Deploy application on Exoscale with Kamal

Objective is to deploy a vote application written in Python (relying on a Redis DB) and vote-ui application written in JS (and serve by NGinx) onto Exoscale cloud provider using Kamal.

Note

We will create our infrastructure on Exoscale using Terraform

Gathering credentials

Note

You will need an Exoscale account that you can obtain via https://portal.exoscale.com/register/ Once created you will need IAM keys that you can found on https://portal.exoscale.com/u/<YOUR_ACCOUNT_NAME>/iam/keys

Note

You also need a Github Personal Access Token to be able to Push/Pull to/from ghcr.io You can create one from https://github.com/settings/tokens

Once you have Exoscale IAM keys and Github Personal Access Token you can create environment variables that we will use against Terraform to create our infrastructure.

bw login
# Exoscale IAM key to deploy our infra
SECRETS=$(bw get item VotingAppDeployment)
export TF_VAR_exoscale_api_key=$(echo $SECRETS | jq -r '.fields[] | select(.name == "EXO_IAM_KEY").value')
export TF_VAR_exoscale_secret_key=$(echo $SECRETS | jq -r '.fields[] | select(.name == "EXO_IAM_SECRET").value')
# Token to access ghcr.io registry
export TF_VAR_ghcrio_token=$(bw get password GHCRIO)

Creating/scaling infrastructure with Terraform

Creating the infrastructure

(cd terraform && \
    terraform init && \
    terraform apply)

Deploying our applications with Kamal

Once our infrastructure is in place and our .env file has been populated by Terraform with IPs of our differents instances, we can deploy our application using Kamal

source .env # to load generated SSH key
(cd vote && kamal setup)
(cd vote && kamal deploy)
(cd vote-ui && kamal deploy)
(cd worker && kamal deploy)

Validation of our setup

Once our applications have been deployed, we can do some validations

Validate that vote application work:

source .env
$ curl -X POST -H "Content-Type: application/json" -H "Host: vote" -d '{"vote": "foo"}' http://$WEB_NLB

Should return something like

{"hostname":"159.100.242.73-19bc3792a704","voter_id":"910797520b4cd4"}

Then we can validate that UI is working as expected:

curl http://$WEB_NLB

Which should return some HTML content about Cats/Dogs

Kamal on a daily basis

Cheking status of our deployment

kamal audit will report status of our application and accessories

Application lifecycle

kamal app logs will show logs our application

kamal app exec <COMMAND> will allow to execute a command inside the application container

Maintenance

kamal app containers to retrieve the version we want to rollback to

kamal rollback <VERSION> to rollback application to a given version

Servers handling

kamal server exec --roles=vote <COMMAND>

Secrets handling

kamal secrets