As you’ve probably guessed by Docker posts, I’m a huge fan of containerisation. Therefore instead of installing Prometheus on a host, let’s instead spin it up in a container. As described on the Prometheus website, we can accomplish this by issuing only a single command:
docker run -p 9090:9090 -v /tmp/prometheus.yml:/etc/prometheus/prometheus.yml prom/prometheus
Let’s break down each component of this command to make sure we fully understand what it is doing:
docker run: Spin up a container
-p 9090:9090: Bind a port on our Docker host to a container port. This enables devices outside of the Docker host to reach the container on port 9090
-v /tmp/prometheus.yml:/etc/prometheus/prometheus.yml: Binds the
/tmp/prometheus.yml file stored on the Docker host to
/etc/prometheus/prometheus.yml inside of the container
<user_account>/<container_name> that we want to use
In the previous post we may have started running before we could walk. In this post we’ll first take a few steps back to make sure we cover the basics before diving deeper.
Building an image
When we examined the
python:3.6.3-alpine3.6 image’s dockerfile, we saw the components which are used to create a Docker image:
- A single
OK, so we already know that the
FROM alpine3.6 command means that the Python image is going to use the Apline 3.6 as its Linux operating system.
ENV, as its name suggests, is used to specify environment variables for the image. That leaves us with
For those new to Docker, you’re probably wondering – What is it exactly?
“Docker is the company driving the container movement and the only container platform provider to address every application across the hybrid cloud.”
OK, it’s the name of a company. The next question is, what are containers? Rather than give you another quote, I’ll give you my own definition…
What are containers?
Containers are like portable executables. You know, the applications that come as a standalone
exe file and don’t require installation? I draw this comparison for the following reasons: