Tag: InfluxDB 1.8

Create graph for swap usage using Grafana, InfluxDB and collectd

This article shows how to make a graph showing a Linux machine’s swap memory. This plugin gathers physical swap memory utilization – cached, free, and used. In general, this module collects simple data for the swap memory like the Linux command free. The purpose of this article is to make a graph showing swap memory usage and consumption.

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example usage of swap usage

The Linux machine is using collectd to gather the swap memory 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 Swap collectd plugin

  • The collectd plugin Swap official page – https://collectd.org/wiki/index.php/Plugin:Swap
  • The Swap plugin options – https://collectd.org/documentation/manpages/collectd.conf.5.shtml#plugin_swap This article relies on the default plugin’s options 
    <Plugin swap>
#       ReportByDevice false
#       ReportBytes true
#       ValuesAbsolute true
#       ValuesPercentage false
#       ReportIO true
</Plugin>

    All the devices are reported as a single device not per device and bytes and absolute values are used not percentages.

  • to enable the Swap plugin, load the plugin with the load directive in /etc/collectd.conf 
    LoadPlugin swap
  • The Swap plugin collects data every 10 seconds.
  • swap_value – includes a single Gauge value under swap type – a metric, which value that can go up and down. It is used to count the swap occupancy for the different categories (the category is saved in a tag value of one record, and the categories are free, used and etc.). So there are multiple gauge values with different tags for the different swap categories at a given time. And a second counter under swap_io type
    tag key tag value description
    host server hostname The name of the source this measurement was recorded.
    type swap | swap_io swap is the type, which will group the swap usage categories (cached, free, used). The swap_io groups the swap IO usage – how many IO operations are executed (in, out).
    type_instance swap categories The categories are cached, free, used.
  • 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.

  • A 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/swap, /proc/meminfo and /proc/vmstat 
    [root@srv ~]# cat /proc/swaps
Filename                                Type            Size    Used    Priority
/dev/zram0                              partition       16777212        2533856 -1
[root@srv ~]# cat /proc/meminfo |egrep -e "^(SwapTotal:|SwapFree:|SwapCached:)"
SwapCached:       175416 kB
SwapTotal:      16777212 kB
SwapFree:       14202396 kB
[root@srv ~]# cat /proc/vmstat |egrep -e "^(pswpout|pswpin)"
pswpin 877611681
pswpout 376878365

    The swap_io values are multiplied by the page size of the current system. For Linux, it is 4K. Note, by default, the ReportBytes collectd option is not enabled, so the swap_io measurement is in pages since the last reboot. The swap_io counter is read from the pswpout and pswpin (i.e. they also represent the pages since the last reboot). In fact, these two values are really important to track down because they tell how much the system touches swap device(s) and it could point out a problem with the physical memory shortages.

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Run podman/docker InfluxDB 1.8 container to collect statistics from collectd

Yet another article on the topic of the InfluxDB 1.8 and collectd gathering statistics, in continuation of the articles Monitor and analyze with Grafana, influxdb 1.8 and collectd under Ubuntu 22.04 LTS and Monitor and analyze with Grafana, influxdb 1.8 and collectd under CentOS Stream 9. This time, the InfluxDB runs in a container created with podman or docker software.

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podman run and show databases

Here are the important points to mind when running InfluxDB 1.8 in a docker/podman container:
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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

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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!

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:

  1. Grafana – an analytics and a web visualization tool. It supports dashboards, charts, graphs, alerts, and many more.
  2. influxdb – a time series database. Bleeding fast reads and writes and optimized for time.
  3. 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:

  1. 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.
  2. 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.
  3. 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.
  4. 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

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