Site goes down at the same time every day in memory-constrained environment

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#5

This is a relatively new problem cc @sam

1 Like
#6

For the record, I just checked that I have automatic backups disabled, unless it’s something else that e.g. redis does every day and isn’t exposed to the Discourse admin config. But I’ve increased swap anyway and we’ll see how tomorrow goes!

#7

Hi Alex,

429 is a very odd response code for the site to be sending due to memory problems. That’s normally because someone on the same IP address is doing something untoward. Is there any chance someone else on the same connection (a person or machine in your office, for example) is running some sort of scraping batch job at the same time?

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#8

Those might be a red herring – I’m running the container behind an nginx on the host so I can keep some old LAMP apps up on a couple other subdomains, and I think it just gets hit a lot by people trying to access the site when it goes down like this, with that being the result.

And I know I probably shouldn’t be doing that at or below minimum spec, so you’re free to disavow, but those haven’t changed in a dog’s age and this has only started happening with the most recent Discourse versions, always at the same time of day.

#9

Well one thing I would check is that NGINX inside the container (that has the rate limiting template enabled) does not think every single user has the same IP address.

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#10

I don’t think the nginx inside the container has diverged from stock at all, I use the provided launcher script for all the docker stuff.

This is what the host nginx config for the site looks like if you’re curious, but I don’t think this is the problem:

root@selectbutton:/etc/nginx/sites-enabled# cat discourse

server {

listen 443 ssl;
server_name selectbutton.net;
ssl_certificate /etc/letsencrypt/live/selectbutton.net/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/selectbutton.net/privkey.pem;

location /basic_status {
    stub_status on;
    access_log off;
    allow 127.0.0.1;
    allow 172.31.20.111;
    allow 52.35.138.13;
    deny all;
}

location / {
    root /var/www/discourse-root;
    try_files $uri @discourse;
}

location @discourse {
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_pass https://localhost:4443;
}
}

server {
listen 80;
server_name selectbutton.net;
return 301 https://$host$request_uri;
}
#11

I’m on a server with 2 GB of ram and I’m seeing the same behavior as of a few days ago. Seems to happen around backup time.

#12

Well you would be using this:

And if I had to bet a :money_with_wings: you do not have a template setting:

real_ip_header X-Forwarded-For;

The internal NGINX is going to have to trust that header.

2 Likes
#13

Ah, OK, good to know. So I should add that to the host nginx or the container nginx (which is to say, that to: block in the app.yml?)

#14

You need to run a replace command in the internal NGINX.

After making the changes, look at the actual file on disk to confirm that you got what you wanted.

A trick I use is:

  1. ./launcher enter app
  2. cd /etc/nginx/conf.d/
  3. edit the discourse.conf file
  4. sv restart nginx
  5. see that my desired effect was achieved
  6. turn that change into a yml replace command
  7. rebuild
  8. confirm file is good
2 Likes
#15

OK, will test if it goes down again tomorrow despite increasing swap. Any other ideas if this turns out not to be it? The timeliness still makes me quite skeptical.

#16

Yeah, the strict periodicity (in the absence of scheduled backups) is a very confusing aspect to this. Seems like a heck of a big clue, if you can figure out what’s running at that exact time, I think you’ll be 90% done.

3 Likes
#17

Same problem for me :frowning:
I’m tired of rebuild after every crash.

#18

Check your /sidekiq and see if anything is running at that time.

What also might help is to start psql to take a look at what is going on in your database at that time.

SELECT pid, age(query_start, clock_timestamp()), usename, query FROM pg_stat_activity;

2 Likes
#19

Sidekiq is idle :thinking:

#20

And of course it seems not to have happened today after occurring several days in a row at this exact time. Huh. swap usage hasn’t ticked over 900M either. Oh well! Stay tuned I guess.

#21

The error 429 means you are hitting a rate limit, so no amount of additional resources are going to help you there…

2 Likes
#22

It’s not always a 429 – throws 408’s too.

#23

First you need to fix the issue where IP addresses are not reported correctly to the app, as stated upstream in this topic…

#24

At the moment I’m failing to work out where I can add it to the container nginx so that it’ll actually have an effect; the container’s access log is always reporting the same IP from every hit after each time I’ve tried adding it to a different block of the discourse nginx and restarting. the nginx docs suggest that module has to be built separately but I’m assuming it already is in your docker distribution?

Also, curious whether this has changed upstream semi-recently; as recently as Oct 10 (when I was probably not more than a month or so behind on updates) the Discourse site was able to identify external IPs other than localhost and report them properly, and our nginx configs haven’t changed in over a year.