Add option to specify the toolchain config file

README.md

@@ -17,7 +17,7 @@ jobs:
 
 This action will automatically install the appropriate toolchain with `rustup` by inspecting the
 `RUSTUP_TOOLCHAIN` environment variable or the `rust-toolchain.toml` (preferred) or `rust-toolchain`
-configuration files. If no toolchain found, will default to `stable`.
+configuration files. To specify the location of the toolchain configuration files you can use `rust-toolchain-file` option. If no toolchain found, will default to `stable`.
 
 ```toml
 # rust-toolchain.toml

action.yml

@@ -9,6 +9,8 @@ inputs:
   cache:
     description: 'Toggle caching of ~/.cargo/registry and /target/debug directories.'
     default: true
+  rust-toolchain-file:
+    description: 'Path to a rust-toolchain file to install.'
   channel:
     description: 'Toolchain specification/channel to install.'
   components:

src/rust.ts

@@ -94,7 +94,16 @@ export function detectToolchain(): Toolchain {
 		});
 	} else {
 		core.info('Loading rust-toolchain.toml or rust-toolchain file');
+    const toolchainFile = core.getInput('rust-toolchain-file');
 
+    if (toolchainFile) {
+      if (fs.existsSync(toolchainFile)) {
+        Object.assign(toolchain, parseConfig(toolchainFile));
+      } else {
+        core.setFailed('Not found toolchain config file');
+        throw new Error('Not found toolchain config file');
+      }
+    } else {
       for (const configName of ['rust-toolchain.toml', 'rust-toolchain']) {
         const configPath = path.join(process.cwd(), configName);
 
@@ -106,6 +115,7 @@ export function detectToolchain(): Toolchain {
         }
       }
     }
+	}
 
 	core.info('Inheriting toolchain settings from inputs');