improvement: add explicit warn message

Added explicit warn that include path cannot be resolved from Dockerfile ARG and ENV variables

core/src/plugins/container/helpers.ts

@@ -28,7 +28,7 @@ import { LogEntry } from "../../logger/log-entry"
 import chalk from "chalk"
 import isUrl from "is-url"
 import titleize from "titleize"
-import { stripQuotes } from "../../util/string"
+import { deline, stripQuotes } from "../../util/string"
 import { PluginContext } from "../../plugin-context"
 import { ModuleVersion } from "../../vcs/vcs"
 
@@ -386,6 +386,11 @@ const helpers = {
       } else if (path.match(/(?<!\\)(?:\\\\)*\$[{\w]/)) {
         // If the path contains a template string we can't currently reason about it
         // TODO: interpolate args into paths
+        log.warn(chalk.yellow(deline`
+          Resolving include paths from Dockerfile ARG and ENV variables is not supported yet. Please specify 
+          required path in Dockerfile explicitly or use ${chalk.bold("include")} for path assigned to ARG or ENV.
+          `)
+        )
         return undefined
       }
     }