Version 2.6 is a legacy release, and these documents are no longer being maintained.


The behavior of PHP code often depends strongly on the values of many configuration settings, including fundamental changes to things like how errors are handled.

We defined some sane configuration defaults in our installation instructions. Namely, these settings are defined in the PHP pool (/etc/php7.2/fpm/php-fpm.conf) and they are prioritized over those defined in /etc/php/7.2/fpm/php.ini. Be aware that multiple configuration files are read when PHP starts up, therefore it is a good practice to check the final configuration state when you are deploying AtoM. You can use phpinfo() for that purpose.

See also

There are certain settings in PHP that could be tweaked as a security measure but they may have unexpected results in AtoM. For example, you may be tempted to disable allow_url_fopen but that would make impossible for AtoM to fetch digital objects from remote resources. These settings only seem convenient for hosting providers running untrusted code from their users or willing to limit their abilities in runtime.

Making AtoM read-only

In some cases, you may want to prevent users from being able to log into the application via the user interface - for example, if you are running a separate AtoM instance as a read-only front end, while maintaining a read/write site internally and using a replication script to copy data to the public site periodically.


Artefactual maintains a public replication script that can be used to support a two-site deployment, as in the example above. For more information, see:

There are two places in AtoM where you can configure read-only mode - be sure to check both locations.


Before you do, there is also a user interface setting that can be set to hide the login button - you might want to enable this before disabling login. See:

Hide or show the login button

The first is an environment variable defined in the PHP pool set up during installation. The location of this file may vary depending on your PHP version and installation method, but typically for PHP 7.2, you can find this file at /etc/php/7.2/fpm/pool.d/atom.conf.

The file contains an environment variable called ATOM_READ_ONLY. To put AtoM into read-only mode (so login is disabled), change this value to “on,” like so:

env[ATOM_READ_ONLY] = "on"

You will need to restart PHP-FPM after making this change. See:

Restarting PHP-FPM

There is also a setting found in the config/app.yml configuration file. Change this value to:

read_only: true

Once again, you will need to restart PHP-FPM after editing tihs file.


The environment variable located in the PHP pool takes precedence over this config/app.yml configuration file, so changing the setting here, but not also in the PHP pool may not prevent login. We recommend changing the value in both places.

AtoM security panel settings

AtoM’s user interface also has some security settings that can be configured by an administrator, such as the ability to require strong passwords, or limiting login to a specific IP or range. For more information, see: