trying to install mysql but I cannot start the service and cannot locate mysqld.sock

Question

I’m trying to install mysql but I cannot start the service and cannot locate mysqld.sock

I am following the how to here: https://www.digitalocean.com/community/tutorials/how-to-install-linux-apache-mysql-php-lamp-stack-on-ubuntu-16-04

And get stuck trying to run $ mysql_secure_installation

I get this error:

Error: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

Checking the version does show it installed.

mysql --version
mysql  Ver 8.0.21-0ubuntu0.20.04.4 for Linux on x86_64 ((Ubuntu))

I am unable to locate the mysqld.sock file anywhere and there is also no mysqld dir in /var/run/

I’ve also been through this troubleshooting doc https://www.digitalocean.com/community/tutorials/how-to-troubleshoot-socket-errors-in-mysql

But I can’t start the mysql service and there is nothing in the mysql.cnf file other than this

# The MySQL database client configuration file
#
# Ref to https://dev.mysql.com/doc/refman/en/mysql-command-options.html

[mysql]

This is what mysql.service shows

systemctl status mysql.service
● mysql.service - MySQL Community Server
     Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
     Active: activating (start) since Thu 2020-09-10 14:31:23 UTC; 15s ago
    Process: 8847 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
   Main PID: 8855 (mysqld)
     Status: "Server startup in progress"
      Tasks: 4 (limit: 533)
     Memory: 2.5M
     CGroup: /system.slice/mysql.service
             └─8855 [mysqld]

If I run it again the Process / Main PID changes. Does that mean it’s just taking a while to complete and I need to be patient?

I’ve uninstalled mysql a few different times but can’t seem to get it sorted.

Any help appreciated.

Answer 1

bobbyiliev September 11, 2020

Hi there @dezshredder,

To me it looks like that your MySQL service is stuck in a crash loop as the status output that you’ve shared indicates that the status is: "Server startup in progress" and the uptime is 15 seconds.

I would recommend checking your MySQL error log for more information on what might be wrong.

Also, I could suggest checking your /var/log/syslog log for more information as well.

Feel free to share the errors from the logs here so that I could try to advise you further.

Regards,
Bobby

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Answer 2

dezshredder September 11, 2020

Yeah something is definitely stuck.

tailing syslog shows mysql restarting over and over

Sep 11 15:15:15 ubuntu-s-1vcpu-512mb-nyc1-01 kernel: [ 1598.053913] [   2123]     0  2123     2743      723    61440        0             0 sudo
Sep 11 15:15:15 ubuntu-s-1vcpu-512mb-nyc1-01 kernel: [ 1598.053914] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/system.slice/mysql.service,task=mysqld,pid=2058,uid=112
Sep 11 15:15:15 ubuntu-s-1vcpu-512mb-nyc1-01 kernel: [ 1598.053966] Out of memory: Killed process 2058 (mysqld) total-vm:1231176kB, anon-rss:326860kB, file-rss:0kB, shmem-rss:0kB, UID:112 pgtables:968kB oom_score_adj:0
Sep 11 15:15:15 ubuntu-s-1vcpu-512mb-nyc1-01 kernel: [ 1598.088100] oom_reaper: reaped process 2058 (mysqld), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
Sep 11 15:15:15 ubuntu-s-1vcpu-512mb-nyc1-01 systemd[1]: mysql.service: Main process exited, code=killed, status=9/KILL
Sep 11 15:15:15 ubuntu-s-1vcpu-512mb-nyc1-01 systemd[1]: mysql.service: Failed with result 'signal'.
Sep 11 15:15:15 ubuntu-s-1vcpu-512mb-nyc1-01 systemd[1]: Failed to start MySQL Community Server.
Sep 11 15:15:15 ubuntu-s-1vcpu-512mb-nyc1-01 systemd[1]: mysql.service: Scheduled restart job, restart counter is at 19.
Sep 11 15:15:15 ubuntu-s-1vcpu-512mb-nyc1-01 systemd[1]: Stopped MySQL Community Server.
Sep 11 15:15:15 ubuntu-s-1vcpu-512mb-nyc1-01 systemd[1]: Starting MySQL Community Server...

It went from restart count 17 to 24 while writing this response.

Also load is very high on this droplet. htop shows average of 3.96

I also rebooted the whole droplet when I saw the load so high but it just started climbing again presumably due to mysql issues.

Thanks for the help @bobbyiliev .

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bobbyiliev September 12, 2020

Hi there @dezshredder,

It looks like MySQL is being killed due to out of memory.

What I could suggest here is adding a little bit extra RAM to the Droplet and also adding a swap file so that you could have some extra buffer:

https://www.digitalocean.com/community/tutorials/how-to-add-swap-space-on-ubuntu-20-04

Another thing that I could suggest is to run htop and see what exactly is consuming your RAM.

Also, you could check your Apache or Nginx access logs to see if there are any brute-force attacks that could be causing the issue. You can use the following script to summarize your access log:

BASH Script to Summarize Your NGINX and Apache Access Logs

Let me know how it goes!
Regards,
Bobby

How To Add Swap Space on Ubuntu 20.04
by Brian Boucheron
One way to guard against out-of-memory errors in applications is to add some swap space to your server. In this guide, we will cover how to add a swap file to an Ubuntu 20.04 server.
Reply Report

Answer 3

bobbyiliev September 12, 2020

Hi there @dezshredder,

It looks like MySQL is being killed due to out of memory.

What I could suggest here is adding a little bit extra RAM to the Droplet and also adding a swap file so that you could have some extra buffer:

https://www.digitalocean.com/community/tutorials/how-to-add-swap-space-on-ubuntu-20-04

Another thing that I could suggest is to run htop and see what exactly is consuming your RAM.

Also, you could check your Apache or Nginx access logs to see if there are any brute-force attacks that could be causing the issue. You can use the following script to summarize your access log:

BASH Script to Summarize Your NGINX and Apache Access Logs

Let me know how it goes!
Regards,
Bobby

How To Add Swap Space on Ubuntu 20.04
by Brian Boucheron
One way to guard against out-of-memory errors in applications is to add some swap space to your server. In this guide, we will cover how to add a swap file to an Ubuntu 20.04 server.
Reply Report

Answer 4

dezshredder September 14, 2020

Bumping up the Droplet did the trick!

I’m up and running.

Guess that’s what I get for being frugal and going with the cheapest option.

Thanks for the help @bobbyiliev!

Reply Report

bobbyiliev September 15, 2020

Hi there,

No problem at all! Happy to hear that you’ve got it up and running now!

Regards,
Bobby
Reply Report

Answer 5

bobbyiliev September 15, 2020

Hi there,

No problem at all! Happy to hear that you’ve got it up and running now!

Regards,
Bobby
Reply Report

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