Configuration Options

The following are commonly requested options which can be configured in the file local.config.php located in the config directory.

For a full list of available configuration keys, please see the developer documentation page on configuration settings.

Password settings

You can change the requirements for user passwords in the config file. Options include minimum length, number of upper and lowercase letters, and setting allowed symbols.

    'password' => [
        'min_length' => 6,
        'min_lowercase' => null,
        'min_uppercase' => null,
        'min_number' => null,
        'min_symbol' => null,
        'symbol_list' => '`~!@#$%^&*()-=_+[]\{}|;:",./<>?\'',

Requirements will display on the user creation and edit pages.


The thumbnails configuration key holds most thumbnail settings:

    'thumbnails' => [
        'types' => [
            'large' => ['constraint' => 800],
            'medium' => ['constraint' => 200],
            'square' => ['constraint' => 200],
        'thumbnailer_options' => [
            'imagemagick_dir' => null,

Under types, set the maximum dimensions for derivative images for media files. There are separate options for large, medium, and square. Defaults for these are 800, 200, and 200 respectively (all sizes are pixels)

thumbnailer_options is an array of options passed to the specific thumbnailer in use. For example, the imagemagick_dir thumbnail option sets the path to the folder where ImageMagick's convert command can be found on the server. This can be useful if Omeka S can't auto-detect the correct path for ImageMagick.

The thumbnailer to use is set under the service_manager key, by setting the alias for Omeka\File\Thumbnailer:

    'service_manager' => [
        'aliases' => [
            'Omeka\File\Thumbnailer' => 'Omeka\File\Thumbnailer\ImageMagick',

The default thubnailer is Omeka\File\Thumbnailer\ImageMagick. Also available are Omeka\File\Thumbnailer\Imagick (which uses the imagick PHP extension) and Omeka\File\Thumbnailer\Gd (which uses the commonly available gd PHP extension).

You can also set the thumbnailer to Omeka\File\Thumbnailer\NoThumbnail, which will prevent your Omeka S installation from generating thumbnails.

PHP Path

Omeka S uses background jobs for some long-running tasks that operate on many items or just otherwise might take a long time. Omeka S uses the PHP CLI (command-line interface) to run these jobs, the php command.

Omeka S by default will try to automatically detect the path to the PHP CLI on the server, but for some servers this detection doesn't work, or there are multiple different php commands to choose from. In these situations you can manually configure the correct path in the configuration file:

    'cli' => [
        'phpcli_path' => '/usr/local/bin/php',

(Note: the path here is just an example; the proper path will be specific to your server)


The mail key can be used to configure how Omeka S sends emails.

The default is to use sendmail, where the server is responsible for having mail delivery configured and set up. Sendmail generally requires no configuration on the Omeka S side.

Another option for some servers is to configure a direct SMTP connection for sending mail. An example configuration, to be added at the end of local.config.php follows (see the laminas-mail docs for clarification):

    'mail' => [
        'transport' => [
            'type' => 'smtp',
            'options' => [
                'name' => 'localhost',
                'host' => '',
                'port' => 25, // 465 for 'ssl', and 587 for 'tls'
                'connection_class' => 'smtp', // 'plain', 'login', or 'crammd5'
                'connection_config' => [
                    'username' => null,
                    'password' => null,
                    'ssl' => null, // 'ssl' or 'tls'
                    'use_complete_quit' => true,