feat(config): support reading from local file if it exists

Signed-off-by: Liam Stanley <me@liamstanley.io>

action.yml

@@ -7,7 +7,7 @@ inputs:
     required: false
     default: '${{ github.token }}'
   configuration-path:
-    description: 'Path to the labeler.yml configuration file'
+    description: "The path to the label configuration file. If the file doesn't exist at the specified path on the runner, action will read from the source repository via the Github API."
     required: true
   enable-versioned-regex:
     description: 'Controls if versioned regex templates are being used'

src/main.ts

@@ -1,6 +1,7 @@
 import { getInput, setFailed, debug, setOutput } from "@actions/core";
 import { context, getOctokit } from "@actions/github";
 import { load as loadYaml } from "js-yaml";
+import fs from "fs";
 
 type GitHubClient = ReturnType<typeof getOctokit>["rest"];
 
@@ -151,21 +152,31 @@ function regexifyConfigPath(configPath: string, version: string) {
 /** Load the configuration file */
 async function loadConfig(client: GitHubClient, configPath: string) {
   try {
-    const { data } = await client.repos.getContent({
-      owner: context.repo.owner,
-      repo: context.repo.repo,
-      ref: context.sha,
-      path: configPath,
-    });
+    let configContent: string
 
-    if (!("content" in data)) {
-      throw new TypeError(
-        "The configuration path provided is not a valid file. Exiting"
-      );
-    }
+    if (fs.existsSync(configPath)) {
+      console.log(`Configuration file (path: ${configPath}) exists locally, loading from file`);
 
-    const configContent = Buffer.from(data.content, "base64").toString("utf8");
+      configContent = fs.readFileSync(configPath, { encoding: "utf8" });
+    } else {
+      console.log(`Configuration file (path: ${configPath}) does not exist locally, fetching via the API`);
 
+      const { data } = await client.repos.getContent({
+        owner: context.repo.owner,
+        repo: context.repo.repo,
+        ref: context.sha,
+        path: configPath,
+      });
+
+      if (!("content" in data)) {
+        throw new TypeError(
+          "The configuration path provided is not a valid file. Exiting"
+        );
+      }
+
+      configContent = Buffer.from(data.content, "base64").toString("utf8");
+    }
+
     // loads (hopefully) a `{[label:string]: string | string[]}`, but is `any`:
     const configObject = loadYaml(configContent);