From 26a254dd86c0fec34a63c3cd39a520c784c6d961 Mon Sep 17 00:00:00 2001
From: Sam Tay <sam.chong.tay@gmail.com>
Date: Tue, 13 Dec 2016 00:40:02 -0500
Subject: [PATCH] Implement COP rendering, WIP

---
 TODO.md                   |  3 ++-
 dockmaster.cabal          |  1 +
 src/Dockmaster.hs         |  7 ++----
 src/Dockmaster/Compose.hs | 47 +++++++++++++++++++++++++++++++++++++++
 src/Dockmaster/Types.hs   | 11 +++++----
 5 files changed, 59 insertions(+), 10 deletions(-)
 create mode 100644 src/Dockmaster/Compose.hs

diff --git a/TODO.md b/TODO.md
index f5bffd4..2aa358f 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,9 +1,10 @@
 # todo
 
 ## mvp
-1. Use COP to generate docker-compose.yml and pipe to `docker-compose -f -`
+1. Fixup haddock docs and add to /docs directory for github.io. Use `stack build --haddock` to check coverage and get output
 2. Parse `DOCKMASTER_HOME` from config.yml PATHS into `get_env "DOCKMASTER_HOME" ~> "~/.dockmaster/home" or whatever
 
 ## later
+0. --local flag to execute on local machine instead of docker-machine targets
 1. Use monad transformer to stack Sh on top of Either (error transformer)
 2. Read up on exception handling link in haskell-fun-times resources
diff --git a/dockmaster.cabal b/dockmaster.cabal
index fe9ca25..17711b5 100644
--- a/dockmaster.cabal
+++ b/dockmaster.cabal
@@ -24,6 +24,7 @@ library
                      , Dockmaster.Config.Parser
   other-modules:       Dockmaster.Types
                      , Dockmaster.Config.Types
+                     , Dockmaster.Compose
                      , Dockmaster.Utils
   build-depends:       base >= 4.7 && < 5
                      , bytestring
diff --git a/src/Dockmaster.hs b/src/Dockmaster.hs
index 0c9d16e..1924adf 100644
--- a/src/Dockmaster.hs
+++ b/src/Dockmaster.hs
@@ -13,6 +13,7 @@ import Data.Maybe
 -- Local modules
 import Dockmaster.Parser
 import Dockmaster.Config.Parser
+import Dockmaster.Compose
 
 -- External modules
 import Shelly
@@ -40,11 +41,7 @@ dm path command args = do
         Right dmYml -> do
           let targets = map targetName $ dmTargets dmYml -- just grabbing machine name
           (flip mapM_) targets $ \m -> dockermachine m $ do
-            hookWrap' dmYml command $ dockercompose $ command : args
-
--- | Run docker-compose command
-dockercompose :: [T.Text] -> Sh ()
-dockercompose = (print_stdout True) . (run_ "docker-compose")
+            hookWrap' dmYml command $ dockercompose dmYml $ command : args
 
 -- | Takes machine name and Sh action, and wraps Sh action in scope of
 -- docker-machine env
diff --git a/src/Dockmaster/Compose.hs b/src/Dockmaster/Compose.hs
new file mode 100644
index 0000000..68e3d8c
--- /dev/null
+++ b/src/Dockmaster/Compose.hs
@@ -0,0 +1,47 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ExtendedDefaultRules #-}
+{-# OPTIONS_GHC -fno-warn-type-defaults #-}
+module Dockmaster.Compose
+  ( -- * Orchestration for docker-compose.yml
+    dockercompose
+  ) where
+
+-- Local modules
+import Dockmaster.Types
+import Dockmaster.Utils (parsePath, toText)
+
+-- External modules
+import Control.Monad ((<=<))
+import Shelly
+import Prelude hiding (FilePath)
+import qualified Data.Text as T
+default (T.Text)
+
+-- | Runs docker-compose but uses compiled docker-compose.yml file
+-- if template/vars are specified in dockmaster.yml
+dockercompose :: Dockmaster -> [T.Text] -> Sh ()
+dockercompose cfg optargs = print_stdout True $ maybe
+  (run_ "docker-compose" optargs) -- default run on docker-compose.yml, as usual
+  (composeViaTemplate optargs)
+  (dmFile cfg)
+
+-- | Uses 'ComposeFile' argument to build templated docker-compose.yml content
+-- and pipes it directly to docker-compose
+--
+-- TODO make sure the pipe doesnt output garbage
+-- If we need shell-level pipe this is possible:
+-- https://hackage.haskell.org/package/shelly-1.6.8.1/docs/Shelly.html#v:-45--124--45-
+composeViaTemplate :: [T.Text] -> ComposeFile -> Sh ()
+composeViaTemplate optargs cf =
+  compileTemplate cf -|- run_ "docker-compose" (optargs ++ ["-f", "-"])
+
+-- | Leverages @cop@ to build docker-compose.yml content from template/vars
+--
+-- This function returns the stdout wrapped in 'Sh'. It can then be piped to
+-- docker-compose via @docker-compose -f -@ -- see documentation for docker-compose.
+compileTemplate :: ComposeFile -> Sh T.Text
+compileTemplate cf = do
+  file <- parse (cfPath cf)
+  vars <- mapM parse (cfVars cf)
+  run "cop" $ ["--render-template", file] ++ vars
+    where parse = toText <=< parsePath <=< toText
diff --git a/src/Dockmaster/Types.hs b/src/Dockmaster/Types.hs
index 7694be7..3cfa86b 100644
--- a/src/Dockmaster/Types.hs
+++ b/src/Dockmaster/Types.hs
@@ -1,11 +1,14 @@
 {-# LANGUAGE OverloadedStrings #-}
 module Dockmaster.Types where
 
+import Dockmaster.Config.Types
+
 import Data.Yaml
 import Control.Applicative
 import Data.HashMap.Lazy (HashMap, lookup, member)
 import Data.Monoid (mempty)
-import Prelude hiding (lookup)
+import Shelly
+import Prelude hiding (lookup, FilePath)
 import qualified Data.Text as T
 
 -- | Dockmaster configuration (specified by dockmaster.yml)
@@ -15,8 +18,8 @@ data Dockmaster = Dockmaster { dmFile   :: Maybe ComposeFile
                              } deriving (Show)
 
 -- | Configuration for docker-compose.yml file template & vars
-data ComposeFile = ComposeFile { cfPath :: Maybe T.Text
-                               , cfConfig :: [T.Text]
+data ComposeFile = ComposeFile { cfPath :: FilePath
+                               , cfVars :: [FilePath]
                                } deriving (Show)
 
 -- | Targets are used to identify where compositions are run
@@ -36,7 +39,7 @@ data CommandConfig = CommandConfig { ccCompose :: Bool
 
 instance FromJSON ComposeFile where
   parseJSON (Object v) = ComposeFile
-                         <$> v .:? "path"
+                         <$> v .: "path"
                          <*> v .:? "config" .!= []
 
 instance FromJSON Target where