This project is designed to show you how to create an auto-scaling elixir cluster using Elixir 1.9 and Kubernetes. Each branch of the project is designed to follow the slide deck of the associated presentation.
The branches are ordered from 01-22 so that you can easily see what is changed at each step. If a branch is missing it's because that slide contained only commands, not code changes. This README also covers a summary of what is done top to bottom.
From the working directory on your local development machine
$ mix phx.new el_kube
I am using vscode
$ cd el_kube && code .
elixir: "~> 1.9",
def application do
[
mod: {ElKube.Application, []},
extra_applications: [:logger, :runtime_tools, :peerage]
]
end
Add peerage
defp deps do
[
{:phoenix, "~> 1.4.6"},
{:phoenix_pubsub, "~> 1.1"},
{:phoenix_ecto, "~> 4.0"},
{:ecto_sql, "~> 3.0"},
{:postgrex, ">= 0.0.0"},
{:phoenix_html, "~> 2.11"},
{:phoenix_live_reload, "~> 1.2", only: :dev},
{:gettext, "~> 0.11"},
{:jason, "~> 1.0"},
{:plug_cowboy, "~> 2.0"},
{:peerage, "~> 1.0"}
]
end
Don't forget to $ mix deps.get if necessary
$ mix release.init
Uncomment RELEASE_DISTRIBUTION and RELEASE_NODE and change the localhost IP to an environment variable
export RELEASE_DISTRIBUTION=name
export RELEASE_NODE=<%= @release.name %>@${HOSTNAME}
This file won't be used
$ rm config/prod.secret.exs
$ touch config/releases.exs
import Config
service_name = System.fetch_env!("SERVICE_NAME")
db_url = System.fetch_env!("DB_URL")
secret_key_base = System.fetch_env!("SECRET_KEY_BASE")
port = System.fetch_env!("PORT")
config :el_kube, ElKube.Repo, url: db_url
config :el_kube, ElKubeWeb.Endpoint,
http: [port: port],
secret_key_base: secret_key_base,
url: [host: {:system, "APP_HOST"}, port: {:system, "PORT"}]
config :peerage, via: Peerage.Via.Dns,
dns_name: service_name,
app_name: "el_kube"
- Remove the url key from the endpoint config
- Add endpoint config key/value
server: true
- Remove the import_config "prod.secret.exs" at the bottom of config/prod.exs
This demonstrates how you can put base values in the config and layer on top with the environment specific configs
config :el_kube, ElKube.Repo,
adapter: Ecto.Adapters.Postgres,
pool_size: 10
So that it will run quietly in development
config :peerage,
via: Peerage.Via.List,
node_list: [:"[email protected]"],
log_results: false
$ mix phx.digest
$ MIX_ENV=prod mix release
$ mix ecto.create
Console 1:
DB_URL=ecto://postgres:postgres@localhost/el_kube_dev RELEASE_COOKIE=foo SECRET_KEY_BASE=foo HOSTNAME=127.0.0.1 SERVICE_NAME=localhost.svc APP_HOST=localhost PORT=4000 _build/prod/rel/el_kube/bin/el_kube start
You should now be able to open http://localhost:4000
The :ok tuple indicates success.
From Console 2:
DB_URL=ecto://postgres:postgres@localhost/el_kube_dev RELEASE_COOKIE=foo SECRET_KEY_BASE=foo HOSTNAME=127.0.0.1 PORT=4000 MIX_ENV=prod SERVICE_NAME=localhost.svc APP_HOST=localhost _build/prod/rel/el_kube/bin/el_kube remote
Interactive Elixir (1.8.1) - press Ctrl+C to exit (type h() ENTER for help)
iex([email protected])1> Ecto.Adapters.SQL.query(ElKube.Repo, "Select 1 as testing")
17:34:23.041 [debug] QUERY OK db=0.3ms queue=0.6ms
Select 1 as testing []
{:ok,
%Postgrex.Result{
columns: ["testing"],
command: :select,
connection_id: 20104,
messages: [],
num_rows: 1,
rows: [[1]]
}}
iex([email protected])2>
FROM elixir:1.9.0-alpine AS builder
ENV MIX_ENV=prod
WORKDIR /usr/local/el_kube
# This step installs all the build tools we'll need
RUN apk update \
&& apk upgrade --no-cache \
&& apk add --no-cache \
nodejs-npm \
alpine-sdk \
openssl-dev \
&& mix local.rebar --force \
&& mix local.hex --force
# Copies our app source code into the build container
COPY . .
# Compile Elixir
RUN mix do deps.get, deps.compile, compile
# Compile Javascript
RUN cd assets \
&& npm install \
&& ./node_modules/webpack/bin/webpack.js --mode production \
&& cd .. \
&& mix phx.digest
# Build Release
RUN mkdir -p /opt/release \
&& mix release \
&& mv _build/${MIX_ENV}/rel/el_kube /opt/release
# Create the runtime container
FROM erlang:22-alpine as runtime
# Install runtime dependencies
RUN apk update \
&& apk upgrade --no-cache \
&& apk add --no-cache gcc
WORKDIR /usr/local/el_kube
COPY --from=builder /opt/release/el_kube .
CMD [ "bin/el_kube", "start" ]
HEALTHCHECK --interval=30s --timeout=30s --start-period=5s --retries=2 \
CMD nc -vz -w 2 localhost 4000 || exit 1
_build/
.elixir_ls/
.git/
.vscode/
deps/
priv/static/
k8s/
test/
.dockerignore
.env
.formatter.exs
.gitignore
.travis.yml
Dockerfile
README.md
$ docker build -t el_kube:latest .
$ docker network create el-kube-net
$ docker run --rm -d -h db -e POSTGRES_DB=el_kube_prod -p 5432 --name db --network el-kube-net postgres:9.6
$ docker run -it --rm -e DB_URL=ecto://postgres:postgres@db/el_kube_prod -e RELEASE_COOKIE=secret-cookie -e SERVICE_NAME=el-kube -e SECRET_KEY_BASE=foo -e PORT=4000 -e APP_HOST=localhost -p 4000 --network el-kube-net --publish 4000:4000 el_kube:latest
$ curl http://localhost:4000
# you should get back some html and a 200
The filename is in the comment at the top of the yaml file.
$ mkdir k8s
# k8s/pvc.yaml
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: postgres-pvc
labels:
app: postgres
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
# k8s/db.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: db
spec:
replicas: 1
strategy:
type: Recreate
template:
metadata:
creationTimestamp: null
labels:
app: postgresql
spec:
containers:
- env:
- name: POSTGRES_DB
value: el_kube_prod
image: postgres:9.6
name: db
ports:
- containerPort: 5432
resources: {}
volumeMounts:
- mountPath: /var/lib/postgresql/data
name: data
hostname: db
restartPolicy: Always
volumes:
- name: data
persistentVolumeClaim:
claimName: postgres-pvc
# k8s/db-svc.yaml
apiVersion: v1
kind: Service
metadata:
labels:
app: postgresql
name: db
spec:
ports:
- name: postgres
port: 5432
targetPort: 5432
selector:
app: postgresql
# k8s/el-kube-svc.yaml
apiVersion: v1
kind: Service
metadata:
name: el-kube
spec:
clusterIP: None
selector:
app: el-kube
ports:
- name: http
port: 4000
- name: epmd
port: 4369
$ eval $(minikube docker-env)
$ docker build -t el_kube:latest .
# k8s/el-kube.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: el-kube-deployment
labels:
app: el-kube
spec:
replicas: 3
selector:
matchLabels:
app: el-kube
strategy:
type: RollingUpdate
rollingUpdate:
maxSurge: 34%
maxUnavailable: 34%
template:
metadata:
name: el-kube
labels:
app: el-kube
spec:
containers:
- name: el-kube
image: el_kube:latest
imagePullPolicy: Never
env:
- name: APP_HOST
value: el-kube.com
- name: DB_URL
value: ecto://postgres:postgres@db/el_kube_prod
- name: HOSTNAME
valueFrom:
fieldRef:
fieldPath: status.podIP
- name: PORT
value: "4000"
- name: RELEASE_COOKIE
value: el-kube-secret-cookie
- name: SECRET_KEY_BASE
value: super-secret-key-base
- name: SERVICE_NAME
value: el-kube.default.svc.cluster.local
resources: {}
securityContext:
privileged: false
procMount: Default
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 30
$ kubectl exec -it el-kube-deployment-<hash> sh
/usr/local/el_kube # bin/el_kube remote
Erlang/OTP 22 [erts-10.4.4] [source] [64-bit] [smp:2:2] [ds:2:2:10] [async-threads:1] [hipe]
Interactive Elixir (1.9.0) - press Ctrl+C to exit (type h() ENTER for help)
iex([email protected])1> Node.list
[:"[email protected]", :"[email protected]"]
iex([email protected])2> ElKube.Repo.query("select 1 as testing")
{:ok,
%Postgrex.Result{
columns: ["testing"],
command: :select
...
$ # update the number of replicas to 5 in k8s/el-kube.yaml
$ kubectl apply -f k8s/el-kube.yaml
deployment.apps/el-kube-deployment configured
$ k exec -it el-kube-deployment-zzzzz sh
iex([email protected])1> Node.list
[:"[email protected]", :"[email protected]", :"[email protected]", :"[email protected]"]
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent