Add env var alternative to dependency-caching input

src/environment.ts

@@ -98,4 +98,11 @@ export enum EnvVar {
    * We check this later to ensure that it hasn't been tampered with by a late e.g. `setup-go` step.
    */
   GO_BINARY_LOCATION = "CODEQL_ACTION_GO_BINARY",
+
+  /**
+   * Used as an alternative to the `dependency-caching` input for the `init` Action.
+   * Useful for experiments where it is easier to set an environment variable than
+   * change the inputs to the Action.
+   */
+  DEPENDENCY_CACHING = "CODEQL_ACTION_DEPENDENCY_CACHING",
 }

src/init-action.ts

@@ -727,7 +727,9 @@ async function recordZstdAvailability(
 /** Determines whether dependency caching is enabled. */
 function getDependencyCachingEnabled(): boolean {
   // If the workflow specified something always respect that
-  const dependencyCaching = getOptionalInput("dependency-caching");
+  const dependencyCaching =
+    getOptionalInput("dependency-caching") ||
+    process.env[EnvVar.DEPENDENCY_CACHING];
   if (dependencyCaching !== undefined) return dependencyCaching === "true";
 
   // On self-hosted runners which may have dependencies installed centrally, disable caching by default