January 2019 - dancer-users - lists.preshweb.co.uk

Debugging sessions
by Nikola Mitev 29 Jun '23

29 Jun '23

Hi all, I have an annoyingly intermittent problem where on successful authentication the session info disappears and the user is endlessly redirected to the login page. It happens about once a month on a site with 10-20 logins daily. Once it happens to a user, it keeps happening for that user only. A restart of the app usually fixes the issue, and I am yet to see someone who had this problem to report it again at a later stage. Had about 10 cases so far in total. The cookie is generated on accessing the login page, stored in the browser and sent with the login POST request so I can verify cookies are enabled. The user is then authenticated, data added to the session including an 'authenticated' flag and they are redirected to their dashboard. Right before the redirection the session data is present. They make a request for the dashboard following the redirect, this triggers a session authenticated check which fails as no data is available for the session. They are then redirected for authentication and so on in a loop. If I restart the app the issue vanishes. hook before => sub { # <snip> if (!session('authenticated')) { forward '/login'; } } post '/login' => sub { # user authentication and session storage here, then the debug code and the redirecton: my $authenticated = session('authenticated'); $log->info("User authenticated ($authenticated), redirecting to $target_route"); return redirect $target_route; }; I don't have an explicit check on cookie size - not sure how to check it doesn't exceed 4K - but find it unlikely this is the issue. If that was the problem it should be happening persistently for a user regardless of restarts etc? Hope all this makes sense, I am looking for general advice on how to troubleshoot this but any ideas at all will be very much appreciated. Nik

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Help 504 Gateway Timeout
by Richard Reina 15 Jan '19

15 Jan '19

If any one can help I have a bit of an emergency. I made some changes to my dancer app that runs on starman/nginx and now I get error 502 timeout. Know very little about how to trouble shoot in and if I don't solve in the next few hours I am in big trouble. Any ideas appreciated. Thanks

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Dynamic config setting upon startup [D1]
by Hermann Calabria 03 Jan '19

03 Jan '19

Hi all, I’m using Dancer::Session::Cookie and facing a bit of a conundrum with the session_cookie_key a setup in the config file. As we all know it’s not recommended to include live secrets in a git repository, so I’m attempting to create the session_cookie_key dynamically upon Dancer startup (documented here: https://metacpan.org/pod/Dancer::Config#SETTINGS) as follows: use Dancer; set session_cookie_key => crypto_nonce(20); ... dance; where crypto_nonce() is a cryptographically strong nonce generator (this approach happens to work for this particular app, because it’s an admin/dashboard panel with a small number of infrequent users, and the it runs on a single machine). I try to run the app, and get the following error: The setting session_cookie_key must be defined at /home/hermann/perl5/perlbrew/perls/perl-5.26.2/lib/site_perl/5.26.2/Dancer/Session/Cookie.pm line 38 So I add the following to environments/production.yml: session_cookie_key : “1” Try to run the app again, and not unexpectedly, I end up with session_cookie_key = 1. I can work around the problem by adding a hook: hook 'before' => sub { if ( length(config->{'session_cookie_key'}) < 5 ) { set session_cookie_key => crypto_nonce(20); } ... }; I’m wondering if there’s a more elegant way to accomplish what I’m trying to do? Thanks in advance! Hermann

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