/jpeg
      Cache-Control
      File caching mechanism
      no-cache: Indicates that cache cannot be used directly, but whether the object has been updated must be verified first with the server. If the object has been updated, it indicates that the cache is expired, and the object must be re-downloaded from the server; if the object has not been updated, the cache is not expired, and the local cache will be used.
      max-age=200: Indicates the relative expiration time of the cached content, in seconds.
      Content-Disposition
      Extension of MIME protocol
      inline: Directly previews the content of the file.
      attachment: Downloads to the specified path in the browser with the original filename.
      attachment; filename="FileName": You should download it to the specified path in the browser with a custom filename. FileName defines the name of the file after download, for example, example.jpg. If the attachment name is in Chinese, it needs to be URL encoded, for example, attachment; filename* = UTF-8' '%E4%B8%AD%E6%96%87.txt
      Content-Encoding
      File encoding format
      gzip
      Note: If the Content-Encoding in the header has been modified as gzip, but the file has not been compressed with gzip, a decoding error will occur.
      Expires
      Expiration date of the cache
      Wed, 21 Oct 2015 07:28:00 GMT
      x-cos-meta-[custom suffix]
      User-defined content
      x-cos-meta-via: homepage
      Note: Header names support only hyphens (-), digits, and English letters (a-z). Uppercase letters in English will be converted to lowercase letters; other characters, including underscores (_), are not supported.

      License request example

      Assume that a bucket named "examplebucket-1250000000" was created under account APPID 1250000000, and an object "exampleobject.txt" was uploaded to the bucket's root directory.

      Non-custom HTTP header of objects

      The sample below shows the headers returned for a request to download this object through a browser or client if no custom HTTP headers are specified.

      Request

      GET /exampleobject.txt HTTP/1.1
      Host: examplebucket-1250000000.cos.ap-beijing.myqcloud.com
      Date: Fri, 10 Apr 2020 09:35:16 GMT
      Authorization: q-sign-algorithm=sha1&q-ak=AKID8A0fBVtYFrNm02oY1g1JQQF0c3JO****&q-sign-time=1586511316;1586518516&q-key-time=1586511316;1586518516&q-header-list=date;host&q-url-param-list=&q-signature=1bd1898e241fb978df336dc68aaef4c0acae****
      Connection: close

      Response

      HTTP/1.1 200 OK
      Content-Type: text/plain
      Access-Control-Allow-Origin: *
      Last-Modified: Fri, 10 Apr 2020 09:35:05 GMT

      Custom HTTP header of objects

      Refer to directions to add the following custom header configuration:
      Parameter
      Value
      Content-Type
      image/jpeg
      Cache-Control
      no-cache
      Content-Disposition
      attachment; filename* = UTF-8' '%E4%B8%AD%E6%96%87.jpeg
      x-cos-meta-md5
      1234
      then the headers returned for new requests will be as follows:

      Request

      GET /exampleobject.txt HTTP/1.1
      Host: examplebucket-1250000000.cos.ap-beijing.myqcloud.com
      Date: Fri, 10 Apr 2020 09:35:16 GMT
      Authorization: q-sign-algorithm=sha1&q-ak=AKID8A0fBVtYFrNm02oY1g1JQQF0c3JO****&q-sign-time=1586511316;1586518516&q-key-time=1586511316;1586518516&q-header-list=date;host&q-url-param-list=&q-signature=1bd1898e241fb978df336dc68aaef4c0acae****
      Connection: close

      Response

      HTTP/1.1 200 OK
      Cache-Control: no-cache
      Content-Type: image/jpeg
      Content-Disposition: attachment; filename* = UTF-8' '%E4%B8%AD%E6%96%87.jpeg
      x-cos-meta-md5: 1234
      Access-Control-Allow-Origin: *
      Last-Modified: Fri, 10 Apr 2020 09:35:05 GMT
      It can be seen that when custom headers are used, the response format of the page can be changed.
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