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Viewing the progress of MySQL 8 Cluster InnoDB recovery

This article will show several handy MySQL commands for viewing the progress of MySQL 8 Cluster recovery and how the administrators may keep track of how much time will need a MySQL InnoDB Cluster node will need to complete the recovering procedure.

main menu — SHOW REPLICA STATUS CHANNEL ‘group_replication_recovery’

If the reader needs to recover from a node failure there is the other article – Recovery of MySQL 8 Cluster instance after server crash and corrupted data in log event. In this article, the MySQL commands are executed on a CentOS Stream 8 with MySQL InnoDB 8 Cluster (here is how it is installed – Install and deploy MySQL 8 InnoDB Cluster with 3 nodes under CentOS 8 and MySQL Router for HA), which one node had been offline for about several weeks. The node was powered off normally, so the MySQL instance on the server was shut down gracefully.
Initially, the cluster state after the power down was two nodes with a missing one.
Use MySQL Shell Console to view the MySQL InnoDB 8 Cluster status:

[root@db-cluster-1 ~]# mysqlsh
MySQL Shell 8.0.28

Copyright (c) 2016, 2022, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its affiliates.
Other names may be trademarks of their respective owners.

Type '\help' or '\?' for help; '\quit' to exit.
 MySQL  JS > \connect clusteradmin@db-cluster-1
Creating a session to 'clusteradmin@db-cluster-1'
Fetching schema names for autocompletion... Press ^C to stop.
Your MySQL connection id is 158633505 (X protocol)
Server version: 8.0.28 MySQL Community Server - GPL
No default schema selected; type \use <schema> to set one.
 MySQL  db-cluster-1:33060+ ssl  JS > var cluster = dba.getCluster()
 MySQL  db-cluster-1:33060+ ssl  JS > cluster.status()
{
    "clusterName": "mycluster1", 
    "defaultReplicaSet": {
        "name": "default", 
        "primary": "db-cluster-2:3306", 
        "ssl": "REQUIRED", 
        "status": "OK_NO_TOLERANCE", 
        "statusText": "Cluster is NOT tolerant to any failures. 1 member is not active.", 
        "topology": {
            "db-cluster-1:3306": {
                "address": "db-cluster-1:3306", 
                "memberRole": "SECONDARY", 
                "mode": "R/O", 
                "readReplicas": {}, 
                "replicationLag": null, 
                "role": "HA", 
                "status": "ONLINE", 
                "version": "8.0.28"
            }, 
            "db-cluster-2:3306": {
                "address": "db-cluster-2:3306", 
                "memberRole": "PRIMARY", 
                "mode": "R/W", 
                "readReplicas": {}, 
                "replicationLag": null, 
                "role": "HA", 
                "status": "ONLINE", 
                "version": "8.0.28"
            }, 
            "db-cluster-3:3306": {
                "address": "db-cluster-3:3306", 
                "memberRole": "SECONDARY", 
                "mode": "n/a", 
                "readReplicas": {}, 
                "role": "HA", 
                "shellConnectError": "MySQL Error 2003: Could not open connection to 'db-cluster-3:3306': Can't connect to MySQL server on 'db-cluster-3:3306' (111)", 
                "status": "(MISSING)"
            }
        }, 
        "topologyMode": "Single-Primary"
    }, 
    "groupInformationSourceMember": "db-cluster-2:3306"
}
 MySQL  db-cluster-1:33060+ ssl  JS >

When the third server in the cluster is started (from a clean shutdown), the third node will be in a recovery state. Here is the same status command and the third node in recovery. Still, with the MySQL Shell Console:
Keep on reading!

Move or backup all database measurements for a single host to another Influxdb server

This article demonstrates how to move part of the data from one InfluxDB server to another InfluxDB sThect, the data is split by criteria to another server. The InfluxDB server is version 1.8 and the InfluxQL language is used. All useful InfluxQL queries will be included. All queries are executed in the influx command-line tool, which connects to the default InfluxDB location – http://localhost:8086. It is important to be able to connect to the InfluxDB using the influx command-line tool. Unfortunately, it is not possible to use the influxd backup command to select only certain data from a database despite it being easily selectable by a unique tag value such as the hostname of the reporting server. The whole setup is following this article Monitor and analyze with Grafana, influxdb 1.8 and collectd under CentOS Stream 9

The initial setup – get known the database scheme

There is the initial setup of the first InfluxDB server. Multiple servers (i.e. hosts) report data to this InfluxDB server and the target is to move all measurement data of a single reporting server to another InfluxDB server, which has already been accepting the new data. So moving the old data from the first InfluxDB server to the other InfluxDB server the historical data is preserved for this reporting server (i.e. hosts).

InfluxDB database with name collectd.

[root@srv ~]# influx
Connected to http://localhost:8086 version 1.8.10
InfluxDB shell version: 1.8.10
> SHOW DATABASES
name: databases
name
----
_internal
collectd
>

It is important to show the retention policy, too. The retention policy is used to build the queries.

[root@srv ~]# influx
Connected to http://localhost:8086 version 1.8.10
InfluxDB shell version: 1.8.10
> SHOW RETENTION POLICIES ON "collectd"
name    duration shardGroupDuration replicaN default
----    -------- ------------------ -------- -------
default 0s       168h0m0s           1        true

The retention policy name of the database name “collectd” is “default”. Always check the retention policy, because it might be with a different name. For example, creating a database without specifying a retention policy will add a retention policy with the default name “autogen”.

There are multiple measurements in the collectd database. Show all measurements associated with this database (i.e. collectd)
```
[root@srv ~]# influx
Connected to http://localhost:8086 version 1.8.10
InfluxDB shell version: 1.8.10
> SHOW MEASUREMENTS LIMIT 10
name: measurements
name
----
clickhouse_value
conntrack_value
cpu_value
dbi_value
df_value
disk_io_time
disk_read
disk_value
disk_weighted_io_time
disk_write
```
There is a limit clause – “LIMIT 10” to show only the first 10 measurements because the whole list may be too big. The limit clause could be missed to show the whole list of measurements associated with the database collectd.
Keep on reading!

Create graph for Linux Processes grouped by states using Grafana, InfluxDB and collectd

This article shows how to make a graph showing a Linux machine’s processes states. This plugin could gather the number of the processes grouped by their state or metadata per the selected process defined in the configuration (metadata includes process state, size of the resident segment size (RSS), system/user time used, and so on.). The purpose of this article is to make a graph with all the processes grouped by their state. Graphs per process data are not included here.

The Linux machine is using collectd to gather the processes statistics and send them to the time series back-end – InfluxDB. Grafana is used to visualize the data stored in the time series back-end InfluxDB and organize the graphs in panels and dashboards. Check out the previous articles on the subject to install and configure such software to collect, store and visualize data – Monitor and analyze with Grafana, influxdb 1.8 and collectd under CentOS Stream 9, Monitor and analyze with Grafana, influxdb 1.8 and collectd under Ubuntu 22.04 LTS and Create graph for Linux CPU usage using Grafana, InfluxDB and collectd
The collectd daemon is used to gather data on the Linux system and to send it to the back-end InfluxDB.

Key knowledge for the Processes collectd plugin

The collectd plugin Processes official page – https://collectd.org/wiki/index.php/Plugin:Processes
The Processes plugin options – https://collectd.org/documentation/manpages/collectd.conf.5.shtml#plugin_processes
to enable the Processes plugin, load the plugin with the load directive in /etc/collectd.conf
```
LoadPlugin processes
```
The Processes plugin collects data every 10 seconds.

processses_value – a single Gauge value – a metric, which value that can go up and down. It is used to count the number of processes in the different states (the state is saved in a tag value of one record). So there are multiple gauge values with different tags for the different process states at a given time.

tag key	tag value	description
host	server hostname	The name of the source this measurement was recorded.
type	cpu	ps_state is the type, which will group the processes by states.
type_instance	processes’ states	States are – blocked, paging, running, sleeping, stopped, zombies.

A Gauge value – a metric, which value that can go up and down. More on the topic – Data sources.

A GAUGE value is simply stored as-is. This is the right choice for values which may increase as well as decrease, such as temperatures or the amount of memory used.

To cross check the value, the user can use the /proc/stat

[root@srv ~]# cat /proc/stat 
cpu  804 0 732 6240 198 106 25 0 0 0
cpu0 444 0 345 3092 121 44 14 0 0 0
cpu1 359 0 387 3147 76 62 11 0 0 0
intr 72376 117 9 0 0 0 0 0 0 1 2 0 0 156 0 187 187 0 0 188 273 0 0 0 0 0 0 6574 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
ctxt 216350
btime 1667997331
processes 1359
procs_running 2
procs_blocked 0
softirq 38704 2 5003 5 290 6565 0 74 5796 0 20969

Some of the lines are pretty clear about what they mean by “procs_running“, “processes“, “procs_blocked” and so on.

Keep on reading!

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Run a docker container with bigger storage

By default, the Docker command-line utility docker runs containers with 10G storage, which in most cases is enough, but if the user wants to just run a specific container with bigger storage there is an option for the docker command:

docker run --storage-opt size=50G

The option size=50G will set the docker container storage for the current only run command!

Run a Ubuntu 22.04 Docker container with 50G root storage:

root@srv ~ # docker run --storage-opt size=50G -it ubuntu:22.04 bash
Unable to find image 'ubuntu:22.04' locally
22.04: Pulling from library/ubuntu
e96e057aae67: Pull complete 
Digest: sha256:4b1d0c4a2d2aaf63b37111f34eb9fa89fa1bf53dd6e4ca954d47caebca4005c2
Status: Downloaded newer image for ubuntu:22.04
root@4caab8c61157:/# df -h
Filesystem                                                                                          Size  Used Avail Use% Mounted on
/dev/mapper/docker-253:0-39459726-2f2d655687e5bd39620a2a083960ac969d8163b806152765a1fc166f0a82d3d9   50G  170M   50G   1% /
tmpfs                                                                                                64M     0   64M   0% /dev
tmpfs                                                                                               7.8G     0  7.8G   0% /sys/fs/cgroup
shm                                                                                                  64M     0   64M   0% /dev/shm
/dev/mapper/map-99f55d81-4132-42d4-9515-33d8cc11d3e2                                                3.6T  1.5T  2.2T  40% /etc/hosts
tmpfs                                                                                               7.8G     0  7.8G   0% /proc/asound
tmpfs                                                                                               7.8G     0  7.8G   0% /proc/acpi
tmpfs                                                                                               7.8G     0  7.8G   0% /proc/scsi
tmpfs

It’s worth mentioning this option “–storage-opt size=50G” is different from the “–storage-opt dm.basesize=50G“, the first one is used as a command argument to the docker command-line utility. The second one is used with the dockerd daemon to change the default Docker behavior from 10G to 50G storage. Note, either option cannot change the storage size of the already started container.

Create graph for Linux CPU usage using Grafana, InfluxDB and collectd

This article shows how to make a graph showing a Linux machine’s CPU Usage.

The Linux machine is using collectd to gather the load average and send it to the time series back-end – InfluxDB. Grafana is used to visualize the data stored in the time series back-end InfluxDB and organize the graphs in panels and dashboards. Check out the previous articles on the subject to install and configure such software to collect, store and visualize data – Monitor and analyze with Grafana, influxdb 1.8 and collectd under CentOS Stream 9 and Monitor and analyze with Grafana, influxdb 1.8 and collectd under Ubuntu 22.04 LTS.
The collectd daemon is used to gather data on the Linux system and to send it to the back-end InfluxDB.

Key knowledge for the cpu collectd plugin

The collectd plugin CPU official page – https://collectd.org/wiki/index.php/Plugin:CPU
The CPU plugin options – https://collectd.org/documentation/manpages/collectd.conf.5.shtml#plugin_cpu
to enable the CPU plugin, load the plugin with the load directive in /etc/collectd.conf
```
LoadPlugin cpu
```
The CPU plugin collects data every 10 seconds.

cpu_value – 1 derive value is saved in the database. All values are in jiffies – the kernel unit of time. Showing just jiffers is not practical, that’s why all CPU graphs convert jiffers to CPU percentage usage.

tag key	tag value	description
host	server hostname	The name of the source this measurement was recorded.
instance	execution units number	The execution unit this measurement was recorded. For example, systems with 8 cores will have 8 different execution units, so instances from 0 to 7. A graph representing the usage of a single CPU core is possible.
type	cpu	The only type available is cpu.
type_instance	CPU usage metrics	CPU metrics – idle, interrupt, nice, softirq, steal, system, user, wait.

DERIVE value – a metric, in which the change of the value is interesting. For example, it can go up indefinitely and it is important how fast it goes up, there are functions and queries, which will give the user the derivative value.

These data sources assume that the change of the value is interesting, i.e. the derivative. Such data sources are very common with events that can be counted, for example, the number of emails that have been received per second by an MTA since it was started. The total number of emails is not interesting.

To cross check the value, the user can use the /proc/stat

[root@srv ~]# cat /proc/stat 
cpu  939 0 988 51486 200 261 56 0 0 0
cpu0 483 0 473 25796 89 114 25 0 0 0
cpu1 455 0 514 25690 110 147 31 0 0 0
intr 123072 118 9 0 0 0 0 0 0 1 6 0 0 156 0 409 409 0 0 1184 501 0 0 0 0 0 0 6823 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
ctxt 279137
btime 1666874114
processes 1373
procs_running 1
procs_blocked 0
softirq 64069 2 13685 7 544 6967 0 77 15801 0 26986

Keep on reading!

Pages: 12345

Create graph for Linux Load Average using Grafana, InfluxDB and collectd

This article shows how to make a graph showing a Linux machine’s load average.

The Linux machine is using collectd to gather the load average and send it to the time series back-end – InfluxDB. Grafana is used to visualize the data stored in the time series back-end InfluxDB and organize the graphs in panels and dashboards. Check out the previous articles on the subject to install and configure such software to collect, store and visualize data – Monitor and analyze with Grafana, influxdb 1.8 and collectd under CentOS Stream 9 and Monitor and analyze with Grafana, influxdb 1.8 and collectd under Ubuntu 22.04 LTS.
The collectd daemon is used to gather data on the Linux system and to send it to the back-end InfluxDB.

Key knowledge for the load collectd plugin

The collectd plugin Load official page – https://collectd.org/wiki/index.php/Plugin:Load
The Load plugin options – https://collectd.org/documentation/manpages/collectd.conf.5.shtml#plugin_load
to enable the load plugin, load the plugin with the load directive in /etc/collectd.conf
```
LoadPlugin load
```
The Load plugin collects data every 10 seconds.
load_longterm, load_midterm, load_shortterm – 3 gauge values are saved in the database.
Gauge value – a metric, which value that can go up and down.

A GAUGE value is simply stored as-is. This is the right choice for values which may increase as well as decrease, such as temperatures or the amount of memory used.

To cross check the value, the user can use the uptime command under Linux or /proc/loadavg

[root@srv ~]# uptime
 23:08:09 up 52 min,  2 users,  load average: 1.00, 0.77, 0.38
[root@srv ~]# cat /proc/loadavg 
1.00 0.77 0.38 2/176 1900

Keep on reading!

Pages: 123

Monitor and analyze with Grafana, influxdb 1.8 and collectd under Ubuntu 22.04 LTS

This is an updated version of the previous version of this topic – Monitor and analyze with Grafana, influxdb 1.8 and collectd under CentOS Stream 9, but this time for Ubuntu 22.04 LTS. The article describes how to build modern analytic and monitoring solutions for system and application performance metrics. A solution, which may host all the server’s metrics and a sophisticated application, allows easy analyses of the data and powerful graphs to visualize the data.
A brief introduction to the main three software used to build the proposed solution:

Grafana – an analytics and a web visualization tool. It supports dashboards, charts, graphs, alerts, and many more.
influxdb – a time series database. Bleeding fast reads and writes and optimized for time.
collectd – a data collection daemon, which obtain metrics from the host it is started and sends the metrics to the database (i.e. influxdb). It has around 170 plugins to collect metrics.

What is the task of each tool:

collectd – gathers metrics and statistics using its plugins every 10 seconds on the host it runs and then sends the data over UDP to the influxdb using a simple text-based protocol.
influxdb – listens on an open UDP port for data coming from multiple collectd instances installed on many different devices. In this case, a Linux server running Ubuntu 22.04 LTS.
Grafana – an analytics and a web visualization tool. A web application, which connects to the InfluxDB and visualizes the time series metrics in graphs organized in dashboards. Graphs for CPU, memory, network, storage usage, and many more.
nginx to enable SSL and proxy in front of the Grafana.

The whole solution uses the Ubuntu 22.04 LTS server edition distro. Installing the Ubuntu 22.04 LTS is a mandatory step to proceed further with this article – Installation of base Ubuntu server 22.04 LTS
The UDP influxdb port should be open per IP basis and web port of the web server (nginx) is up to the purpose of the solution – it can be behind a VPN or openly accessible by Internet.

STEP 1) Install additional repositories for Grafana, InfluxDB and collectd.

collectd is part of the Ubuntu official repositories. Grafana and InfluxDB maintain their official repositories. Here is how to install them.
Add the InfluxDB repository by first, importing the key of the InfluxDB repository and add the URL of the repository in /etc/apt/sources.list.

myuser@srv:~$ sudo curl -sL https://repos.influxdata.com/influxdb.key | sudo apt-key add -
Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).
OK
echo 'deb https://repos.influxdata.com/debian stable main' > /etc/apt/sources.list.d/influxdata.list

Then, repeated the same procedure with the Grafana repository:

myuser@srv:~$ sudo curl -sL https://packages.grafana.com/gpg.key | sudo apt-key add -
Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).
OK
echo 'deb https://packages.grafana.com/oss/deb stable main' > /etc/apt/sources.list.d/grafana.list

Execute apt update to include the available file packages from all repositories including the ones:

apt update

Keep on reading!

Pages: 123

How to install collectd in Ubuntu 22.04 LTS and in general under Ubuntu

It appears Ubuntu 22.04 LTS still does not include in its packages base one of the best server software to gather metrics from different sources. collectd is a small and fast daemon, which can gather metrics from more than 80 different sources.
In fact, Ubuntu 22.04 LTS does not include it, but the new not LTS Ubuntu 22.10 provides the package in the universe repository – https://packages.ubuntu.com/kinetic/collectd-core. At least, one more file should be installed collectd from https://packages.ubuntu.com/kinetic/collectd. The name of the package is collectd, collectd-core and there are 4 more files of interests – collectd-dev, collectd-utils, libcollectdclient-dev, libcollectdclient1.
Check out the pool folder of an Ubuntu mirror, for example, the mirror – http://mirrors.kernel.org/ubuntu/pool/universe/c/collectd/ and download the latest file.
Now, the latest files are http://mirrors.kernel.org/ubuntu/pool/universe/c/collectd/collectd-core_5.12.0-11_amd64.deb and http://mirrors.kernel.org/ubuntu/pool/universe/c/collectd/collectd_5.12.0-11_amd64.deb. Download them and install the files with apt like usually but pointing to the files:
Keep on reading!

Add source InfluxDB 1.8 with basic authentication in Grafana using the web interface

This article shows how to add a new source in Grafana with screenshots. The source is InluxDB 1.8 with basic authentication enabled. The main purpose of this article is to give the user knowledge of how to:

Enable basic authentication in InfluxDB
Create users – administrative and ordinary ones in InfluxDB and give permissions for the database.
Add the InfluxDB source in Grafana using web interface. with basic authentication enabled with credentials created in the article.

It is supposed the InfluxDB is installed and running on the loopback 127.0.0.1, at least. If the InfluxDB service is not local for the Grafana service replace the 127.0.0.1 with the appropriate IP and adjust the firewall such that it accepts connections from the Grafana server IP. For installing InfluxDB with detailed information including firewall modifications there is another article here – Monitor and analyze with Grafana, InfluxDB 1.8 and collectd under CentOS Stream 9.
No installation information for InfluxDB or Grafana is included in this article and if they are needed check out the article above.

STEP 1) Create users in InfluxDB.

By default, InfluxDB authentication is disabled and no users are required to access and manage the service and the databases. That’s why, the first thing to do is to create an administrative user, which will manage the databases when the basic authentication will be enabled. At the same time, when creating the administrative user, ordinary users may be created, too.
To connect to the InfluxDB to manage the service the InfluxDB command-line tool influx will be used. influx connects to http://127.0.0.1:8086 – an HTTP interface to access the InfluxDB service.

[root@srv ~]# influx
Connected to http://localhost:8086 version 1.8.10
InfluxDB shell version: 1.8.10
> CREATE USER admin WITH PASSWORD 'aiqu8ohth9Cheeshai]c' WITH ALL PRIVILEGES
> SHOW USERS
user  admin
----  -----
admin true
> CREATE USER collectd WITH PASSWORD 'ohg|ahTh9Sa|quoh8zoh'
> GRANT READ ON "collectd" TO "collectd"
> SHOW USERS
user     admin
----     -----
admin    true
collectd false
>

First, the administrative user with admin name is created, and then the ordinary user with the collectd name. For the ordinary user, the access privileges are granted only for READ on the collectd database. It is typical to name the database and the user accessing it with the same name. The format of the GRANT command is the following:

GRANT "[PRIVILEGES]" ON "[database_name]" TO "[user_name]"

READ privileges are enough for Grafana to access the data.
Keep on reading!

Monitor and analyze with Grafana, influxdb 1.8 and collectd under CentOS Stream 9

This article describes how to build a modern analytic and monitoring solutions for system and application performance metrics. A solution, which may host all the server’s metrics and a sophisticated application, allows easy analyses of the data and powerful graphs to visualize the data.
A brief introduction to the main three software used to build the proposed solution:

Grafana – an analytics and a web visualization tool. It supports dashboards, charts, graphs, alerts, and many more.
influxdb – a time series database. Bleeding fast reads and writes and optimized for time.
collectd – a data collection daemon, which obtain metrics from the host it is started and sends the metrics to the database (i.e. influxdb). It has around 170 plugins to collect metrics.

What is the task of each tool:

collectd – gathers metrics and statistics using its plugins every 10 seconds on the host it runs and then sends the data over UDP to the influxdb using a simple text-based protocol.
influxdb – listens on an open UDP port for data coming from multiple collectd instances installed on many different devices. In this case, a Linux server running CentOS Stream 9.
Grafana – an analytics and a web visualization tool. A web application, which connects to the InfluxDB and visualizes the time series metrics in graphs organized in dashboards. Graphs for CPU, memory, network, storage usage, and many more.
nginx to enable SSL and proxy in front of the Grafana.

The whole solution uses the CentOS Stream 9 Linux distro. Installing the CentOS Stream 9 is a mandatory step to proceed further with this article – Network installation of CentOS Stream 9 (20220606.0) – minimal server installation
The UDP influxdb port should be open per IP basis and web port of the web server (nginx) is up to the purpose of the solution – it can be behind a VPN or openly accessible by Internet.

STEP 1) Install additional repositories for Grafana, influxdb and collectd.

Install CentOS official EPEL and OpsTools repositories. EPEL provides additional packages to the base CentOS packages and OpsTools provides collectd and more collectd plugins than the ones included in the built-in repositories.

dnf install -y epel-release centos-release-opstools

Add the InfluxDB repository by creating a file in /etc/yum.repos.d/influxdb.repo

[influxdb]
name = InfluxDB Repository - RHEL $releasever
baseurl = https://repos.influxdata.com/centos/$releasever/$basearch/stable
enabled = 1
gpgcheck = 1
gpgkey = https://repos.influxdata.com/influxdb.key

Finally, add the Grafana repository in file /etc/yum.repos.d/grafana.repo

[grafana]
name=grafana
baseurl=https://packages.grafana.com/oss/rpm
repo_gpgcheck=1
enabled=1
gpgcheck=1
gpgkey=https://packages.grafana.com/gpg.key
sslverify=1
sslcacert=/etc/pki/tls/certs/ca-bundle.crt

Keep on reading!

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