Last Updated: March 23, 2021
· namklabs

The treacherous journey from Pantheon to localhost

We entered into a Drupal project that had been going on for a while. It was a live site hosted on Pantheon, and I was suddenly in charge of maintaining and improving it.

I wanted to document the steps it took to get the site working locally in WAMP, because it was a very long and confusing process. Pantheon is super weird if you've been working with a normal XAMP stack your whole life.

If you are looking to work on a Pantheon Drupal site locally, then this Protip is for you.

Let's Git Started

Sorry about that.

So, the first thing you need is Git knowledge. Your Pantheon Drupal site's code resides within a Git repository, and Pantheon will give you the info you need to clone it locally. Pantheon also allows you to download a copy of the database so you can import it into your localhost phpMyAdmin that comes with WAMP or whatever MySQL server that you use. Easy enough, right?


Well, the first problem is going to be with the settings.php file located in your newly-cloned Drupal folder... Let's say this folder is called mysite. So the settings.php file would then be mysite/sites/default/settings.php.

Pantheon has a custom database configuration built into the settings.php file so that they can load-balance your site's databases automagically. And now that your site is on localhost, this Pantheon database magic no longer works, so we need to add in some code to point your Drupal site to your local MySQL server. Put this code in settings.php somewhere before the line that says * Access control for update.php script.. Make sure this code is not commented out, as several nearby code blocks are.

  $databases['default']['default'] = array(
    'driver' => 'mysql',
    'database' => 'mysite_dev',
    'username' => 'root',
    'password' => '',
    'host' => 'localhost',
    'port' => '',
    'prefix' => '',

This if statement checks to see if Pantheon's environment variable (read: signature) exists on your server. If it does not, the if statement proceeds by connecting to your local MySQL server. Be sure to replace the database, username, password, and host with the credentials to your local MySQL server. Also be sure that you imported that database you downloaded from Pantheon into the correct database locally.

Once that's taken care of, we only have a few more things to do in settings.php before we can move on with our lives.

Find the line that says $cookie_domain = ''; Hint: it will say your domain instead of "mysite".

Change to .mysite.local. Note the preceding period.

Next, find the line that says extract(json_decode($_SERVER['PRESSFLOW_SETTINGS'], TRUE));. It's near the bottom of the file.

Change that line to this:

  extract(json_decode($_SERVER['PRESSFLOW_SETTINGS'], TRUE));

This checks for the Pantheon environment variable once again to see if Pantheon is available. If it is, it executes the extract command. If it isn't (which is the case locally) it ignores the extract command. We are doing this because the extract command will cause an error, but we don't want to get rid of it completely, just in case. If you are brave 'n stuff, just delete that line, but be sure not to commit your changes to settings.php.

This concludes the changes to settings.php, but we aren't done yet.


You'll need to create records in your hosts file to point mysite.local to your localhost.

Protip: MAKE A BACKUP OF THE HOSTS FILE. DO NOT CHANGE THE LINE ENDINGS OF THE HOSTS FILE. Sublime Text did this to me once and it took me a few hours to figure out why my MAMP server was completely broken. Depending on whether you are on Windows or OS X, your hosts file is supposed to have the corresponding line ending type. It's a good idea to create a copy of the hosts file before you edit it, just in case.

Find the hosts file on Windows by opening up C:\Windows\System32\drivers\etc\hosts (on a Mac it's located at /private/etc/hosts ) in a text editor with administrative privileges. Add a line like this at the end of the file:   mysite.local

Save the file and close 'er up. Now, in case you don't know why you had to do that, here's the short version. The hosts file is checked when you try to reach a domain from your computer, and your computer will follow whatever IP address is listed for that domain, regardless of what the rest of the world thinks. We made it so that mysite.local will refer to your local machine instead of trying to find a real website called mysite.local somewhere on the internet (which doesn't exist and would yield an error.)


Now, create Virtual host record in your XAMP config for mysite.local and point it to your mysite Drupal folder. This little snippet goes at the end of your C:\Users\myself\wamp\bin\apache\Apache2.2.21\conf\extra\httpd-vhosts.conf file:

<VirtualHost *:80>
    DocumentRoot "C:\Users\myself\wamp\www\mysite"
    ServerName mysite.local
    ServerAlias www.mysite.local
    ErrorLog "logs/mysite/error_log"
    CustomLog "logs/mysite/access_log" common

Of course, some of the paths might be different. You might even have to use forward slashes instead of backslashes if you're on a Mac / MAMP server. And the path to httpd-vhosts.conf might be different too. You might have a different version of Apache or something, it's okay. Just stay cool and look for similar folders, you'll be fine.

After you update your virtual hosts file, restart WAMP or whatever web server you are using.

Alright, so we've nearly configured everything that needs to be configured, but there's one last thing, and there's only one or two more steps to go.

Clear your caches

Open up a browser — and reopen your browser if you had it open already — and go to mysite.local. It should come up. Log in and clear the caches under mysite.local/admin/config/development/performance.

Now that you've done that, you should be up and running!... unless... you have the Domain Access module installed. Then you have do one more thing.

Domain Access database table

If you have the Domain Access module installed and your localhost site isn't working, go to phpMyAdmin (or whatever MySQL thingy you are using) to edit the database. Go to the domain table. Look for the record that has under the subdomain column. You'll need to change that to mysite.local. You'll also need to change the scheme column to be http instead of https because you probably don't have https configured on your localhost environment. If it's already http then don't worry about changing that. But you still need to make sure the subdomain says mysite.local.

Darn that Domain Access module, making things more complicated! Well, at least your site will work now.

Some things to remember

Don't commit your settings.php file like it is. If you want to commit it, you'll need to modify the line with $cookie_domain line to check for the Pantheon environment variable and change the $cookie_domain variable depending on whether you're on Pantheon or not. That will allow you to commit this file and keep both your local and remote installations working.

When you push from local to Pantheon, it deploys your latest commit to the Dev environment. That's a good thing to remember.

Anyways, I sure hope that this helps someone out. Thanks for reading.

6 Responses
Add your response

You are my hero. Thanks for this.

over 1 year ago ·

To handle loading config outside of Pantheon it is actually quite simple to do the following at the end of settings.php:

 * Load local development override configuration, if available.
 * Use settings.local.php to override variables on secondary (staging,
 * development, etc) installations of this site. Typically used to disable
 * caching, JavaScript/CSS compression, re-routing of outgoing e-mails, and
 * other things that should not happen on development and testing sites.
 * Keep this code block at the end of this file to take full effect.
if (!defined('PANTHEON_ENVIRONMENT')) {
        $conf_path = conf_path();
        if (file_exists(DRUPAL_ROOT . '/' . $conf_path . '/settings.local.php')) {
          include DRUPAL_ROOT . '/' . $conf_path . '/settings.local.php';

Then in your settings.local.php file:

$databases = array (
  'default' =>
  array (
    'default' =>
    array (
      'database' => 'some_db',
      'username' => 'some_user',
      'password' => 'some_pw',
      'host' => '',
      'port' => '',
      'driver' => 'mysql',
      'prefix' => '',

// Other stuff useful during development

// Disable cache
$conf['cache'] = 0;

// Disable css and javascript aggregation by default
$conf['preprocess_css'] = 0;
$conf['preprocess_js'] = 0;

$base_url = '';

If you are running php 5.4 or later and drush 6 or newer you can just run drush rs --dns from the sites root.

over 1 year ago ·

Hello Nicholas,

thanks for the article. Unfortunately for me it did not work. I changed the settings, as you suggested, made db-backup via backup and migrate and changed to sftp-mode and downloaded the files-folder.
But my site comes locally without any css.
Does someone have an idea how to fix this?
By the way: I put my settings.php into the .gitignore-file. This is what you mean by: Do not upload the settings.php to the server?

Thanks a lot!

over 1 year ago ·

Hi rockie667,

Yes, putting the settings.php in the .gitignore was what I meant. Sounds like you did it correctly.

I had trouble with the CSS showing up for a few different reasons. If you are using the Domain Access module like I talked about in the article, then make sure you follow those instructions.

The second reason for CSS not showing up is that you need to clear the cache once you get your site working locally. You should be able to do this through the admin interface by going to Configuration > Performance > Clear all caches

If this still doesn't fix your CSS problem, take a look at the source of the page and look at the path that your CSS files have. If the path is different from what your local path should be, there must be a setting somewhere that is incorrect. I'm not an expert at this particular problem, but I would suggest that you look in your settings.php file because it might be telling the site to use a certain path or something like that. Maybe the cookie_domain setting is wrong or something?

I hope this helps!

over 1 year ago ·

Maybe if you go to the Configuration -> Performance,

and uncheck

Aggregate and compress CSS files,

it might work.

Worth a try.

over 1 year ago ·

I would recommend considering using Lando for all local Development.

Traditional stacks are dying by the day and since your host is containerized, so should your local environment. Not without mention is the deep Pantheon integration built into Lando making cloning, editing, and pushing changes as easy as a command-line event. - Check it out.. it will change your life (for the better )

over 1 year ago ·