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DEVELOPMENT.md

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Setup, build and deploy

A typical setup using snaps, for deployments to a microk8s cluster can be done using the following commands.

Install the dependencies:

sudo snap install juju --classic
sudo snap install microk8s --classic
microk8s.enable dns hostpath-storage

Create a controller named micro into the cloud microk8s:

juju bootstrap microk8s micro

In Juju, you interact with the client (the juju command on your local machine). It connects to a controller. The controller is hosted on a cloud and controls models.

juju add-model redis-model

Then you build and deploy this charm into the model you just created:

charmcraft pack
juju deploy ./redis-k8s_ubuntu-22.04-amd64.charm --resource redis-image=ghcr.io/canonical/charmed-redis:7.2.5-22.04-edge

Once Redis starts up it will be running on its default port, 6379. To check it you run:

juju status

to discover the IP Redis is running behind. The output will have lines like:

Unit          Workload    Agent  Address       Ports     Message
redis-k8s/0*  active      idle   10.1.168.69

To retrieve the password to access the database, use the get-initial-admin-password action:

juju run-action redis-k8s/0 get-initial-admin-password --wait

Then, from your local machine, you can:

redis-cli -h 10.1.168.69 -p 6379 -a <password>

Another option is to port-forward the Redis pod or service port from k8s to a local port. For example, forwarding a node's port

microk8s.kubectl --namespace=redis-model port-forward pod/redis-8485b69dfd-6hgvj 6379:6379

However, it is simpler to forward the service port as it will abstract the node name behind it:

microk8s.kubectl --namespace=redis-model port-forward service/redis 6379:6379

Then you can simply:

redis-cli

From a k8s non-charmed scenario Redis will be exposed as Service named redis on the default port 6379.

Developing

The charm is based on the operator framework. Create and activate a tox virtual environment with the development requirements:

virtualenv -p python3 venv
source venv/bin/activate
pip install -r requirements.txt

In order to check the result of a modification, rebuild and upgrade the charm:

# Consider now that you are inside redis-k8s directory.
charmcraft pack
juju upgrade-charm --path="./redis-k8s_ubuntu-20.04-amd64.charm" redis-k8s --force-units

Or you can clean up things on different levels, application, model, and controller:

juju remove-application redis-k8s --force --no-wait
juju destroy-model redis-model --destroy-storage --force --no-wait
juju destroy-controller micro --destroy-all-models

Debugging

In order to enable TRACE level at the unit to make everything shows:

juju model-config logging-config="<root>=WARNING;unit=TRACE"

To show the logs for a specific mode:

juju debug-log -m redis-model

To show the logs for all the units in the model:

microk8s.kubectl get all --namespace=redis-model

To see the logs for a specific pod:

microk8s.kubectl --namespace=redis-model logs redis-k8s-0

Testing

The Python operator framework includes a very nice harness for testing operator behaviour without full deployment.

tox -e fmt           # update your code according to linting rules
tox -e lint          # code style
tox -e unit          # unit tests
tox -e integration   # integration tests
tox                  # runs 'lint' and 'unit' environments

Canonical Contributor Agreement

Canonical welcomes contributions to the Charmed Redis Operator. Please check out our contributor agreement if you're interested in contributing to the solution.