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.

8 files changed, 160 insertions, 54 deletions

diff --git a/config/apt.go b/config/apt.go
new file mode 100644
index 0000000..e6ad22c
--- /dev/null
+++ b/config/apt.go
@@ -0,0 +1,28 @@
+package config
+
+import (
+	"bytes"
+	"strings"
+)
+
+type AptConfig struct {
+	Packages []string `json:packages`
+}
+
+func (apt *AptConfig) Merge(apt2 AptConfig) {
+	apt.Packages = append(apt.Packages, apt2.Packages...)
+}
+
+func (apt AptConfig) Commands() []string {
+	if len(apt.Packages) < 1 {
+		return []string{}
+	}
+
+	buffer := new(bytes.Buffer)
+
+	buffer.WriteString("apt-get update && apt-get install -y ")
+	buffer.WriteString(strings.Join(apt.Packages, " "))
+	buffer.WriteString(" && rm -rf /var/lib/apt/lists/*")
+
+	return []string{buffer.String()}
+}
diff --git a/config/artifacts.go b/config/artifacts.go
new file mode 100644
index 0000000..78b6276
--- /dev/null
+++ b/config/artifacts.go
@@ -0,0 +1,7 @@
+package config
+
+type ArtifactsConfig struct {
+	From string `json:from`
+	Source string `json:source`
+	Destination string `json:destination`
+}
diff --git a/config/common.go b/config/common.go
new file mode 100644
index 0000000..ae2e438
--- /dev/null
+++ b/config/common.go
@@ -0,0 +1,23 @@
+package config
+
+type CommonConfig struct {
+	Base string `json:base`
+	Apt AptConfig `json:apt`
+	Npm NpmConfig `json:npm`
+	Run RunConfig `json:run`
+	EntryPoint []string `json:entrypoint`
+}
+
+func (cc1 *CommonConfig) Merge(cc2 CommonConfig) {
+	if cc2.Base != "" {
+		cc1.Base = cc2.Base
+	}
+
+	cc1.Apt.Merge(cc2.Apt)
+	cc1.Npm.Merge(cc2.Npm)
+	cc1.Run.Merge(cc2.Run)
+
+	if len(cc1.EntryPoint) < 1 {
+		cc1.EntryPoint = cc2.EntryPoint
+	}
+}
diff --git a/config/config.go b/config/config.go
new file mode 100644
index 0000000..36eb6e4
--- /dev/null
+++ b/config/config.go
@@ -0,0 +1,10 @@
+package config
+
+type Config struct {
+	CommonConfig
+	Variants map[string]VariantConfig `json:variants`
+}
+
+type CommandCompileable interface {
+	Commands() []string
+}
diff --git a/config/npm.go b/config/npm.go
new file mode 100644
index 0000000..d563045
--- /dev/null
+++ b/config/npm.go
@@ -0,0 +1,36 @@
+package config
+
+import (
+	"bytes"
+)
+
+type NpmConfig struct {
+  Install bool `json:install`
+	Env string `json:env`
+}
+
+func (npm *NpmConfig) Merge(npm2 NpmConfig) {
+	npm.Install = npm.Install || npm2.Install
+
+	if npm2.Env != "" {
+		npm.Env = npm2.Env
+	}
+}
+
+func (npm NpmConfig) Commands() []string {
+	if !npm.Install {
+		return []string{}
+	}
+
+	buffer := new(bytes.Buffer)
+
+	buffer.WriteString("npm install")
+
+	if npm.Env == "production" {
+		buffer.WriteString(" --production")
+	}
+
+	buffer.WriteString(" && npm dedupe")
+
+	return []string{buffer.String()}
+}
diff --git a/config/run.go b/config/run.go
new file mode 100644
index 0000000..c3ffd08
--- /dev/null
+++ b/config/run.go
@@ -0,0 +1,44 @@
+package config
+
+import (
+	"strconv"
+	"strings"
+)
+
+type RunConfig struct {
+	In string `json:in`
+	As string `json:as`
+	Uid int `json:uid`
+	Gid int `json:gid`
+}
+
+func (run *RunConfig) Merge(run2 RunConfig) {
+	if run2.In != "" { run.In = run2.In }
+	if run2.As != "" { run.As = run2.As }
+	if run2.Uid != 0 { run.Uid = run2.Uid }
+	if run2.Gid != 0 { run.Gid = run2.Gid }
+}
+
+func (run RunConfig) Commands() []string {
+	cmds := []string{}
+
+	if run.In != "" {
+		cmds = append(cmds, strings.Join([]string{"mkdir -p", run.In}, " "))
+	}
+
+	if run.As != "" {
+		cmd := []string{
+			"groupadd -o -g", strconv.Itoa(run.Gid), "-r", run.As, "&&",
+			"useradd -o -m -r -g", run.As, "-u", strconv.Itoa(run.Uid), run.As,
+		}
+
+		cmds = append(cmds, strings.Join(cmd, " "))
+
+		if run.In != "" {
+			owner := strings.Join([]string{run.As, ":", run.As}, "")
+			cmds = append(cmds, strings.Join([]string{"chown", owner, run.In}, " "))
+		}
+	}
+
+	return cmds
+}
diff --git a/config/types.go b/config/types.go
deleted file mode 100644
index 9fb742c..0000000
--- a/config/types.go
+++ /dev/null
@@ -1,54 +0,0 @@
-package config
-
-type Config struct {
-	CommonConfig
-	Variants map[string]VariantConfig `json:variants`
-}
-
-type CommonConfig struct {
-	Base string `json:base`
-	Apt AptConfig `json:apt`
-	Npm NpmConfig `json:npm`
-	EntryPoint []string `json:entrypoint`
-}
-
-type AptConfig struct {
-	Packages []string `json:packages`
-}
-
-type NpmConfig struct {
-  Use string `json:use`
-}
-
-type VariantConfig struct {
-	Includes []string `json:includes`
-	Artifacts []ArtifactsConfig `json:artifacts`
-	CommonConfig
-}
-
-type ArtifactsConfig struct {
-	From string `json:from`
-	Source string `json:source`
-	Destination string `json:destination`
-}
-
-func (vc1 *VariantConfig) Merge(vc2 VariantConfig) {
-	vc1.Artifacts = append(vc1.Artifacts, vc2.Artifacts...)
-	vc1.CommonConfig.Merge(vc2.CommonConfig)
-}
-
-func (cc1 *CommonConfig) Merge(cc2 CommonConfig) {
-	if cc1.Base == "" {
-		cc1.Base = cc2.Base
-	}
-
-	cc1.Apt.Packages = append(cc1.Apt.Packages, cc2.Apt.Packages...)
-
-	if cc1.Npm.Use == "" {
-		cc1.Npm.Use = cc2.Npm.Use
-	}
-
-	if len(cc1.EntryPoint) < 1 {
-		cc1.EntryPoint = cc2.EntryPoint
-	}
-}
diff --git a/config/variant.go b/config/variant.go
new file mode 100644
index 0000000..d1640bb
--- /dev/null
+++ b/config/variant.go
@@ -0,0 +1,12 @@
+package config
+
+type VariantConfig struct {
+	Includes []string `json:includes`
+	Artifacts []ArtifactsConfig `json:artifacts`
+	CommonConfig
+}
+
+func (vc1 *VariantConfig) Merge(vc2 VariantConfig) {
+	vc1.Artifacts = append(vc1.Artifacts, vc2.Artifacts...)
+	vc1.CommonConfig.Merge(vc2.CommonConfig)
+}