Cache HIT/MISS header

Perhaps use the X-Debug header:
https://docs.trafficserver.apache.org/en/7.1.x/admin-guide/plugins/xdebug.en.html
and maybe a global header_rewrite rule to add the magic header to make
the debug part appear?

On Mon, Dec 11, 2017 at 8:57 AM, Benjamin Morel

Post by Benjamin Morel
Sorry if this has been asked before, but I couldn't find it in the docs.
I'm using ATS as a forward proxy. Is there a way to add a response header to
tell me if the request was a HIT or a MISS?
Something like: X-Cache: HIT
Thanks in advance,
Benjamin

Igor Cicimov

2017-12-12 00:29:08 UTC

You can use the Via header:

##############################################################################
# Via: headers. Docs:
#
https://docs.trafficserver.apache.org/records.config#proxy-config-http-insert-response-via-str
##############################################################################
CONFIG proxy.config.http.insert_request_via_str INT 1
CONFIG proxy.config.http.insert_response_via_str INT 3
CONFIG proxy.config.http.response_via_str STRING ATS

that will insert values like below that you can decode:

# traffic_via '[cHs f ]'
Via header is [cHs f ], Length is 8
Via Header Details:
*Result of Traffic Server cache lookup for URL :in cache, fresh (a
cache "HIT")*
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed

for detailed stats (insert_response_via_str INT 3):

# traffic_via 'uScHs f p eN:t cCHi p s '
Via header is uScHs f p eN:t cCHi p s , Length is 24
Via Header Details:
Request headers received from client :simple request (not
conditional)
*Result of Traffic Server cache lookup for URL :in cache, fresh (a
cache "HIT")*
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
Proxy operation result :unknown
Error codes (if any) :no error
Tunnel info :no tunneling
Cache Type :cache
*Cache Lookup Result :cache hit*
ICP status :no icp
Parent proxy connection status :no parent proxy or
unknown
Origin server connection status :no server
connection needed

but you might be already familiar with it and not exactly what you need.

Post by Miles Libbey
https://docs.trafficserver.apache.org/en/7.1.x/admin-
guide/plugins/xdebug.en.html
and maybe a global header_rewrite rule to add the magic header to make
the debug part appear?
On Mon, Dec 11, 2017 at 8:57 AM, Benjamin Morel

Post by Benjamin Morel
Sorry if this has been asked before, but I couldn't find it in the docs.
I'm using ATS as a forward proxy. Is there a way to add a response

header to

Post by Benjamin Morel
tell me if the request was a HIT or a MISS?
Something like: X-Cache: HIT
Thanks in advance,
Benjamin

Veiko Kukk

2017-12-12 12:10:41 UTC

Hi,

I recently had exact same task: to include cache status in response
headers. That's what I did:

* proxy.config.http.insert_response_via_str 2
* Using header_rewrite plugin to create additional header with following
config:
cond %{SEND_RESPONSE_HDR_HOOK} [AND]
cond %{HEADER:Via} /(\[cH|\[cR)/
set-header X-Cache "HIT"

Veiko

Post by Igor Cicimov
############################################################
##################
# https://docs.trafficserver.apache.org/records.config#
proxy-config-http-insert-response-via-str
############################################################
##################
CONFIG proxy.config.http.insert_request_via_str INT 1
CONFIG proxy.config.http.insert_response_via_str INT 3
CONFIG proxy.config.http.response_via_str STRING ATS
# traffic_via '[cHs f ]'
Via header is [cHs f ], Length is 8
*Result of Traffic Server cache lookup for URL :in cache, fresh
(a cache "HIT")*
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
# traffic_via 'uScHs f p eN:t cCHi p s '
Via header is uScHs f p eN:t cCHi p s , Length is 24
Request headers received from client :simple request
(not conditional)
*Result of Traffic Server cache lookup for URL :in cache, fresh
(a cache "HIT")*
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
Proxy operation result :unknown
Error codes (if any) :no error
Tunnel info :no tunneling
Cache Type :cache
*Cache Lookup Result :cache hit*
ICP status :no icp
Parent proxy connection status :no parent proxy or
unknown
Origin server connection status :no server
connection needed
but you might be already familiar with it and not exactly what you need.

Post by Miles Libbey
https://docs.trafficserver.apache.org/en/7.1.x/admin-guide/
plugins/xdebug.en.html
and maybe a global header_rewrite rule to add the magic header to make
the debug part appear?
On Mon, Dec 11, 2017 at 8:57 AM, Benjamin Morel

Post by Benjamin Morel
Sorry if this has been asked before, but I couldn't find it in the docs.
I'm using ATS as a forward proxy. Is there a way to add a response

header to

Post by Benjamin Morel
tell me if the request was a HIT or a MISS?
Something like: X-Cache: HIT
Thanks in advance,
Benjamin

Veiko Kukk

2017-12-13 09:43:26 UTC

If you also need MISS (our setup does not, we know amount of requests and
amount of HIT's), you need to add another condition with set-header X-Cache
"MISS"
--
Veiko

Post by Veiko Kukk
Hi,
I recently had exact same task: to include cache status in response
* proxy.config.http.insert_response_via_str 2
* Using header_rewrite plugin to create additional header with following
cond %{SEND_RESPONSE_HDR_HOOK} [AND]
cond %{HEADER:Via} /(\[cH|\[cR)/
set-header X-Cache "HIT"
Veiko

Post by Igor Cicimov
############################################################
##################
# https://docs.trafficserver.apache.org/records.config#proxy-
config-http-insert-response-via-str
############################################################
##################
CONFIG proxy.config.http.insert_request_via_str INT 1
CONFIG proxy.config.http.insert_response_via_str INT 3
CONFIG proxy.config.http.response_via_str STRING ATS
# traffic_via '[cHs f ]'
Via header is [cHs f ], Length is 8
*Result of Traffic Server cache lookup for URL :in cache, fresh
(a cache "HIT")*
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
# traffic_via 'uScHs f p eN:t cCHi p s '
Via header is uScHs f p eN:t cCHi p s , Length is 24
Request headers received from client :simple request
(not conditional)
*Result of Traffic Server cache lookup for URL :in cache, fresh
(a cache "HIT")*
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
Proxy operation result :unknown
Error codes (if any) :no error
Tunnel info :no tunneling
Cache Type :cache
*Cache Lookup Result :cache hit*
ICP status :no icp
Parent proxy connection status :no parent proxy
or unknown
Origin server connection status :no server
connection needed
but you might be already familiar with it and not exactly what you need.

Post by Miles Libbey
https://docs.trafficserver.apache.org/en/7.1.x/admin-guide/p
lugins/xdebug.en.html
and maybe a global header_rewrite rule to add the magic header to make
the debug part appear?
On Mon, Dec 11, 2017 at 8:57 AM, Benjamin Morel

Post by Benjamin Morel
Sorry if this has been asked before, but I couldn't find it in the

docs.

Post by Benjamin Morel
I'm using ATS as a forward proxy. Is there a way to add a response

header to

Post by Benjamin Morel
tell me if the request was a HIT or a MISS?
Something like: X-Cache: HIT
Thanks in advance,
Benjamin

Benjamin Morel

2017-12-13 17:33:55 UTC

Thank you all for your replies. TBH I expected it to be much simpler!

That being said, proxy.config.http.insert_request_via_str, and parsing the
resulting Via header, looks like the way to go.

Apart from the obscure decoder, is there a documentation for the format of
the Via transaction codes?
With a listing of all possible statuses (cR = fresh Ram hit, cH = fresh
hit, ...)

I couldn't find this in the doc.

Thanks in advance,
Ben

Post by Veiko Kukk
If you also need MISS (our setup does not, we know amount of requests and
amount of HIT's), you need to add another condition with set-header X-Cache
"MISS"
--
Veiko

Post by Igor Cicimov
############################################################
##################
# https://docs.trafficserver.apache.org/records.config#proxy-c
onfig-http-insert-response-via-str
############################################################
##################
CONFIG proxy.config.http.insert_request_via_str INT 1
CONFIG proxy.config.http.insert_response_via_str INT 3
CONFIG proxy.config.http.response_via_str STRING ATS
# traffic_via '[cHs f ]'
Via header is [cHs f ], Length is 8
*Result of Traffic Server cache lookup for URL :in cache, fresh
(a cache "HIT")*
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
# traffic_via 'uScHs f p eN:t cCHi p s '
Via header is uScHs f p eN:t cCHi p s , Length is 24
Request headers received from client :simple request
(not conditional)
*Result of Traffic Server cache lookup for URL :in cache, fresh
(a cache "HIT")*
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
Proxy operation result :unknown
Error codes (if any) :no error
Tunnel info :no tunneling
Cache Type :cache
*Cache Lookup Result :cache hit*
ICP status :no icp
Parent proxy connection status :no parent proxy
or unknown
Origin server connection status :no server
connection needed
but you might be already familiar with it and not exactly what you need.

Post by Miles Libbey
https://docs.trafficserver.apache.org/en/7.1.x/admin-guide/p
lugins/xdebug.en.html
and maybe a global header_rewrite rule to add the magic header to make
the debug part appear?
On Mon, Dec 11, 2017 at 8:57 AM, Benjamin Morel

Post by Benjamin Morel
Sorry if this has been asked before, but I couldn't find it in the

docs.

Post by Benjamin Morel
I'm using ATS as a forward proxy. Is there a way to add a response

header to

Post by Benjamin Morel
tell me if the request was a HIT or a MISS?
Something like: X-Cache: HIT
Thanks in advance,
Benjamin

Veiko Kukk

2017-12-14 11:03:34 UTC

Hi Benjamin,

I used the source as documentation
https://github.com/apache/trafficserver/blob/master/cmd/traffic_via/traffic_via.cc

Veiko

Post by Benjamin Morel
Thank you all for your replies. TBH I expected it to be much simpler!
That being said, proxy.config.http.insert_request_via_str, and parsing
the resulting Via header, looks like the way to go.
Apart from the obscure decoder, is there a documentation for the format of
the Via transaction codes?
With a listing of all possible statuses (cR = fresh Ram hit, cH = fresh
hit, ...)
I couldn't find this in the doc.
Thanks in advance,
Ben

Post by Veiko Kukk
If you also need MISS (our setup does not, we know amount of requests and
amount of HIT's), you need to add another condition with set-header X-Cache
"MISS"
--
Veiko

Post by Igor Cicimov
############################################################
##################
# https://docs.trafficserver.apache.org/records.config#proxy-c
onfig-http-insert-response-via-str
############################################################
##################
CONFIG proxy.config.http.insert_request_via_str INT 1
CONFIG proxy.config.http.insert_response_via_str INT 3
CONFIG proxy.config.http.response_via_str STRING ATS
# traffic_via '[cHs f ]'
Via header is [cHs f ], Length is 8
*Result of Traffic Server cache lookup for URL :in cache,
fresh (a cache "HIT")*
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
# traffic_via 'uScHs f p eN:t cCHi p s '
Via header is uScHs f p eN:t cCHi p s , Length is 24
Request headers received from client :simple request
(not conditional)
*Result of Traffic Server cache lookup for URL :in cache,
fresh (a cache "HIT")*
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
Proxy operation result :unknown
Error codes (if any) :no error
Tunnel info :no tunneling
Cache Type :cache
*Cache Lookup Result :cache hit*
ICP status :no icp
Parent proxy connection status :no parent proxy
or unknown
Origin server connection status :no server
connection needed
but you might be already familiar with it and not exactly what you need.

Post by Miles Libbey
https://docs.trafficserver.apache.org/en/7.1.x/admin-guide/p
lugins/xdebug.en.html
and maybe a global header_rewrite rule to add the magic header to make
the debug part appear?
On Mon, Dec 11, 2017 at 8:57 AM, Benjamin Morel

Post by Benjamin Morel
Sorry if this has been asked before, but I couldn't find it in the

docs.

Post by Benjamin Morel
I'm using ATS as a forward proxy. Is there a way to add a response

header to

Post by Benjamin Morel
tell me if the request was a HIT or a MISS?
Something like: X-Cache: HIT
Thanks in advance,
Benjamin

Miles Libbey

2017-12-14 16:35:59 UTC

On Wed, Dec 13, 2017 at 9:33 AM, Benjamin Morel

https://docs.trafficserver.apache.org/en/7.1.x/appendices/faq.en.html#how-do-i-interpret-the-via-header-code

Post by Benjamin Morel
With a listing of all possible statuses (cR = fresh Ram hit, cH = fresh hit,
...)
I couldn't find this in the doc.
Thanks in advance,
Ben

Post by Veiko Kukk
If you also need MISS (our setup does not, we know amount of requests and
amount of HIT's), you need to add another condition with set-header X-Cache
"MISS"
--
Veiko

Post by Igor Cicimov
##############################################################################
#
https://docs.trafficserver.apache.org/records.config#proxy-config-http-insert-response-via-str
##############################################################################
CONFIG proxy.config.http.insert_request_via_str INT 1
CONFIG proxy.config.http.insert_response_via_str INT 3
CONFIG proxy.config.http.response_via_str STRING ATS
# traffic_via '[cHs f ]'
Via header is [cHs f ], Length is 8
Result of Traffic Server cache lookup for URL :in cache, fresh
(a cache "HIT")
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
# traffic_via 'uScHs f p eN:t cCHi p s '
Via header is uScHs f p eN:t cCHi p s , Length is 24
Request headers received from client :simple request
(not conditional)
Result of Traffic Server cache lookup for URL :in cache, fresh
(a cache "HIT")
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
Proxy operation result :unknown
Error codes (if any) :no error
Tunnel info :no tunneling
Cache Type :cache
Cache Lookup Result :cache hit
ICP status :no icp
Parent proxy connection status :no parent proxy
or unknown
Origin server connection status :no server
connection needed
but you might be already familiar with it and not exactly what you need.

Post by Miles Libbey
https://docs.trafficserver.apache.org/en/7.1.x/admin-guide/plugins/xdebug.en.html
and maybe a global header_rewrite rule to add the magic header to make
the debug part appear?
On Mon, Dec 11, 2017 at 8:57 AM, Benjamin Morel

Benjamin Morel

2017-12-19 11:16:15 UTC

I used the source as documentation https://github.
com/apache/trafficserver/blob/master/cmd/traffic_via/traffic_via.cc

https://docs.trafficserver.apache.org/en/7.1.x/

appendices/faq.en.html#how-do-i-interpret-the-via-header-code

Thanks to both of you!

Ben

On Wed, Dec 13, 2017 at 9:33 AM, Benjamin Morel

Post by Benjamin Morel
Thank you all for your replies. TBH I expected it to be much simpler!
That being said, proxy.config.http.insert_request_via_str, and parsing

the

Post by Benjamin Morel
resulting Via header, looks like the way to go.
Apart from the obscure decoder, is there a documentation for the format

Post by Benjamin Morel
the Via transaction codes?

https://docs.trafficserver.apache.org/en/7.1.x/
appendices/faq.en.html#how-do-i-interpret-the-via-header-code

Post by Benjamin Morel
With a listing of all possible statuses (cR = fresh Ram hit, cH = fresh

hit,

Post by Benjamin Morel
...)
I couldn't find this in the doc.
Thanks in advance,
Ben

Post by Veiko Kukk
If you also need MISS (our setup does not, we know amount of requests

and

Post by Veiko Kukk
amount of HIT's), you need to add another condition with set-header

X-Cache

Post by Veiko Kukk
"MISS"
--
Veiko

following

Post by Veiko Kukk
cond %{SEND_RESPONSE_HDR_HOOK} [AND]
cond %{HEADER:Via} /(\[cH|\[cR)/
set-header X-Cache "HIT"
Veiko

Post by Igor Cicimov
############################################################

##################

Post by Igor Cicimov
#
https://docs.trafficserver.apache.org/records.config#

proxy-config-http-insert-response-via-str

Post by Igor Cicimov
############################################################

##################

Post by Igor Cicimov
CONFIG proxy.config.http.insert_request_via_str INT 1
CONFIG proxy.config.http.insert_response_via_str INT 3
CONFIG proxy.config.http.response_via_str STRING ATS
# traffic_via '[cHs f ]'
Via header is [cHs f ], Length is 8
Result of Traffic Server cache lookup for URL :in cache,

fresh

Post by Igor Cicimov
(a cache "HIT")
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
# traffic_via 'uScHs f p eN:t cCHi p s '
Via header is uScHs f p eN:t cCHi p s , Length is 24
Request headers received from client :simple request
(not conditional)
Result of Traffic Server cache lookup for URL :in cache,

fresh

Post by Igor Cicimov
(a cache "HIT")
Response information received from origin server :no server
connection needed
Result of document write-to-cache: :no cache write
performed
Proxy operation result :unknown
Error codes (if any) :no error
Tunnel info :no tunneling
Cache Type :cache
Cache Lookup Result :cache hit
ICP status :no icp
Parent proxy connection status :no parent

proxy

Post by Igor Cicimov
or unknown
Origin server connection status :no server
connection needed
but you might be already familiar with it and not exactly what you

need.

Post by Igor Cicimov

Post by Miles Libbey
https://docs.trafficserver.apache.org/en/7.1.x/admin-

guide/plugins/xdebug.en.html

Post by Igor Cicimov

Post by Miles Libbey
and maybe a global header_rewrite rule to add the magic header to

make

Post by Igor Cicimov

Post by Miles Libbey
the debug part appear?
On Mon, Dec 11, 2017 at 8:57 AM, Benjamin Morel

Post by Benjamin Morel
Sorry if this has been asked before, but I couldn't find it in the docs.
I'm using ATS as a forward proxy. Is there a way to add a response
header to
tell me if the request was a HIT or a MISS?
Something like: X-Cache: HIT
Thanks in advance,
Benjamin

James Peach

2017-12-13 19:09:21 UTC

Post by Benjamin Morel
Sorry if this has been asked before, but I couldn't find it in the docs.
I'm using ATS as a forward proxy. Is there a way to add a response header to tell me if the request was a HIT or a MISS?
Something like: X-Cache: HIT

I'd use the `xdebug` plugin, see <https://docs.trafficserver.apache.org/en/7.1.x/admin-guide/plugins/xdebug.en.html>. If you want the `X-Cache` header in every response, then you can use `header_rewrite` to inject the appropriate `X-Debug` header on every request.

J

Veiko Kukk

2017-12-14 11:00:46 UTC