<p dir="ltr">Random data string is good: you can easily cut it twice to decrease length and it will still be useful and pretty random. For example, twitter zipkin works with 64 bit request id. Uuid doesn't have this property.</p>
<div class="gmail_quote">27 Апр 2016 г. 11:41 пользователь "Andrew Hutchings" <<a href="mailto:ahutchings@nginx.com">ahutchings@nginx.com</a>> написал:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi,<br>
<br>
Or you could use UUIDv1 and then it would also give you uniqueness and the ability to have some debugging of IDs if required.<br>
<br>
Kind Regards<br>
Andrew<br>
<br>
On 27/04/16 06:23, SplitIce wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi,<br>
<br>
We have been using something like this for ~2 years.<br>
<br>
For ours we used a random number to start and the Process ID & Process<br>
start time to try and increase uniqueness between reloads (ours is a<br>
128bit ID). Then applying an increment, with future requests having a<br>
higher id.<br>
<br>
Perhaps that would be better than just 128bit of random data?<br>
<br>
On Wed, Apr 27, 2016 at 12:14 PM, Alexey Ivanov <<a href="mailto:savetherbtz@gmail.com" target="_blank">savetherbtz@gmail.com</a><br>
<mailto:<a href="mailto:savetherbtz@gmail.com" target="_blank">savetherbtz@gmail.com</a>>> wrote:<br>
<br>
Same here, in our environment we:<br>
* get current request id from a header<br>
* validate it against our guidelines<br>
* if not already present or does not pass validation:<br>
* re-generate using `RAND_bytes()`<br>
* propagate it to the upstream<br>
* echo it back to the downstream<br>
* log it to the access.log<br>
<br>
It would be nice if new nginx code can be used more or less drop-in<br>
replacement for our homegrown lua-stuff.<br>
<br>
We currently use following pseudo-code to<br>
validate/generate/propagate/echo-back request_ids:<br>
<br>
```<br>
set_by_lua $request_id '<br>
local success, req_id = pcall(request_id.get_hex_or_generate,<br>
ngx.var.http_x_dropbox_request_id)<br>
if not success then<br>
return "-"<br>
end<br>
return req_id<br>
';<br>
more_set_headers "X-Dropbox-Request-Id: $request_id";<br>
proxy_set_header X-Dropbox-Request-Id $request_id ;<br>
```<br>
<br>
```<br>
--[[<br>
Helper function that verifies request_id or generates new one in<br>
case<br>
validation fails.<br>
<br>
@req_id: current request id<br>
--]]<br>
function request_id.get_hex_or_generate(req_id)<br>
...<br>
end<br>
```<br>
<br>
<br>
> On Apr 26, 2016, at 9:51 AM, ToSHiC <<a href="mailto:toshic.toshic@gmail.com" target="_blank">toshic.toshic@gmail.com</a><br>
<mailto:<a href="mailto:toshic.toshic@gmail.com" target="_blank">toshic.toshic@gmail.com</a>>> wrote:<br>
><br>
> Hello,<br>
><br>
> We are using such variable for more than a year, and I suggest to<br>
add ability to extract request_id from header. It's very usefull for<br>
systems with frontend and backend installed on different servers.<br>
><br>
> On Tue, Apr 26, 2016 at 7:38 PM, Vladimir Homutov <<a href="mailto:vl@nginx.com" target="_blank">vl@nginx.com</a><br>
<mailto:<a href="mailto:vl@nginx.com" target="_blank">vl@nginx.com</a>>> wrote:<br>
> details: <a href="http://hg.nginx.org/nginx/rev/59f8f2dd8b31" rel="noreferrer" target="_blank">http://hg.nginx.org/nginx/rev/59f8f2dd8b31</a><br>
> branches:<br>
> changeset: 6531:59f8f2dd8b31<br>
> user: Vladimir Homutov <<a href="mailto:vl@nginx.com" target="_blank">vl@nginx.com</a> <mailto:<a href="mailto:vl@nginx.com" target="_blank">vl@nginx.com</a>>><br>
> date: Tue Apr 26 19:31:46 2016 +0300<br>
> description:<br>
> Variable $request_id.<br>
><br>
> The variable contains text representation based on random data,<br>
usable as<br>
> a unique request identifier.<br>
><br>
> diffstat:<br>
><br>
> src/http/ngx_http_variables.c | 47<br>
+++++++++++++++++++++++++++++++++++++++++++<br>
> 1 files changed, 47 insertions(+), 0 deletions(-)<br>
><br>
> diffs (71 lines):<br>
><br>
> diff -r 1d0e03db9f8e -r 59f8f2dd8b31 src/http/ngx_http_variables.c<br>
> --- a/src/http/ngx_http_variables.c Fri Dec 18 19:05:27 2015 +0300<br>
> +++ b/src/http/ngx_http_variables.c Tue Apr 26 19:31:46 2016 +0300<br>
> @@ -98,6 +98,8 @@ static ngx_int_t ngx_http_variable_reque<br>
> ngx_http_variable_value_t *v, uintptr_t data);<br>
> static ngx_int_t<br>
ngx_http_variable_request_time(ngx_http_request_t *r,<br>
> ngx_http_variable_value_t *v, uintptr_t data);<br>
> +static ngx_int_t ngx_http_variable_request_id(ngx_http_request_t *r,<br>
> + ngx_http_variable_value_t *v, uintptr_t data);<br>
> static ngx_int_t ngx_http_variable_status(ngx_http_request_t *r,<br>
> ngx_http_variable_value_t *v, uintptr_t data);<br>
><br>
> @@ -274,6 +276,10 @@ static ngx_http_variable_t ngx_http_cor<br>
> { ngx_string("request_time"), NULL,<br>
ngx_http_variable_request_time,<br>
> 0, NGX_HTTP_VAR_NOCACHEABLE, 0 },<br>
><br>
> + { ngx_string("request_id"), NULL,<br>
> + ngx_http_variable_request_id,<br>
> + 0, 0, 0 },<br>
> +<br>
> { ngx_string("status"), NULL,<br>
> ngx_http_variable_status, 0,<br>
> NGX_HTTP_VAR_NOCACHEABLE, 0 },<br>
> @@ -2068,6 +2074,47 @@ ngx_http_variable_request_time(ngx_http_<br>
><br>
><br>
> static ngx_int_t<br>
> +ngx_http_variable_request_id(ngx_http_request_t *r,<br>
> + ngx_http_variable_value_t *v, uintptr_t data)<br>
> +{<br>
> + u_char *id;<br>
> +<br>
> +#if (NGX_OPENSSL)<br>
> + u_char random_bytes[16];<br>
> +#endif<br>
> +<br>
> + id = ngx_pnalloc(r->pool, 32);<br>
> + if (id == NULL) {<br>
> + return NGX_ERROR;<br>
> + }<br>
> +<br>
> + v->valid = 1;<br>
> + v->no_cacheable = 0;<br>
> + v->not_found = 0;<br>
> +<br>
> + v->len = 32;<br>
> + v->data = id;<br>
> +<br>
> +#if (NGX_OPENSSL)<br>
> +<br>
> + if (RAND_bytes(random_bytes, 16) == 1) {<br>
> + ngx_hex_dump(id, random_bytes, 16);<br>
> + return NGX_OK;<br>
> + }<br>
> +<br>
> + ngx_ssl_error(NGX_LOG_ERR, r->connection->log, 0,<br>
"RAND_bytes() failed");<br>
> +<br>
> +#endif<br>
> +<br>
> + ngx_sprintf(id, "%08xD%08xD%08xD%08xD",<br>
> + (uint32_t) ngx_random(), (uint32_t) ngx_random(),<br>
> + (uint32_t) ngx_random(), (uint32_t) ngx_random());<br>
> +<br>
> + return NGX_OK;<br>
> +}<br>
> +<br>
> +<br>
> +static ngx_int_t<br>
> ngx_http_variable_connection(ngx_http_request_t *r,<br>
> ngx_http_variable_value_t *v, uintptr_t data)<br>
> {<br>
><br>
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</blockquote>
<br>
-- <br>
Andrew Hutchings (LinuxJedi)<br>
Technical Product Manager, NGINX Inc.<br>
<br>
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