2025-01 on Funky Si's Test

Set up Grafana for .NET with Docker

funkysi1701@gmail.com (funkysi1701) — Mon, 27 Jan 2025 20:00:00 +0000

Grafana is an open-source analytics and monitoring platform that lets you query, visualise, and alert on metrics. It pairs well with Prometheus for scraping application endpoints. This post walks through a Docker Compose stack that monitors a simple .NET API.

Setting up Grafana

To visualise metrics data, we need a few components. The .NET application exposes a /metrics endpoint. Prometheus scrapes it on an interval and stores the samples. Grafana then queries Prometheus and renders dashboards.

Docker Compose File

Start with a Compose file for Prometheus and Grafana. Pin image tags so rebuilds stay reproducible (bump them when you deliberately upgrade):

services:
 prometheus:
 image: prom/prometheus:v3.4.0
 ports:
 - 5431:9090
 volumes:
 - ./prometheus/:/etc/prometheus/
 - prometheus:/prometheus 

 grafana:
 image: grafana/grafana:11.6.0
 expose:
 - "3000"
 ports:
 - 3000:3000
 volumes:
 - grafana:/var/lib/grafana

volumes:
 prometheus:
 grafana:

This brings up Grafana and Prometheus, maps ports, and mounts config/data volumes.

Prometheus Configuration

Next, create a prometheus.yml file to configure Prometheus:

global:
 scrape_interval: 15s
 evaluation_interval: 15s 

scrape_configs:
 - job_name: 'api'
 scheme: 'https'
 tls_config:
 insecure_skip_verify: true
 scrape_interval: 10s
 scrape_timeout: 5s
 static_configs:
 - targets: ['api.example.com:443']

This configures how often the /metrics endpoint should be scraped. By default Prometheus expects something like http://api.example.com/metrics. Because my API ran under HTTPS I set scheme to https and skipped TLS verification in this lab setup. scrape_interval is how often the endpoint is scraped; if scrape_timeout is omitted the global value is used.

More information about configuring Prometheus can be found here .

Grafana Config

You can now log into Grafana on http://localhost:3000 with the default username and password of admin/admin. You will be prompted to change the password. Add a Prometheus data source next. Prometheus is published on the host as http://localhost:5431 , but from another container you usually cannot use localhost for a sibling service.

If Grafana needs to reach Prometheus on the host (for example when Prometheus is published only to the host network), use host.docker.internal (Docker Desktop and many Linux setups with the host-gateway mapping): http://host.docker.internal:5431 . Prefer the Compose service name (http://prometheus:9090) when both services share the same Compose network.

Dashboard

The next thing we need to do is build a dashboard — the .NET team has done much of the hard work. They published a Grafana dashboard you can import.

You can also build panels yourself in the Grafana UI (graphs, gauges, and other visualisations).

Metrics endpoint

If your .NET application is using .NET Aspire, this /metrics endpoint is often already set up for you. Look in Extensions.cs in your ServiceDefaults project for something like the following (you need the NuGet package OpenTelemetry.Exporter.Prometheus.AspNetCore):

public static WebApplication MapDefaultEndpoints(this WebApplication app)
{
 // The following line enables the Prometheus endpoint (requires the OpenTelemetry.Exporter.Prometheus.AspNetCore package)
 app.MapPrometheusScrapingEndpoint();
}

If you are not using .NET Aspire, you can add app.MapPrometheusScrapingEndpoint() to your Program.cs file (with the same package referenced).

Conclusion

With Compose, Prometheus, and Grafana in place you can scrape a .NET /metrics endpoint and watch live dashboards — useful for latency, exceptions, and ASP.NET Core built-in meters. Happy monitoring!

Prefer classic host and service checks? Try monitoring with Nagios in Docker . If Aspire already wires OpenTelemetry for you, getting started with Aspire is a useful companion to the metrics endpoint notes above.

If you have enjoyed this article and want to get a monthly email with all my latest articles, please sign up to my newsletter . If you have any questions or comments, please feel free to reach out or leave a comment below.

Adding Elasticsearch with .Net Aspire

funkysi1701@gmail.com (funkysi1701) — Mon, 20 Jan 2025 20:00:00 +0000

A few weeks ago I talked about .Net Aspire , well lets take a look at how we can use it with Elasticsearch. Elastic search is a powerful search engine that can be used to index and search data. It is built on top of Lucene and provides a powerful way to search through your data.

Aspire allows dependencies like elasticsearch to be added to a project programmatically. Lets look at how this can work.

Add this nuget package to your AppHost project (as of writing this is a preview package):

<PackageReference Include="Aspire.Hosting.Elasticsearch" Version="9.0.0-preview.5.24551.3" />

In your AppHost project, add the following code to your Program.cs file:

var elasticsearch = builder
 .AddElasticsearch("elasticsearch");

Now if you run your project it will add an elasticsearch containter to your project. A common way to administer elasticsearch is to use Kibana. You can add this to your project by adding the following code to your Program.cs file:

var kibana = builder
 .AddContainer("kibana", "kibana", "8.15.3") // Add Kibana from the image kibana, and tag 8.15.3 and give it a name kibana
 .WithReference(elasticsearch) // Add a reference to the elasticsearch container
 .WithEndpoint(5601, 5601); // Expose a port so you can connect

Now if you run your project you will have an elasticsearch and kibana container running. You can access kibana by going to http://localhost:5601, and elasticsearch by going to http://localhost:9200.

Troubleshooting Kibana

However when I do that I get the error Kibana server is not ready yet. Looking at the kibana container logs, I see the following error:

2025-01-19T21:42:13 [2025-01-19T21:42:13.558+00:00][WARN ][plugins.security.config] Generating a random key for xpack.security.encryptionKey. To prevent sessions from being invalidated on restart, please set xpack.security.encryptionKey in the kibana.yml or use the bin/kibana-encryption-keys command.
Unable to retrieve version information from Elasticsearch nodes. security_exception

This is due to the security settings in Elasticsearch. To fix this, you can turn off this security feature by enabling an environment variable:

var elasticsearch = builder
 .AddElasticsearch("elasticsearch")
 .WithEnvironment("xpack.security.enabled", "false");

As Aspire is only running locally, this is fine, but in a production environment, you would want to secure your Elasticsearch and Kibana instances.

Using Elasticsearch in Your Project

Now that you have Elasticsearch added to your project, how can you use it? In the .NET project that wants to connect and interact with Elasticsearch, you can add the following NuGet package:

Aspire.Elastic.Clients.Elasticsearch (version 9.0.0-preview.5.24551.3 as of writing)

In the Program.cs file of your .NET project you can add the following code:

builder.AddElasticsearchClient("elasticsearch");

No need to specify any complex connection strings or settings, Aspire will handle all of that for you.

This is pretty much all of the Aspire specific code you need, but lets have a quick look at indexing some data and returning it with a search. Elastic Search has extensive documentation on how to do this with the dotnet libraries.

To index some data you can use the following code:

 await _client.Indices.CreateAsync("searchindex", cancellationToken); // Create an index called searchindex

 var documents = context.Episode.ToList(); // Get the documents you want to index from Entity Framework or any other source

 await _client.IndexManyAsync(documents, index: "searchindex", cancellationToken); // Index the documents into the searchindex index

ElasticsearchClient can be injected in via dependency injection, again no need to specify any connection strings or settings.

To search for data you can use the following code:

 // Create a search request with a wildcard query which searches in the title field of your indexed documents.
 var searchRequest = new ESSearchRequest("searchindex")
 {
 From = 0,
 Size = 10,
 Query = new WildcardQuery("title") { Value = $"*{SearchQuery}*" },
 };
 // Execute the search request and get the response.
 var response = await _client.SearchAsync<Episode>(searchRequest, cancellationToken);

 if (response.IsValidResponse)
 {
 // Return the documents from the response.
 return response.Documents.ToList();
 }

Conclusion

By following these steps, you can successfully integrate Elasticsearch and Kibana into your .NET Aspire project. This setup allows you to leverage powerful search and analytics capabilities in your application. Remember to secure your instances in a production environment to ensure data safety.

NuGet central package management

funkysi1701@gmail.com (funkysi1701) — Mon, 13 Jan 2025 20:00:00 +0000

Managing dependencies in .NET projects can become complex, especially when dealing with multiple projects that share common packages. NuGet Central Package Management (CPM) is a feature that simplifies this process by allowing you to manage package versions centrally.

What is NuGet Central Package Management?

NuGet Central Package Management allows you to define and manage package versions in a central location, rather than specifying them individually in each project file. This approach ensures consistency across projects and simplifies the process of updating package versions.

Setting Up Central Package Management

To get started with Central Package Management, follow these steps:

Create a Directory.Packages.props File: This file will contain the central package version definitions. Create this file in the root directory of your solution.

Define Package Versions: In the Directory.Packages.props file, define the package versions you want to manage centrally. For example:

<Project>
 <PropertyGroup>
 <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
 </PropertyGroup>
 <ItemGroup>
 <PackageVersion Include="Newtonsoft.Json" Version="13.0.1" />
 <PackageVersion Include="Serilog" Version="2.10.0" />
 <PackageVersion Include="Microsoft.EntityFrameworkCore" Version="9.0.0" />
 <PackageVersion Include="Microsoft.EntityFrameworkCore.SqlServer" Version="9.0.0" />
 </ItemGroup>
</Project>

Update all your csproj files: In each project file (.csproj), remove the version number information:

<ItemGroup>
 <PackageReference Include="Newtonsoft.Json" />
 <PackageReference Include="Serilog" />
 <PackageReference Include="Microsoft.EntityFrameworkCore" />
 <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" />
</ItemGroup>

Benefits of Central Package Management

Using Central Package Management offers several benefits:

Consistency: Ensures that all projects use the same package versions, reducing the risk of version conflicts.
Simplified Updates: Updating a package version in the central file automatically updates it across all projects.
Reduced Maintenance: Simplifies the process of managing package versions, especially in large solutions with many projects.

If for any reason you want to disable Central Package Management, you can set the ManagePackageVersionsCentrally property to false in the Directory.Packages.props file, or in the csproj file if you only want to disable for a single project.

Conclusion

NuGet Central Package Management simplifies the process of managing package versions across multiple projects in a .NET solution. By defining package versions in a central file, you can ensure consistency, simplify updates, and reduce maintenance efforts. Give it a try in your next .NET project to experience the benefits firsthand.

For more information, visit the official NuGet documentation .

Setting Up Nagios Monitoring with Docker

funkysi1701@gmail.com (funkysi1701) — Mon, 06 Jan 2025 20:00:00 +0000

A long time ago in my SysAdmin days, I was a big fan of Nagios . Recently, I decided to revisit it and see if I could run it in a Docker container to monitor my local network. This guide will walk you through the process of setting up Nagios monitoring using Docker.

Finding a Docker Image for Nagios

First, we need to find a suitable Docker image for Nagios. The manios/nagios image looks like it should do the job.

Running the Nagios Docker Container

The basics of running this container are as follows:

docker run -d --name nagios -p 8080:80 manios/nagios

This command will pull the Nagios image from Docker Hub and run it in a container, mapping port 80 in the container to port 8080 on your host machine.

docker run -d --name nagios \
 -v /path-to-nagios/etc/:/opt/nagios/etc/ \
 -v /path-to-nagios/var:/opt/nagios/var/ \
 -v /path-to-nagios/ssmtp.conf:/etc/ssmtp/ssmtp.conf \
 -v /path-to-custom-plugins:/opt/Custom-Nagios-Plugins \
 -p 8080:80 \
 manios/nagios

I prefer running via docker compose, which looks like this:

 nagios:
 image: manios/nagios:latest
 container_name: monitoring_nagios
 ports:
 - 8081:80
 restart: always
 volumes:
 - ./nagios/localhost.cfg:/opt/nagios/etc/objects/localhost.cfg
 - ./nagios/windows.cfg:/opt/nagios/etc/objects/windows.cfg
 - nagios_data:/opt/nagios/var/
 environment:
 - NAGIOSADMIN_USER=nagiosadmin
 - NAGIOSADMIN_PASS=nagiosadmin
 - NAGIOS_TIMEZONE=UTC
 - NAGIOS_WEB_USER=nagiosadmin
 - NAGIOS_WEB_PASS=nagiosadmin

Accessing the Nagios Web Interface

Once the container is running, you can access the Nagios web interface by navigating to http://localhost:8080 in your web browser. You should see the Nagios login page.

Configuring Nagios

To configure Nagios, you’ll need to edit the configuration files located in the container. You can do this by accessing the container’s shell:

docker exec -it nagios /bin/bash

From here, you can navigate to the Nagios configuration directory and make the necessary changes:

cd /opt/nagios/etc

Adding Hosts and Services

To monitor your local network, you’ll need to add hosts and services to the Nagios configuration. This involves editing the configuration files and adding each host and service you want to monitor.

I have added a few extra hosts to the localhost.cfg file to monitor my router, and a few other devices on my network. I have also added a Volume to store the nagios data, so after a restart of the container the data is still there.

Lets have a look at how hosts and services are defined in the config files.

define host{
 use linux-server
 host_name router
 alias router
 parents localhost; Hosts that this host is dependent on 
 address 192.168.2.1; IP Address or DNS name of the host
}

define service{
 use local-service,graphed-service
 host_name localhost, router
 service_description PING
 check_command check_ping!100.0,20%!500.0,60%
}

When making changes to your config files it is useful to check the config is valid. To do this with the docker file you can run the following command:

docker exec -it mynagioscontainer bin/nagios -v etc/nagios.cfg

It may have been 10 years since I last looked at Nagios, but the UI hasn’t changed much. Host are checked if they are Up or Down, and every Host can have a number of services associated with it and this are checked if they are Up or Down.

Conclusion

By following these steps, you can set up Nagios monitoring using Docker to keep an eye on your local network. Nagios is a powerful tool for network monitoring, and running it in a Docker container makes it easy to deploy and manage. Happy monitoring!

For application metrics and dashboards rather than host ping checks, see setting up Grafana with Prometheus. I also wrote about loving Nagios the first time around — the UI has barely moved since.

2025-01 on Funky Si's Test

Set up Grafana for .NET with Docker

Setting up Grafana

Docker Compose File

Prometheus Configuration

Grafana Config

Dashboard

Metrics endpoint

Conclusion

Related on this blog

Adding Elasticsearch with .Net Aspire

Troubleshooting Kibana

Using Elasticsearch in Your Project

Conclusion

NuGet central package management

What is NuGet Central Package Management?

Setting Up Central Package Management

Benefits of Central Package Management

Conclusion

Setting Up Nagios Monitoring with Docker

Finding a Docker Image for Nagios

Running the Nagios Docker Container

Accessing the Nagios Web Interface

Configuring Nagios

Adding Hosts and Services

Conclusion

Related on this blog