Implementing Redirections for Static Sites

This blogs talks about handling redirects in Static Sites

Implementing Redirections for Static Sites
Server Side Redirection
Table of Contents

This approach is a two fold implementation

  • Generating pages which redirects the user on client side using javascript
  • Implementing Redirects with CDN (This talks about cloudfront)

Generating index.html for redirects

We generate an index.html page for the redirected paths. This has the below components

  • http-equiv="refresh": The number of seconds until the page should redirect to another - only if the content attribute contains a non-negative integer followed by the string ';url=', and a valid URL.
    • 0;url==https://path/to/redirect: redirects to the given url after 0 seconds.
  • robots meta tag, asks the crawlers to not index the page.
  • canonical link tag: it defines the preferred URL for the current document, which helps search engines reduce duplicate content.
  • body has a anchor tag, which points to the redirected page

Sample Code

<!doctype html>
<html>
  <head>
    <title>Redirecting to https://path/to/redirect</title>
    <meta http-equiv="refresh" content="0;url=https://path/to/redirect" />
    <meta name="robots" content="noindex" />
    <link rel="canonical" href="https://path/to/redirect" />
  </head>
  <body>
    <a href="https://path/to/redirect"> Redirect to https://path/to/redirect </a>
  </body>
</html>

Configuring Redirects with _redirects for supported hosting provider

A lot of hosting providers, supports redirection using _redirects file. Eg. For sujeet.pro, I use cloudflare pages which supports redirection in this way.

The contents of this file is space separated values in format of redirect-from redirect-to.

Below is the snippet from the redirection configuration used for sujeet.pro

/gh https://github.com/sujeet-pro
/in https://www.linkedin.com/in/sujeetkrjaiswal/
/linkedin https://www.linkedin.com/in/sujeetkrjaiswal/
/twitter https://twitter.com/sujeetpro
/x https://twitter.com/sujeetpro

Configuring Redirection for Cloudfront with lambda@edge

If your static site is in S3 and is backed by a Cloudfront CDN, you can use this approach.

Cloudfront supports interceptors using lambda@edge and cloudfront funtions.

  • Viewer Request Interceptor (lambda@edge or Cloufront Functions)
  • Origin Request Interceptor (only lambda@edge)
  • Origin Response Interceptor (only lambda@edge)
  • Viewer Response Interceptor (lambda@edge or Cloufront Functions)

Origin Interceptor for redirection We can use lambda@edge function to redirect the users. For data on what urls to redirect and where to redirect, we can deploy a json configuration along with the code.

'use strict'
 
exports.handler = (event, context, callback) => {
  let request = event.Records[0].cf.request
  //if URI matches to 'pretty-url' then redirect to a different URI
  if (request.uri == '/pretty-url') {
    //Generate HTTP redirect response to a different landing page.
    const redirectResponse = {
      status: '301',
      statusDescription: 'Moved Permanently',
      headers: {
        location: [
          {
            key: 'Location',
            value: '/somecampaign/index.html'
          }
        ],
        'cache-control': [
          {
            key: 'Cache-Control',
            value: 'max-age=3600'
          }
        ]
      }
    }
    callback(null, redirectResponse)
  } else {
    // for all other requests proceed to fetch the resources
    callback(null, request)
  }
}

Redirection using Web Server

If you serve your static files via your won web servers, all the web servers supports redirections.

Configuring Nginx

server {
 # Temporary redirect to an individual page
 rewrite ^/oldpage1$ http://www.domain.com/newpage1 redirect;
 
 # Permanent redirect to an individual page
 rewrite ^/oldpage2$ http://www.domain.com/newpage2 permanent;
 }

References

#Performance #Web Development