The Web Redirects File specification is an extension of the Subdomain Gateway and DNSLink Gateway specifications.
Developers can enable URL redirects or rewrites by adding redirect rules to a file named _redirects
stored underneath the root CID of their website.
This can be used, for example, to enable URL rewriting for hosting a single-page application, to redirect invalid URLs to a pretty 404 page, or to avoid link rot when moving to IPFS-based website hosting.
The Redirects File MUST be named _redirects
and stored underneath the root CID of the website.
The Redirects File MUST be a text file containing one or more lines with the following format (brackets indication optionality).
from to [status]
The path to redirect from.
The URL or path to redirect to.
An optional integer specifying the HTTP status code to return from the request. Supported values are:
200
- OK
301
- Permanent Redirect (default)302
- Found (commonly used for Temporary Redirect)303
- See Other (replacing PUT and POST with GET)307
- Temporary Redirect (explicitly preserving body and HTTP method of original request)308
- Permanent Redirect (explicitly preserving body and HTTP method of original request)404
- Not Found
410
- Gone451
- Unavailable For Legal ReasonsPlaceholders are named variables that can be used to match path segments in the from
path and inject them into the to
path.
For example:
/posts/:month/:day/:year/:slug /articles/:year/:month/:day/:slug
This rule will redirect a URL like /posts/06/15/2022/hello-world
to /articles/2022/06/15/hello-world
.
If a from
path ends with an asterisk (i.e. *
), the remainder of the from
path is slurped up into the special :splat
placeholder, which can then be injected into the to
path.
For example:
/posts/* /articles/:splat
This rule will redirect a URL like /posts/2022/06/15/hello-world
to /articles/2022/06/15/hello-world
.
Splat logic MUST only apply to a single trailing asterisk, as this is a greedy match, consuming the remainder of the path.
Lines MUST be terminated by either \n
or \r\n
.
The file size MUST NOT exceed 64 KiB.
Rules MUST only be evaluated when hosted on a Subdomain or DNSLink Gateway, so that we have Same-Origin isolation.
Rules MUST be evaluated in order, redirecting or rewriting using the first matching rule.
All redirect logic MUST only be evaluated if the requested path is not present in the DAG. This means that any performance impact associated with checking for the existence of a _redirects
file or evaluating redirect rules will only be incurred for non-existent paths.
If the _redirects
file exists but there is an error reading or parsing it, the errors MUST be returned to the user with a 500 HTTP status code.
This functionality will only be evaluated for Subdomain or DNSLink Gateways, to ensure that redirect paths are relative to the root CID hosted at the specified domain name.
Parsing of the _redirects
file should be done safely to prevent any sort of injection vector or daemon crash.
The max file size helps to prevent an additional denial of service attack vector.
Sample files for various test cases can be found in QmQyqMY5vUBSbSxyitJqthgwZunCQjDVtNd8ggVCxzuPQ4
.
Implementations SHOULD use it for internal testing.
$ ipfs ls QmQyqMY5vUBSbSxyitJqthgwZunCQjDVtNd8ggVCxzuPQ4
QmcBcFnKKqgpCVMxxGsriw9ByTVF6uDdKDMuEBq3m6f1bm - bad-codes/
QmYBhLYDwVFvxos9h8CGU2ibaY66QNgv8hpfewxaQrPiZj - examples/
QmU7ysGXwAtiV7aBarZASJsxKoKyKmd9Xrz2FFamSCbg8S - forced/
QmWHn2TunA1g7gQ7q9rwAoWuot2hMpojZ6cZ9ERsNKm5gE - good-codes/
QmRgpzYQESidTtTojN8zRWjiNs9Cy6o7KHRxh7kDpJm3KH - invalid/
QmYzMrtPyBv7LKiEAGLLRPtvqm3SjQYLWxwWQ2vnpxQwRd - newlines/
QmQTfvjGmvTfxFpUcZNLdTLuKV227KJkGiN6xooHVeVZAS - too-large/
For example, the "examples" site can be found in QmYBhLYDwVFvxos9h8CGU2ibaY66QNgv8hpfewxaQrPiZj
.
$ ipfs ls /ipfs/QmYBhLYDwVFvxos9h8CGU2ibaY66QNgv8hpfewxaQrPiZj
Qmd9GD7Bauh6N2ZLfNnYS3b7QVAijbud83b8GE8LPMNBBP 7 404.html
QmSmR9NShZ89VEBrn9SBy7Xxvjw8Qe6XArD5GqtHvbtBM3 7 410.html
QmVQqj9oZig9tH3ENHo4bxV5pNgssUwFCXUjAJAVcZVbJG 7 451.html
QmZU3kboiyi9jV59D8Mw8wzuvsr3HmvskqhYRRhdFA8wRq 317 _redirects
QmaWDLb4gnJcJbT1Df5X3j91ysiwkkyxw6329NLiC1KMDR - articles/
QmS6ZNKE9s8fsHoEnArsZXnzMWijKddhXXDsAev8LdTT5z 9 index.html
QmNwEgMrExwSsE8DCjZjahYfHUfkSWRhtqSkQUh4Fk3udD 7 one.html
QmVe2GcTbEPZkMbjVoQ9YieVGKCHmuHMcJ2kbSCzuBKh2s - redirected-splat/
QmUGVnZaofnd5nEDvT2bxcFck7rHyJRbpXkh9znjrJNV92 7 two.html
The _redirects
file is as follows.
$ ipfs cat /ipfs/QmYBhLYDwVFvxos9h8CGU2ibaY66QNgv8hpfewxaQrPiZj/_redirects
/redirect-one /one.html
/301-redirect-one /one.html 301
/302-redirect-two /two.html 302
/200-index /index.html 200
/posts/:year/:month/:day/:title /articles/:year/:month/:day/:title 301
/splat/* /redirected-splat/:splat 301
/not-found/* /404.html 404
/gone/* /410.html 410
/unavail/* /451.html 451
/* /index.html 200
The non-existent paths that are being requested should be intercepted and redirected to the destination path and the specified HTTP status code returned. The rules are evaluated in the order they appear in the file.
Any request for an existing file should be returned as is, and not intercepted by the last catch all rule.
2.4.2 Comments
Any line beginning with
#
will be treated as a comment and ignored at evaluation time.For example:
is functionally equivalent to