API diabled: body_rewrite_by_lua and ngx.location.capture using ngx.timer.at

rohit.c.joshi

Hello,

I am integrating Openresty as a service proxy with Oracle Coherence Cache as a remote cache . When remote cache not found, request is sent to the upstream and response should be stored into Coherence Cache. I am trying to

I tried using ngx.location.capture inside body_rewrite_by_lua to send request to coherence cache but getting error ngx.timer is disabled.

I tried replacing body_filter_by_lua with log_by_lua but getting errors.

body_filter_by_lua '

local function write_to_coherence(resp_headers)

ngx.log(ngx.DEBUG, "Timer expired. invoking write_to_coherence()")

local capi_util = require("common.utils")

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 resp_body = table.concat(buffered)

ngx.ctx.buffered = nil

ngx.arg[1] = resp_body

local resp = {}

resp["headers"] = resp_headers

resp["body"] = resp_body

resp["status"] = ngx.status

local resp_json = capi_util.lua_to_json(resp)

local options = { copy_all_vars = true, method = ngx.HTTP_PUT, body=resp_json }

local result = ngx.location.capture("/coherence_set" .. "?key=" .. ngx.var.custom_cache_key , options)

end

end -- function write_to_coherence() end

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

local ok, err = ngx.timer.at(0, write_to_coherence, resp_headers)

agentzh

Hello!

On Sat, Nov 28, 2015 at 12:37 AM, RJoshi wrote:
>   I am integrating Openresty as a service proxy with Oracle Coherence Cache
> as  a remote cache .  When remote cache not found, request is sent to the
> upstream and response should be stored into Coherence Cache. I am trying to
>
> I tried using ngx.location.capture inside  body_rewrite_by_lua  to send
> request to coherence cache but getting error ngx.timer is disabled.
>  I tried replacing body_filter_by_lua with log_by_lua but getting errors.
>

ngx.location.capture* are disabled in the contexts of
body_filter_by_lua* and log_by_lua*. The error message already
indicates that (so does the documentation). This is because of the
internal limintations in the nginx core that we cannot do anything
about.

The ngx.timer.at() API should be available in those contexts which can
serve as a work-around (but be careful about too many pending
timers!).

Regards,
-agentzh

rohit.c.joshi

I tried calling ngx.location.capture inside a function invoked by ngx.timer.at (0, xx) but getting below error.

2015/11/29 19:47:28 [error] 85739#0: lua entry thread aborted: runtime error: /opt/openresty/nginx/lua/body_filter_by_lua.lua:68: API disabled in the context of ngx.timer

stack traceback:

coroutine 0:

[C]: in function 'capture'

e.g

local function write_to_coherence(resp_headers, resp_body, status)

local resp = {}

resp["headers"] = resp_headers

resp["body"] = resp_body

resp["status"] = status

local json_body = util.lua_to_json(resp)

local options = { copy_all_vars = true, method = ngx.HTTP_PUT, body= json_body }

local result = ngx.location.capture( uri, options)

end

-- read headers and body which works fine

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

local resp_body = -- ngx.arg[1] + ngx.ctx.buffered logic

local ok, err = ngx.timer.at(0, write_to_coherence, resp_headers, resp_body, ngx.status)

On Friday, 27 November 2015 23:34:13 UTC-5, agentzh wrote:

Hello!

On Sat, Nov 28, 2015 at 12:37 AM, RJoshi wrote:
> I am integrating Openresty as a service proxy with Oracle Coherence Cache
> as a remote cache . When remote cache not found, request is sent to the
> upstream and response should be stored into Coherence Cache. I am trying to
>
> I tried using ngx.location.capture inside body_rewrite_by_lua to send
> request to coherence cache but getting error ngx.timer is disabled.
> I tried replacing body_filter_by_lua with log_by_lua but getting errors.
>

ngx.location.capture* are disabled in the contexts of
body_filter_by_lua* and log_by_lua*. The error message already
indicates that (so does the documentation). This is because of the
internal limintations in the nginx core that we cannot do anything
about.

The ngx.timer.at() API should be available in those contexts which can
serve as a work-around (but be careful about too many pending
timers!).

Regards,
-agentzh

agentzh

Hello!

On Mon, Nov 30, 2015 at 9:03 AM, RJoshi wrote:
> I tried calling ngx.location.capture inside a function invoked by
> ngx.timer.at (0, xx) but  getting below error.
>

Nope, subrequests do not make sense in the timer handler context since
timers are detached from any running requests, by definition. You
should use cosockets to talk to the outside world instead of using
subrequests.

Regards,
-agentzh

rohit.c.joshi

Thanks. That's working.

On Sunday, 29 November 2015 21:30:37 UTC-5, agentzh wrote:

Hello!

On Mon, Nov 30, 2015 at 9:03 AM, RJoshi wrote:
> I tried calling ngx.location.capture inside a function invoked by
> ngx.timer.at (0, xx) but getting below error.
>

Nope, subrequests do not make sense in the timer handler context since
timers are detached from any running requests, by definition. You
should use cosockets to talk to the outside world instead of using
subrequests.

Regards,
-agentzh