jnsgruk / hello-kubecon

A Charmed Operator demonstration for Operator Day 2021, hosted by Canonical

Operator Day 2021 Demo Charm

Contents

Overview
Quickstart
Development Setup
Build and Deploy Locally
Testing
Get Help & Community
More Information/Related

Overview

This charm is a demonstration of a charm implemeting the sidecar pattern used during Operator Day 2021. You can grab the slides from the demo here.

The charm is written using the Charmed Operator Framework. It deploys gosherve, relying upon the charm container to populate a shared volume with a simple landing-page style website and configure the app before it is started.

Slides for the demo are available and there is a supporting Github Gist that contains copy-and- pastable content from the slide deck.

The finished charm is published on Charmhub.

The charm will:

• Deploy a container running gosherve
• Fetch a website from Github
• Place the downloaded file in a storage volume
• Expose a redirect-map config item to configure gosherve redirects
• Expose a pull-site action to pull the latest version of the test site
• Utilise an ingress relation using the nginx-ingress-integrator library

Each branch of this repository represents a different stage from the demonstration:

• 1-specify-workload
• 2-handle-configuration
• 3-storage
• 4-action
• 5-ingress
• master

Quickstart

Assuming you already have Juju installed and bootstrapped on a cluster (if you do not, see the next section):

# Create a juju model
$ juju add-model dev
# Deploy the charm
$ juju deploy hello-kubecon
# Deploy the ingress charm
$ juju deploy traefik-k8s --trust
$ juju config traefik-k8s external_hostname=juju.local
$ juju config traefik-k8s routing_mode=subdomain
# Relate our app to the ingress
$ juju relate hello-kubecon traefik-k8s
# Wait for the deployment to complete
$ watch -n1 --color juju status --color
# Add an entry to /etc/hosts
$ echo "<traefik-k8s-address> dev-hello-kubecon.juju.local" | sudo tee -a /etc/hosts

You should be able to visit http://dev-hello-kubecon.juju.local in your browser.

Development Setup

To set up a local test environment with MicroK8s:

# Install MicroK8s
$ sudo snap install --classic microk8s
# Wait for MicroK8s to be ready
$ sudo microk8s status --wait-ready
# Enable features required by Juju controller & charm
$ sudo microk8s enable storage dns metallb
# (Optional) Alias kubectl bundled with MicroK8s package
$ sudo snap alias microk8s.kubectl kubectl
# (Optional) Add current user to 'microk8s' group
# This avoid needing to use 'sudo' with the 'microk8s' command
$ sudo usermod -aG microk8s $(whoami)
# Activate the new group (in the current shell only)
# Log out and log back in to make the change system-wide
$ newgrp microk8s
# Install Charmcraft
$ sudo snap install charmcraft
# Install juju
$ sudo snap install --classic juju
# Bootstrap the Juju controller on MicroK8s
$ juju bootstrap microk8s micro
# Add a new model to Juju
$ juju add-model dev

Build and Deploy Locally

# Clone the charm code
$ git clone https://github.com/jnsgruk/hello-kubecon && cd hello-kubecon
# Build the charm package
$ charmcraft pack
# Create a juju model
$ juju add-model dev
# Deploy!
$ juju deploy ./hello-kubecon_ubuntu-20.04-amd64.charm --resource gosherve-image=jnsgruk/gosherve:latest
# Deploy the ingress charm
$ juju deploy traefik-k8s --trust
$ juju config traefik-k8s external_hostname=juju.local
$ juju config traefik-k8s routing_mode=subdomain
# Relate our app to the ingress
$ juju relate hello-kubecon traefik-k8s
# Wait for the deployment to complete
$ watch -n1 --color juju status --color
# Add an entry to /etc/hosts
$ echo "<traefik-k8s-address> dev-hello-kubecon.juju.local" | sudo tee -a /etc/hosts

You should be able to visit http://dev-hello-kubecon.juju.local in your browser.

Testing

# Clone the charm code
$ git clone https://github.com/jnsgruk/hello-kubecon && cd hello-kubecon
# Install python3-virtualenv
$ sudo apt update && sudo apt install -y python3-virtualenv
# Create a virtualenv for the charm code
$ virtualenv venv
# Activate the venv
$ source ./venv/bin/activate
# Install dependencies
$ pip install -r requirements-dev.txt
# Run the tests
$ ./run_tests

Get Help & Community

If you get stuck deploying this charm, or would like help with charming generally, come and join the charming community!

• Community Discourse
• Community Chat

More Information/Related

Below are some links related to this demonstration:

• Charmed Operator Framework Documentation
• Charmed Operator Framework Source
• Juju Documentation
• Charmhub
• Pebble
• The Future of Charmed Operators on Kubernetes

hello-kubecon's Issues

charm can be stuck in waiting state if pebble-ready fires after config-changed

Currently the charm can end up stuck in a waiting state if pebble-ready fires after config-changed. See below for details.

mthaddon@finistere:~/repos/k8s-charms/hello-kubecon/hello-kubecon$ juju debug-log --no-tail --replay| grep ' ran '
unit-hello-kubecon-0: 11:22:24 INFO juju.worker.uniter.operation ran "install" hook (via hook dispatching script: dispatch)
unit-hello-kubecon-0: 11:22:24 INFO juju.worker.uniter.operation ran "ingress-relation-created" hook (via hook dispatching script: dispatch)
unit-hello-kubecon-0: 11:22:25 INFO juju.worker.uniter.operation ran "leader-elected" hook (via hook dispatching script: dispatch)
unit-hello-kubecon-0: 11:22:25 INFO juju.worker.uniter.operation ran "webroot-storage-attached" hook (via hook dispatching script: dispatch)
unit-hello-kubecon-0: 11:22:25 INFO juju.worker.uniter.operation ran "config-changed" hook (via hook dispatching script: dispatch)
unit-hello-kubecon-0: 11:22:26 INFO juju.worker.uniter.operation ran "start" hook (via hook dispatching script: dispatch)
unit-nginx-ingress-integrator-0: 11:22:26 INFO juju.worker.uniter.operation ran "install" hook (via hook dispatching script: dispatch)
unit-hello-kubecon-0: 11:22:26 INFO juju.worker.uniter.operation ran "ingress-relation-joined" hook (via hook dispatching script: dispatch)
unit-nginx-ingress-integrator-0: 11:22:26 INFO juju.worker.uniter.operation ran "ingress-relation-created" hook (via hook dispatching script: dispatch)
unit-hello-kubecon-0: 11:22:27 INFO juju.worker.uniter.operation ran "ingress-relation-changed" hook (via hook dispatching script: dispatch)
unit-nginx-ingress-integrator-0: 11:22:27 INFO juju.worker.uniter.operation ran "leader-elected" hook (via hook dispatching script: dispatch)
unit-nginx-ingress-integrator-0: 11:22:27 INFO juju.worker.uniter.operation ran "config-changed" hook (via hook dispatching script: dispatch)
unit-hello-kubecon-0: 11:22:28 INFO juju.worker.uniter.operation ran "gosherve-pebble-ready" hook (via hook dispatching script: dispatch)
unit-nginx-ingress-integrator-0: 11:22:28 INFO juju.worker.uniter.operation ran "start" hook (via hook dispatching script: dispatch)
unit-nginx-ingress-integrator-0: 11:22:29 INFO juju.worker.uniter.operation ran "ingress-relation-changed" hook (via hook dispatching script: dispatch)
unit-hello-kubecon-0: 11:22:29 INFO juju.worker.uniter.operation ran "ingress-relation-changed" hook (via hook dispatching script: dispatch)
unit-nginx-ingress-integrator-0: 11:22:29 INFO juju.worker.uniter.operation ran "ingress-relation-joined" hook (via hook dispatching script: dispatch)
unit-nginx-ingress-integrator-0: 11:22:30 INFO juju.worker.uniter.operation ran "ingress-relation-changed" hook (via hook dispatching script: dispatch)
mthaddon@finistere:~/repos/k8s-charms/hello-kubecon/hello-kubecon$ juju status
Model     Controller          Cloud/Region        Version  SLA          Timestamp
ing-test  microk8s-localhost  microk8s/localhost  3.0.0    unsupported  11:27:14+01:00

App                       Version  Status   Scale  Charm                     Channel  Rev  Address         Exposed  Message
hello-kubecon                      waiting      1  hello-kubecon             stable    14  10.152.183.132  no       installing agent
nginx-ingress-integrator           active       1  nginx-ingress-integrator  stable    37  10.152.183.25   no       Ingress with service IP(s): 10.152.183.59

Unit                         Workload  Agent  Address       Ports  Message
hello-kubecon/0*             waiting   idle   10.1.129.141         waiting for Pebble in workload container
nginx-ingress-integrator/0*  active    idle   10.1.129.139         Ingress with service IP(s): 10.152.183.59

`_fetch_site` doesn't respect the `JUJU_CHARMS_*_PROXY` environment variables

https://github.com/jnsgruk/hello-kubecon/blob/master/src/charm.py#L100-L110

urlretrieve method fails when the charm is deployed behind a proxy

Deployment Documentation Nitpick

Hey Jon, quick nitpick in case it helps your new users. Thanks for the tutorial.

Under Build and Deploy Locally and Quickstart in the README:

You should be able to visit http://hellokubecon.juju in your browser.

The previous instructions deploy to http://hello-kubecon

Based on falling back to the app name due to no external hostname set and then running

# Add an entry to /etc/hosts
$ echo "127.0.1.1 hello-kubecon" | sudo tee -a /etc/hosts

(PR: #7 )

Alternatively, update external hostname to "hellokubecon.juju" and change readme to:

# Add an entry to /etc/hosts
$ echo "127.0.1.1 hellokubecon.juju" | sudo tee -a /etc/hosts

which would be more consistent with your tutorial/slides. lmk if you'd prefer that, happy to spin up a quick pr.

README.md contains different model name under Development Setup

Hi!
Just a minor comment for the README.md file:

While sections Quickstart, Build and Deploy Locally call for the creation of a Juju model named dev, the Development Setup section mentions a model named development.