Flame K8s Adapter

Advanced Flame k8s Adapter basead on Operator Pattern.

Installation

If available in Hex, the package can be installed by adding flame_k8s to your list of dependencies in mix.exs:

def deps do
  [
    {:flame_k8s, "~> 0.1.0"}
  ]
end

NOTE: You need to install our Kubernetes Controller in the Kubernetes where you want to run your application. Follow the instructions below

Install Kubernetes Controller

To install flame-k8s kubernetes controller, just download the manifest from the release page and apply it to your cluster.

Usage

Configure the flame backend in our configuration.

# config.exs
if config_env() == :prod do
  config :flame, :backend, FLAME.K8sBackend
  config :flame, FLAME.K8sBackend, log: :debug
end

You need to enable Flame in Kubernetes as well. See the example below:

# my-application.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: flame-parent-example
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: flame-parent-example
  template:
    metadata:
      annotations:
        flame.org/enabled: "true"
        flame.org/dist-auto-config: "true"
        flame.org/otp-app: "my_app_release_name"
    spec:
      containers:
        - image: eigr/flame-parent-example:1.1.1
          name: flame-parent-example
          resources:
            limits:
              cpu: 200m
              memory: 200Mi
            requests:
              cpu: 200m
              memory: 200Mi

The most important part is:

template:
  metadata:
    annotations:
      flame.org/enabled: "true"
      flame.org/dist-auto-config: "true"
      flame.org/otp-app: "my_app_release_name"

See what each annotation means in the following table:

Annotation	Default	Detail
flame.org/enabled	"false"	Enable or disable Flame.
flame.org/dist-auto-config	"false"	Auto configure RELEASE_DISTRIBUTION and RELEASE_NODE based on otp application name.
flame.org/otp-app		Application release name. Required if dist-auto-config is set to "true".
flame.org/pool-config-ref	"default-pool"	Flame Pool configuration reference name. See more in the Configuration section.
flame.org/runner-termination-timeout	60000	Timeout in milliseconds that the Runner will have to finish before the controller sends the POD delete command.

Now you can start scaling your applications with Flame... with a little help from eigr \0/

Configuration

TODO

1. Flame Runner Pool

The Flame k8s Controller gives you the possibility to configure different runner profiles. These profiles will be used when creating PODs to run Runners in Kubernetes. To configure a new Runner Pool, simply define the following yaml file and apply it to the Kubernetes cluster.

# my-runner.yaml
---
apiVersion: flame.org/v1
kind: FlamePool
metadata:
  name: my-runner-pool
  namespace: default
spec:
  podTemplate:
    spec: # This is a pod template specification. See https://kubernetes.io/docs/concepts/workloads/pods/#pod-templates
      containers:
        - env:
            - name: MY_VAR
              value: "my-value"
          resources:
            limits:
              cpu: 200m
              memory: 1Gi
            requests:
              cpu: 200m
              memory: 2Gi
          volumeMounts:
            - mountPath: /app/.cache/bakeware/
              name: bakeware-cache
      volumes:
        - name: bakeware-cache
          emptyDir: {}

Then:

kubectl apply -f my-runner.yaml

Once this is done, simply add the annotation flame.org/pool-config-ref to your Deployment file. Example:

# my-application.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: flame-parent-example
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: flame-parent-example
  template:
    metadata:
      annotations:
        flame.org/enabled: "true"
        flame.org/pool-config-ref: "my-runner-pool"
    spec:
      containers:
        - image: eigr/flame-parent-example:1.1.1
...        

You can also list all Runner pools configured on the system with the command:

kubectl --all-namespaces get pools

The controller also defines a default Pool which in turn has the following configuration:

---
apiVersion: flame.org/v1
kind: FlamePool
metadata:
  name: default-pool
  namespace: flame
spec:
  podTemplate:
    spec:
      containers:
        - env:
          - name: PHX_SERVER
            value: "false"
          - name: MIX_ENV
            value: prod
          - name: POD_NAME
            valueFrom:
              fieldRef:
                fieldPath: metadata.name
          - name: POD_NAMESPACE
            valueFrom:
              fieldRef:
                fieldPath: metadata.namespace
          - name: POD_IP
            valueFrom:
              fieldRef:
                fieldPath: status.podIP
          # Other vars...
          resources:
            requests:
              cpu: 50m
              memory: 128Mi