fix: Update agent script on create and read

The prior behavior led to create not having an agent script.
This ensures it's set on create and update, leaving no room
for an empty state!

Author: kylecarbs

Diff for: internal/provider/provider.go

@@ -64,17 +64,17 @@ func New() *schema.Provider {
 						// Default to start!
 						transition = "start"
 					}
-					rd.Set("transition", transition)
+					_ = rd.Set("transition", transition)
 					count := 0
 					if transition == "start" {
 						count = 1
 					}
-					rd.Set("start_count", count)
+					_ = rd.Set("start_count", count)
 					owner := os.Getenv("CODER_WORKSPACE_OWNER")
 					if owner == "" {
 						owner = "default"
 					}
-					rd.Set("owner", owner)
+					_ = rd.Set("owner", owner)
 					name := os.Getenv("CODER_WORKSPACE_NAME")
 					if name == "" {
 						name = "default"
@@ -109,46 +109,17 @@ func New() *schema.Provider {
 		ResourcesMap: map[string]*schema.Resource{
 			"coder_agent": {
 				Description: "Use this resource to associate an agent.",
-				CreateContext: func(c context.Context, rd *schema.ResourceData, i interface{}) diag.Diagnostics {
+				CreateContext: func(c context.Context, resourceData *schema.ResourceData, i interface{}) diag.Diagnostics {
 					// This should be a real authentication token!
-					rd.SetId(uuid.NewString())
-					err := rd.Set("token", uuid.NewString())
+					resourceData.SetId(uuid.NewString())
+					err := resourceData.Set("token", uuid.NewString())
 					if err != nil {
 						return diag.FromErr(err)
 					}
-					return nil
+					return updateInitScript(resourceData, i)
 				},
 				ReadContext: func(c context.Context, resourceData *schema.ResourceData, i interface{}) diag.Diagnostics {
-					config, valid := i.(config)
-					if !valid {
-						return diag.Errorf("config was unexpected type %q", reflect.TypeOf(i).String())
-					}
-					auth, valid := resourceData.Get("auth").(string)
-					if !valid {
-						return diag.Errorf("auth was unexpected type %q", reflect.TypeOf(resourceData.Get("auth")))
-					}
-					operatingSystem, valid := resourceData.Get("os").(string)
-					if !valid {
-						return diag.Errorf("os was unexpected type %q", reflect.TypeOf(resourceData.Get("os")))
-					}
-					arch, valid := resourceData.Get("arch").(string)
-					if !valid {
-						return diag.Errorf("arch was unexpected type %q", reflect.TypeOf(resourceData.Get("arch")))
-					}
-					accessURL, err := config.URL.Parse("/")
-					if err != nil {
-						return diag.Errorf("parse access url: %s", err)
-					}
-					script := os.Getenv(fmt.Sprintf("CODER_AGENT_SCRIPT_%s_%s", operatingSystem, arch))
-					if script != "" {
-						script = strings.ReplaceAll(script, "${ACCESS_URL}", accessURL.String())
-						script = strings.ReplaceAll(script, "${AUTH_TYPE}", auth)
-					}
-					err = resourceData.Set("init_script", script)
-					if err != nil {
-						return diag.FromErr(err)
-					}
-					return nil
+					return updateInitScript(resourceData, i)
 				},
 				DeleteContext: func(c context.Context, rd *schema.ResourceData, i interface{}) diag.Diagnostics {
 					return nil
@@ -234,3 +205,38 @@ func New() *schema.Provider {
 		},
 	}
 }
+
+// updateInitScript fetches parameters from a "coder_agent" to produce the
+// agent script from environment variables.
+func updateInitScript(resourceData *schema.ResourceData, i interface{}) diag.Diagnostics {
+	config, valid := i.(config)
+	if !valid {
+		return diag.Errorf("config was unexpected type %q", reflect.TypeOf(i).String())
+	}
+	auth, valid := resourceData.Get("auth").(string)
+	if !valid {
+		return diag.Errorf("auth was unexpected type %q", reflect.TypeOf(resourceData.Get("auth")))
+	}
+	operatingSystem, valid := resourceData.Get("os").(string)
+	if !valid {
+		return diag.Errorf("os was unexpected type %q", reflect.TypeOf(resourceData.Get("os")))
+	}
+	arch, valid := resourceData.Get("arch").(string)
+	if !valid {
+		return diag.Errorf("arch was unexpected type %q", reflect.TypeOf(resourceData.Get("arch")))
+	}
+	accessURL, err := config.URL.Parse("/")
+	if err != nil {
+		return diag.Errorf("parse access url: %s", err)
+	}
+	script := os.Getenv(fmt.Sprintf("CODER_AGENT_SCRIPT_%s_%s", operatingSystem, arch))
+	if script != "" {
+		script = strings.ReplaceAll(script, "${ACCESS_URL}", accessURL.String())
+		script = strings.ReplaceAll(script, "${AUTH_TYPE}", auth)
+	}
+	err = resourceData.Set("init_script", script)
+	if err != nil {
+		return diag.FromErr(err)
+	}
+	return nil
+}