From 7e1cdd9cf8586c8fcd888ea118a44822e29579f1 Mon Sep 17 00:00:00 2001
From: Drew Hess <src@drewhess.com>
Date: Sun, 24 Sep 2023 18:25:48 +0100
Subject: [PATCH] feat: add support for Buildkite agent-stack-k8s pipelines

This mode is set by setting the environment variable `PIPELINE_TYPE`
to `kubernetes`. The container image used in the pipeline is set by
the `KUBERNETES_CONTAINER_IMAGE` environment variable, and is
`nixos/nix:latest` by default.

Signed-off-by: Drew Hess <src@drewhess.com>
---
 exe-nix-buildkite/Main.hs  | 50 ++++++++++++++++++++++++++++++++++++--
 nix-buildkite-plugin.cabal |  2 +-
 2 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/exe-nix-buildkite/Main.hs b/exe-nix-buildkite/Main.hs
index 90f6563..39367d4 100644
--- a/exe-nix-buildkite/Main.hs
+++ b/exe-nix-buildkite/Main.hs
@@ -45,10 +45,26 @@ import Data.Text (Text, isPrefixOf, pack, unpack)
 import qualified Data.Text as T
 import Data.Text.IO (readFile)
 
+data PipelineType = Nix | Kubernetes
+
 main :: IO ()
 main = do
   jobsExpr <- fromMaybe "./jobs.nix" . listToMaybe <$> getArgs
 
+  pipelineType <- do
+    pt <- lookupEnv "PIPELINE_TYPE"
+    case pt of
+      Nothing -> return Nix
+      Just "kubernetes" -> return Kubernetes
+      Just "nix" -> return Nix
+      Just invalid -> error $ "Invalid PIPELINE_TYPE" <> invalid
+
+  containerImage <- do
+    image <- lookupEnv "KUBERNETES_CONTAINER_IMAGE"
+    case image of
+      Nothing -> return "nixos/nix:latest"
+      Just image' -> return $ pack image'
+
   postBuildHook <- do
     cmd <- lookupEnv "POST_BUILD_HOOK"
     case cmd of
@@ -106,7 +122,37 @@ main = do
 
   g <- foldr (\(_, drv) m -> m >>= \g -> add g drv) (pure empty) drvs
 
-  let steps = map (uncurry step) drvs
+  let steps Kubernetes = map (uncurry step) drvs
+        where
+          step label drvPath =
+            ( label
+            , object
+                [ "label" .= unpack label
+                , "plugins"
+                    .= [ object
+                          [ "kubernetes"
+                              .= [ object
+                                    [ "podSpec"
+                                        .= object
+                                          [ "containers"
+                                              .= [ object
+                                                    [ "image" .= containerImage
+                                                    , "command" .= String "nix-store"
+                                                    , "args" .= (postBuildHook <> ["-r", drvPath])
+                                                    ]
+                                                 ]
+                                          ]
+                                    ]
+                                 ]
+                          ]
+                       ]
+                , "key" .= stepify drvPath
+                , "depends_on" .= dependencies
+                ]
+            )
+            where
+              dependencies = map stepify $ filter (`elem` map snd drvs) $ drop 1 $ reachable drvPath g
+      steps Nix = map (uncurry step) drvs
         where
           step label drvPath =
             ( label
@@ -124,7 +170,7 @@ main = do
     encode $
       object
         [ "agents" .= agentTags
-        , "steps" .= map snd (sortOn fst steps)
+        , "steps" .= map snd (sortOn fst $ steps pipelineType)
         ]
 
 -- Transform nix platforms into buildkite emoji
diff --git a/nix-buildkite-plugin.cabal b/nix-buildkite-plugin.cabal
index 06aa816..6a13b99 100644
--- a/nix-buildkite-plugin.cabal
+++ b/nix-buildkite-plugin.cabal
@@ -1,6 +1,6 @@
 cabal-version:      3.0
 name:               nix-buildkite-plugin
-version:            0.2.0.0
+version:            0.3.0.0
 license-file:       LICENSE
 author:             Hackworth Ltd <src@hackworthltd.com>
 maintainer:         src@hackworthltd.com