Apache: X-Request-ID like in Heroku

Question

I like X-Request-ID:

The Heroku router generates a unique request ID for every incoming HTTP request that it receives. This unique ID is then passed to your application as an HTTP header called X-Request-ID.

From https://devcenter.heroku.com/articles/http-request-id

How can I configure Apache to provide X-Request-ID which is different, even if a multi-threaded MPM gets used?

score 2 · Accepted Answer · answered Aug 18 '16 at 09:00

2

You need to do two things:

Load the unique_id_module. This provides the UNIQUE_ID environment variable which serves this purpose.
```
LoadModule mod_unique_id.c
```
Copy the UNIQUE_ID into the X-Request-ID header in the appropriate virtual host using the RequestHeader directive.
```
RequestHeader setifempty X-Request-ID %{UNIQUE_ID}e
ProxyPass ...
ProxyPassReverse ...
```

Optionally, you can also put %{UNIQUE_ID}e into a custom log format so that you can log it from Apache (possibly in addition to within your application).

answered Aug 18 '16 at 09:00

Michael Hampton

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Since "X-Request-ID" seems the more common name, I will add this to the log format, and not "UNIQUE_ID". Do you agree? – guettli Aug 18 '16 at 09:21
@guettli Do you want the actual unique ID logged, or the literal string "X-Request-ID"? – Michael Hampton Aug 18 '16 at 09:26
I want the contents of the variable: the unique id, not the literal string. I would like to have a set up which is like on Heroku: https://devcenter.heroku.com/articles/http-request-id – guettli Aug 25 '16 at 10:43
@guettli Then you should do what I advised. – Michael Hampton Aug 25 '16 at 20:34

score -1 · Answer 2 · answered Sep 02 '22 at 15:15

You might want to escape the value of %{UNIQUE_ID}e for the header. This article describes it as the first example: https://httpd.apache.org/docs/trunk/env.html#examples

#
# The following works around a client sending a broken Accept_Encoding
# header.
#
SetEnvIfNoCase ^Accept.Encoding$ ^(.*)$ fix_accept_encoding=$1
RequestHeader set Accept-Encoding %{fix_accept_encoding}e env=fix_accept_encoding

Apache: X-Request-ID like in Heroku

2 Answers2