nginx regex - match variable number of fields

Question

I have a route with urls that can have an optional extra field. It can be either of the form :

"/my-route/azezaezaeazeaze.123x456.jpg"
"/my-route/azezaezaeazeaze.123x456.6786786786.jpg"

with :

"azezaezaeazeaze" being a mongoId
123x456 two integers separated by "x"
6786786786 a unix timestamp
jpg an image extension (could be jpeg, png, gif...)
all those are separated by a "."

I would like to remove the optional part (the timestamp) from the request with the http rewrite module. So that the second url effectively becomes lie the first.

I made a small test on regex101 to get the groups, but : - it doesn't seem to be the right syntax for nginx - I do not see how it will allow me to remove the timestamp

How can I remove the timestamp from that url?

meuh · Accepted Answer · 2015-10-06 09:36:38Z

1

Starting from the right-hand end, you need to match a dot followed by anything except a dot, so we have (\.[^.]*)$, then moving to the left, we want to match a dot followed by only digits \.[0-9]*, which we dont want to capture, and then to the left of that we want everything. I ended up with something like this:

rewrite ^(.*)\.[0-9]*(\.[^.]*)$ $1$2 ;

edited Oct 6, 2015 at 9:36

answered Oct 5, 2015 at 18:30

meuh

12.4k2 gold badges35 silver badges48 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

nha Over a year ago

So it matches the url, but it is not rewriting it correctly. I am trying to figure out what the problem is.

meuh Over a year ago

sorry, \1\2 was the syntax for the substitution in your regex101 example. It should be $1$2 for nginx. As to the flags, that depends on the rest of your setup.

nha Over a year ago

Ah you are correct it seems, I accepted your answer. Would you say that your regex is more efficient than mine (since it seems more strict with the digits) ?

meuh Over a year ago

it's not particularly efficient as .* ends up matching too much and causes backtracking until .[0-9] matches. You might try versions using several \.[^.]* as they will progress without backtracking.

nha · Accepted Answer · 2015-10-06 09:08:27Z

0

Capitalizing on my first attempt and @meuh answer, I ended up with the following :

rewrite ^(/.*\..*)(\..*)(\..*)$ $1$3 last;

Now it works, but I would welcome any comment regarding the style/efficiency of this rewrite.

answered Oct 6, 2015 at 9:08

nha

18.1k15 gold badges95 silver badges141 bronze badges

Collectives™ on Stack Overflow

nginx regex - match variable number of fields

2 Answers 2

4 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related