Re: [Snowdrift-dev] [PATCH] Discourse SSO support

2016-12-05 Thread Bryan Richter
Thanks for this. I think the best way to make use of this is to package
up the logic specific to handling SSO requests in an independent
library, so we can use it later.

That's not about you, or about this code. :) It's just that I am going
to push back hard on having SSO be the second major feature we add to
our website (or the third, or even the tenth).

We'll see where that discussion goes.

On Mon, Dec 05, 2016 at 04:13:42AM +0200, fr33domlover wrote:
> From: fr33domlover 
> 
> ---
>  website/Snowdrift.cabal  |  7 
>  website/config/routes|  2 ++
>  website/config/settings.yml  |  4 +++
>  website/src/Application.hs   |  1 +
>  website/src/Discourse.hs | 73 
> 
>  website/src/Handler/Discourse.hs | 55 ++
>  website/src/Settings.hs  |  4 +++
>  7 files changed, 146 insertions(+)
>  create mode 100644 website/src/Discourse.hs
>  create mode 100644 website/src/Handler/Discourse.hs
> 
> diff --git a/website/Snowdrift.cabal b/website/Snowdrift.cabal
> index 9c1664c..b5cfaa5 100644
> --- a/website/Snowdrift.cabal
> +++ b/website/Snowdrift.cabal
> @@ -40,6 +40,7 @@ library
>  Avatar
>  Application
>  Css
> +Discourse
>  Email
>  Foundation
>  Import
> @@ -49,6 +50,7 @@ library
>  Settings.StaticFiles
>  Handler
>  Handler.Dashboard
> +Handler.Discourse
>  Handler.PaymentInfo
>  Handler.Pledge
>  Handler.Project
> @@ -74,6 +76,7 @@ library
>  , bytestring >= 0.9 && < 0.11
>  , classy-prelude >= 0.10.2
>  , classy-prelude-yesod   >= 0.10.2
> +, cryptonite
>  , data-default
>  , errors
>  , esqueleto
> @@ -82,8 +85,10 @@ library
>  , formattable
>  , hjsmin >= 0.1
>  , http-client
> +, http-types
>  , lens
>  , libravatar
> +, memory
>  , mime-mail
>  , monad-logger   >= 0.3 && < 0.4
>  , nonce
> @@ -99,6 +104,7 @@ library
>  , text   >= 0.11&& < 2.0
>  , time
>  , titlecase
> +, transformers
>  , unordered-containers
>  , wai
>  , wai-extra  >= 3.0 && < 3.1
> @@ -122,6 +128,7 @@ library
>  RecordWildCards
>  ScopedTypeVariables
>  TemplateHaskell
> +TupleSections
>  TypeFamilies
>  ViewPatterns
>  
> diff --git a/website/config/routes b/website/config/routes
> index 9e4e079..30fdef8 100644
> --- a/website/config/routes
> +++ b/website/config/routes
> @@ -26,6 +26,8 @@
>  /p/snowdrift SnowdriftProjectR GET
>  /pledge/snowdrift PledgeSnowdriftR POST DELETE
>  
> +/discourse/sso DiscourseR GET
> +
>  -- ## Backward compatibility routes
>  
>  -- Prevents breakage of external links to the old wiki. See
> diff --git a/website/config/settings.yml b/website/config/settings.yml
> index 3c30c0f..e4e30bb 100644
> --- a/website/config/settings.yml
> +++ b/website/config/settings.yml
> @@ -44,3 +44,7 @@ send-email: "_env:SD_EMAILS:false"
>  # chreekat for assistance.
>  stripe-secret-key: "_env:STRIPE_SECRET_KEY:"
>  stripe-publishable-key: "_env:STRIPE_PUBLISHABLE_KEY:"
> +
> +# Discourse SSO
> +discourse-url: "https://discourse.snowdrift.coop";
> +discourse-sso-secret: ""
> diff --git a/website/src/Application.hs b/website/src/Application.hs
> index 8ccd6b2..761d3f8 100644
> --- a/website/src/Application.hs
> +++ b/website/src/Application.hs
> @@ -35,6 +35,7 @@ import qualified Yesod.GitRev as G
>  
>  import Handler
>  import Handler.Dashboard
> +import Handler.Discourse
>  import Handler.PaymentInfo
>  import Handler.Pledge
>  import Handler.Project
> diff --git a/website/src/Discourse.hs b/website/src/Discourse.hs
> new file mode 100644
> index 000..cca0bb1
> --- /dev/null
> +++ b/website/src/Discourse.hs
> @@ -0,0 +1,73 @@
> +module Discourse where
> +
> +import Prelude
> +
> +import Crypto.Hash.Algorithms (SHA256)
> +import Crypto.MAC.HMAC
> +import Data.ByteArray.Encoding
> +import Data.ByteString (ByteString)
> +import Data.Maybe (catMaybes)
> +import Data.Text (Text, pack)
> +import Data.Text.Encoding (encodeUtf8)
> +import Network.HTTP.Types.URI (renderSimpleQuery)
> +
> +import qualified Data.ByteString as B (drop)
> +
> +import Model
> +
> +-- | Information we send back to Discourse once the user logs in through our
> +-- UI.
> +data UserInfo = UserInfo
> +{ ssoEmail :: Text
> +, ssoId:: UserId
> +, ssoUsername  :: Maybe Text
> +, ssoFullName  :: Maybe Text
> +, ssoAvatarUrl :: Maybe Text
> +, ssoBio   :: Maybe Text
> +}
> +
> +-- | Type restricted convenience wrapper that computes our HMAC.
> +hmacSHA256 :: ByteString -> ByteString -> HMAC SHA256
> +hmacSHA256 = hmac
> +
> +-- | Given secret known in advance and pay

Re: [Snowdrift-dev] [PATCH] Discourse SSO support

2016-12-05 Thread Aaron Wolf
On 12/05/2016 11:34 AM, Bryan Richter wrote:
> Thanks for this. I think the best way to make use of this is to package
> up the logic specific to handling SSO requests in an independent
> library, so we can use it later.
> 
> That's not about you, or about this code. :) It's just that I am going
> to push back hard on having SSO be the second major feature we add to
> our website (or the third, or even the tenth).
> 
> We'll see where that discussion goes.
> 

I *strongly* like the idea of packaging SSO between Yesod app and
Discourse as an independent library we just use because that's in
general a great way to deal with generalized stuff like that.

But I want SSO implemented ASAP, immediately if possible. The
cleanliness and ease of managing everything about our use of Discourse
going forward and the site itself will be really nice if we start
Discourse with SSO from the get-go. I don't want all sorts of awkward
challenges in transition later after we have bunches of disconnected
users on each system and then try to push SSO then.

> On Mon, Dec 05, 2016 at 04:13:42AM +0200, fr33domlover wrote:
>> From: fr33domlover 
>>
>> ---
>>  website/Snowdrift.cabal  |  7 
>>  website/config/routes|  2 ++
>>  website/config/settings.yml  |  4 +++
>>  website/src/Application.hs   |  1 +
>>  website/src/Discourse.hs | 73 
>> 
>>  website/src/Handler/Discourse.hs | 55 ++
>>  website/src/Settings.hs  |  4 +++
>>  7 files changed, 146 insertions(+)
>>  create mode 100644 website/src/Discourse.hs
>>  create mode 100644 website/src/Handler/Discourse.hs
>>
>> diff --git a/website/Snowdrift.cabal b/website/Snowdrift.cabal
>> index 9c1664c..b5cfaa5 100644
>> --- a/website/Snowdrift.cabal
>> +++ b/website/Snowdrift.cabal
>> @@ -40,6 +40,7 @@ library
>>  Avatar
>>  Application
>>  Css
>> +Discourse
>>  Email
>>  Foundation
>>  Import
>> @@ -49,6 +50,7 @@ library
>>  Settings.StaticFiles
>>  Handler
>>  Handler.Dashboard
>> +Handler.Discourse
>>  Handler.PaymentInfo
>>  Handler.Pledge
>>  Handler.Project
>> @@ -74,6 +76,7 @@ library
>>  , bytestring >= 0.9 && < 0.11
>>  , classy-prelude >= 0.10.2
>>  , classy-prelude-yesod   >= 0.10.2
>> +, cryptonite
>>  , data-default
>>  , errors
>>  , esqueleto
>> @@ -82,8 +85,10 @@ library
>>  , formattable
>>  , hjsmin >= 0.1
>>  , http-client
>> +, http-types
>>  , lens
>>  , libravatar
>> +, memory
>>  , mime-mail
>>  , monad-logger   >= 0.3 && < 0.4
>>  , nonce
>> @@ -99,6 +104,7 @@ library
>>  , text   >= 0.11&& < 2.0
>>  , time
>>  , titlecase
>> +, transformers
>>  , unordered-containers
>>  , wai
>>  , wai-extra  >= 3.0 && < 3.1
>> @@ -122,6 +128,7 @@ library
>>  RecordWildCards
>>  ScopedTypeVariables
>>  TemplateHaskell
>> +TupleSections
>>  TypeFamilies
>>  ViewPatterns
>>  
>> diff --git a/website/config/routes b/website/config/routes
>> index 9e4e079..30fdef8 100644
>> --- a/website/config/routes
>> +++ b/website/config/routes
>> @@ -26,6 +26,8 @@
>>  /p/snowdrift SnowdriftProjectR GET
>>  /pledge/snowdrift PledgeSnowdriftR POST DELETE
>>  
>> +/discourse/sso DiscourseR GET
>> +
>>  -- ## Backward compatibility routes
>>  
>>  -- Prevents breakage of external links to the old wiki. See
>> diff --git a/website/config/settings.yml b/website/config/settings.yml
>> index 3c30c0f..e4e30bb 100644
>> --- a/website/config/settings.yml
>> +++ b/website/config/settings.yml
>> @@ -44,3 +44,7 @@ send-email: "_env:SD_EMAILS:false"
>>  # chreekat for assistance.
>>  stripe-secret-key: "_env:STRIPE_SECRET_KEY:"
>>  stripe-publishable-key: "_env:STRIPE_PUBLISHABLE_KEY:"
>> +
>> +# Discourse SSO
>> +discourse-url: "https://discourse.snowdrift.coop";
>> +discourse-sso-secret: ""
>> diff --git a/website/src/Application.hs b/website/src/Application.hs
>> index 8ccd6b2..761d3f8 100644
>> --- a/website/src/Application.hs
>> +++ b/website/src/Application.hs
>> @@ -35,6 +35,7 @@ import qualified Yesod.GitRev as G
>>  
>>  import Handler
>>  import Handler.Dashboard
>> +import Handler.Discourse
>>  import Handler.PaymentInfo
>>  import Handler.Pledge
>>  import Handler.Project
>> diff --git a/website/src/Discourse.hs b/website/src/Discourse.hs
>> new file mode 100644
>> index 000..cca0bb1
>> --- /dev/null
>> +++ b/website/src/Discourse.hs
>> @@ -0,0 +1,73 @@
>> +module Discourse where
>> +
>> +import Prelude
>> +
>> +import Crypto.Hash.Algorithms (SHA256)
>> +import Crypto.MAC.HMAC
>> +import Data.ByteArray.Encoding
>> +import Data.ByteString (ByteStri

Re: [Snowdrift-dev] [PATCH] Discourse SSO support

2016-12-05 Thread Aaron Wolf
On 12/05/2016 11:34 AM, Bryan Richter wrote:
> Thanks for this. I think the best way to make use of this is to package
> up the logic specific to handling SSO requests in an independent
> library, so we can use it later.
> 
> That's not about you, or about this code. :) It's just that I am going
> to push back hard on having SSO be the second major feature we add to
> our website (or the third, or even the tenth).
> 
> We'll see where that discussion goes.
> 

I *strongly* like the idea of packaging SSO between Yesod app and
Discourse as an independent library we just use because that's in
general a great way to deal with generalized stuff like that.

But I want SSO implemented ASAP, immediately if possible. The
cleanliness and ease of managing everything about our use of Discourse
going forward and the site itself will be really nice if we start
Discourse with SSO from the get-go. I don't want all sorts of awkward
challenges in transition later after we have bunches of disconnected
users on each system and then try to push SSO then.

> On Mon, Dec 05, 2016 at 04:13:42AM +0200, fr33domlover wrote:
>> From: fr33domlover 
>>
>> ---
>>  website/Snowdrift.cabal  |  7 
>>  website/config/routes|  2 ++
>>  website/config/settings.yml  |  4 +++
>>  website/src/Application.hs   |  1 +
>>  website/src/Discourse.hs | 73 
>> 
>>  website/src/Handler/Discourse.hs | 55 ++
>>  website/src/Settings.hs  |  4 +++
>>  7 files changed, 146 insertions(+)
>>  create mode 100644 website/src/Discourse.hs
>>  create mode 100644 website/src/Handler/Discourse.hs
>>
>> diff --git a/website/Snowdrift.cabal b/website/Snowdrift.cabal
>> index 9c1664c..b5cfaa5 100644
>> --- a/website/Snowdrift.cabal
>> +++ b/website/Snowdrift.cabal
>> @@ -40,6 +40,7 @@ library
>>  Avatar
>>  Application
>>  Css
>> +Discourse
>>  Email
>>  Foundation
>>  Import
>> @@ -49,6 +50,7 @@ library
>>  Settings.StaticFiles
>>  Handler
>>  Handler.Dashboard
>> +Handler.Discourse
>>  Handler.PaymentInfo
>>  Handler.Pledge
>>  Handler.Project
>> @@ -74,6 +76,7 @@ library
>>  , bytestring >= 0.9 && < 0.11
>>  , classy-prelude >= 0.10.2
>>  , classy-prelude-yesod   >= 0.10.2
>> +, cryptonite
>>  , data-default
>>  , errors
>>  , esqueleto
>> @@ -82,8 +85,10 @@ library
>>  , formattable
>>  , hjsmin >= 0.1
>>  , http-client
>> +, http-types
>>  , lens
>>  , libravatar
>> +, memory
>>  , mime-mail
>>  , monad-logger   >= 0.3 && < 0.4
>>  , nonce
>> @@ -99,6 +104,7 @@ library
>>  , text   >= 0.11&& < 2.0
>>  , time
>>  , titlecase
>> +, transformers
>>  , unordered-containers
>>  , wai
>>  , wai-extra  >= 3.0 && < 3.1
>> @@ -122,6 +128,7 @@ library
>>  RecordWildCards
>>  ScopedTypeVariables
>>  TemplateHaskell
>> +TupleSections
>>  TypeFamilies
>>  ViewPatterns
>>  
>> diff --git a/website/config/routes b/website/config/routes
>> index 9e4e079..30fdef8 100644
>> --- a/website/config/routes
>> +++ b/website/config/routes
>> @@ -26,6 +26,8 @@
>>  /p/snowdrift SnowdriftProjectR GET
>>  /pledge/snowdrift PledgeSnowdriftR POST DELETE
>>  
>> +/discourse/sso DiscourseR GET
>> +
>>  -- ## Backward compatibility routes
>>  
>>  -- Prevents breakage of external links to the old wiki. See
>> diff --git a/website/config/settings.yml b/website/config/settings.yml
>> index 3c30c0f..e4e30bb 100644
>> --- a/website/config/settings.yml
>> +++ b/website/config/settings.yml
>> @@ -44,3 +44,7 @@ send-email: "_env:SD_EMAILS:false"
>>  # chreekat for assistance.
>>  stripe-secret-key: "_env:STRIPE_SECRET_KEY:"
>>  stripe-publishable-key: "_env:STRIPE_PUBLISHABLE_KEY:"
>> +
>> +# Discourse SSO
>> +discourse-url: "https://discourse.snowdrift.coop";
>> +discourse-sso-secret: ""
>> diff --git a/website/src/Application.hs b/website/src/Application.hs
>> index 8ccd6b2..761d3f8 100644
>> --- a/website/src/Application.hs
>> +++ b/website/src/Application.hs
>> @@ -35,6 +35,7 @@ import qualified Yesod.GitRev as G
>>  
>>  import Handler
>>  import Handler.Dashboard
>> +import Handler.Discourse
>>  import Handler.PaymentInfo
>>  import Handler.Pledge
>>  import Handler.Project
>> diff --git a/website/src/Discourse.hs b/website/src/Discourse.hs
>> new file mode 100644
>> index 000..cca0bb1
>> --- /dev/null
>> +++ b/website/src/Discourse.hs
>> @@ -0,0 +1,73 @@
>> +module Discourse where
>> +
>> +import Prelude
>> +
>> +import Crypto.Hash.Algorithms (SHA256)
>> +import Crypto.MAC.HMAC
>> +import Data.ByteArray.Encoding
>> +import Data.ByteString (ByteStri

[Snowdrift-dev] [PATCH] Discourse SSO support

2016-12-05 Thread fr33domlover
From: fr33domlover 

---
 website/Snowdrift.cabal  |  8 
 website/config/routes|  2 +
 website/config/settings.yml  |  3 ++
 website/src/Application.hs   |  1 +
 website/src/Discourse.hs | 86 
 website/src/Handler/Discourse.hs | 49 +++
 website/src/Settings.hs  |  2 +
 7 files changed, 151 insertions(+)
 create mode 100644 website/src/Discourse.hs
 create mode 100644 website/src/Handler/Discourse.hs

diff --git a/website/Snowdrift.cabal b/website/Snowdrift.cabal
index 9c1664c..8eca05d 100644
--- a/website/Snowdrift.cabal
+++ b/website/Snowdrift.cabal
@@ -40,6 +40,7 @@ library
 Avatar
 Application
 Css
+Discourse
 Email
 Foundation
 Import
@@ -49,6 +50,7 @@ library
 Settings.StaticFiles
 Handler
 Handler.Dashboard
+Handler.Discourse
 Handler.PaymentInfo
 Handler.Pledge
 Handler.Project
@@ -70,10 +72,12 @@ library
 , crowdmatch
 -- Other
 , aeson  >= 0.6 && < 0.12
+, base64-bytestring
 , blaze-html
 , bytestring >= 0.9 && < 0.11
 , classy-prelude >= 0.10.2
 , classy-prelude-yesod   >= 0.10.2
+, cryptonite
 , data-default
 , errors
 , esqueleto
@@ -82,8 +86,10 @@ library
 , formattable
 , hjsmin >= 0.1
 , http-client
+, http-types
 , lens
 , libravatar
+, memory
 , mime-mail
 , monad-logger   >= 0.3 && < 0.4
 , nonce
@@ -99,6 +105,7 @@ library
 , text   >= 0.11&& < 2.0
 , time
 , titlecase
+, transformers
 , unordered-containers
 , wai
 , wai-extra  >= 3.0 && < 3.1
@@ -122,6 +129,7 @@ library
 RecordWildCards
 ScopedTypeVariables
 TemplateHaskell
+TupleSections
 TypeFamilies
 ViewPatterns
 
diff --git a/website/config/routes b/website/config/routes
index 9e4e079..30fdef8 100644
--- a/website/config/routes
+++ b/website/config/routes
@@ -26,6 +26,8 @@
 /p/snowdrift SnowdriftProjectR GET
 /pledge/snowdrift PledgeSnowdriftR POST DELETE
 
+/discourse/sso DiscourseR GET
+
 -- ## Backward compatibility routes
 
 -- Prevents breakage of external links to the old wiki. See
diff --git a/website/config/settings.yml b/website/config/settings.yml
index 3c30c0f..61ff751 100644
--- a/website/config/settings.yml
+++ b/website/config/settings.yml
@@ -44,3 +44,6 @@ send-email: "_env:SD_EMAILS:false"
 # chreekat for assistance.
 stripe-secret-key: "_env:STRIPE_SECRET_KEY:"
 stripe-publishable-key: "_env:STRIPE_PUBLISHABLE_KEY:"
+
+# Discourse SSO
+discourse-sso-secret: ""
diff --git a/website/src/Application.hs b/website/src/Application.hs
index 8ccd6b2..761d3f8 100644
--- a/website/src/Application.hs
+++ b/website/src/Application.hs
@@ -35,6 +35,7 @@ import qualified Yesod.GitRev as G
 
 import Handler
 import Handler.Dashboard
+import Handler.Discourse
 import Handler.PaymentInfo
 import Handler.Pledge
 import Handler.Project
diff --git a/website/src/Discourse.hs b/website/src/Discourse.hs
new file mode 100644
index 000..83106bb
--- /dev/null
+++ b/website/src/Discourse.hs
@@ -0,0 +1,86 @@
+module Discourse where
+
+import Prelude
+
+import Control.Monad.Trans.Except
+import Crypto.Hash.Algorithms (SHA256)
+import Crypto.MAC.HMAC
+import Data.ByteArray.Encoding
+import Data.ByteString (ByteString)
+import Data.Maybe (catMaybes)
+import Data.Text (Text, pack)
+import Data.Text.Encoding (encodeUtf8, decodeUtf8')
+import Network.HTTP.Types.URI (renderSimpleQuery, parseSimpleQuery)
+
+import qualified Data.ByteString as B (drop)
+import qualified Data.ByteString.Base64 as B64 (decodeLenient)
+
+import Model
+
+-- | Information we send back to Discourse once the user logs in through our
+-- UI.
+data UserInfo = UserInfo
+{ ssoEmail :: Text
+, ssoId:: UserId
+, ssoUsername  :: Maybe Text
+, ssoFullName  :: Maybe Text
+, ssoAvatarUrl :: Maybe Text
+, ssoBio   :: Maybe Text
+}
+
+-- | Type restricted convenience wrapper that computes our HMAC.
+hmacSHA256 :: ByteString -> ByteString -> HMAC SHA256
+hmacSHA256 = hmac
+
+-- | Given secret known in advance and payload given in the query, compute the
+-- HMAC-SHA256, to which Discourse refers as the signature.
+generateSig
+:: ByteString -- ^ Secret
+-> ByteString -- ^ Base64 encoded payload
+-> ByteString
+generateSig secret payload =
+convertToBase Base16 $ hmacGetDigest $ hmacSHA256 secret payload
+
+-- | This validates the payloads's authenticity (i.e. make sure it's really our
+-- trusted local Discourse instance) by using the signature as a proof that it
+-- knows the SSO secret. This is done by verifying that the HMAC-SH

Re: [Snowdrift-dev] [PATCH] Discourse SSO support

2016-12-05 Thread fr33domlover
Hello Bryan,

If you look at the code you'll see there are 2 parts. The logic, which is a
simple single file, and the handler that uses it. Both are quite trivial, it's
hardly worth having them separately. I do think it would be great to have them
both as a separate package that offers a Yesod subsite or at least the handler
function.

I didn't do that because Snowdrift uses its own auth class so if I
used YesodAuth we wouldn't be able to use the library. Sure I can add some
AuthBackend class stuff in the library, but that just begins to be ugly and not
worth it, at least at the beginning. The quickest way to get the code ready was
to add it straight to the web app,

I already sent a new patch, JazzyEagle and I are debugging it and very soon the
code will be ready. After that, we can think about moving the code to a
separate package and solving issues like the auth class. I'm not sure *I* will
be doing that part, but hey, at least I wrote the SSO implementation itself :-)

--fr33



On Mon, 5 Dec 2016 11:34:17 -0800
Bryan Richter  wrote:

> Thanks for this. I think the best way to make use of this is to package
> up the logic specific to handling SSO requests in an independent
> library, so we can use it later.
> 
> That's not about you, or about this code. :) It's just that I am going
> to push back hard on having SSO be the second major feature we add to
> our website (or the third, or even the tenth).
> 
> We'll see where that discussion goes.
> 
> On Mon, Dec 05, 2016 at 04:13:42AM +0200, fr33domlover wrote:
> > From: fr33domlover 
> > 
> > ---
> >  website/Snowdrift.cabal  |  7 
> >  website/config/routes|  2 ++
> >  website/config/settings.yml  |  4 +++
> >  website/src/Application.hs   |  1 +
> >  website/src/Discourse.hs | 73
> >  website/src/Handler/Discourse.hs |
> > 55 ++ website/src/Settings.hs  |  4 +++
> >  7 files changed, 146 insertions(+)
> >  create mode 100644 website/src/Discourse.hs
> >  create mode 100644 website/src/Handler/Discourse.hs
> > 
> > diff --git a/website/Snowdrift.cabal b/website/Snowdrift.cabal
> > index 9c1664c..b5cfaa5 100644
> > --- a/website/Snowdrift.cabal
> > +++ b/website/Snowdrift.cabal
> > @@ -40,6 +40,7 @@ library
> >  Avatar
> >  Application
> >  Css
> > +Discourse
> >  Email
> >  Foundation
> >  Import
> > @@ -49,6 +50,7 @@ library
> >  Settings.StaticFiles
> >  Handler
> >  Handler.Dashboard
> > +Handler.Discourse
> >  Handler.PaymentInfo
> >  Handler.Pledge
> >  Handler.Project
> > @@ -74,6 +76,7 @@ library
> >  , bytestring >= 0.9 && < 0.11
> >  , classy-prelude >= 0.10.2
> >  , classy-prelude-yesod   >= 0.10.2
> > +, cryptonite
> >  , data-default
> >  , errors
> >  , esqueleto
> > @@ -82,8 +85,10 @@ library
> >  , formattable
> >  , hjsmin >= 0.1
> >  , http-client
> > +, http-types
> >  , lens
> >  , libravatar
> > +, memory
> >  , mime-mail
> >  , monad-logger   >= 0.3 && < 0.4
> >  , nonce
> > @@ -99,6 +104,7 @@ library
> >  , text   >= 0.11&& < 2.0
> >  , time
> >  , titlecase
> > +, transformers
> >  , unordered-containers
> >  , wai
> >  , wai-extra  >= 3.0 && < 3.1
> > @@ -122,6 +128,7 @@ library
> >  RecordWildCards
> >  ScopedTypeVariables
> >  TemplateHaskell
> > +TupleSections
> >  TypeFamilies
> >  ViewPatterns
> >  
> > diff --git a/website/config/routes b/website/config/routes
> > index 9e4e079..30fdef8 100644
> > --- a/website/config/routes
> > +++ b/website/config/routes
> > @@ -26,6 +26,8 @@
> >  /p/snowdrift SnowdriftProjectR GET
> >  /pledge/snowdrift PledgeSnowdriftR POST DELETE
> >  
> > +/discourse/sso DiscourseR GET
> > +
> >  -- ## Backward compatibility routes
> >  
> >  -- Prevents breakage of external links to the old wiki. See
> > diff --git a/website/config/settings.yml b/website/config/settings.yml
> > index 3c30c0f..e4e30bb 100644
> > --- a/website/config/settings.yml
> > +++ b/website/config/settings.yml
> > @@ -44,3 +44,7 @@ send-email: "_env:SD_EMAILS:false"
> >  # chreekat for assistance.
> >  stripe-secret-key: "_env:STRIPE_SECRET_KEY:"
> >  stripe-publishable-key: "_env:STRIPE_PUBLISHABLE_KEY:"
> > +
> > +# Discourse SSO
> > +discourse-url: "https://discourse.snowdrift.coop";
> > +discourse-sso-secret: ""
> > diff --git a/website/src/Application.hs b/website/src/Application.hs
> > index 8ccd6b2..761d3f8 100644
> > --- a/website/src/Application.hs
> > +++ b/website/src/Application.hs
> > @@ -35,6 +35,7 @@ import qualified Yesod.GitRev as G
> >  
> >  import Handler
> >  imp