Add dhall-kubernetes support for "schemas" (#84)

For lack of a better term, I'm calling the `{ Type = …, default = … }`
record that the record completion operator expects a "schema".  This
change adds `dhall-kubernetes` support for auto-generating these schemas
for ease of use with the new `::` operator.

See the included example for how this would be used

dhall-kubernetes-generator/src/Dhall/Kubernetes/Convert.hs

@@ -2,6 +2,7 @@ module Dhall.Kubernetes.Convert
   ( toTypes
   , toDefault
   , getImportsMap
+  , mkImport
   ) where
 
 import qualified Data.List              as List

dhall-kubernetes-generator/src/Main.hs

@@ -1,3 +1,5 @@
+{-# LANGUAGE OverloadedLists #-}
+
 module Main (main) where
 
 import qualified Data.Map.Strict                       as Data.Map
@@ -74,15 +76,32 @@ main = do
     let path = "./defaults" Turtle.</> Turtle.fromText (name <> ".dhall")
     writeDhall path expr
 
+  let toSchema (ModelName key) _ _ =
+        Dhall.RecordLit
+          [ ("Type", Dhall.Embed (Convert.mkImport ["types", ".."] (key <> ".dhall")))
+          , ("default", Dhall.Embed (Convert.mkImport ["defaults", ".."] (key <> ".dhall")))
+          ]
+
+  let schemas = Data.Map.intersectionWithKey toSchema types defaults
+
+  -- Output schemas that combine both the types and defaults
+  Turtle.mktree "schemas"
+  for_ (Data.Map.toList schemas) $ \(ModelName name, expr) -> do
+    let path = "./schemas" Turtle.</> Turtle.fromText (name <> ".dhall")
+    writeDhall path expr
+
   -- Output the types record, the defaults record, and the giant union type
   let objectNames = Data.Map.keys types
       typesMap = Convert.getImportsMap objectNames "types" $ Data.Map.keys types
       defaultsMap = Convert.getImportsMap objectNames "defaults" $ Data.Map.keys defaults
+      schemasMap = Convert.getImportsMap objectNames "schemas" $ Data.Map.keys schemas
 
       typesRecordPath = "./types.dhall"
       typesUnionPath = "./typesUnion.dhall"
       defaultsRecordPath = "./defaults.dhall"
+      schemasRecordPath = "./schemas.dhall"
 
   writeDhall typesUnionPath (Dhall.Union $ fmap Just typesMap)
   writeDhall typesRecordPath (Dhall.RecordLit typesMap)
   writeDhall defaultsRecordPath (Dhall.RecordLit defaultsMap)
+  writeDhall schemasRecordPath (Dhall.RecordLit schemasMap)

examples/aws-iam-authenticator-chart.dhall

@@ -0,0 +1,104 @@
+let kubernetes = ../schemas.dhall
+
+let release = "wintering-rodent"
+
+let name = "aws-iam-authenticator"
+
+let fullName = "${release}-${name}"
+
+let version = "0.1.1"
+
+let chart = "${name}-${version}"
+
+let heritage = "dhall"
+
+in  kubernetes.DaemonSet::{
+    , metadata = kubernetes.ObjectMeta::{
+      , name = fullName
+      , labels = toMap
+        { app = name
+        , chart = chart
+        , release = release
+        , heritage = heritage
+        }
+      }
+    , spec = Some kubernetes.DaemonSetSpec::{
+      , updateStrategy = Some kubernetes.DaemonSetUpdateStrategy::{
+        , type = Some "RollingUpdate"
+        }
+      , template = kubernetes.PodTemplateSpec::{
+        , metadata = kubernetes.ObjectMeta::{
+          , name = name
+          , annotations = toMap
+            { `scheduler.alpha.kubernetes.io/critical-pod` = ""
+            }
+          , labels = toMap
+            { app = name
+            , release = release
+            }
+          }
+        , spec = Some kubernetes.PodSpec::{
+          , hostNetwork = Some True
+          , nodeSelector = toMap
+            { `node-role.kubernetes.io/master` = ""
+            }
+          , tolerations =
+            [ kubernetes.Toleration::{
+              , effect = Some "NoSchedule"
+              , key = Some "node-role.kubernetes.io/master"
+              }
+            , kubernetes.Toleration::{
+              , effect = Some "CriticalAddonsOnly"
+              , key = Some "Exists"
+              }
+            ]
+          , containers =
+            [ kubernetes.Container::{
+              , name = fullName
+              , image = Some "gcr.io/heptio-images/authenticator:v0.1.0"
+              , args =
+                [ "server"
+                , "--config=/etc/aws-iam-authenticator/config.yaml"
+                , "--state-dir=/var/aws-iam-authenticator"
+                , "--generate-kubeconfig=/etc/kubernetes/aws-iam-authenticator/kubeconfig.yaml"
+                ]
+              , volumeMounts =
+                [ kubernetes.VolumeMount::{
+                  , name = "config"
+                  , mountPath = "/etc/aws-iam-authenticator/"
+                  }
+                , kubernetes.VolumeMount::{
+                  , name = "state"
+                  , mountPath = "/var/aws-iam-authenticator/"
+                  }
+                , kubernetes.VolumeMount::{
+                  , name = "output"
+                  , mountPath = "/etc/kubernetes/aws-iam-authenticator/"
+                  }
+                ]
+              }
+            ]
+          , volumes =
+            [ kubernetes.Volume::{
+              , name = "config"
+              , configMap = Some kubernetes.ConfigMapVolumeSource::{
+                , name = Some fullName
+                }
+              }
+            , kubernetes.Volume::{
+              , name = "output"
+              , hostPath = Some kubernetes.HostPathVolumeSource::{
+                , path = "/srv/kubernetes/aws-iam-authenticator/"
+                }
+              }
+            , kubernetes.Volume::{
+              , name = "state"
+              , hostPath = Some kubernetes.HostPathVolumeSource::{
+                , path = "/srv/kubernetes/aws-iam-authenticator/"
+                }
+              }
+            ]
+          }
+        }
+      }
+    }