[nginx] Variable $request_id.

[SplitIce]

Hi,

We have been using something like this for ~2 years.

For ours we used a random number to start and the Process ID & Process
start time to try and increase uniqueness between reloads (ours is a 128bit
ID). Then applying an increment, with future requests having a higher id.

Perhaps that would be better than just 128bit of random data?

On Wed, Apr 27, 2016 at 12:14 PM, Alexey Ivanov <savetherbtz at gmail.com>
wrote:

> Same here, in our environment we:
> * get current request id from a header
> * validate it against our guidelines
> * if not already present or does not pass validation:
>   * re-generate using `RAND_bytes()`
> * propagate it to the upstream
> * echo it back to the downstream
> * log it to the access.log
>
> It would be nice if new nginx code can be used more or less drop-in
> replacement for our homegrown lua-stuff.
>
> We currently use following pseudo-code to
> validate/generate/propagate/echo-back request_ids:
>
> ```
> set_by_lua $request_id '
>     local success, req_id = pcall(request_id.get_hex_or_generate,
> ngx.var.http_x_dropbox_request_id)
>     if not success then
>         return "-"
>     end
>     return req_id
> ';
> more_set_headers "X-Dropbox-Request-Id: $request_id";
> proxy_set_header  X-Dropbox-Request-Id  $request_id ;
> ```
>
> ```
> --[[
>     Helper function that verifies request_id or generates new one in case
>     validation fails.
>
>     @req_id: current request id
> --]]
> function request_id.get_hex_or_generate(req_id)
>     ...
> end
> ```
>
>
> > On Apr 26, 2016, at 9:51 AM, ToSHiC <toshic.toshic at gmail.com> wrote:
> >
> > Hello,
> >
> > We are using such variable for more than a year, and I suggest to add
> ability to extract request_id from header. It's very usefull for systems
> with frontend and backend installed on different servers.
> >
> > On Tue, Apr 26, 2016 at 7:38 PM, Vladimir Homutov <vl at nginx.com> wrote:
> > details:   http://hg.nginx.org/nginx/rev/59f8f2dd8b31
> > branches:
> > changeset: 6531:59f8f2dd8b31
> > user:      Vladimir Homutov <vl at nginx.com>
> > date:      Tue Apr 26 19:31:46 2016 +0300
> > description:
> > Variable $request_id.
> >
> > The variable contains text representation based on random data, usable as
> > a unique request identifier.
> >
> > diffstat:
> >
> >  src/http/ngx_http_variables.c |  47
> +++++++++++++++++++++++++++++++++++++++++++
> >  1 files changed, 47 insertions(+), 0 deletions(-)
> >
> > diffs (71 lines):
> >
> > diff -r 1d0e03db9f8e -r 59f8f2dd8b31 src/http/ngx_http_variables.c
> > --- a/src/http/ngx_http_variables.c     Fri Dec 18 19:05:27 2015 +0300
> > +++ b/src/http/ngx_http_variables.c     Tue Apr 26 19:31:46 2016 +0300
> > @@ -98,6 +98,8 @@ static ngx_int_t ngx_http_variable_reque
> >      ngx_http_variable_value_t *v, uintptr_t data);
> >  static ngx_int_t ngx_http_variable_request_time(ngx_http_request_t *r,
> >      ngx_http_variable_value_t *v, uintptr_t data);
> > +static ngx_int_t ngx_http_variable_request_id(ngx_http_request_t *r,
> > +    ngx_http_variable_value_t *v, uintptr_t data);
> >  static ngx_int_t ngx_http_variable_status(ngx_http_request_t *r,
> >      ngx_http_variable_value_t *v, uintptr_t data);
> >
> > @@ -274,6 +276,10 @@ static ngx_http_variable_t  ngx_http_cor
> >      { ngx_string("request_time"), NULL, ngx_http_variable_request_time,
> >        0, NGX_HTTP_VAR_NOCACHEABLE, 0 },
> >
> > +    { ngx_string("request_id"), NULL,
> > +      ngx_http_variable_request_id,
> > +      0, 0, 0 },
> > +
> >      { ngx_string("status"), NULL,
> >        ngx_http_variable_status, 0,
> >        NGX_HTTP_VAR_NOCACHEABLE, 0 },
> > @@ -2068,6 +2074,47 @@ ngx_http_variable_request_time(ngx_http_
> >
> >
> >  static ngx_int_t
> > +ngx_http_variable_request_id(ngx_http_request_t *r,
> > +    ngx_http_variable_value_t *v, uintptr_t data)
> > +{
> > +    u_char  *id;
> > +
> > +#if (NGX_OPENSSL)
> > +    u_char   random_bytes[16];
> > +#endif
> > +
> > +    id = ngx_pnalloc(r->pool, 32);
> > +    if (id == NULL) {
> > +        return NGX_ERROR;
> > +    }
> > +
> > +    v->valid = 1;
> > +    v->no_cacheable = 0;
> > +    v->not_found = 0;
> > +
> > +    v->len = 32;
> > +    v->data = id;
> > +
> > +#if (NGX_OPENSSL)
> > +
> > +    if (RAND_bytes(random_bytes, 16) == 1) {
> > +        ngx_hex_dump(id, random_bytes, 16);
> > +        return NGX_OK;
> > +    }
> > +
> > +    ngx_ssl_error(NGX_LOG_ERR, r->connection->log, 0, "RAND_bytes()
> failed");
> > +
> > +#endif
> > +
> > +    ngx_sprintf(id, "%08xD%08xD%08xD%08xD",
> > +                (uint32_t) ngx_random(), (uint32_t) ngx_random(),
> > +                (uint32_t) ngx_random(), (uint32_t) ngx_random());
> > +
> > +    return NGX_OK;
> > +}
> > +
> > +
> > +static ngx_int_t
> >  ngx_http_variable_connection(ngx_http_request_t *r,
> >      ngx_http_variable_value_t *v, uintptr_t data)
> >  {
> >
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> >
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>
>
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