Google Client API - Missing require parameter: redirect_uri

Just use method setRedirectUri($absoluteUrl) on a client object:

$client = new Google_Client();
$client->setRedirectUri('http://' . $_SERVER['HTTP_HOST'] . '/oauth2callback.php');

via:

https://developers.google.com/api-client-library/php/auth/web-app

This answer might not fully satisfy your needs, but:

If you only need read access to the sheet, all you need is a Google Service Account credentials file (credentials.json).

One can simply slice out the token-retrieving part of the example like so:

<?php
require __DIR__ . '/vendor/autoload.php';

if (php_sapi_name() != 'cli') {
    throw new Exception('This application must be run on the command line.');
}

/**
 * Returns an authorized API client.
 * @return Google_Client the authorized client object
 */
function getClient()
{
    $client = new Google_Client();
    $client->setApplicationName('Google Sheets API PHP Quickstart');
    $client->setScopes(Google_Service_Sheets::SPREADSHEETS_READONLY);
    $client->setAuthConfig('credentials.json');
    $client->setAccessType('offline');
    $client->setPrompt('select_account consent');
    return $client;
}


// Get the API client and construct the service object.
$client = getClient();
$service = new Google_Service_Sheets($client);

// Prints the names and majors of students in a sample spreadsheet:
// https://docs.google.com/spreadsheets/d/1BxiMVs0XRA5nFMdKvBdBZjgmUUqptlbs74OgvE2upms/edit
$spreadsheetId = '1BxiMVs0XRA5nFMdKvBdBZjgmUUqptlbs74OgvE2upms';
$range = 'Class Data!A2:E';
$response = $service->spreadsheets_values->get($spreadsheetId, $range);
$values = $response->getValues();

if (empty($values)) {
    print "No data found.\n";
} else {
    print "Name, Major:\n";
    foreach ($values as $row) {
        // Print columns A and E, which correspond to indices 0 and 4.
        printf("%s, %s\n", $row[0], $row[4]);
    }
}

Google should have mentioned this in their example IMO.

Google's "PHP Quick Start" documentation for the Sheet API seems to be out of date at https://developers.google.com/sheets/api/quickstart/php.

To get their demo working with PHP 7.2+ I had to modify quite a bit, and it's not all that clear what's going on. Below is a commented, updated version of their quick start that may be helpful to anyone else having trouble working with the Google Sheets API and PHP.

<?php
/**
 * Updated Google Sheets Quickstart
 *
 * https://developers.google.com/sheets/api/quickstart/php
 */
require __DIR__ . '/vendor/autoload.php';

/**
* Appends one slash at the end, and removes any extra slashes
* https://stackoverflow.com/a/9339669/812973
*
* @return string $path with the slash appended
*/
function addTrailingSlash ($path)
{
    return rtrim ($path, '/') . '/';
}

/**
 * Returns an authorized API client.
 * @return Google_Client the authorized client object
 */
function getClient() {

     // Change this to a secure location where you'll save your config *.json files
     // Make sure it isn't publicly available on the web
    $configPath = addTrailingSlash (getcwd());

    // This get's generated by the script, so don't create it
    $credentialsPath = $configPath . 'credentials.json';

    $client = new Google_Client();

    // Matches the "Application Name" you enter during the "Step 1" wizard
    $client->setApplicationName( 'API App Name' );
    $client->setScopes( Google_Service_Sheets::SPREADSHEETS_READONLY );

    // You need to go through "Step 1" steps to generate this file: https://developers.google.com/sheets/api/quickstart/php
    $client->setAuthConfig( $configPath . 'client_secret.json' );
    $client->setAccessType( 'offline' );

    // This must match the "callback URL" that you enter under "OAuth 2.0 client ID" in the Google APIs console at https://console.developers.google.com/apis/credentials
    $client->setRedirectUri( 'https://' . $_SERVER['HTTP_HOST'] . '/' . basename( __FILE__, '.php' ) );

    // We have a stored credentials file, try using the data from there first
    if ( file_exists( $credentialsPath ) ) {
        $accessToken = json_decode( file_get_contents( $credentialsPath ), true );
    }

    // No stored credentials found, we'll need to request them with OAuth
    else {

        // Request authorization from the user
        $authUrl = $client->createAuthUrl();
        if ( ! isset( $_GET['code'] ) ) {
            header( "Location: $authUrl", true, 302 );
            exit;
        }

        // The authorization code is sent to the callback URL as a GET parameter.
        // We use this "authorization code" to generate an "access token". The
        // "access token" is what's effectively used as a private API key.
        $authCode = $_GET['code'];
        $accessToken = $client->fetchAccessTokenWithAuthCode( $authCode );

        // Create credentials.json if it doesn't already exist (first run)
        if ( ! file_exists( dirname( $credentialsPath ) ) ) {
            mkdir( dirname( $credentialsPath ), 0700, true );
        }

        // Save the $accessToken object to the credentials.json file for re-use
        file_put_contents( $credentialsPath, json_encode( $accessToken ) );
    }

    // Provide client with API access token
    $client->setAccessToken( $accessToken );

    // If the $accessToken is expired then we'll need to refresh it
    if ( $client->isAccessTokenExpired() ) {
        $client->fetchAccessTokenWithRefreshToken( $client->getRefreshToken() );
        file_put_contents( $credentialsPath, json_encode( $client->getAccessToken() ) );
    }

    return $client;
}

// Get the API client and construct the service object.
$client = getClient();
$service = new Google_Service_Sheets( $client );

// Get values from a spreadheet and print
// https://developers.google.com/sheets/api/reference/rest/v4/spreadsheets.values/get
$spreadsheetId = '1BxiMVs0XRA5nFMdKvBdBZjgmUUqptlbs74OgvE2upms';
$range = 'Class Data!A2:E';
$response = $service->spreadsheets_values->get($spreadsheetId, $range);
$values = $response->getValues();

if (empty($values)) {
    print "No data found.\n";
} else {
    print "Name, Major:\n";
    foreach ($values as $row) {
        // Print columns A and E, which correspond to indices 0 and 4.
        printf("%s, %s\n", $row[0], $row[4]);
    }
}

I got it to work. What I had to do was go back into Google Developer Console and delete the project I had created. Then when making a NEW project it allowed me to save my localhost url. The issue that was occuring was when I went to go add my localhost url to the redirect url it would say its not possible at this time. When I set the redirect url before hitting the create button it accepts it just fine.