PHP Redis extension version 4 safe?

borpin · 2018-10-12T17:21:13.853Z

Which version of REDIS should I install? I know from this post it needs to be at least 3.1.3…

However, the Stretch documentation was revised to use apt-get to install php-redis in place of using PECL. It’s been a while since I have installed via apt-get so I cannot recall if the symlinks are done for you or not. But, regardless, the version installed by apt-get is 3.1.1 which we know has issues with rounding as floats are 32bits rather than 64bits when versions prior to 3.1.3 are used (see https://github.com/emoncms/emoncms/issues/660) this was fixed in 3.1.3 so we should be using PECL not apt-get as per the Stretch guide (see the apt-get install list for "php-redis https://github.com/emoncms/emoncms/blob/master/docs/RaspberryPi/readme.md#installation).

But I just did a pecl install redis and it is offering redis-4.1.1

Is this safe or do I need to force 3.1.3? If so how?

If it is safe, what is the answer to the question!

root@DietPi-EmoncmsVM:~# pecl install redis
WARNING: channel "pecl.php.net" has updated its protocols, use "pecl channel-update pecl.php.net" to update
downloading redis-4.1.1.tgz ...
Starting to download redis-4.1.1.tgz (220,894 bytes)
..............................................done: 220,894 bytes
25 source files, building
running: phpize
Configuring for:
PHP Api Version:         20151012
Zend Module Api No:      20151012
Zend Extension Api No:   320151012
enable igbinary serializer support? [no] :

pb66 · 2018-10-12T17:30:50.732Z

github.com/emoncms/emoncms

Possible breaking api changes in php-redis

opened 09:42AM - 03 May 18 UTC

closed 08:48AM - 17 Jan 19 UTC

pb66

question

Whilst helping a user on the OEM forum I noticed that PECL was installing v4.0.2… and read the [changelog](https://pecl.php.net/package-changelog.php?package=redis&release=4.0.2). The changelog states "*** WARNING! THIS RELEASE CONTAINS BRAKING API CHANGES! ***" for all versions above 4 and all I could find on those changes is this issue https://github.com/phpredis/phpredis/issues/1333 which has a couple of interesting linked issues. @TrystanLea or @chaveiro are you able to confirm if these changes are going to impact emoncms? Can we continue to use the latest phpredis versions, now at 4.x.x without changes? Or can the required changes be made to emoncms? Or do we need to stick with 3.x.x (currently 3.1.6) and only get critical updates moving forward? There is always a concern about how long devs will maintain a backwards compatible version and it also presents a "hiccup" in the installation guide as we will need to define a version (eg pecl install redis-3.1.6) instead of leaving it open (eg pecl install redis) and then that needs maintaining in both the guide and any future install or update scripts. I hope for option 1, or 2 if possible, I think 3 will start to reintroduce the issues we have not long seen resolved over v2.2.5 vs >v2.2.7 and again with php5 vs php7 prior to v3.1.3. The apt-get package is still at [3.1.1 for Stretch](https://packages.debian.org/stretch/php-redis) which is prior to the rounding issue fix we saw in 3.1.3 and 2.2.5 for Jessie which is prior to the memory leak fix in v2.2.7 (current emonSD image version) so I think we do still need to stick with PECL. I am unable to test v4.0.0 right now as both my test and live instances are currently on the same server so I cannot use on "test" without the risk of breaking "live". Any thoughts?

I’m using 3.1.6, the last version before v4 until someone confirms emoncms is ok with v4>. So the command to use would be

sudo pecl install redis-3.1.6

(for the benefit of other readers, I note you are actually running as root so don’t need sudo)

I have not recommended changing the guide(s) as it would require explanation and possibly cause further confusion down the line and we have not long cleared up the confusion brought about by the 1st emonpi image, IMO it would be better to confirm the position with emoncms and fix if needed. I had no idea such a core question would go unresolved for so long.

[edit] just hit enter to answer the question, it will use the default answer offered “no”

borpin · 2018-10-12T17:32:37.964Z

I think the guides need updating in case this is an issue. It might cause unexpected problems. If the guides use a version known to work, it helps.

Thanks for your help.

pb66 · 2018-10-12T17:44:14.279Z

…also the second line of the output you showed us above, points out you need to run an update, that too is part of the guide (or at least one of them)

sudo pecl channel-update pecl.php.net

(see https://github.com/emoncms/emoncms/tree/master/docs/RaspberryPi#installation)

borpin:

I think the guides need updating in case this is an issue. It might cause unexpected problems. If the guides use a version known to work, it helps.

I’m not disagreeing with you, but I have raised an issue to discuss the matter (over 5mths ago) and it has fallen on deaf ears, I’ve pointed out it might break so a decision should indeed be made to test/fix emoncms or plug the hole with a edit to the guides, but it’s not my decision to make, if it was, it would be tested and fixed already.

I’m not able to confirm if the emoncms code is safe or not, v4+ might be perfectly ok to use, I have no idea. I only reported the “possible breaking changes” for someone that knows to confirm and I choose to use 3.1.6 in the interim rather than using my live server as a guinea pig.

[edit] Also for the benefit of other readers, what we’re discussing here is not “Redis” the in memory database, but the “phpredis” PHP extension that is referred to as just “Redis” in the PHP modules listings.