index.js

const Core = require('@actions/core');
const Github = require('@actions/github');
const Path = require("path")
const fs = require('fs')
const {globSync} = require('glob')

try {
    // Get octokit
    const Octokit = Github.getOctokit(Core.getInput('token'));
    // Read & parse release note
    let note_content = fs.readFileSync(Path.resolve(Core.getInput('note')), {encoding: 'utf8'});
    const [tag_str, tag_name] = note_content.match(/^\`(.*)\`\n/);
    note_content = note_content.substring(tag_str.length);
    const [name_str, release_name] = note_content.match(/^#\s+(.*)\n/);
    note_content = note_content.substring(name_str.length);
    // Get assets
    const asset_paths = Core.getInput('assets').length ? Core.getInput('assets').split("\n").reduce((prev, cur) =>  prev.concat(globSync(cur.trim())), []) : [];

    // Create release
    Octokit.rest.repos.createRelease({
        owner: Github.context.repo.owner,
        repo: Github.context.repo.repo,
        tag_name: tag_name,
        target_commitish: Github.context.sha,
        name: release_name,
        body: note_content,
        draft: Core.getInput('draft', {trimWhitespace: true}) == "true"
    })
    // Upload assets
    .then(res => Promise.all(asset_paths.map(asset => Octokit.rest.repos.uploadReleaseAsset({
        owner: Github.context.repo.owner,
        repo: Github.context.repo.repo,
        release_id: res.data.id,
        name: Path.basename(asset),
        data: fs.readFileSync(asset)
    }))))
    .then(() => {
        console.log("Release created!")
    })
} catch (error) {
    Core.setFailed(error.message);
}