Add opcache validate/re-validate setupCheck (or warning in Updater)

[joshtrichards]

Inform operator if restarting mod_php/fpm is more likely than not to be needed after triggering an Upgrade so people are less surprised when this happens and/or to remind people that adjust these values but then later forget. :)

Options:

• An info level message in existing PhpOpcacheSetup setupcheck
• Something within updatenotification app that gets displayed on the Updater screen
• Something in Updater itself

Or:

• Just tell people to restart always :man_shrugging:

Currently going to focus on clarifying in the documentation: nextcloud/documentation#11872

Related:

• 45490, #45504, among others (forum posts too)

• 39079

• https://core.trac.wordpress.org/ticket/36455 (much bigger topic; we could make some things better with some changes with how we handle both Server and app upgrades, but there's no foolproof solution)

[joshtrichards]

pseudo code (all wrapped behind a check that opcache.enable === 1)

// will revalidate on every request so no problem
if `opcache.validate_timestamps === 1` and `opcache.revalidate_freq === 0` {
    return;
}

// handle the default (for PHP)
if `opcache.validate_timestamps === 1` and `opcache.revalidate_freq === 2` {
    return; 
    // note: technically this could still create some issues but it's less likely at least (and our bigger concerns are the below)
}

// handle the optimization scenario of validation being completely disabled
if `opcache.validate_timestamps === 0` {
    WARN: You presumably know what you're doing since you disabled validation, but as a consequence you're expected to restart mod_php or fpm after upgrading Server or Apps
    // note: For Server, technically it would be best if they did this after they push out the code update (i.e. after Updater runs or they upload the new code), but before db/app upgrades
}

// handle the optimization scenario of validation being on but it being big enough that it's likely to create server (and app) upgrade problems
if `opcache.validate_timestamps === 1` and `opcache.revalidate_freq > 2` {
    WARN: You presumably know what you're doing since you increased validation frequency from the default, but as a consequence you're expected to restart mod_php or fpm after ugprading Server or Apps
    // note: For Server, technically it would be best if they did this after they push out the code update (i.e. after Updater runs or they upload the new code), but before db/app upgrades
}

// handle when setup check is ran from the CLI
if (setupCheck ran from the CLI) {
        WARN: Unable to check your opcache [maybe with some further explanation/suggestion to check from web]
}

I was originally leaning towards putting this in the updatenotification app or Updater itself, but opcache validation impacts app upgrades too. So I'm thinking a standard setupcheck for now, maybe with a only documented in config.php.sample parameter that can be used to disable the general setupcheck for this.

This would allow those operators that adjust validation to not be permanently nagged by the warning in the general setupchecks... but still would allow us to later add in friendly and non-intrusive reminders in updatenotifcation / Updater and app store / occ app that ignores this flag and just prints a reminder to "Update done! Please restart mod_php/fpm".

This approach has the benefit of:

• alerting admins that may not even know they did this (forgot or just followed some tutorial) to revisit their config
• requiring one more "Yes I really want to do this" decision by adding the override
• still cover situations where this is likely to be a problem by allowing us to add polite reminders when/where it's most critical to restart things
• not just making the default that we tell people to be "restart" (though that's tempting)
• providing a "heads up" to those that are using shared hosting (or cloud VPSes or particular distributions or whatever) where the validation values have been changed without them even knowing

[joshtrichards]

Both AIO and the micro-services Docker images sets opcache.revalidate_freq to 60.

That's obviously more than the default of 2.

Need to decide how to handle that. The higher the number goes the higher the likelihood of people experiencing weird behavior when making config changes or upgrades. :thinking: