End of life plans for 5.x php versions & planning for 7.0 EOL

We have had some discussion about EOL on php 5.x versions. The text below is a proposed blog post:

**End of life plans for 5.x php versions & planning for 7.0 EOL **

This blog serves as advance notice of our intention to stop supporting php versions 5.5, 5.6 and our ongoing evaluation of 7.0.

For php 5.5 we intend to end support in January 2019. This is already unsupported by php and we strongly recommend you upgrade off it as soon as possible. The release in February 2019 will be the first release that does not support php 5.5

For php 5.6 our TARGET is to end support in September 2019 (Oct release would support php 7.0+). 5.6 and 7.0 will unsupported by php from the end of this year. Usage of these versions is still pretty high amongst CiviCRM users http://stats.civicrm.org/?tab=sites so we will review this target in the first quarter of next year & extend it if we feel it will cause undue pain. Supporting 5.6 has downsides in that it restricts the external packages and versions of those packages we can use. As time goes on the risk of it leaving us without a secure option increases, as well as reducing opportunities to use more modern packages and to improve our code and product.

For php 7.0 our TARGET is the end of 2019. We will be reviewing this in March as well to see how reasonable that is. There is less to gain from dropping 7.0 than 5.6 so we will take that into account.

What version of php should you be using? In general you should aim to be on php 7.1 or 7.2. For drupal 7 users you may find that there are extensions that you rely on that do not yet support php 7.1 - although this will be less and less likely over time. See https://www.drupal.org/docs/7/system-requirements/drupal-7-php-requirements#php_required for more information.

Note that as of writing there are only a small number of sites on 7.2 http://stats.civicrm.org/?tab=technology so you may wish to check php 7.2 adoption stats before choosing php 7.1 over php 7.2 in case there are any remaining issues.