Tag Archives: InfluxDB

Gathering performance metrics using InfluxDB and Grafana #coding @grafana @InfluxDB

Collecting metrics in a log file is pretty effective when you have one process doing that logging. You have the data and can do whatever you need to with it. This approach has served me well for many years, but occasionally you want to log metrics from multiple processes to the same source at the same time. Trying to pull together data from 30+ log files and make sense of it is difficult. You can log it to SQL Server or some other datastore, but then what, more often than not you want to graph the metrics over time.

I thought I’d give some opensource tools a try, let’s walk through how to setup InfluxDB as the datastore and Grafana as the dashboard to make sense of it all.

Download

(please review licenses before doing so)
https://portal.influxdata.com/downloads#influxdb
https://grafana.com/grafana/download?platform=windows

I’m using https://dl.influxdata.com/influxdb/releases/influxdb-1.2.4_windows_amd64.zip
and https://s3-us-west-2.amazonaws.com/grafana-releases/release/grafana-4.3.2.windows-x64.zip

Initial Setup

You will need to look further into security, licenses and your specific needs, but for me it’s as simple as extracting the two zip files.

Start the servers

Run influxd (.exe) from influxdb-1.2.4-1
Run grafana-server (.exe) from grafana-4.3.2\bin

Where does data get stored?

InfluxDB seems to use C:\Users\{current-user}\.influxdb
Grafana seems to use subdirectories.
Please let me know if you find more.

Getting a metric into InfluxDB

First you (like with any DBMS) need to create a DB instance, I did mine via the command line (though if you read the documentation you can do it via HTTP too):

influx -execute "CREATE DATABASE MetricDb1"
influx -execute "CREATE RETENTION POLICY "two_hours" ON "MetricDb1" DURATION 2h REPLICATION 1 DEFAULT"

Note: influx.exe is in influxdb-1.2.4-1, it is best to run from within that folder to avoid path problems.

As you can imagine, with those settings you are going to lose a metric some time in excess of two hours after it was written, so choose careful and read up on the documentation.

You might think the next command is CREATE TABLE… but it’s not required, it’s magic…

Inserting and selecting data from command line

For the insert the retention policy name is required, kind of like a schema name, but it’s very similar to SQL, though very reduced functionality:

influx -execute "INSERT INTO MetricDb1.two_hours cpu,host=sausages,region=eu_north value=0.69"

For the select you can leave off the retention policy when you can assume it is the default one, but do note the two full stops:

influx -execute "SELECT * FROM MetricDb1..cpu"

Or you can specify it:

influx -execute "SELECT * FROM MetricDb1.two_hours.cpu"

Inserting data from C#

using (var client = new HttpClient
{
    BaseAddress = new Uri("http://localhost:8086/"),
    Timeout = TimeSpan.FromMilliseconds(10000)
})
{
    await client.PostAsync("/write?db=MetricDb1", new StringContent("cpu,host=sausages,region=eu_north value=0.69"), CancellationToken.None);
}

Of course, opening the client every time is not how you would code it for a real application, but you get the idea.

Graphing it

  1. Open grafana web site http://localhost:3000
  2. Login with admin user, password admin (yeah, you might want to change that)
  3. From the Home Dashboad (should be the landing page when you login), click Add data source
  4. Give it a name
  5. Choose InfluxDB
  6. Url is http://localhost:8086
  7. Access is direct
  8. No Http Auth (until you configure some)
  9. Database is MetricDb1
  10. No User or Password (until you configure them)
  11. Click Add
  12. Go to @ (grafana logo) -> Dashboards -> New
  13. Click Graph
  14. Click on Panel Title then Edit. Or find some other way to edit the graph.
  15. On the Metrics tab you should be able to enter your query. I chose FROM two_hours cpu SELECT field (value) mean () GROUP BY time ($__interval) fill (null)
  16. Choose a Group by time interval, I chose >1s
  17. I wanted a bar chart, so I chose Bars option for Draw Models on Display tab.
  18. Save the dashboard when you are happy with it via disk icon or CTRL+S.

That should be all you need to get started and see data in the dashboard. There are options for auto-refresh and all manner of good things so do make sure you explore grafana. I find Last 5 minutes very useful to start with and Refresh every 5s.

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