This is an assignment done for MailerLite's interview process.

This operator manages custom resources for configuring email sending and sending of emails via a transactional email provider like MailerSend. The operator works cross namespace, and sends from multiple providers such as MailerSend and Mailgun.

The code for these is available in the Dockerfile and manifests/deployment.yaml.

• go version v1.22.0+
• docker version 17.03+.
• kubectl version v1.11.3+.
• Access to a Kubernetes v1.11.3+ cluster.

This shows a quickstart way of deploying and testing.

Clone this repository and install all the dependencies:

make
make manifests
make install

We can then create the image:

# To push to remote registry
# $ make docker-build docker-push IMG=example/my-operator:latest
# But I install locally 
$ make docker-build IMG=mailerlite.io/mail-operator:latest

# You can then deploy using the make command, or use the deployment manifest in the [`manifests`](./manifests/) folder.
# $ make deploy IMG=example/my-operator:latest

Create a Secret with the API token of the service you are gonna do:

kubectl create secret generic --from-literal=token=[API TOKEN]

Then create a EmailSenderConfig object. There's an example of the manifest in config/samples.

apiVersion: email.mailerlite.io/v1
kind: EmailSenderConfig
metadata:
  labels:
    app.kubernetes.io/name: mailerlite-sre-assignment
    app.kubernetes.io/managed-by: kustomize
  name: emailsenderconfig-sample
  namespace: default
spec:
  ApiTokenSecretRef: [Name of secret with API token]
  SenderEmail: [email protected]
  Provider: mailersend # or mailgun

And deploy it.

You can then do the same with an Email object.

apiVersion: email.mailerlite.io/v1
kind: Email
metadata:
  name: e-1
  namespace: default
spec:
  senderConfigRef: emailsenderconfig-sample # Name of the EmailSenderConfig object
  recipientEmail: [email protected]
  subject: This is an example subject
  body: This is an example body

You can then check the status of the email:

kubectl get mails e-1 -oyaml

Build and push your image to the location specified by IMG:

make docker-build docker-push IMG=<some-registry>/mailerlite-sre-assignment:tag

NOTE: This image ought to be published in the personal registry you specified. And it is required to have access to pull the image from the working environment. Make sure you have the proper permission to the registry if the above commands don’t work.

Install the CRDs into the cluster:

make install

Deploy the Manager to the cluster with the image specified by IMG:

make deploy IMG=<some-registry>/mailerlite-sre-assignment:tag

NOTE: If you encounter RBAC errors, you may need to grant yourself cluster-admin privileges or be logged in as admin.

Create instances of your solution You can apply the samples (examples) from the config/sample:

kubectl apply -k config/samples/

NOTE: Ensure that the samples has default values to test it out.

Delete the instances (CRs) from the cluster:

kubectl delete -k config/samples/

Delete the APIs(CRDs) from the cluster:

make uninstall

UnDeploy the controller from the cluster:

make undeploy

The API declarations are all in api/v1, and the code for the controllers are all in internal/controller.

The extra code used to keep the structure tidy can be found in the pkg folder.

A deployment manifest can be found in the manifests folder.

Following are the steps to build the installer and distribute this project to users.

1. Build the installer for the image built and published in the registry:

make build-installer IMG=<some-registry>/mailerlite-sre-assignment:tag

NOTE: The makefile target mentioned above generates an 'install.yaml' file in the dist directory. This file contains all the resources built with Kustomize, which are necessary to install this project without its dependencies.

2. Using the installer

Users can just run kubectl apply -f to install the project, i.e.:

kubectl apply -f https://raw.githubusercontent.com/<org>/mailerlite-sre-assignment/<tag or branch>/dist/install.yaml

Copyright 2024.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http:https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.