¿Cuándo usar curl y controles de salud en Docker?

When to use curl and healthchecks in Docker?

There are some great blog posts on using healthchecks, and the typical example looks like this: That uses the curl command to make an HTTP request inside the container, which checks that the web app in the container does respond. It exits with a 0 if the response is good, or a 1 if not – which tells Docker the container is unhealthy.

The healthcheck is captured in the image with a HEALTHCHECK instruction in the Dockerfile. There are some great blog posts on using healthchecks, and the typical example looks like this: That uses the curl command to make an HTTP request inside the container, which checks that the web app in the container does respond.

The first is Cloud Run, which is very simple and easy to use, and will get the job done for most people. Containers are treated as “services,” which are allotted a specific amount of memory and a CPU core (or two) to use. You can make custom domains to the containers, and run apps off of different ports.

When Docker starts a container, it monitors the process that the container runs. If the process ends, the container exits. That’s just a basic liveness check, because Docker doesn’t know or care what your app is actually doing.

My action endpoints are usually http://localhost:50000/Method/egFunction but when I run the app on a docker container, I am not able to call the api endpoint, I get errors instead. I use docker-compose and here is my code (mongodb also doesn’t work yet, I’m trying to get the endpoint working first).

This is how the Docker CLI works behind the scenes. Let’s start the alpine Docker container and mount this path using the -v flag: Next, let’s install some utilities in the container:

Instead you should look at writing a custom healthchecking app. The curl / iwr option is nice and simple, but it has some pretty significant drawbacks when you’re working on a production-grade Docker image. In Linux images, you need to have curl available. You can start FROM alpine and have a 4MB base image.

To make it simple Docker allows you as a web developer or web-ops to easily create and use a transportable environment in which you can deploy your PHP applications. As you will see below you can define the features you want your environment to have, then export and import them wherever and whenever you prefer.

It exits with a 0 if the response is good, or a 1 if not – which tells Docker the container is unhealthy. Windows has a curl alias for Invoke-WebRequest, but it’s not exactly the same. And PowerShell handles exit codes slightly differently, so in a Windows Dockerfile the equivalent is this: Neither of those options is great.

A healthcheck is how you tell Docker to test your app is really healthy, so if your web process is maxing out, Docker can mark the container as unhealthy and take evasive action (in swarm mode Docker replaces unhealthy containers by spinning up replacements).