Tarantool Kubernetes operator

The Tarantool Operator provides automation that simplifies the administration of Tarantool Cartridge-based cluster on Kubernetes.

The Operator introduces new API version tarantool.io/v1alpha1 and installs custom resources for objects of three custom types: Cluster, Role, and ReplicasetTemplate.

Resources
Resource ownership
Deploying the Tarantool operator on minikube
Example: key-value storage

Resources

Cluster represents a single Tarantool Cartridge cluster.

Role represents a Tarantool Cartridge user role.

ReplicasetTemplate is a template for StatefulSets created as members of Role.

Resource ownership

Resources managed by the Operator being deployed have the following resource ownership hierarchy:

Resource ownership directly affects how Kubernetes garbage collector works. If you execute a delete command on a parent resource, then all its dependants will be removed.

Deploying the Tarantool operator on minikube

Install the required deployment utilities:
- kubectl
- helm
Pick one of these to run a local kubernetes cluster
To install and configure a local minikube installation:
1. Create a minikube cluster:
```
minikube start --memory=4096
```
  You will need 4Gb of RAM allocated to the minikube cluster to run examples.
  
  Ensure minikube is up and running:
```
minikube status
```
  In case of success you will see this output:
```
host: Running
kubelet: Running
apiserver: Running
```
2. Enable minikube Ingress add-on:
```
minikube addons enable ingress
```

Install the operator

helm install tarantool-operator ci/helm-chart --namespace tarantool --create-namespace

Ensure the operator is up:

watch kubectl get pods -n tarantool

Wait for tarantool-operator-xxxxxx-xx Pod's status to become Running.

Example Application: key-value storage

examples/kv contains a Tarantool-based distributed key-value storage. Data are accessed via HTTP REST API.

Application topology

Running the application

We assume that commands are executed from the repository root and Tarantool Operator is up and running.

Create a cluster:

helm install examples-kv-cluster examples/kv/helm-chart --namespace tarantool

Wait until all the cluster Pods are up (status becomes Running):

watch kubectl -n tarantool get pods

Ensure cluster became operational:

kubectl -n tarantool describe clusters.tarantool.io examples-kv-cluster

wait until Status.State is Ready:

...
Status:
  State:  Ready
...

Access the cluster web UI:
- If using minikube:
  - Get minikube vm IP-address:
```
minikube ip
```
  - Open http://MINIKUBE_IP in your browser. Replace MINIKUBE_IP with the IP-address reported by the previous command.
  NOTE: Due to a recent bug in Ingress, web UI may be inaccessible. If needed, you can try this workaround.
- If using kubernetes in docker-desktop
  
  Run: (MINIKUBE_IP will be localhost:8081 in this case)
```
kc port-forward -n tarantool routers-0-0 8081:8081
```

Access the key-value API:

Store some value:

curl -XPOST http://MINIKUBE_IP/kv -d '{"key":"key_1", "value": "value_1"}'

In case of success you will see this output:

{"info":"Successfully created"}

Access stored values:

curl http://MINIKUBE_IP/kv_dump

In case of success you will see this output:

{"store":[{"key":"key_1","value":"value_1"}]}

Scaling the application

Increase the number of replica sets in Storages Role:

in the examples-kv helm chart, edit the examples/kv/helm-chart/values.yaml file to be
```
- RoleName: storage
  ReplicaCount: 1
  ReplicaSetCount: 2
```
Then run:
```
helm upgrade examples-kv-cluster examples/kv/helm-chart --namespace tarantool
```
This will add another storage role replica set to the existing cluster. View the new cluster topology via the cluster web UI.
Increase the number of replicas across all Storages Role replica sets:

in the examples-kv helm chart, edit the examples/kv/helm-chart/values.yaml file to be
```
- RoleName: storage
  ReplicaCount: 2
  ReplicaSetCount: 2
```
Then run:
```
helm upgrade examples-kv-cluster examples/kv/helm-chart --namespace tarantool
```
This will add one more replica to each Storages Role replica set. View the new cluster topology via the cluster web UI.

Development

Regenerate the Custom Resource Definitions

make crds

Building tarantool-operator docker image

make docker

Running tests

# In the examples/kv directory
make build
make start
./bootstrap.sh
make test

vlsav/tarantool-operator