Refactor builder to support file requirements and run pre-install

The builder configuration has proven useful for supporting generic
pre-entrypoint commands such as dependency managers not otherwise
supported by specific Blubber configuration. Adding additional
`builder.requirements` config expands support for such commands by
allowing the user to specify files that should be copied into the image
before the builder command runs.

To support this extra configuration, `builder` had to be changed from a
simple string to a mapping. The builder command must now by given as
`builder.command`.

The pattern of creating parent directories, copying files, and executing
one or more commands prior to the entrypoint has become a common
one. Some of the implementation of this pattern was moved from
`PythonConfig` into shared build macros `build.SortFilesByDir` and
`build.SyncFiles`. All config types that must have requirements files
copied over independently of the entire source tree (`PythonConfig`,
`BuilderConfig`, `NodeConfig`) now delegate to these functions.

Change-Id: I67f33034f22cee2851ec866cfb07ab20c23eba8c

1 files changed, 43 insertions, 7 deletions

diff --git a/config/builder_test.go b/config/builder_test.go
index a35221e..773ddd1 100644
--- a/config/builder_test.go
+++ b/config/builder_test.go
@@ -13,23 +13,37 @@ func TestBuilderConfigYAML(t *testing.T) {
 	cfg, err := config.ReadConfig([]byte(`---
     version: v2
     base: foo
+    builder:
+      command: [make, -f, Makefile, test]
+      requirements: [Makefile]
     variants:
+      test: {}
       build:
-        builder: [make, -f, Makefile]`))
+        builder:
+          command: [make]
+          requirements: []`))
 
 	if assert.NoError(t, err) {
-		variant, err := config.ExpandVariant(cfg, "build")
+		variant, err := config.ExpandVariant(cfg, "test")
 
-		assert.Equal(t, []string{"make", "-f", "Makefile"}, variant.Builder)
+		if assert.NoError(t, err) {
+			assert.Equal(t, []string{"make", "-f", "Makefile", "test"}, variant.Builder.Command)
+			assert.Equal(t, []string{"Makefile"}, variant.Builder.Requirements)
+		}
 
-		assert.Nil(t, err)
+		variant, err = config.ExpandVariant(cfg, "build")
+
+		if assert.NoError(t, err) {
+			assert.Equal(t, []string{"make"}, variant.Builder.Command)
+			assert.Equal(t, []string{}, variant.Builder.Requirements)
+		}
 	}
 }
 
 func TestBuilderConfigInstructions(t *testing.T) {
-	cfg := config.BuilderConfig{Builder: []string{"make", "-f", "Makefile"}}
+	cfg := config.BuilderConfig{Command: []string{"make", "-f", "Makefile"}}
 
-	t.Run("PhasePostInstall", func(t *testing.T) {
+	t.Run("PhasePreInstall", func(t *testing.T) {
 		assert.Equal(t,
 			[]build.Instruction{
 				build.Run{
@@ -37,7 +51,29 @@ func TestBuilderConfigInstructions(t *testing.T) {
 					[]string{"-f", "Makefile"},
 				},
 			},
-			cfg.InstructionsForPhase(build.PhasePostInstall),
+			cfg.InstructionsForPhase(build.PhasePreInstall),
+		)
+	})
+}
+
+func TestBuilderConfigInstructionsWithRequirements(t *testing.T) {
+	cfg := config.BuilderConfig{
+		Command:      []string{"make", "-f", "Makefile", "foo"},
+		Requirements: []string{"Makefile", "foo", "bar/baz"},
+	}
+
+	t.Run("PhasePreInstall", func(t *testing.T) {
+		assert.Equal(t,
+			[]build.Instruction{
+				build.Run{"mkdir -p", []string{"bar/"}},
+				build.Copy{[]string{"Makefile", "foo"}, "./"},
+				build.Copy{[]string{"bar/baz"}, "bar/"},
+				build.Run{
+					"make",
+					[]string{"-f", "Makefile", "foo"},
+				},
+			},
+			cfg.InstructionsForPhase(build.PhasePreInstall),
 		)
 	})
 }