.github/workflows/main.yml

name: 'Test Inputs'
description: 'Tests GitHub Actions inputs parsing options'

inputs:
  test_string:
    description: 'Test string input of Actions'
    default: 'Spam Slam'
    required: true

runs:
  using: 'node12'
  main: lib/test-env-inputs.js

The documentation on inputs states that the IDs are up-cased and prefixed with INPUT_, and documentation on workflows states that with: is how inputs are assigned by ID when included within jobs:.

lib/test-env-inputs.js

console.log(`process.env.INPUT_TEST_STRING -> ${process.env.INPUT_TEST_STRING}`);

console.log('process.env...');
console.table(process.env);

.github/actions/test-inputs/action.yml

on: push

jobs:
  one:
    runs-on: ubuntu-16.04
    steps:
      - name: First tests
        uses: S0AndS0/gha-tests/.github/actions/test-inputs@master
        with:
          test_string: 'Ham Fan?'

Action files are named action.yml thus organizing in separate repositories or subdirectories is required.

The above uses: line’s syntax <author|organization>/<repository>/<path>@<branch|reference> was used (though documentation eludes to using relative paths being an option), because errors are more on point when debugging an action.

Example Log

The logs should show something similar to the following. Most note worthy will the final value of test_string/INPUT_TEST_STRING

.env.test_string -> Ham Fan?

________________________________________________________________________________________________________________________________________
      VCPKG_INSTALLATION_ROOT      |                                      '/usr/local/share/vcpkg'
             ANT_HOME              |                                          '/usr/share/ant'
              GOROOT               |                                         '/usr/local/go1.12'
             JAVA_HOME             |                                  '/usr/lib/jvm/zulu-8-azure-amd64'
         JAVA_HOME_11_X64          |                                 '/usr/lib/jvm/zulu-11-azure-amd64'
          GITHUB_ACTIONS           |                                               'true'
            GRADLE_HOME            |                                         '/usr/share/gradle'
          GOROOT_1_10_X64          |                                         '/usr/local/go1.10'
         JAVA_HOME_12_X64          |                                 '/usr/lib/jvm/zulu-12-azure-amd64'
            RUNNER_USER            |                                              'runner'
            BOOST_ROOT             |                                   '/usr/local/share/boost/1.69.0'
          JAVA_HOME_7_X64          |                                  '/usr/lib/jvm/zulu-7-azure-amd64'
     PERFLOG_LOCATION_SETTING      |                                          'RUNNER_PERFLOG'
         RUNNER_TOOL_CACHE         |                                       '/opt/hostedtoolcache'
          GOROOT_1_11_X64          |                                         '/usr/local/go1.11'
         BOOST_ROOT_1_69_0         |                                   '/usr/local/share/boost/1.69.0'
             LEIN_JAR              |                 '/usr/local/lib/lein/self-installs/leiningen-2.9.1-standalone.jar'
          JAVA_HOME_8_X64          |                                  '/usr/lib/jvm/zulu-8-azure-amd64'
               LANG                |                                            'en_US.UTF-8'
           ImageVersion            |                                               '156.2'
              M2_HOME              |                                   '/usr/share/apache-maven-3.6.1'
               PATH                | '/usr/share/rust/.cargo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin'
           ANDROID_HOME            |                                    '/usr/local/lib/android/sdk'
        DEPLOYMENT_BASEPATH        |                                            '/opt/runner'
          RUNNER_PERFLOG           |                                       '/home/runner/perflog'
             LEIN_HOME             |                                        '/usr/local/lib/lein'
               HOME                |                                           '/home/runner'
               CONDA               |                                       '/usr/share/miniconda'
               USER                |                                              'runner'
 DOTNET_SKIP_FIRST_TIME_EXPERIENCE |                                                 '1'
          GOROOT_1_12_X64          |                                         '/usr/local/go1.12'
         ANDROID_SDK_ROOT          |                                    '/usr/local/lib/android/sdk'
          GOROOT_1_9_X64           |                                         '/usr/local/go1.9'
        RUNNER_TRACKING_ID         |                            'github_90e782bb-15c3-4d41-a541-90d39f33f200'
            CHROME_BIN             |                                      '/usr/bin/google-chrome'
         INPUT_TEST_STRING         |                                             'Ham Fan?'
            GITHUB_REF             |                                         'refs/heads/master'
            GITHUB_SHA             |                             '57c0813746f0fb5673e6ea76459bc551bd3946f4'
         GITHUB_REPOSITORY         |                                         'S0AndS0/gha-tests'
           GITHUB_ACTOR            |                                              'S0AndS0'
          GITHUB_WORKFLOW          |                                    '.github/workflows/main.yml'
          GITHUB_HEAD_REF          |                                                 ''
          GITHUB_BASE_REF          |                                                 ''
         GITHUB_EVENT_NAME         |                                               'push'
         GITHUB_WORKSPACE          |                               '/home/runner/work/gha-tests/gha-tests'
           GITHUB_ACTION           |                                         'S0AndS0gha-tests'
         GITHUB_EVENT_PATH         |                        '/home/runner/work/_temp/_github_workflow/event.json'
             RUNNER_OS             |                                               'Linux'
            RUNNER_TEMP            |                                      '/home/runner/work/_temp'
         RUNNER_WORKSPACE          |                                    '/home/runner/work/gha-tests'
________________________________________________________________________________________________________________________________________