Python: ModuleNotFoundError: No module named 'memcache'

[NickMous]

Self-Hosted Version

24.1.0

CPU Architecture

x86_64

Docker Version

25.0.0

Docker Compose Version

2.24.1

Steps to Reproduce

1. Have sentry self-hosted previous version installed
2. do git pull
3. run ./install.sh

Expected Result

A working sentry

Actual Result

While upgrading it already stated that it couldn't do anything with redis, because of memcached. This was only a warning, so it went through. But now it also shows up in the logs of the sentry web runner, and I get a 502 bad gateway.

Event ID

No response

[lukasleitsch]

A workaround until the issue is fixed in the nightly image.

SENTRY_IMAGE=getsentry/sentry:24.1.0 ./install.sh

[NickMous]

Thanks! I switched to the 24.1.0 label for the time being :)

[aldy505]

Hi @NickMous can you confirm that the solution on this works? #2722

[NickMous]

Hi @aldy505 ! I unfortunately was sick, but now I've taken the time for testing this, and this is what I now have:
When pulling the latest from master there are errors still remaining about memcache, but now mainly AttributeError: module 'django.core.cache.backends.memcached' has no attribute 'MemcachedCache'`.
So far with replacing the image version from nightly to 24.1.0 I get another error that the app_bootstrap_initializeMain is not found. I'll try to rerun the install.sh, I'll get back in a sec

[NickMous]

For some reason running without the tag to give y'all insight for errors and manually saying yes, the install worked now and it's up and running. So it has not been fixed yet on master/nightly, but master/SENTRY_IMAGE=getsentry/sentry:24.1.0 works

[bobvandevijver]

I believe I hit this issue when upgrading from 24.1.0 to 24.1.1.

django.core.cache.backends.base.InvalidCacheBackendError: Could not find backend 'django.core.cache.backends.memcached.MemcachedCache': Module "django.core.cache.backends.memcached" does not define a "MemcachedCache" attribute/class
Error in install/set-up-and-migrate-database.sh:12.

Full log here: sentry_install_log-2024-01-27_09-32-14.txt

Reverting to 24.1.0 allows me to get Sentry back up and running again.

[asottile-sentry]

you'll want to change your configuration to use the pymemcache backend -- django no longer ships a backend for python-memcached https://docs.djangoproject.com/en/4.2/topics/cache/#memcached

[csvan]

@bobvandevijver update your sentry.conf.py to contain this for CACHES:

CACHES = {
    "default": {
        "BACKEND": "django.core.cache.backends.memcached.PyMemcacheCache",
        "LOCATION": ["memcached:11211"],
        "TIMEOUT": 3600,
        "OPTIONS": {"ignore_exc": True}
    }
}

[bobvandevijver]

@asottile-sentry / @csvan Thank you for pointing me to that, I always forget to check these config files for changes! It is now working as it should :)

[msschl]

@bobvandevijver update your sentry.conf.py to contain this for CACHES:

CACHES = {
    "default": {
        "BACKEND": "django.core.cache.backends.memcached.PyMemcacheCache",
        "LOCATION": ["memcached:11211"],
        "TIMEOUT": 3600,
        "OPTIONS": {"ignore_exc": True}
    }
}

This worked for me when upgrading from 24.1.0 to 24.1.1.

[chadwhitacre]

We at least need a note in the release notes for whatever version introduced this configuration change.

It seems, though, like we should add something under install.sh to rewrite sentry.conf.py automatically.

[hubertdeng123]

We at least need a note in the release notes for whatever version introduced this configuration change.

This is done already here: https://github.com/getsentry/self-hosted/releases/tag/24.1.1

It seems, though, like we should add something under install.sh to rewrite sentry.conf.py automatically.

Agreed here

[bobvandevijver]

@hubertdeng123 But that wasn't there when the release was made (and therefor not included in the Github notification I got). But good to see it is there now.

[chadwhitacre]

We should get something in to fix up sentry.conf.py automatically asap, and definitely before shipping 24.2.0 (#2714). I propose we rewrite the conf file automatically if it contains the default value, and report on what we did (whether rewrite or skip).

[Apollon77]

PS: Also the release note wording "you may need to" do not really imply that it is a thing you need to do :-)

( I also run into it while upgrading to 24.1.1)

[clayvan]

Am I the only one who still experiences this even with the updated config?

Trying to deploy 24.1.1 with this config (note my memcached service name is different on purpose)

      CACHES = {
        "default": {
          "BACKEND": "django.core.cache.backends.memcached.PyMemcacheCache",
          "LOCATION": ["sentry-memcached:11211"],
          "TIMEOUT": 3600,
          "OPTIONS": {"ignore_exc": True}
        }
      }

and I still receive:

ModuleNotFoundError: No module named 'memcache'