393 lines
11 KiB
Markdown
393 lines
11 KiB
Markdown
---
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title: Monitor instances
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description: Export metrics, collect them, visualize them.
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date: 2024-05-17 07:00:00+0000
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image: chris-yang-1tnS_BVy9Jk-unsplash.jpg
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categories:
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- Nix
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- Guide
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- Sysadmin
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- Monitoring
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tags:
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- Nix
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- Nginx
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- Prometheus
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- Exporters
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- Monitoring
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- Docker compose
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draft: false
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writingTime: "20m"
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---
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# Monitoring
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Monitoring your instances allow you to keep track of servers load and its health overtime. Even looking at the stats once a day can make a huge difference as it allows you to prevent catastrophic disasters before they even happen.
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I have been monitoring my servers with this method for years and I had many cases I was grateful for setting it all up.
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In this small article I have included two guides to set these services up. First is with [NixOs](#nixos) and I also explain with [docker-compose](#docker-compose) but it's very sore as the main focus of this article is NixOS.
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**Prometheus**
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Prometheus is an open-source monitoring system. It helps to track, collect, and analyze
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metrics from various applications and infrastructure components. It collects metrics from other software called _exporters_ that server a HTTP endpoint that return data in the prometheus data format.
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Here is an example from `node-exporter`
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```nix
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# curl http://localhost:9100
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# HELP node_cpu_seconds_total Seconds the CPUs spent in each mode.
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# TYPE node_cpu_seconds_total counter
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node_cpu_seconds_total{cpu="0",mode="idle"} 2.54196405e+06
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node_cpu_seconds_total{cpu="0",mode="iowait"} 4213.44
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node_cpu_seconds_total{cpu="0",mode="irq"} 0
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node_cpu_seconds_total{cpu="0",mode="nice"} 0.06
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node_cpu_seconds_total{cpu="0",mode="softirq"} 743.4
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...
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```
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**Grafana**
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Grafana is an open-source data visualization and monitoring platform. It has hundreds of features embedded that can help you query from data sources like Prometheus, InfluxDB, MySQL and so on...
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## NixOs
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Nix makes it trivial to set up these services, as there are already predefined options for it in nixpkgs. I will give you example configuration files below that you can just copy and paste.
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I have a guide on [remote deployment](/p/remote-deployments-on-nixos/) for NixOs, below you can see an example on a folder structure you can use to deploy the services.
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{{< filetree/container >}}
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{{< filetree/folder name="server1" state="closed" >}}
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{{< filetree/folder name="services" state="closed" >}}
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{{< filetree/file name="some-service.nix" >}}
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{{< filetree/folder name="monitoring" state="closed" >}}
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{{< filetree/file name="prometheus.nix" >}}
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{{< filetree/file name="grafana.nix" >}}
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{{< filetree/folder name="exporters" state="closed" >}}
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{{< filetree/file name="node.nix" >}}
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{{< filetree/file name="smartctl.nix" >}}
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{{< /filetree/folder >}}
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{{< /filetree/folder >}}
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{{< /filetree/folder >}}
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{{< filetree/file name="configuration.nix" >}}
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{{< filetree/file name="flake.nix" >}}
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{{< filetree/file name="flake.lock" >}}
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{{< /filetree/folder >}}
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{{< /filetree/container >}}
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### Exporters
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First is node-exporter. It exports all kind of system metrics ranging from cpu usage, load average and even systemd service count.
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#### Node-exporter
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```nix
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# /services/monitoring/exporters/node.nix
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{ pkgs, ... }: {
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services.prometheus.exporters.node = {
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enable = true;
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#port = 9001; #default is 9100
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enabledCollectors = [ "systemd" ];
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};
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}
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```
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#### Smartctl
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Smartctl is a tool included in the smartmontools package. It is a collection of monitoring tools for hard-drives, SSDs and filesystems.
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This exporter enables you to check up on the health of your drive(s). And it will also give you a wall notifications if one of your drives has a bad sector(s), which mainly suggests it's dying off.
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```nix
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# /services/monitoring/exporters/smartctl.nix
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{ pkgs, ... }: {
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# exporter
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services.prometheus.exporters.smartctl = {
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enable = true;
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devices = [ "/dev/sda" ];
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};
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# for wall notifications
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services.smartd = {
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enable = true;
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notifications.wall.enable = true;
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devices = [
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{
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device = "/dev/sda";
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}
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];
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};
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}
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```
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If you happen to have other drives you can just use `lsblk` to check their paths
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```bash
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nix-shell -p util-linux --command lsblk
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```
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For example here is my pc's drives
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```
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NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
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sda 8:0 1 0B 0 disk
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nvme1n1 259:0 0 476,9G 0 disk
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├─nvme1n1p1 259:1 0 512M 0 part /boot
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├─nvme1n1p2 259:2 0 467,6G 0 part
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│ └─luks-bbb8e429-bee1-4b5e-8ce8-c54f5f4f29a2
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│ 254:0 0 467,6G 0 crypt /nix/store
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│ /
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└─nvme1n1p3 259:3 0 8,8G 0 part
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└─luks-f7e86dde-55a5-4306-a7c2-cf2d93c9ee0b
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254:1 0 8,8G 0 crypt [SWAP]
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nvme0n1 259:4 0 931,5G 0 disk /mnt/data
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```
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### Prometheus
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Now that we have setup these two exporters we need to somehow collect their metrics.
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Here is a config file for prometheus, with the scrape configs already written down.
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```nix
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# /services/monitoring/prometheus.nix
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{pkgs, config, ... }:{
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services.prometheus = {
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enable = true;
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scrapeConfigs = [
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{
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job_name = "node";
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scrape_interval = "5s";
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static_configs = [
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{
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targets = [ "localhost:${toString config.services.prometheus.exporters.node.port}" ];
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labels = { alias = "node.server1.local"; };
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}
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];
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}
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{
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job_name = "smartctl";
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scrape_interval = "5s";
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static_configs = [
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{
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targets = [ "localhost:${toString config.services.prometheus.exporters.smartctl.port}" ];
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labels = { alias = "smartctl.server1.local"; };
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}
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];
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}
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];
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};
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}
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```
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I recommend setting the 5s delay to a bigger number if you have little storage as you can imagine it can generate a lot of data.
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~16kB average per scrape (node-exporter). 1 day has 86400 seconds, divide that by 5 thats 17280 scrapes a day.
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17280 \* 16 = 276480 kB. Thats 270 megabytes a day. And if you have multiple servers that causes X times as much.
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30 days of scarping is about 8 gigabytes (1x). **But remember, by default prometheus stores data for 30 days!**
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### Grafana
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Now let's get onto gettin' a sexy dashboard like this. First we gotta setup grafana.
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```nix
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# /services/monitoring/grafana.nix
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{ pkgs, config, ... }:
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let
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grafanaPort = 3000;
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in
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{
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services.grafana = {
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enable = true;
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settings.server = {
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http_port = grafanaPort;
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http_addr = "0.0.0.0";
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};
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provision = {
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enable = true;
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datasources.settings.datasources = [
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{
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name = "prometheus";
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type = "prometheus";
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url = "http://127.0.0.1:${toString config.services.prometheus.port}";
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isDefault = true;
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}
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];
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};
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};
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networking.firewall = {
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allowedTCPPorts = [ grafanaPort ];
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allowedUDPPorts = [ grafanaPort ];
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};
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}
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```
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If you want to access it via the internet, change the following:
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- `http_addr = "127.0.0.1"`
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- remove the firewall allowed ports
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This insures data will only flow thru the nginx reverse proxy
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Remember to set `networking.domain = "example.com"` to your domain.
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```nix
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# /services/nginx.nix
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{ pkgs, config, ... }:
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let
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url = "http://127.0.0.1:${toString config.services.grafana.settings.server.http_port}";
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in {
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services.nginx = {
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enable = true;
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virtualHosts = {
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"grafana.${config.networking.domain}" = {
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# Auto cert by let's encrypt
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forceSSL = true;
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enableACME = true;
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locations."/" = {
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proxyPass = url;
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extraConfig = "proxy_set_header Host $host;";
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};
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locations."/api" = {
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extraConfig = ''
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proxy_http_version 1.1;
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proxy_set_header Upgrade $http_upgrade;
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proxy_set_header Connection $connection_upgrade;
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proxy_set_header Host $host;
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'';
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proxyPass = url;
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};
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};
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};
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};
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# enable 80 and 443 ports for nginx
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networking.firewall = {
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enable = true;
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allowedTCPPorts = [
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443
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80
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];
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allowedUDPPorts = [
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443
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80
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];
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};
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}
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```
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### Log in
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The default user is `admin` and password is `admin`. Grafana will ask you to change it upon logging-in!
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### Add the dashboards
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For node-exporter you can go to dashboards --> new --> import --> paste in `1860`
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Now you can see all the metrics of all your server(s).
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## Docker-compose
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{{< filetree/container >}}
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{{< filetree/folder name="monitoring-project" state="closed" >}}
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{{< filetree/file name="docker-compose.yml" >}}
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{{< filetree/file name="prometheus.nix" >}}
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{{< /filetree/folder >}}
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{{< /filetree/container >}}
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### Compose project
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I did not include a reverse proxy, neither smartctl as I forgot how to actually do it, that's how long I've been using nix :/
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```yaml
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# docker-compose.yml
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version: "3.8"
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networks:
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monitoring:
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driver: bridge
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volumes:
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prometheus_data: {}
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services:
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node-exporter:
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image: prom/node-exporter:latest
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container_name: node-exporter
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restart: unless-stopped
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hostname: node-exporter
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volumes:
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- /proc:/host/proc:ro
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- /sys:/host/sys:ro
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- /:/rootfs:ro
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command:
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- "--path.procfs=/host/proc"
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- "--path.rootfs=/rootfs"
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- "--path.sysfs=/host/sys"
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- "--collector.filesystem.mount-points-exclude=^/(sys|proc|dev|host|etc)($$|/)"
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networks:
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- monitoring
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prometheus:
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image: prom/prometheus:latest
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container_name: prometheus
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restart: unless-stopped
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hostname: prometheus
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volumes:
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- ./prometheus.yml:/etc/prometheus/prometheus.yml
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- prometheus_data:/prometheus
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command:
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- "--config.file=/etc/prometheus/prometheus.yml"
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- "--storage.tsdb.path=/prometheus"
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- "--web.console.libraries=/etc/prometheus/console_libraries"
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- "--web.console.templates=/etc/prometheus/consoles"
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- "--web.enable-lifecycle"
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networks:
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- monitoring
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grafana:
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image: grafana/grafana:latest
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container_name: grafana
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networks:
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- monitoring
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restart: unless-stopped
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ports:
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- '3000:3000'
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```
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```yaml
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# ./prometheus.yml
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global:
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scrape_interval: 5s
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scrape_configs:
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- job_name: "node"
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static_configs:
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- targets: ["node-exporter:9100"]
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```
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```bash
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docker compose up -d
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```
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### Setup prometheus as data source inside grafana
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Head to Connections --> Data sources --> Add new data source --> Prometheus
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Type in http://prometheus:9090 as the URL, on the bottom click `Save & test`.
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Now you can add the dashboards, [explained in this section](#add-the-dashboards)
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Photo by <a href="https://unsplash.com/@chrisyangchrisfilm?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash">Chris Yang</a> on <a href="https://unsplash.com/photos/silhouette-photography-of-man-1tnS_BVy9Jk?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash">Unsplash</a>
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