I need a regex that will be able to match AWS EC2 instance IDs. Instance IDs have the following criteria:
Valid instance IDs are: i-ed3a2f7a
or i-096e0bec99b504f82
or i-0cad9e810fbd12f4f
Invalid instance IDs are e123g12
or i-1fz5645m
I was able to create the following regex i-[a-f0-9](?:.{7}|.{16})$
but it is also accepting i-abcdeffh
. h
is not between af
Grateful if someone could help me out
You can make a regex to match the 8-character ID value and add an optional 9 characters after it:
^i-[a-f0-9]{8}(?:[a-f0-9]{9})?$
Note we use start and end of line anchors to prevent matching additional characters before or after the ID value. This regex will match only 8 or 17 character ID values, not 12 or 11 or 5 etc.
You seem to be able to just use:
^i-(?:[a-f\d]{8}|[a-f\d]{17})$
See an online demo
^i-
- Start-line anchor followed by literally 'i-'; (?:
- Open non-capture group for alternation;
[af\d]{8}
- Match 8 times any character from given character class; |
- Or; [af\d]{17}
- Match 17 times any character from given character class; $
- End-line anchor.
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