- 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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Dancer Config System Without Dancer Dependencies
by Mikko Johannes Koivunalho 28 Jun '23

28 Jun '23

The Dancer configuration system with different config files and environments is usable also without Dancer. Especially it is usable when developing and running command line applications which are utilities for the same project where Dancer is at the core. I have several such utilities for different purposes, e.g. for database administration and worker queue maintenance. These programs load Dancer2 package only to get access to the configuration and to ensure they get exactly the same config as the Dancer apps get. Could we isolate the configuration system from Dancer2 and make it usable by itself? -- Mikko Koivunalho

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New Dancer, Dancer2 plus ecosystem updates
by Jason A. Crome 05 Feb '23

05 Feb '23

Welcome to 2023 (just a little bit late)! We've put together a number of long overdue updates for Dancer, Dancer2, and other parts of the ecosystem. Dancer2 version 0.400001: [ BUG FIXES ] * PR #1247: Fix edge case in plugin compat (Sawyer X) * GH #1621: Fix recursion error in TT after longjump (Andy Beverley, Russell @veryrusty Jenkins) * PR #1667: Remove failing module from GitHub Actions config (Jason A. Crome) [ ENHANCEMENTS ] * GH #769, PR #829, #1662: Rename show_errors as show_stacktrace (Nuno Ramos Carvalho, Sawyer X) * GH #1594: Use Unicode::UTF8 if available (Sawyer X) [ DOCUMENTATION ] * GH #1657: Fix the Dancer2::DeprecationPolicy abstract (Jason A. Crome) * GH #1661: Add 'gen' command to 'dancer2' runs (Steve Bertrand) * PR #1671: Fix broken links in POD; avoid passive voice (Tom Hukins) Dancer2::Template::Xslate version 0.2.0: - Add docs/warning about using Dancer2 layouts with cascading templates (Pedro Melo) Dancer2::Session::CHI version 0.05: - Various doc fixes Task::Dancer2 version 0.07: * This was woefully out of date. Updated for all `Dancer2::*` modules available today (thanks to GeekRuthie for the assistance) Dancer version 1.3521 will be hitting CPAN soon: - Fix XML serializer tests (gregoa & Debian team) The Dancer2 Wiki (https://github.com/PerlDancer/Dancer2/wiki) has seen some updates, too. Do you want to contribute, but aren't sure where to start? This handy guide has some good places to get started; there's a number of plugins for Dancer that haven't been ported to Dancer2, for example. Is there something you'd like to see? Please add it to the wishlist(https://github.com/PerlDancer/Dancer2/wiki/Wishlist)! As a final reminder, we marked a number of keywords, methods, and other code in Dancer2 for deprecation last year. Hard deprecation will take effect by the end of March, so any plugins built still relying on deprecated code will need to be updated. See https://blogs.perl.org/users/jason_a_crome/2022/03/dancer2-0400000-released… for more information. Looking forward to a great 2023! As always, happy Dancing! Jason/CromeDome -- Jason A. Crome / CromeDome CPAN: https://metacpan.org/author/CROMEDOME GitHub: https://github.com/cromedome Twitter: https://twitter.com/cromedome Blog: https://cromedome.net

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Opinions for architecture of a new web application
by Andy Beverley 04 Apr '22

04 Apr '22

Dear all, I'm interested in your opinions on how you would architecture a new web application, if you were to start one today. I'll be starting a new application soon and this is a chance to take a fresh look at things. Normally I would go with a simple Dancer/Template::Toolkit setup. However, I'm thinking that I should make this an "API first" application (i.e. using static HTML pages and rendering all the content using a Jaavscript framework making API calls) That then begs the question as to what the best back-end architecture is, if only using it to render JSON. Also, if only serving API requests with the back-end, how would you manage authentication? Would you still use cookies or would you use some sort of tokens? Any thoughts welcome! Thanks, Andy

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Dancer2 0.400000 Released
by Jason A. Crome 14 Mar '22

14 Mar '22

Dancer2 0.400000 has been released, and is on its way to CPAN. We realize that some of you might be curious as to the large version bump. There are a couple of reasons for this: * Modules we depend on bumped their minimum Perl version to 5.12, requiring us to follow suit. * As of 2022, Dancer2 has an official deprecation policy. We are implementing this policy effective with this release, and it will help shape and guide future development. * We've officially marked a lot of outdated and unused API as being deprecated. With that, the following APIs, methods, etc. are now officially deprecated: * Dancer2::Test * request->dispatch_path * push_header * header * headers * context * Named placeholders: splat and capture In plugins: * plugin_setting * dancer_app * request * var * hook To discuss any of these, you can find issue for each of the above here: https://github.com/PerlDancer/Dancer2/milestone/27 We realize some users may be frustrated by the minimum version bump to 5.12. This was not a decision we arrived at lightly. Maintaining backwards compatability to Perl 5.8 requires resources we lack; resources we do have are better spent on work that advances the web framework for everyone. If you're affected by this and would like to discuss, please reach out to the Dancer Core Team. All changes in this release: 0.400000 2022-03-13 22:16:13-04:00 America/New_York [ BUG FIXES ] * PR #1634: Fix CI push setting to run tests on branches with / in the name (Stefan Hornburg - Racke) * PR #1641: Fix uninitialized warnings from parsing routes with mixed regex/splats (Russell @veryrusty Jenkins) [ ENHANCEMENTS ] * PR #1627: Set minimum Perl to 5.10.1 (Peter Mottram - SysPete) * PR #1643: Set minimum Perl to 5.12.5 (Jason A. Crome) [ DOCUMENTATION ] * PR #1633: Fix YAML example in the tutorial (Tina Müller) * PR #1644: Add deprecation policy to docs; link git guide (Jason A. Crome) This release would not have been possible without help and support from the Dancer Core Team, specifically Sawyer, Yanick, veryrusty, SysPete, Racke, and bigpresh; it also doesn't happen without GeekRuthie cheering this on down the stretch. To all of of you that took the time to contribute to our deprecation policy, submit a patch, report a bug... thank you. I am truly grateful to each and every one of you for helping to make this release happen. Happy Dancing! Jason / CromeDome -- Jason A. Crome / CromeDome CPAN: https://metacpan.org/author/CROMEDOME GitHub: https://github.com/cromedome Twitter: https://twitter.com/cromedome Blog: https://cromedome.net

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Mixed content & uri_for function
by Wanjuan Yang 07 Feb '22

07 Feb '22

Hi, We have an web application using dancer2 framework.The website is using https. But in the page, it calls other page using uri_for. i.e The url is generated by uri_for and sending it to template. The url generated is automatically set ‘http’, so the page has mixed content. And thus doesn’t load. My question is where is the uri_for located. Why is automatically set ‘http’, how can I specify it to be ‘https’? Many thanks Wendy -- The Wellcome Sanger Institute is operated by Genome Research Limited, a charity registered in England with number 1021457 and a company registered in England with number 2742969, whose registered office is 215 Euston Road, London, NW1 2BE.

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Dancer2 Error Hooks
by Mikko Johannes Koivunalho 02 Jan '22

02 Jan '22

Dear Dancer users, I am using my own hierarchy of errors in files and libraries which are used in my Dancer2 app. These errors are based on class Throwable::Error. 1) Can I catch these errors in Dancer2 error hooks, e.g. in /on_route_exception/ and 2) maybe transform them into Dancer2::Core::Error objects 3) which I can then handle in views/400.tt template, or even change the page template? -- Mikko Koivunalho

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Draft: Deprecation Policy
by Jason A. Crome 29 Dec '21

29 Dec '21

Hello fellow Dancers! I have posted a draft deprecation policy for the Dancer2 code base for public review: https://github.com/PerlDancer/Dancer2/issues/1635 We've done our best to look at this every which way and cover all potential issues and use cases, but we're sure to have missed something here or there. So take a look and let us know. Your feedback is welcome - please add comments, feedback, and suggestions on the issue. Thanks in advance! :-) -- Jason A. Crome / CromeDome CPAN: https://metacpan.org/author/CROMEDOME GitHub: https://github.com/cromedome Twitter: https://twitter.com/cromedome Blog: https://cromedome.net

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Re: [dancer-users] dancer-users Digest, Vol 124, Issue 4
by Mikko Johannes Koivunalho 27 Jul '21

27 Jul '21

The alternatives suggested all have shortcomings in my view. A script which creates config_local.yaml on the fly and then starts Dancer2 app would otherwise work but it means that container won't be immutable. Immutable is one of the architectural best practices listed by Google. As it happens, this container is planned to run on Google Container Engine. You mentioned there are other ways to do this in Kubernetes. How? Using a tmpfs is also not an option because it would mean that container is dependent on the way it is being run (the runtime environment). Substituting variables in config.yaml is not overly complicated in my mind. Many platforms use environment variables to pass information to containers, docker or others, e.g. Java jar. I have used Openshift platform and it gave me a very good example of how env vars are governed in order to provide secrets to the container. By stating the env vars in the configuration, we make it clear to the programmer and to operations what is expected from the runtime environment. Besides this, it also makes local development easier if you "practice dotenv" - what The Twelve-Factor App recommends. I keep my environment in a .env file and I also use the same file when testing the container with local docker. See: * https://cloud.google.com/architecture/best-practices-for-operating-containe… * https://docs.docker.com/storage/tmpfs/ * https://12factor.net/config On 27/07/2021 13:00, dancer-users-request(a)lists.preshweb.co.uk wrote: > Send dancer-users mailing list submissions to > dancer-users(a)lists.preshweb.co.uk > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.preshweb.co.uk/mailman/listinfo/dancer-users > or, via email, send a message with subject or body 'help' to > dancer-users-request(a)lists.preshweb.co.uk > > You can reach the person managing the list at > dancer-users-owner(a)lists.preshweb.co.uk > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of dancer-users digest..." > > > Today's Topics: > > 1. Re: Passing environment to dockerized Dancer2 (Adam Clarke) > 2. Re: Passing environment to dockerized Dancer2 (Adam Clarke) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 19 Jul 2021 10:51:08 +1000 > From: Adam Clarke <adamc(a)strategicdata.com.au> > To: Perl Dancer users mailing list <dancer-users(a)lists.preshweb.co.uk> > Subject: Re: [dancer-users] Passing environment to dockerized Dancer2 > Message-ID: > <FF6A5F5E-448C-4F0D-B829-1DA2BDAE3BAC(a)strategicdata.com.au> > Content-Type: text/plain; charset=utf-8 > > >> On 19 Jul 2021, at 2:54 am, Mikko Johannes Koivunalho <mikko.koivunalho(a)iki.fi> wrote: >>> Problem: >>> How do I pass the environment dependent parts of the configuration to >>> the docker? I cannot use file `config_local.yaml` because then I would >>> need to copy that file somehow into the container when it starts. >>> >>> Possible solution: >>> I would pass parts of the configuration as environment variables, e.g. >>> /DB_HOST/ and/SITE_URL/, and then apply these over the values in >>> config.yaml when I am creating the endpoints. >>> >>> Suggestion: >>> Change the command `/config/` (or the underlying file reader function) >>> so that it can transpose environment variables into config strings, e.g. >>> plugins->database->connections->main->host = '${DB_HOST}'. >> >> I have built a solution to this. >> I have not yet submitted a Pull Request. >> I am using this solution in my build and web application. >> Please comment. Would this be a good pull request? > > I?m not clear that this complexity is required give that the solution can be > achieved using a startup script as per Racke?s previous reply. Also I?m > assuming you?re not running your containers under Docker swarm or > Kubernetes but if you are there are more advanced ways to achieve what I > describe below. > > In case Racke?s approach wasn?t clear, what you do is add an entry point > script to your Docker image build using the ENTRYPOINT instruction. > e.g. startup.sh. This script will always run at container start up. > > The startup script would use the environment you had set to build an > appropriate config_local.yaml inside your container before Dancer is > invoked. There are lots of ways to do this, one simple and way from a > shell script is to use envsubst. The last thing the startup script would do > is start your Dancer app. > > If you want or need your container to run in read only mode then you > can combine this technique with a tempfs mount for config_local.yaml. > > See: > * https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#e… > * https://www.gnu.org/software/gettext/manual/html_node/envsubst-Invocation.h… > > > > ------------------------------ > > Message: 2 > Date: Tue, 20 Jul 2021 17:52:48 +1000 > From: Adam Clarke <adamc(a)strategicdata.com.au> > To: Perl Dancer users mailing list <dancer-users(a)lists.preshweb.co.uk> > Subject: Re: [dancer-users] Passing environment to dockerized Dancer2 > Message-ID: > <EF3743C7-C62A-477D-BD13-D82F0E7714DB(a)strategicdata.com.au> > Content-Type: text/plain; charset=utf-8 > > >> On 19 Jul 2021, at 2:54 am, Mikko Johannes Koivunalho <mikko.koivunalho(a)iki.fi> wrote: >>> Problem: >>> How do I pass the environment dependent parts of the configuration to >>> the docker? I cannot use file `config_local.yaml` because then I would >>> need to copy that file somehow into the container when it starts. >>> >>> Possible solution: >>> I would pass parts of the configuration as environment variables, e.g. >>> /DB_HOST/ and/SITE_URL/, and then apply these over the values in >>> config.yaml when I am creating the endpoints. >>> >>> Suggestion: >>> Change the command `/config/` (or the underlying file reader function) >>> so that it can transpose environment variables into config strings, e.g. >>> plugins->database->connections->main->host = '${DB_HOST}'. >> >> I have built a solution to this. >> I have not yet submitted a Pull Request. >> I am using this solution in my build and web application. >> Please comment. Would this be a good pull request? > > I?m not clear that this complexity is required give that the solution can be > achieved using a startup script as per Racke?s previous reply. Also I?m > assuming you?re not running your containers under Docker swarm or > Kubernetes but if you are there are more advanced ways to achieve what I > describe below. > > In case Racke?s approach wasn?t clear, what you do is add an entry point > script to your Docker image build using the ENTRYPOINT instruction. > e.g. startup.sh. This script will always run at container start up. > > The startup script would use the environment you had set to build an > appropriate config_local.yaml inside your container before Dancer is > invoked. There are lots of ways to do this, one simple and way from a > shell script is to use envsubst. The last thing the startup script would do > is start your Dancer app. > > If you want or need your container to run in read only mode then you > can combine this technique with a tempfs mount for config_local.yaml. > > See: > * https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#e… > * https://www.gnu.org/software/gettext/manual/html_node/envsubst-Invocation.h… > > > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > dancer-users mailing list > dancer-users(a)lists.preshweb.co.uk > https://lists.preshweb.co.uk/mailman/listinfo/dancer-users > > > ------------------------------ > > End of dancer-users Digest, Vol 124, Issue 4 > ******************************************** >

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dancer1 and DBIx: can I modify the returned result in a view?
by John Stoffel 21 Jul '21

21 Jul '21

Hi all, I'm tasked with hacking an old Dancer1 app I wrote back in 2014/2015 which basically just returns from results from a DB query. One of the fields is called 'url' and I need to tweak it, since the URL in the DB is completely wrong. I've tried poking at it in my views/search.tt file, but I can't figure out the right syntax to make it work. My results loop looks like this: <% IF results.size %> Results (found <% results.size %> matches): <ul> <% FOREACH result IN results %> <li><% result.full_name.replace("((?i)$tobold)",'<b>$1</b>') %> <ul> <% FOREACH a IN result.account %> <li><a href="<% a.url() %>" target="_blank"> Account # <% a.account_number %>, <% IF a.volume() %> Volume: <% a.volume() %>, <% END %> <% IF a.box() %> Box: <% a.box() %>, <% END %> <% IF a.folder() %> Folder: <% a.folder() %>, <% END %> <% IF a.range() %> Range: <% a.range() %> <% END %> </a> <% newurl %><br> <% END %> </ul> <% END %> And I need to pull out the a.url, do some manipulations on it, then display it. I tried doing: <% FOREACH a IN result.account %> <% a.url = a.url.replace("http://gigi.mwa.org/netpub/server.np", "https://gigi.mwa.org/imagearchive/filename/") %> <li><a href="<% a.url() %>" target="_blank"> Account # <% a.account_number %>, <% IF a.volume() %> Volume: <% a.volume() %>, <% END %> <% IF a.box() %> Box: <% a.box() %>, <% END %> <% IF a.folder() %> Folder: <% a.folder() %>, <% END %> <% IF a.range() %> Range: <% a.range() %> <% END %> </a> <% newurl %><br> <% END %> </ul> But that didn't seem to work. Should I be doing this search and replace in the lib/Foo.pm file in the _perform_search function instead? And if so, how do I deal with the DBIx resultset properly so I can loop through and update these URLs? I really don't want to have to do this in SQL somewhere, though I guess I could be convinced to do this hack until the DB itself is updated. Thanks, John

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