Erlang White Label
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WhiteLabel Erlang Adventures in the undocumented wilds of inet_dns
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Geoff Cant Whitelabel Erlang covers the trials, tribulations and technologies used in building a whitelabel ejabberd hosting service.The talk explains the rationale behind the choices of web server, templating system, email module, page optimizers and other web framework components. The talk also covers the documented and undocumented DNS query and caching modules in OTP and introduces 'dns' - a convenient new API for using them. Finally, the talk describes some tips and tricks useful for whitelabel hosting solutions that require customer DNS updates.
Transcript of Erlang White Label
WhiteLabel ErlangAdventures in the undocumented wilds of inet_dns
Who is this guy?Geoff Cant <[email protected]>Current (xmpp|mailto):[email protected] [email protected] on http://github, irc:freenode/#erlang
What have I been up to?ejabberd
debuggingvirtual hostingdebugging large clustersporting patchesdebugging patches
What have I been up to?Whitelabel ejabberd hosting
Web Frameworks (why Mochiweb)Other libraries (ejango, esmtp, erlydtl)DNS (OTP Undocumented)Tricks and Lessons
A rant in four parts
ErlywebYAWSinetsThe Erlang WebNitrogen
Web Frameworks
Mochiweb.(No logo, ‘cause they’re too busy coding)
Other piecesTemplatingURL RoutingForm validationEmail
TemplatingerlydtlTemplates compile to modulesWell known template syntax (Django-ish)Template
URL RoutingMust work with RESTful URLsMust be reversible - able to generate URLs tooejango.url_routes
Form ValidationGenerate forms and validate form postsCouldn’t find anything available alreadyDeclarative DSL for form specificationejango.form, ejango.form_validator
Sending Emailsmtp_fsmErlware smtpNo attachments?This should be much easier.esmtp
Mail Sending API
Mime Attachment API
DNSNeed to verify ownership of domainNeed to add XMPP SRV recordsinet:gethostbyname...To the githubs!
DNS Undocumentedinet_res:getbyname/2inet_res:nnslookup/5inet_db - cachinginet_dns - packet encoding/decoding, bugs‘dns’ -- the way forward.
Here be Dragons.Sometimes it’s undocumented for a reasonThe TXT RR is subtle.I reimplemented the same bug.
My DNS decoderTXT RRs are <<Len:8, Data:Len/binary>>* Binary pattern matching rocks
Whitelabel TricksCheck SOA to test if domain existsBypass DNS caching
YSlow OptimisationsInitially got a D on my YSlow reportDecided to gzip and minify content, move js blocks aroundejango.static:compress_docroot/1, ejango.static:serve_compressed/3
Minifying...
LessonsHierarchal modules are a world of hurt.Metaprogramming in Erlang is still too hard.Never trust ADSL routers....
Use Github.
A small plea for helpI have way too many github projectsAdopt my code?Interested in collaborating?
Fin.
