Hi all, this post was incredibly helpful for me (THANK YOU!) and I wanted to share our final configuration, in case it helps anyone else. We’re using Google Kubernetes with libcluster. The Elixir apps are accessible by the web via a load balancer that use a google managed SSL certificate. They can access each other via that headless service.
env.sh.eex
#!/bin/sh
export RELEASE_DISTRIBUTION=name
export RELEASE_NODE=<%= @release.name %>@${POD_IP}
config/prod.exs
config :libcluster,
topologies: [
k8s: [
strategy: Elixir.Cluster.Strategy.Kubernetes.DNS,
config: [
service: "myapp-service-headless",
application_name: "my_app",
polling_interval: 10_000
]
]
]
my_app.ex
def start(_type, _args) do
...
topologies = Application.get_env(:libcluster, :topologies) || []
children = [
{Cluster.Supervisor, [topologies, [name: MyApp.ClusterSupervisor]]},
supervisor(MyApp.Repo, []),
supervisor(MyAppWeb.Endpoint, []),
...
]
opts = [strategy: :one_for_one, name: MyApp.Supervisor]
Supervisor.start_link(children, opts)
end
kubernetes/all-together-now.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: myapp-deployment
namespace: default
spec:
replicas: 2
selector:
matchLabels:
app: myapp
strategy:
rollingUpdate:
maxSurge: 1
maxUnavailable: 1
type: RollingUpdate
template:
metadata:
labels:
app: myapp
spec:
containers:
- image: gcr.io/my-gcp-project-123/my_app_otp:develop-HEAD
name: myapp
lifecycle:
preStop:
exec:
command: ["./prod/rel/my_app/bin/my_app","stop"]
ports:
- containerPort: 4000
protocol: TCP
env:
- name: POD_IP
valueFrom:
fieldRef:
fieldPath: status.podIP
envFrom:
- configMapRef:
name: staging-env-file
command: ["./prod/rel/my_app/bin/my_app"]
args: ["start"]
terminationGracePeriodSeconds: 60
---
apiVersion: v1
kind: Service
metadata:
name: myapp-service
namespace: default
annotations:
cloud.google.com/app-protocols: '{"service-https-port":"HTTPS"}'
cloud.google.com/neg: '{"ingress": true}' # Creates a NEG after an Ingress is created
spec:
ports:
- name: service-https
port: 443
protocol: TCP
targetPort: 4000
selector:
app: myapp
type: NodePort
---
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: myapp-ingress
annotations:
kubernetes.io/ingress.global-static-ip-name: staging-managed-ip
ingress.gcp.kubernetes.io/pre-shared-cert: "staging"
kubernetes.io/ingress.allow-http: "false"
spec:
backend:
serviceName: myapp-service
servicePort: service-https
---
apiVersion: v1
kind: Service
metadata:
name: myapp-service-headless
spec:
ports:
- port: 8000
selector:
app: myapp
clusterIP: None
