Support compilation to multi-stage Dockerfile

Reorganized config type declarations.

Added `RunConfig` for declaring working directory and unprivileged
runtime user. A system for enforcing restrictions should probably be
implemented for this.

Implemented Dockerfile compiler, supporting multi-stage output in cases
whether artifacts from other variants are configured.

1 files changed, 66 insertions, 3 deletions

diff --git a/docker/compiler.go b/docker/compiler.go
index dd92a0b..0f6cd92 100644
--- a/docker/compiler.go
+++ b/docker/compiler.go
@@ -2,12 +2,75 @@ package docker
 
 import (
 	"bytes"
-	"fmt"
 	"github.com/marxarelli/blubber/config"
 )
 
-func Compile(cfg config.ConfigType, variant string) []byte {
+func Compile(cfg *config.Config, variant string) *bytes.Buffer {
 	buffer := new(bytes.Buffer)
 
-	buffer.WriteString("FROM ")
+	vcfg, err := config.ExpandVariant(cfg, variant)
+
+	if err == nil {
+		// write multi-stage sections for each artifact dependency
+		for _, artifact := range vcfg.Artifacts {
+			if artifact.From != "" {
+				dependency, err := config.ExpandVariant(cfg, artifact.From)
+
+				if err == nil {
+					CompileStage(buffer, artifact.From, dependency)
+				}
+			}
+		}
+
+		CompileStage(buffer, variant, vcfg)
+	}
+
+	return buffer
+}
+
+func CompileStage(buffer *bytes.Buffer, stage string, vcfg *config.VariantConfig) {
+	Writeln(buffer, "FROM ", vcfg.Base, " AS ", stage)
+
+	Writeln(buffer, "USER root")
+	Writeln(buffer, "WORKDIR /srv")
+	CompileToCommands(buffer, vcfg.Apt)
+	CompileToCommands(buffer, vcfg.Run)
+
+	if vcfg.Run.As != "" {
+		Writeln(buffer, "USER ", vcfg.Run.As)
+	}
+
+	if vcfg.Run.In != "" {
+		Writeln(buffer, "WORKDIR ", vcfg.Run.In)
+	}
+
+	CompileToCommands(buffer, vcfg.Npm)
+
+	// Artifact copying
+	for _, artifact := range vcfg.Artifacts {
+		Write(buffer, "COPY ")
+
+		if artifact.From != "" {
+			Write(buffer, "--from=", artifact.From, " ")
+		}
+
+		Writeln(buffer, artifact.Source, " ", artifact.Destination)
+	}
+}
+
+func CompileToCommands(buffer *bytes.Buffer, compileable config.CommandCompileable) {
+	for _, command := range compileable.Commands() {
+		Writeln(buffer, "RUN ", command)
+	}
+}
+
+func Write(buffer *bytes.Buffer, strings ...string) {
+	for _, str := range strings {
+		buffer.WriteString(str)
+	}
+}
+
+func Writeln(buffer *bytes.Buffer, strings ...string) {
+	Write(buffer, strings...)
+	buffer.WriteString("\n")
 }