feat(conditional component): allow components to be included conditional (#536)

Use case:

A client has a component that is deployed to multiple regions. However,
some components need to be rolled out in a single region. Supporting
count is the most flexible option I could think of.

This was AI generated, so happy to clean up any stylistic changes or
consider alternatives.

Author: demeyerthom

.changes/unreleased/Added-20250908-152214.yaml

@@ -0,0 +1,3 @@
+kind: Added
+body: Allow count on components for specific module exclusion
+time: 2025-09-08T15:22:14.965735+02:00

internal/config/schemas/schema-1.yaml

@@ -175,6 +175,8 @@ definitions:
     properties:
       name:
         type: string
+      count:
+        type: string
       variables:
         $ref: "#/definitions/MachComposerVariables"
       secrets:

internal/config/site_component.go

@@ -24,6 +24,7 @@ type SiteComponentConfig struct {
 	Variables  variable.VariablesMap `yaml:"variables"`
 	Secrets    variable.VariablesMap `yaml:"secrets"`
 	Deployment *Deployment           `yaml:"deployment"`
+	Count      string                `yaml:"count"`
 
 	DependsOn []string `yaml:"depends_on"`
 }

internal/generator/component.go

@@ -19,6 +19,7 @@ type componentContext struct {
 	ComponentHash       string
 	ComponentVariables  string
 	ComponentSecrets    string
+	ComponentCount      string
 	SiteName            string
 	Environment         string
 	SourceType          string
@@ -155,6 +156,7 @@ func renderComponentModule(_ context.Context, cfg *config.MachConfig, n *graph.S
 	tc := componentContext{
 		ComponentName:    n.SiteComponentConfig.Name,
 		ComponentVersion: n.SiteComponentConfig.Definition.Version,
+		ComponentCount:   n.SiteComponentConfig.Count,
 		SiteName:         n.SiteConfig.Identifier,
 		Environment:      cfg.Global.Environment,
 		Version:          n.SiteComponentConfig.Definition.Version,

internal/generator/component_test.go

@@ -1,12 +1,17 @@
 package generator
 
 import (
+	"context"
+	"strings"
+	"testing"
+
 	"github.com/mach-composer/mach-composer-cli/internal/config"
 	"github.com/mach-composer/mach-composer-cli/internal/config/variable"
+	"github.com/mach-composer/mach-composer-cli/internal/graph"
+	"github.com/mach-composer/mach-composer-cli/internal/plugins"
 	"github.com/mach-composer/mach-composer-cli/internal/state"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
-	"testing"
 )
 
 type mockRenderer struct {
@@ -65,3 +70,161 @@ func TestRenderRemoteSourcesCompactSources(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, "remote-state\nremote-state-2", resp)
 }
+
+func TestRenderComponentModuleWithCount(t *testing.T) {
+	ctx := context.Background()
+
+	// Create mock state renderer
+	rr := new(mockRenderer)
+	rr.On("Identifier").Return("test-site/test-component")
+	rr.On("StateKey").Return("test-component")
+	rr.On("Backend").Return("backend {}", nil)
+
+	// Create state repository
+	r := state.NewRepository()
+	_ = r.Add(rr)
+
+	// Create plugin repository
+	pr := plugins.NewPluginRepository()
+
+	// Create test configuration
+	cfg := &config.MachConfig{
+		Global: config.GlobalConfig{
+			Environment: "test",
+		},
+		Plugins:         pr,
+		StateRepository: r,
+	}
+
+	// Create component definition
+	source := config.Source("./modules/test-component")
+	componentDef := &config.ComponentConfig{
+		Name:    "test-component",
+		Version: "1.0.0",
+		Source:  source,
+	}
+
+	// Create site component with count
+	siteComponent := config.SiteComponentConfig{
+		Name:       "test-component",
+		Definition: componentDef,
+		Count:      "data.sops_external.variables.data[\"region\"] == \"foo\" ? 1 : 0",
+		Variables:  make(variable.VariablesMap),
+		Secrets:    make(variable.VariablesMap),
+		Deployment: &config.Deployment{
+			Type: config.DeploymentSiteComponent,
+		},
+	}
+
+	// Create site config
+	siteConfig := config.SiteConfig{
+		Identifier: "test-site",
+		Variables:  make(variable.VariablesMap),
+		Secrets:    make(variable.VariablesMap),
+	}
+
+	// Create project config
+	projectConfig := config.MachConfig{
+		Global: config.GlobalConfig{
+			Variables: make(variable.VariablesMap),
+			Secrets:   make(variable.VariablesMap),
+		},
+	}
+
+	// Create graph node
+	node := &graph.SiteComponent{
+		SiteComponentConfig: siteComponent,
+		SiteConfig:          siteConfig,
+		ProjectConfig:       projectConfig,
+	}
+
+	// Render the component module
+	result, err := renderComponentModule(ctx, cfg, node)
+	assert.NoError(t, err)
+
+	// Check that count is included in the output
+	assert.Contains(t, result, "count = data.sops_external.variables.data[\"region\"] == \"foo\" ? 1 : 0")
+	assert.Contains(t, result, "module.test-component[*]")
+}
+
+func TestRenderComponentModuleWithoutCount(t *testing.T) {
+	ctx := context.Background()
+
+	// Create mock state renderer
+	rr := new(mockRenderer)
+	rr.On("Identifier").Return("test-site/test-component")
+	rr.On("StateKey").Return("test-component")
+	rr.On("Backend").Return("backend {}", nil)
+
+	// Create state repository
+	r := state.NewRepository()
+	_ = r.Add(rr)
+
+	// Create plugin repository
+	pr := plugins.NewPluginRepository()
+
+	// Create test configuration
+	cfg := &config.MachConfig{
+		Global: config.GlobalConfig{
+			Environment: "test",
+		},
+		Plugins:         pr,
+		StateRepository: r,
+	}
+
+	// Create component definition
+	source := config.Source("./modules/test-component")
+	componentDef := &config.ComponentConfig{
+		Name:    "test-component",
+		Version: "1.0.0",
+		Source:  source,
+	}
+
+	// Create site component without count
+	siteComponent := config.SiteComponentConfig{
+		Name:       "test-component",
+		Definition: componentDef,
+		Count:      "", // No count specified
+		Variables:  make(variable.VariablesMap),
+		Secrets:    make(variable.VariablesMap),
+		Deployment: &config.Deployment{
+			Type: config.DeploymentSiteComponent,
+		},
+	}
+
+	// Create site config
+	siteConfig := config.SiteConfig{
+		Identifier: "test-site",
+		Variables:  make(variable.VariablesMap),
+		Secrets:    make(variable.VariablesMap),
+	}
+
+	// Create project config
+	projectConfig := config.MachConfig{
+		Global: config.GlobalConfig{
+			Variables: make(variable.VariablesMap),
+			Secrets:   make(variable.VariablesMap),
+		},
+	}
+
+	// Create graph node
+	node := &graph.SiteComponent{
+		SiteComponentConfig: siteComponent,
+		SiteConfig:          siteConfig,
+		ProjectConfig:       projectConfig,
+	}
+
+	// Render the component module
+	result, err := renderComponentModule(ctx, cfg, node)
+	assert.NoError(t, err)
+
+	// Check that count is NOT included in the output
+	assert.NotContains(t, result, "count =")
+	// Check that output doesn't have [*] suffix
+	lines := strings.Split(result, "\n")
+	for _, line := range lines {
+		if strings.Contains(line, "value =") && strings.Contains(line, "module.test-component") {
+			assert.NotContains(t, line, "[*]")
+		}
+	}
+}

internal/generator/templates/site_component.tmpl

@@ -10,6 +10,10 @@ module "{{ .ComponentName }}" {
     version = "{{ .Version }}"
 {{ end }}
 
+{{ if .ComponentCount }}
+    count = {{ .ComponentCount }}
+{{ end }}
+
 
 {{ if .ComponentVariables }}
     {{ .ComponentVariables }}
@@ -50,5 +54,5 @@ module "{{ .ComponentName }}" {
 output "{{ .ComponentName }}" {
     description = "The module outputs for {{ .ComponentName }}"
     sensitive = true
-    value =  module.{{ .ComponentName }}
+    value =  module.{{ .ComponentName }}{{ if .ComponentCount }}[*]{{ end }}
 }