Excellent.
I think this is a little misleading as it does not explain why REDIS should be considered optional. Could that be added please?
I think you should also state REDIS needs to be 2.2.7 and higher (according to this).
Thanks @borpin. Iāve added the following note on redis:
- Redis recommended * (2.2 - 3.0 recomended), php5-redis 2.2.7 or above
*If you can install redis and php5-redis then it is recommended to do so. The way redis is used in emoncms reduces disk write load prelonging disk life (noticably on SD cards). Some input-processors also require redis and fail silently if redis is not installed. Some environments such as shared hosting or as far as we have tried windows servers dont support redis hence why emoncms has a fall back mode that allows core operation without redis.
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Iām afraid that line is a bit of a contradiction in terms,
php5-redis is the apt-get package name and only goes as far as v2.2.5 (for Jessie), v2.2.7 WAS the recommended version to be installed by cloning from the phpredis repo IF using php v5.
phpredis versions up to v2.2.8 (or from v3.1.0) work with php v5 and php-redis v3.0.0 onwards work with php7.
We should now be using phpredis v3.1.1 (1st version released that serves both php5 and php7) installed direct from PECL without adding the confusion of either the debian āphp5-redisā package or cloning the phpredis repo.
Just to confuse things a little more the phpredis module AKA php5-redis is actually called just āredisā in the PECL installer.
Thanks @pb66 what would you recommend I leave in its place? Should I just replace:
- Redis recommended * (2.2 - 3.0 recomended), php5-redis 2.2.7 or above
with
- Redis recommended *
perhaps?
Sadly it still is the recommended version 
. I have recently followed these instructions so if this is correct (and I do not doubt it) can:
a) the instructions be updated
b) you tell me how to I move forward 
That should be prolonging disk lifeā¦
Amended, thanks @Bill.Thomson
I added a note to the guide to highlight the redis issue, that things have changed:
āFebruary 2017: phpredis v3.1.1 has been released supporting both php5 and php7. It can be installed direct from PECL and is called simply: redis. This guide will be updated to reflect this change once tested in due course.ā
I havent yet had a chance to verify the correct installation procedure.
Is anyone currently running V3.1.1?
2.2.7 is the minimum that works, when testing last year we found that 2.2.5 did not work, from the emonSD card build guide:
Note: at time of writing the version of php5-redis included in the Raspbian Jessie sources (2.2.5-1) caused Apache to crash (segmentation errrors in Apache error log). Installing the latest stable version (2.2.7) of php5-redis from github fixed the issue
What is the current latest version in Jessie? How would an emonSD users update if needed? Am I correct in thinking that since we compiled and installed php-redis manually from source on the emonSD that it will not by upgraded via apt-get
Iāve moved this discussion to a new topic.
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Or any user of a Pi based systemā¦ Looking forward to the answer
Sorry to disappear āmid discussionā Monday, I had a 5am start yesterday morning and then didnāt finish until late.
Latest apt-get version last I checked was still v2.2.5 so that method of update isnāt much use, I would however also be concerned about that using that method even if the package did get updated for Jessie as there could be an unexpected outcome since it still thinks itās running v2.2.5 on the emonSD. If you run sudo apt-cache show php5-redis even after having cloned v2.2.7 it still says v2.2.5,
Installing by apt-get was the best method until v2.2.5 fell behind, now PECL is better as you can specify any version just by using (for example) āredis-v2.2.8ā in place of just āredisā. But I took the plunge and installed v3.1.0 on my live server some months ago and I have not noticed any issues, I upgraded to v3.1.1 at some point too.
Updating via PECL is just as easy as it is via apt-get, I would have to check my notes for the exact syntax, but is is something as easy as pecl update redis or words to that effect.
The current emonSD might get a bit messy to uninstall both the apt-get package and the cloned files and reinstall using PECL but Iām sure itās possible (unless someone beats me to it, I will try it on and emonPi at some point, although I cannot say when that might be right now)
Unless the debian package gets updated I would recommend using the PECL installer alone on the next image and even if Debian does get updated to a version less than v3.1.1 it might be worth sticking with PECL to avoid having to choose the correct one for php5 or php7.
Installation via PECL should be as easy as (Iāve included the apt-get lines just to add clarity)
sudo apt-get php-pear php5-dev
sudo pecl install redis
sudo sh -c 'echo "extension=redis.so" > /etc/php5/mods-available/redis.ini`
sudo php5enmod redis
for php5 or
for php7 something like
sudo apt-get php-pear php7.0-dev
sudo pecl install redis
sudo sh -c 'echo "extension=redis.so" > /etc/php/7.0/mods-available/redis.ini'
sudo phpenmod redis
or
sudo apt-get php-pear
sudo pecl install redis
sudo sh -c 'echo "extension=redis.so" > /etc/php/7.0/mods-available/redis.ini'
sudo ln -s /etc/php/7.0/mods-available/redis.ini /etc/php/7.0/apache2/conf.d/20-redis.ini
sudo ln -s /etc/php/7.0/mods-available/redis.ini /etc/php/7.0/cli/conf.d/20-redis.ini
The php7 suggestions are untested by me as Iām not running php7 but there seems to be some confusion over using āphpenmodā to create the āmodule enablingā symlinks in php7, it definitely works in php5 as thatās what I always use.
I have just reread the install guide for emonSD and was surprised to find the php redis module is actually installed 3 rimes (not 2) by 3 different methods!!! Firstly php5-redis is included in the apt-get packages, then that is ācloned overā direct from the GitHub repo to get v2.2.7, but then āredisā is still included in the PECL install following that! Since there is no version specified it would depend when the command is run as to which version you will get, so as the emonPi image was recompiled in Nov it may already be running a later version than v2.2.7 (it would depend if the order of events in the install guide was adhered to as well).
To get the Debian package version use
sudo apt-cache show php5-redis
should report āVersion: 2.2.5-1ā
then to get the PECL version use
pecl info redis
To see what version is actually in being used create a file called info.php in /var/www/html containing
<?php phpinfo(); ?>
and navigate to http://emonpi/info.php in a browser and scroll down to the redis section, that should be the loaded version.
To check for an upgrade via PEAR/PECL use
pear list-upgrades
if there is a later version available it can be installed using
sudo pecl upgrade redis
After any upgrade of php redis you must restart the server with
sudo service apache2 restart
Just tried updating my test emonPi using the PECL method and emoncms still runs, it reports v3.1.1 via āinfo.phpā but I do not have any feeds currently setup to say if it is fully functional. I do wonder what would happen if there was a bugfix in the Debian php5-redis v2.2.5 package and an apt-get update/upgrade of Raspian was run. so I think the emonSD image needs tidying, perhaps remove the php5-redis module using sudo apt-get purge php5-redis and delete the phpredis repo before upgrading (or reinstalling?) via PECL ? I have no idea if that would 100% definitely clean up all the loose ends though.
In the guides this small piece
sudo pear channel-discover pear.swiftmailer.org
sudo pecl install channel://pecl.php.net/dio-0.0.6 redis swift/swift
is as old as the hillās and has little or no accompanying info, I recommend dispersing it into 2 parts (dio is no longer needed), one for email if wanted or required
sudo pear channel-discover pear.swiftmailer.org
sudo pecl install swift/swift
and include the sudo pecl install redis etc with the āinstalling redisā sections of each of the alternative php5 or php7 guides since it is not needed if redis is not being installed and differs depending on whether php5 ot php7 is used.
I can take a look at updating the guide(s) if you like but Iām not realy sure what is planned with the emoncms install stuff, is it being included in the ānew documentationā? I would hate to invest in rewriting something heading for deletion.
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Wow, thatās a lot for such an in depth post. You have explained the current situation very well. Iāll take a look at upgrading redis on an emonPi and fixing the multiple versions installed. Removing the apt-get version should be easy, Iām not sure how to go about removing 2.2.7 that we cloned then installed from source. Any ideas?
The correct url is http://emonpi/emoncms/php-info.php
The Emoncms install guide will stay where it is on the GitHub. Iāve just made a change to correct update the syntax for installing swiftmailer for pecl:
I did read a while back that PECL has pretty much been abandoned in favour of Composer. Have you heard anything about this?
No, it is right as Paul suggests creating the file in the root html folder not the emoncms one.
Hi Paul, great, many thanks.
On a reasonably clean install from a Jessie Lite base, I had ended up with apt version as 2.2.5 and the info.php responding with 2.2.7 (I think that was correct).
A check with
pear list-upgrades
indicated 3.1.1 was available. I thought Iād remove the apt version first so a quick
sudo apt-get purge php5-redis
cleared that out but I then tried to upgrade and discovered redis had gone completely. Iām sure this is what is meant to happen but was rather disconcerting!
However, 4 commands laterā¦ (you are missing the final ātickā on the redis.so command)
sudo pecl install redis
sudo sh -c 'echo "extension=redis.so" > /etc/php5/mods-available/redis.ini'
sudo php5enmod redis
sudo service apache2 restart
and info.php reports 3.1.1 is installed.
Not sure if I am using it or not but it is now installed 
Cheers
So 2 queries:
If I check with
sudo apt-cache show php5-redis
It tells me version 2.2.5-1. Does this mean it has been reinstalled or can I ignore this?
Secondly, Emoncms system info page reports Redis version as being 2.8.17
The sudo apt-get purge was what wiped out redis altogether.
sudo apt-get remove would have deleted redis, but left the configuration files untouched.
missing?
LOL - twice as well it seems
Aw nuts. 
When I quoted your text, it appeared that nothing had happened, so I clicked my mouse a second timeā¦
apt-cache show gives package info about packages not installed.
More info about the show sub-command here and here.
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Hi Brian
There may be some confusion here, we are discussing the redis extension for php (php5-redis in Debian, phpredis on GitHub and just āredisā in PECL) not the Redis database application (server), this part just adds compatible functionality to php to interface with Redis.
The Redis (server) version shown on the emoncms page is the database application version and independent of any of the comments Iāve made thus far. v2.8.17 sounds correct.
Redis should not have been deleted altogether, but I now think you mean the redis extension was completely removed?
[thanks, Iāve corrected the missing tick]
no I canāt say I have, and it does seem to be bang up to date.though.
I think there is a Debian update in the pipeline, (See Debian -- Details of source package php-redis in sid for details in āSidā)
perhaps a jessie-backport will appear at some point? Either way I do not think we need a fourth install method, 3 is confusing enough for me!
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