fix: add optional param with builder image

When renovate creates lots of PRs docker buildx is rate limited
because it tries to pull its image from Docker Hub.
This commit allows us to configure our own image from ECR.

action.yml

@@ -8,6 +8,9 @@ inputs:
   builder:
     required: false
     description: buildx builder to use
+  builder-image:
+    required: false
+    description: buildx image to use
   context:
     required: false
     description: docker context

src/buildx.ts

@@ -11,7 +11,10 @@ import {debug, endGroup, info, startGroup, warning} from '@actions/core';
 import {HttpClient} from '@actions/http-client';
 import {exec, getExecOutput} from '@actions/exec';
 
-export async function setup(builderName: string): Promise<void> {
+export async function setup(
+  builderName: string,
+  builderImage: string
+): Promise<void> {
   if (!(await isAvailable())) {
     await install();
   }
@@ -22,7 +25,7 @@ export async function setup(builderName: string): Promise<void> {
   if (!builderName) {
     builderName = `builder-${uuid.v4()}`;
     state.setBuilder(builderName);
-    await createBuilder(builderName);
+    await createBuilder(builderName, builderImage);
     await bootBuilder(builderName);
   }
   outputs.setBuilder(builderName);
@@ -44,7 +47,7 @@ export async function stop(builderName: string): Promise<void> {
   endGroup();
 }
 
-async function createBuilder(name: string): Promise<void> {
+async function createBuilder(name: string, image: string): Promise<void> {
   startGroup(`🔨 Creating a new builder instance`);
 
   const context = 'builders';
@@ -56,9 +59,14 @@ async function createBuilder(name: string): Promise<void> {
     '--name',
     name,
     '--driver',
-    'docker-container',
-    context
+    'docker-container'
   ];
+
+  if (image) {
+    args.push('--driver-opt', `image=${image}`);
+  }
+
+  args.push(context);
   await exec('docker', args);
 
   endGroup();

src/inputs.ts

@@ -6,6 +6,7 @@ import {getInput, getMultilineInput} from '@actions/core';
 export interface Inputs {
   buildArgs: string[];
   builder: string;
+  builderImage: string;
   context: string;
   file: string;
   labels: string[];
@@ -36,6 +37,7 @@ export async function getInputs(): Promise<Inputs> {
   const inputs: Inputs = {
     buildArgs: await getInputList('build-args'),
     builder: getInput('builder'),
+    builderImage: getInput('builder-image'),
     context: getInput('context'),
     file: getInput('file'),
     labels: await getInputList('labels'),

src/main.ts

@@ -38,7 +38,7 @@ async function run(): Promise<void> {
     }
 
     await cache.restore(inputs);
-    await buildx.setup(inputs.builder);
+    await buildx.setup(inputs.builder, inputs.builderImage);
     const tag = await docker.build(inputs);
     if (inputs.push) {
       await buildx.inspect(tag);