feat: add base template variables to API (#26425)

coderd/templatebuilder/bases.go

@@ -41,6 +41,7 @@ type BaseManifest struct {
 	DisplayName    string             `json:"display_name"`
 	OS             string             `json:"os"`
 	DefaultContext BaseDefaultContext `json:"default_context"`
+	Variables      []ModuleVariable   `json:"variables"`
 }
 
 // BaseDefaultContext holds default render values stored in base.json.
@@ -192,6 +193,17 @@ func BaseTemplateIDs() []string {
 	return ids
 }
 
+// BaseVariables returns the user-facing variables for a given base
+// template ID. Computed variables are excluded. Returns nil if the
+// base is unknown or has no variables.
+func BaseVariables(exampleID string) []ModuleVariable {
+	bases, err := loadBases()
+	if err != nil || bases[exampleID] == nil {
+		return nil
+	}
+	return bases[exampleID].Manifest.Variables
+}
+
 // BaseTemplateFS returns a filesystem rooted at the given base template
 // directory within the embedded bases catalog. Returns an error if
 // exampleID is not a known base template.

coderd/templatebuilder/bases/kubernetes/base.json

@@ -4,5 +4,24 @@
 	"os": "linux",
 	"default_context": {
 		"container_image": "codercom/enterprise-base:ubuntu"
-	}
+	},
+	"variables": [
+		{
+			"name": "use_kubeconfig",
+			"type": "bool",
+			"description": "Use host kubeconfig. Set to true if the Coder host is running outside the Kubernetes cluster for workspaces.",
+			"default": false,
+			"required": false,
+			"sensitive": false,
+			"computed": false
+		},
+		{
+			"name": "namespace",
+			"type": "string",
+			"description": "The Kubernetes namespace to create workspaces in. Must exist prior to creating workspaces.",
+			"required": true,
+			"sensitive": false,
+			"computed": false
+		}
+	]
 }

coderd/templatebuilder/compose.go

@@ -4,6 +4,7 @@ import (
 	"archive/tar"
 	"bytes"
 	"encoding/json"
+	"maps"
 	"regexp"
 	"strings"
 	"time"
@@ -21,6 +22,9 @@ var numberPattern = regexp.MustCompile(`^-?[0-9]+(\.[0-9]+)?$`)
 // ComposeRequest describes which base template and modules to render.
 type ComposeRequest struct {
 	BaseTemplateID string
+	// BaseVariableValues maps base template variable names to their
+	// user-supplied values.
+	BaseVariableValues map[string]string
 	// RegistryURL is the module registry base URL from the deployment
 	// config (CODER_TEMPLATE_BUILDER_REGISTRY_URL).
 	RegistryURL string
@@ -49,7 +53,7 @@ type ComposeResult struct {
 // source files. It extracts the coder_agent resource name from the
 // rendered base HCL and wires it into each module block.
 func Compose(req ComposeRequest) (*ComposeResult, error) {
-	mainTF, err := renderBase(req.BaseTemplateID)
+	mainTF, err := renderBase(req.BaseTemplateID, req.BaseVariableValues)
 	if err != nil {
 		return nil, err
 	}
@@ -93,9 +97,14 @@ func formatHCL(src []byte) []byte {
 	return hclwrite.Format(src)
 }
 
-// renderBase renders the base template for the given example ID.
-func renderBase(baseTemplateID string) ([]byte, error) {
+// renderBase renders the base template for the given example ID,
+// merging any user-supplied variable values into the render context.
+func renderBase(baseTemplateID string, baseVars map[string]string) ([]byte, error) {
 	renderCtx := DefaultBaseRenderContext(baseTemplateID)
+	if renderCtx.Variables == nil {
+		renderCtx.Variables = make(map[string]string)
+	}
+	maps.Copy(renderCtx.Variables, baseVars)
 	mainTF, err := RenderBaseTemplate(baseTemplateID, "main.tf.tmpl", renderCtx)
 	if err != nil {
 		return nil, xerrors.Errorf("render base template: %w", err)