PowerDNS Admin
Python Django application to manage PowerDNS servers.
gcloud
- Detach a disk from Google Compute Instance
- Install Google Cloud SDK
- Google Cloud apt signatures couldn’t be verified
- Google Cloud SSH using gcloud command line
- Google Cloud open a port in firewall
- Create Kubernetes cluser using gcloud
Cloud SQL
gcloud components
|
1 2 3 |
gcloud components list gcloud components install beta gcloud components update beta |
List current gcloud config
|
1 |
gcloud config list |
Set a region
|
1 |
gcloud config set compute/zone us-west2-b |
Config store in
|
1 |
cat ~/.config/gcloud/configurations/config_default |
Swiitch between multiple gcloud users
|
1 2 |
gcloud config configurations activate default gcloud config configurations activate NAME_HERE |
Detach a disk from Google Compute Instance
To remove a disk from Google Compute instance, run
|
1 |
gcloud compute instances detach-disk INSTANCE_NAME --disk=DISK |
Example
Here “indiameds” is name of the disk i want to detach from google compute instance with name “debug-instance”.
Google Cloud only allow detaching secondary disks. Boot disks can’t be detached, only way to detach a boot disk and attach on a new instance is to delete the instance. Make sure you don’t delete the disk along with the instance.
See gcloud
btc
https://gekko.wizb.it – Gekko is an open source platform for automating trading strategies over bitcoin markets.
varnish
To clear cache, run
|
1 |
/usr/bin/varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082 "ban req.http.host ~ .*" |
Get stats
|
1 |
varnishstat |
See Varnish logs
|
1 |
varnishlog |
mod_rpaf help with showing users real IP when site is behind a proxy or varnish.
Amazon RDS ERROR 1040 (08004): Too many connections
On an Amazon RDS Aurora data base, when i connect, i get error
|
1 2 3 |
root@ip-10-0-0-234:/var/www/html# mysql -h sok.cb21y0qmezhd.us-west-2.rds.amazonaws.com -u sok_wp -p0ZEkrkQx sok_wp ERROR 1040 (08004): Too many connections root@ip-10-0-0-234:/var/www/html# |
This error is due to max_connections setting in MySQL exceeded. By default Amazon RDS set max_connections based on size of RDS instance using following formula.
|
1 |
GREATEST({log(DBInstanceClassMemory/805306368)*45},{log(DBInstanceClassMemory/8187281408)*1000}) |
To see current value, run
|
1 2 3 4 5 6 7 8 9 |
MySQL [sok_wp]> show variables like 'max_connections'; +-----------------+-------+ | Variable_name | Value | +-----------------+-------+ | max_connections | 90 | +-----------------+-------+ 1 row in set (0.00 sec) MySQL [sok_wp]> |
To change default value, you need to create a “Parameter group” under Amazon RDS > Parameter groups
On next page, select “Parameter group family” based on what ever RDS version you are using. In this cause i use Amazon Aurora database, so i select “aurora5.6”
Group name and Description, use any value you like, it is just for identification purpose only.
Once created, it will list all available parameter groups. click on newly created parameter group, on next page, it show all options. In the top search box, type in “max_connections” to find the settings. Edit and save.
Now we need to associate this newly created parameter group with Amazon RDS instance, for this go to Amazon RDS > Instances
Select the instance you need to edit, then from “Instance Actions” drop down menu, select modify.
On next page page, you have the option to select “DB parameter group”, select the newly created parameter group.
On next page, you have option to apply change immediately or apply during maintenance window.
You need to reboot the instance to apply the changes.
hdd
blkid
No space left on device
smartctl
sfdisk
Setup ZFS file system in Ubuntu
Resize Amazon EC2 Boot Disk
Partitioning hard disk for backup
Resize a linux file system with resize2fs
blkid – show UUID for disks.
Linux Software Raid
No space left on device
On a server, when creating new files, i get error – “No space left on device”.
|
1 2 3 |
root@sok:~# touch 2 touch: cannot touch `2': No space left on device root@sok:~# |
Check disk space with df -h, it shows 129 GB disk space is free
|
1 2 3 4 5 6 7 8 9 |
root@sok:~# df -h Filesystem Size Used Avail Use% Mounted on rootfs 383G 243G 129G 66% / udev 10M 0 10M 0% /dev tmpfs 1.6G 224K 1.6G 1% /run tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs 3.5G 0 3.5G 0% /run/shm tmpfs 3.5G 4.0K 3.5G 1% /tmp root@sok:~# |
This can be due to inodes getting full, check inodes usage with “df -i”.
|
1 2 3 4 5 6 7 8 9 |
root@sok:~# df -i Filesystem Inodes IUsed IFree IUse% Mounted on rootfs 25419184 25419184 0 100% / udev 2057538 319 2057219 1% /dev tmpfs 2059026 258 2058768 1% /run tmpfs 2059026 3 2059023 1% /run/lock tmpfs 2059026 2 2059024 1% /run/shm tmpfs 2059026 7 2059019 1% /tmp root@sok:~# |
As you can use Inodes are all used up.
To find where inodes are used up, run
|
1 |
find / -xdev -printf '%h\n' | sort | uniq -c | sort -k 1 -n |
If you have recent version of du, you can use
|
1 |
du --inodes -xS | sort -n |
This will display all folders with inode usage, sorted by inode usage.