Storing request and Response to Redis

rohit.c.joshi · 2015-10-29T05:30:09+00:00

Thanks a lot for your detailed response agentzh!I'll probably stick to a per-worker memory.On Wednesday, October 28, 2015 at 6:39:33 PM UTC-7, agent...

Storing request and Response to Redis

rohit.c.joshi

Hello,

As part of the audit logging requirement, I would like to store the request and response into the Redis.

Currently, I am using body_filter_by_lua.lua file and print to error log which works fine. I am setting custom header message-id as a key and header+body as value.

When I tried to write to Redis, it seems Redis access is not available in body_filter_by_lua.

Here is my code which writes headers/body into the log file.

local resp_headers = ngx.resp.get_headers(100, true)

local hdrs = ""

for k, v in pairs(resp_headers) do

if type(v) == "table" then

hdrs = hdrs .. ", " .. k .. ": " .. table.concat(v, ",")

else

hdrs = hdrs .. ", " .. k .. ": " .. v

end

local chunk, eof = ngx.arg[1], ngx.arg[2]

local buffered = ngx.ctx.buffered

if not buffered then

buffered = {}

ngx.ctx.buffered = buffered

end

if chunk ~= "" then

buffered[#buffered + 1] = chunk

ngx.arg[1] = nil

end

if eof then

local whole = table.concat(buffered)

ngx.ctx.buffered = nil

ngx.arg[1] = whole

local res_key = "Response:X-Message-ID:" .. ngx.var.messageid .. ":" .. hdrs .. "\\r\\n\\r\\n" .. whole .. "\\r\\n\\r\\n"

print(res_key)

end

What are the alternates?

agentzh

Hello!

On Thu, Oct 29, 2015 at 5:30 AM, RJoshi wrote:
>   As part of the audit logging requirement, I would like to store the
> request and response into the Redis.
> Currently, I am using body_filter_by_lua.lua file and print to error log
> which works fine.  I am setting custom header message-id as a key and
> header+body as value.
>
> When I tried to write to Redis, it seems Redis access is not available in
> body_filter_by_lua.
>

Because you're already buffering the whole response data in memory
anyway, there's little point in using the output filter mechanism
which is meant for streaming or nonbuffered processing.

The simplest way to achieve this effect is to use ngx.location.capture
+ ngx_proxy (or just some lua-resty-http library), combined with
lua-resty-redis in a content_by_lua handler.

Regards,
-agentzh

rohit.c.joshi

What would be the most efficient way to retrieve request/response?

On Wednesday, 28 October 2015 21:23:22 UTC-4, agentzh wrote:

Hello!

On Thu, Oct 29, 2015 at 5:30 AM, RJoshi wrote:
> As part of the audit logging requirement, I would like to store the
> request and response into the Redis.
> Currently, I am using body_filter_by_lua.lua file and print to error log
> which works fine. I am setting custom header message-id as a key and
> header+body as value.
>
> When I tried to write to Redis, it seems Redis access is not available in
> body_filter_by_lua.
>

Because you're already buffering the whole response data in memory
anyway, there's little point in using the output filter mechanism
which is meant for streaming or nonbuffered processing.

The simplest way to achieve this effect is to use ngx.location.capture
+ ngx_proxy (or just some lua-resty-http library), combined with
lua-resty-redis in a content_by_lua handler.

Regards,
-agentzh

agentzh

Hello!

On Sun, Nov 1, 2015 at 2:49 AM, RJoshi wrote:
> What would be the most efficient way to retrieve request/response?
>

Depending on the size of your requests and responses. There're quite
some API functions exposed by ngx_lua for different use cases. You can
check them out. In particular, ngx.req.get_body_data,
ngx.req.get_body_file, ngx.req.socket, body_filter_by_lua,
ngx.location.capture, just to name a few.

Regards,
-agentzh