Expose env vars with prefix

engine/engine.go

@@ -18,6 +18,7 @@ import (
 	"github.com/blackstork-io/fabric/eval"
 	"github.com/blackstork-io/fabric/parser"
 	"github.com/blackstork-io/fabric/parser/definitions"
+	"github.com/blackstork-io/fabric/parser/evaluation"
 	"github.com/blackstork-io/fabric/pkg/diagnostics"
 	"github.com/blackstork-io/fabric/plugin"
 	"github.com/blackstork-io/fabric/plugin/resolver"
@@ -37,6 +38,7 @@ type Engine struct {
 	lockFile *resolver.LockFile
 	resolver *resolver.Resolver
 	fileMap  map[string]*hcl.File
+	env      plugin.MapData
 }
 
 // New creates a new Engine instance with the provided options.
@@ -380,6 +382,32 @@ func (e *Engine) FetchData(ctx context.Context, target string) (_ plugin.Data, d
 	return loadedData.FetchData(ctx)
 }
 
+func (e *Engine) loadEnv() plugin.MapData {
+	requiredPrefix := "FABRIC_"
+	if e.config != nil && e.config.EnvVarsPrefix != nil {
+		requiredPrefix = *e.config.EnvVarsPrefix
+	}
+	envMap := plugin.MapData{}
+
+	env := evaluation.EvalContext().Variables["env"].AsValueMap()
+	for k, v := range env {
+		if !strings.HasPrefix(k, requiredPrefix) {
+			continue
+		}
+		envMap[k] = plugin.StringData(v.AsString())
+	}
+	return envMap
+}
+
+func (e *Engine) initialDataCtx() plugin.MapData {
+	if e.env == nil {
+		e.env = e.loadEnv()
+	}
+	return plugin.MapData{
+		"env": e.env,
+	}
+}
+
 func (e *Engine) RenderContent(ctx context.Context, target string) (_ plugin.Content, _ plugin.Data, diags diagnostics.Diag) {
 	ctx, span := e.tracer.Start(ctx, "Engine.RenderContent", trace.WithAttributes(
 		attribute.String("target", target),
@@ -396,7 +424,7 @@ func (e *Engine) RenderContent(ctx context.Context, target string) (_ plugin.Con
 	if diags.Extend(diag) {
 		return nil, nil, diags
 	}
-	content, data, diag := doc.RenderContent(ctx)
+	content, data, diag := doc.RenderContent(ctx, e.initialDataCtx())
 	if diags.Extend(diag) {
 		return nil, nil, diags
 	}
@@ -419,7 +447,7 @@ func (e *Engine) Publish(ctx context.Context, target string) (_ plugin.Content,
 	if diags.Extend(diag) {
 		return nil, nil, diags
 	}
-	content, data, diag := doc.Publish(ctx)
+	content, data, diag := doc.Publish(ctx, e.initialDataCtx())
 	if diags.Extend(diag) {
 		return nil, nil, diags
 	}

engine/engine_test.go

@@ -188,6 +188,74 @@ func TestEngineLint(t *testing.T) {
 	)
 }
 
+func TestEnvPrefix(t *testing.T) {
+	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{
+		AddSource: true,
+		Level:     slog.LevelWarn,
+	})))
+	os.Setenv("OTHER_VAR", "OTHER_VAR")
+	os.Setenv("FABRIC_VAR", "FABRIC_VAR")
+	os.Setenv("FABRIC_TEST_VAR", "FABRIC_TEST_VAR")
+
+	renderTest(
+		t, "Default",
+		[]string{
+			`
+			document "test-doc" {
+				content text {
+					value = "{{.env.OTHER_VAR}}\n{{.env.FABRIC_VAR}}\n{{.env.FABRIC_TEST_VAR}}"
+				}
+			}
+			`,
+		},
+		"test-doc",
+		[]string{
+			"<no value>\nFABRIC_VAR\nFABRIC_TEST_VAR",
+		},
+		diagtest.Asserts{},
+	)
+	renderTest(
+		t, "Custom",
+		[]string{
+			`
+			fabric {
+				expose_env_vars_with_prefix = "FABRIC_TEST_"
+			}
+			document "test-doc" {
+				content text {
+					value = "{{.env.OTHER_VAR}}\n{{.env.FABRIC_VAR}}\n{{.env.FABRIC_TEST_VAR}}"
+				}
+			}
+			`,
+		},
+		"test-doc",
+		[]string{
+			"<no value>\n<no value>\nFABRIC_TEST_VAR",
+		},
+		diagtest.Asserts{},
+	)
+	renderTest(
+		t, "Empty",
+		[]string{
+			`
+			fabric {
+				expose_env_vars_with_prefix = ""
+			}
+			document "test-doc" {
+				content text {
+					value = "{{.env.OTHER_VAR}}\n{{.env.FABRIC_VAR}}\n{{.env.FABRIC_TEST_VAR}}"
+				}
+			}
+			`,
+		},
+		"test-doc",
+		[]string{
+			"OTHER_VAR\nFABRIC_VAR\nFABRIC_TEST_VAR",
+		},
+		diagtest.Asserts{},
+	)
+}
+
 func TestEngineRenderContent(t *testing.T) {
 	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{
 		AddSource: true,

eval/document.go

@@ -48,7 +48,7 @@ func (doc *Document) FetchData(ctx context.Context) (plugin.Data, diagnostics.Di
 	return result, diags
 }
 
-func (doc *Document) RenderContent(ctx context.Context) (plugin.Content, plugin.Data, diagnostics.Diag) {
+func (doc *Document) RenderContent(ctx context.Context, docDataCtx plugin.MapData) (plugin.Content, plugin.Data, diagnostics.Diag) {
 	data, diags := doc.FetchData(ctx)
 	if diags.HasErrors() {
 		return nil, nil, diags
@@ -59,10 +59,9 @@ func (doc *Document) RenderContent(ctx context.Context) (plugin.Content, plugin.
 	}
 	// static portion of the data context for this document
 	// will never change, all changes are made to the clone of this map
-	docDataCtx := plugin.MapData{
-		definitions.BlockKindData:     data,
-		definitions.BlockKindDocument: docData,
-	}
+	docDataCtx[definitions.BlockKindData] = data
+	docDataCtx[definitions.BlockKindDocument] = docData
+
 	diag := ApplyVars(ctx, doc.Vars, docDataCtx)
 
 	if diags.Extend(diag) {
@@ -106,8 +105,8 @@ func (doc *Document) RenderContent(ctx context.Context) (plugin.Content, plugin.
 	return result, data, diags
 }
 
-func (doc *Document) Publish(ctx context.Context) (plugin.Content, plugin.Data, diagnostics.Diag) {
-	content, data, diags := doc.RenderContent(ctx)
+func (doc *Document) Publish(ctx context.Context, docDataCtx plugin.MapData) (plugin.Content, plugin.Data, diagnostics.Diag) {
+	content, data, diags := doc.RenderContent(ctx, docDataCtx)
 	if diags.HasErrors() {
 		return nil, nil, diags
 	}

parser/definitions/global_config.go

@@ -4,6 +4,7 @@ type GlobalConfig struct {
 	CacheDir       string            `hcl:"cache_dir,optional"`
 	PluginRegistry *PluginRegistry   `hcl:"plugin_registry,block"`
 	PluginVersions map[string]string `hcl:"plugin_versions,optional"`
+	EnvVarsPrefix  *string           `hcl:"expose_env_vars_with_prefix,optional"`
 }
 
 type PluginRegistry struct {
@@ -27,5 +28,8 @@ func (g *GlobalConfig) Merge(other *GlobalConfig) {
 			}
 		}
 	}
+	if other.EnvVarsPrefix != nil {
+		g.EnvVarsPrefix = other.EnvVarsPrefix
+	}
 	g.PluginVersions = other.PluginVersions
 }