chore(): New blog post talking about running Prometheus

content-org/blog.org

@@ -5041,6 +5041,246 @@ If you want to go that far, maybe you should invest in a monitoring system with
 **** Conclusion
 Don't judge something by its simplicity. Somethings, out of simple components tied together you can make something interesting and useful.
 With a little of scripting, couple of commands and the power of cron we were able to make /healthchecks/ monitor our websites.
+*** TODO Upgrade your monitoring setup with Prometheus :prometheus:metrics:container:
+:PROPERTIES:
+:EXPORT_HUGO_LASTMOD: 2021-09-17
+:EXPORT_DATE: 2021-09-17
+:EXPORT_FILE_NAME: upgrade-your-monitoring-setup-with-prometheus
+:CUSTOM_ID: upgrade-your-monitoring-setup-with-prometheus
+:END:
+
+After running simple monitoring for quite a while, I decided to upgrade my
+setup. It is about time to get some real metric gathering to see what's going
+on. It's also time to get some proper monitoring setup.
+
+There are a lot of options in this field and I should, probably, write a blog
+post on my views on the topic. For this experiment, on the other hand, the
+solution is already pre-chosen. We'll be running Prometheus.
+
+#+hugo: more
+
+**** Prometheus
+To answer the question, /what is Prometheus?/, we'll rip a page out of the
+Prometheus [[https://prometheus.io/docs/introduction/overview/][docs]].
+
+#+begin_quote
+Prometheus is an open-source systems monitoring and alerting toolkit originally
+built at SoundCloud. Since its inception in 2012, many companies and
+organizations have adopted Prometheus, and the project has a very active
+developer and user community. It is now a standalone open source project and
+maintained independently of any company. To emphasize this, and to clarify the
+project's governance structure, Prometheus joined the Cloud Native Computing
+Foundation in 2016 as the second hosted project, after Kubernetes.
+
+Prometheus collects and stores its metrics as time series data, i.e. metrics
+information is stored with the timestamp at which it was recorded, alongside
+optional key-value pairs called labels.
+#+end_quote
+
+let's decypher all this jargon down to plain English. In simple terms,
+Prometheus is a system that scrape metrics, from your services and applications,
+and stores those metrics, in a time series database, ready to serve back again
+when queried.
+
+Prometheus also offers a way to create rules on those metrics to alert you when
+something goes wrong. Combined with [[https://prometheus.io/docs/alerting/latest/alertmanager/][/Alertmanager/]], you got yourself a full
+monitoring system.
+
+**** Configuration
+Now that we briefly touched on a /few/ features of *Prometheus* and before we
+can deploy, we need to write our configuration.
+
+This is an example of a bare configuration.
+
+#+NAME: prometheus-scraping-config
+#+begin_src yaml
+scrape_configs:
+- job_name: prometheus
+  scrape_interval: 30s
+  static_configs:
+  - targets:
+    - prometheus:9090
+#+end_src
+
+This will make Prometheus scrape itself every 30 seconds for metrics. At least
+you get /some/ metrics to query later. If you want the full experience, I would
+suggest you enable /Prometheus metrics/ for your services. Consult the docs of
+the project to see if and how it can expose metrics for /Prometheus/ to scrape,
+then add the scrape endpoint to your configuration as shown above.
+
+Here's a an example of a couple more, /well known/, projects; [[https://prometheus.io/docs/alerting/latest/alertmanager/][/Alertmanager/]] and
+[[https://github.com/prometheus/node_exporter][/node exporter/]].
+
+#+NAME: prometheus-example-scraping-config
+#+begin_src yaml
+- job_name: alertmanager
+  scrape_interval: 30s
+  static_configs:
+  - targets:
+    - alertmanager:9093
+
+- job_name: node-exporter
+  scrape_interval: 30s
+  static_configs:
+  - targets:
+    - node-exporter:9100
+#+end_src
+
+A wider [[https://prometheus.io/docs/instrumenting/exporters/][list of exporters]] can be found on the Prometheus docs.
+
+**** Deployment
+Now that we got ourselves a cofniguration, let's deploy *Prometheus*.
+
+Luckily for us, Prometheus comes containerized and ready to deploy. We'll be
+using =docker-compose= in this example to make it easier to translate later to
+other types of deployments.
+
+#+BEGIN_EXPORT html
+<div class="admonition note">
+<p class="admonition-title">Note</p>
+#+END_EXPORT
+I'm still running on =2.x= API version. I know I need to upgrade to a newer
+version but that's a bit of networking work. It's an ongoing work.
+#+BEGIN_EXPORT html
+</div>
+#+END_EXPORT
+
+The =docker-compose= file should look like the following.
+
+#+begin_src yaml
+---
+version: '2.3'
+
+services:
+  prometheus:
+    image: quay.io/prometheus/prometheus:v2.27.0
+    container_name: prometheus
+    mem_limit: 400m
+    mem_reservation: 300m
+    restart: unless-stopped
+    command:
+      - --config.file=/etc/prometheus/prometheus.yml
+      - --web.external-url=http://prometheus.localhost/
+    volumes:
+      - "./prometheus/:/etc/prometheus/:ro"
+    ports:
+      - "80:9090"
+#+end_src
+
+A few things to *note*, especially for the new container crowd. The container
+image *version* is explicitly specified, do *not* use =latest= in production.
+
+To make sure I don't overload my host, I set memory limits. I don't mind if it
+goes down, this is a PoC (Proof of Concept) for the time being. In your case,
+you might want to choose higher limits to give it more room to breath. When the
+memory limit is reached, the container will be killed with /Out Of Memory/
+error.
+
+In the *command* section, I specify the /external url/ for Prometheus to
+redirect me correctly. This is what Prometheus thinks its own hostname is. I
+also specify the configuration file, previously written, which I mount as
+/read-only/ in the *volumes* section.
+
+Finally, we need to port-forward =9090= to our hosts' =80= if possible to access
+*Prometheus*. Otherwise, figure out a way to route it properly. This is a local
+installation, which is suggested by the Prometheus /hostname/.
+
+If you made it so far, you should be able to run this with no issues.
+
+#+begin_src bash
+docker-compose up -d
+#+end_src
+
+**** Prometheus Rules
+*Prometheus* supports *two* types of rules; recording and alerting. Let's expand
+a little bit on those two concepts.
+
+***** Recording Rules
+First, let's start off with [[https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/][recording rules]]. I don't think I can explain it
+better than the *Prometheus* documentation which says.
+
+#+begin_quote
+Recording rules allow you to precompute frequently needed or computationally
+expensive expressions and save their result as a new set of time series.
+Querying the precomputed result will then often be much faster than executing
+the original expression every time it is needed. This is especially useful for
+dashboards, which need to query the same expression repeatedly every time they
+refresh.
+#+end_quote
+
+Sounds pretty simple right ? Well it is. Unfortunately, I haven't needed to
+create recording rules yet for my setup so I'll forgo this step.
+
+***** Alerting Rules
+As the name suggests, [[https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/#alerting-rules][alerting rules]] allow you to define conditional expressions
+based on metrics which will trigger notifications to alert you.
+
+This is a very simple example of an /alert rule/ that monitors all the endpoints
+scraped by /Prometheus/ to see if any of them is down. If this expression return
+a result, an alert will fire from /Prometheus/.
+
+#+begin_src yaml
+groups:
+- name: Instance down
+  rules:
+  - alert: InstanceDown
+    expr: up == 0
+    for: 5m
+    labels:
+      severity: page
+    annotations:
+      summary: "Instance {{ $labels.instance }} down"
+      description: "{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 5 minutes."
+#+end_src
+
+To be able to add this alert to *Prometheus*, we need to save it in a
+=rules.yml= file and then include it in the *Prometheus* configuration as follows.
+
+#+NAME: prometheus-rule-files-config
+#+begin_src yaml
+rule_files:
+- "rules.yml"
+#+end_src
+
+Making the configuration intiretly as follows.
+
+#+begin_src yaml :noweb yes
+<<prometheus-rule-files-config>>
+
+<<prometheus-scraping-config>>
+
+<<prometheus-example-scraping-config>>
+#+end_src
+
+At this point, make sure everything is mounted into the container properly and
+rerun your *Prometheus*.
+
+**** Prometheus UI
+Congratulations if you've made it so far. If you visit http://localhost/ at
+stage you should get to Prometheus where you can query your metrics.
+
+#+caption: Prometheus overview
+#+attr_html: :target _blank
+[[file:images/upgrade-your-monitoring-setup-with-prometheus/01-prometheus-overview.png][file:images/upgrade-your-monitoring-setup-with-prometheus/01-prometheus-overview.png]]
+
+You can get all sorts of information under the /status/ drop-down menu.
+
+#+caption: Prometheus Status drop-down menu
+#+attr_html: :target _blank
+[[file:images/upgrade-your-monitoring-setup-with-prometheus/02-prometheus-status-drop-down-menu.png][file:images/upgrade-your-monitoring-setup-with-prometheus/02-prometheus-status-drop-down-menu.png]]
+
+**** Conclusion
+As you can see, deploying *Prometheus* is not too hard. If you're running
+/Kubernetes/, make sure you use the operator. It will make your life a lot
+easier in all sorts of things.
+
+Take your time to familiarise yourself with *Prometheus* and consult the
+documentation as much as possible. It is well written and in most cases your
+best friend. Figure out different ways to create rules for recording and
+alerting. Most people at this stage deploy *Grafana* to start visualizing their
+metrics. Well... Not in this blog post we ain't !
+
+I hope you enjoy playing around with *Prometheus* and until the next post.
 ** Nikola :@nikola:
 *** DONE Welcome back to the old world :blog:org_mode:emacs:rst:
 :PROPERTIES:

content/posts/upgrade-your-monitoring-setup-with-prometheus.md

@@ -0,0 +1,264 @@
++++
+title = "Upgrade your monitoring setup with Prometheus"
+author = ["Elia el Lazkani"]
+date = 2021-09-17
+lastmod = 2021-09-17
+tags = ["prometheus", "metrics", "container"]
+categories = ["monitoring"]
+draft = true
++++
+
+After running simple monitoring for quite a while, I decided to upgrade my
+setup. It is about time to get some real metric gathering to see what's going
+on. It's also time to get some proper monitoring setup.
+
+There are a lot of options in this field and I should, probably, write a blog
+post on my views on the topic. For this experiment, on the other hand, the
+solution is already pre-chosen. We'll be running Prometheus.
+
+<!--more-->
+
+
+## Prometheus {#prometheus}
+
+To answer the question, _what is Prometheus?_, we'll rip a page out of the
+Prometheus [docs](https://prometheus.io/docs/introduction/overview/).
+
+> Prometheus is an open-source systems monitoring and alerting toolkit originally
+> built at SoundCloud. Since its inception in 2012, many companies and
+> organizations have adopted Prometheus, and the project has a very active
+> developer and user community. It is now a standalone open source project and
+> maintained independently of any company. To emphasize this, and to clarify the
+> project's governance structure, Prometheus joined the Cloud Native Computing
+> Foundation in 2016 as the second hosted project, after Kubernetes.
+>
+> Prometheus collects and stores its metrics as time series data, i.e. metrics
+> information is stored with the timestamp at which it was recorded, alongside
+> optional key-value pairs called labels.
+
+let's decypher all this jargon down to plain English. In simple terms,
+Prometheus is a system that scrape metrics, from your services and applications,
+and stores those metrics, in a time series database, ready to serve back again
+when queried.
+
+Prometheus also offers a way to create rules on those metrics to alert you when
+something goes wrong. Combined with [_Alertmanager_](https://prometheus.io/docs/alerting/latest/alertmanager/), you got yourself a full
+monitoring system.
+
+
+## Configuration {#configuration}
+
+Now that we briefly touched on a _few_ features of **Prometheus** and before we
+can deploy, we need to write our configuration.
+
+This is an example of a bare configuration.
+
+<a id="code-snippet--prometheus-scraping-config"></a>
+```yaml
+scrape_configs:
+- job_name: prometheus
+  scrape_interval: 30s
+  static_configs:
+  - targets:
+    - prometheus:9090
+```
+
+This will make Prometheus scrape itself every 30 seconds for metrics. At least
+you get _some_ metrics to query later. If you want the full experience, I would
+suggest you enable _Prometheus metrics_ for your services. Consult the docs of
+the project to see if and how it can expose metrics for _Prometheus_ to scrape,
+then add the scrape endpoint to your configuration as shown above.
+
+Here's a an example of a couple more, _well known_, projects; [_Alertmanager_](https://prometheus.io/docs/alerting/latest/alertmanager/) and
+[_node exporter_](https://github.com/prometheus/node%5Fexporter).
+
+<a id="code-snippet--prometheus-example-scraping-config"></a>
+```yaml
+- job_name: alertmanager
+  scrape_interval: 30s
+  static_configs:
+  - targets:
+    - alertmanager:9093
+
+- job_name: node-exporter
+  scrape_interval: 30s
+  static_configs:
+  - targets:
+    - node-exporter:9100
+```
+
+A wider [list of exporters](https://prometheus.io/docs/instrumenting/exporters/) can be found on the Prometheus docs.
+
+
+## Deployment {#deployment}
+
+Now that we got ourselves a cofniguration, let's deploy **Prometheus**.
+
+Luckily for us, Prometheus comes containerized and ready to deploy. We'll be
+using `docker-compose` in this example to make it easier to translate later to
+other types of deployments.
+
+<div class="admonition note">
+<p class="admonition-title">Note</p>
+
+I'm still running on `2.x` API version. I know I need to upgrade to a newer
+version but that's a bit of networking work. It's an ongoing work.
+
+</div>
+
+The `docker-compose` file should look like the following.
+
+```yaml
+---
+version: '2.3'
+
+services:
+  prometheus:
+    image: quay.io/prometheus/prometheus:v2.27.0
+    container_name: prometheus
+    mem_limit: 400m
+    mem_reservation: 300m
+    restart: unless-stopped
+    command:
+      - --config.file=/etc/prometheus/prometheus.yml
+      - --web.external-url=http://prometheus.localhost/
+    volumes:
+      - "./prometheus/:/etc/prometheus/:ro"
+    ports:
+      - "80:9090"
+```
+
+A few things to **note**, especially for the new container crowd. The container
+image **version** is explicitly specified, do **not** use `latest` in production.
+
+To make sure I don't overload my host, I set memory limits. I don't mind if it
+goes down, this is a PoC (Proof of Concept) for the time being. In your case,
+you might want to choose higher limits to give it more room to breath. When the
+memory limit is reached, the container will be killed with _Out Of Memory_
+error.
+
+In the **command** section, I specify the _external url_ for Prometheus to
+redirect me correctly. This is what Prometheus thinks its own hostname is. I
+also specify the configuration file, previously written, which I mount as
+_read-only_ in the **volumes** section.
+
+Finally, we need to port-forward `9090` to our hosts' `80` if possible to access
+**Prometheus**. Otherwise, figure out a way to route it properly. This is a local
+installation, which is suggested by the Prometheus _hostname_.
+
+If you made it so far, you should be able to run this with no issues.
+
+```bash
+docker-compose up -d
+```
+
+
+## Prometheus Rules {#prometheus-rules}
+
+**Prometheus** supports **two** types of rules; recording and alerting. Let's expand
+a little bit on those two concepts.
+
+
+### Recording Rules {#recording-rules}
+
+First, let's start off with [recording rules](https://prometheus.io/docs/prometheus/latest/configuration/recording%5Frules/). I don't think I can explain it
+better than the **Prometheus** documentation which says.
+
+> Recording rules allow you to precompute frequently needed or computationally
+> expensive expressions and save their result as a new set of time series.
+> Querying the precomputed result will then often be much faster than executing
+> the original expression every time it is needed. This is especially useful for
+> dashboards, which need to query the same expression repeatedly every time they
+> refresh.
+
+Sounds pretty simple right ? Well it is. Unfortunately, I haven't needed to
+create recording rules yet for my setup so I'll forgo this step.
+
+
+### Alerting Rules {#alerting-rules}
+
+As the name suggests, [alerting rules](https://prometheus.io/docs/prometheus/latest/configuration/alerting%5Frules/#alerting-rules) allow you to define conditional expressions
+based on metrics which will trigger notifications to alert you.
+
+This is a very simple example of an _alert rule_ that monitors all the endpoints
+scraped by _Prometheus_ to see if any of them is down. If this expression return
+a result, an alert will fire from _Prometheus_.
+
+```yaml
+groups:
+- name: Instance down
+  rules:
+  - alert: InstanceDown
+    expr: up == 0
+    for: 5m
+    labels:
+      severity: page
+    annotations:
+      summary: "Instance {{ $labels.instance }} down"
+      description: "{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 5 minutes."
+```
+
+To be able to add this alert to **Prometheus**, we need to save it in a
+`rules.yml` file and then include it in the **Prometheus** configuration as follows.
+
+<a id="code-snippet--prometheus-rule-files-config"></a>
+```yaml
+rule_files:
+- "rules.yml"
+```
+
+Making the configuration intiretly as follows.
+
+```yaml
+rule_files:
+- "rules.yml"
+
+scrape_configs:
+- job_name: prometheus
+  scrape_interval: 30s
+  static_configs:
+  - targets:
+    - prometheus:9090
+
+- job_name: alertmanager
+  scrape_interval: 30s
+  static_configs:
+  - targets:
+    - alertmanager:9093
+
+- job_name: node-exporter
+  scrape_interval: 30s
+  static_configs:
+  - targets:
+    - node-exporter:9100
+```
+
+At this point, make sure everything is mounted into the container properly and
+rerun your **Prometheus**.
+
+
+## Prometheus UI {#prometheus-ui}
+
+Congratulations if you've made it so far. If you visit <http://localhost/> at
+stage you should get to Prometheus where you can query your metrics.
+
+{{< figure src="/ox-hugo/01-prometheus-overview.png" caption="Figure 1: Prometheus overview" target="_blank" link="/ox-hugo/01-prometheus-overview.png" >}}
+
+You can get all sorts of information under the _status_ drop-down menu.
+
+{{< figure src="/ox-hugo/02-prometheus-status-drop-down-menu.png" caption="Figure 2: Prometheus Status drop-down menu" target="_blank" link="/ox-hugo/02-prometheus-status-drop-down-menu.png" >}}
+
+
+## Conclusion {#conclusion}
+
+As you can see, deploying **Prometheus** is not too hard. If you're running
+_Kubernetes_, make sure you use the operator. It will make your life a lot
+easier in all sorts of things.
+
+Take your time to familiarise yourself with **Prometheus** and consult the
+documentation as much as possible. It is well written and in most cases your
+best friend. Figure out different ways to create rules for recording and
+alerting. Most people at this stage deploy **Grafana** to start visualizing their
+metrics. Well... Not in this blog post we ain't !
+
+I hope you enjoy playing around with **Prometheus** and until the next post.