mirror of https://github.com/knative/docs.git
300 lines
9.9 KiB
Markdown
300 lines
9.9 KiB
Markdown
---
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title: "Hello World - Elixir"
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linkTitle: "Elixir"
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weight: 1
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type: "docs"
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---
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A simple web application written in [Elixir](https://elixir-lang.org/) using the
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[Phoenix Framework](https://phoenixframework.org/). The application prints all
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environment variables to the main page.
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# Set up Elixir and Phoenix Locally
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Following the
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[Phoenix Installation Guide](https://hexdocs.pm/phoenix/installation.html) is
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the best way to get your computer set up for developing, building, running, and
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packaging Elixir Web applications.
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# Running Locally
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To start your Phoenix server:
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- Install dependencies with `mix deps.get`
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- Install Node.js dependencies with `cd assets && npm install`
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- Start Phoenix endpoint with `mix phx.server`
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Now you can visit [`localhost:4000`](http://localhost:4000) from your browser.
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# Recreating the sample code
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1. Generate a new project.
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```shell
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mix phoenix.new helloelixir
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```
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When asked, if you want to `Fetch and install dependencies? [Yn]` select `y`
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1. Follow the direction in the output to change directories into start your
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local server with `mix phoenix.server`
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1. In the new directory, create a new Dockerfile for packaging your application
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for deployment
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```docker
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# Start from a base image for elixir
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# Phoenix works best on pre 1.7 at the moment.
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FROM elixir:1.6.6-alpine
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# Set up Elixir and Phoenix
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ARG APP_NAME=hello
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ARG PHOENIX_SUBDIR=.
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ENV MIX_ENV=prod REPLACE_OS_VARS=true TERM=xterm
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WORKDIR /opt/app
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# Update nodejs, rebar, and hex.
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RUN apk update \
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&& apk --no-cache --update add nodejs nodejs-npm \
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&& mix local.rebar --force \
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&& mix local.hex --force
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COPY . .
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# Download and compile dependencies, then compile Web app.
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RUN mix do deps.get, deps.compile, compile
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RUN cd ${PHOENIX_SUBDIR}/assets \
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&& npm install \
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&& ./node_modules/brunch/bin/brunch build -p \
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&& cd .. \
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&& mix phx.digest
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# Create a release version of the application
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RUN mix release --env=prod --verbose \
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&& mv _build/prod/rel/${APP_NAME} /opt/release \
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&& mv /opt/release/bin/${APP_NAME} /opt/release/bin/start_server
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# Prepare final layer
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FROM alpine:latest
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RUN apk update && apk --no-cache --update add bash openssl-dev ca-certificates
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# Add a user so the server will run as a non-root user.
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RUN addgroup -g 1000 appuser && \
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adduser -S -u 1000 -G appuser appuser
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# Pre-create necessary temp directory for erlang and set permissions.
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RUN mkdir -p /opt/app/var
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RUN chown appuser /opt/app/var
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# Run everything else as 'appuser'
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USER appuser
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ENV MIX_ENV=prod REPLACE_OS_VARS=true
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WORKDIR /opt/app
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COPY --from=0 /opt/release .
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ENV RUNNER_LOG_DIR /var/log
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# Command to execute the application.
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CMD ["/opt/app/bin/start_server", "foreground", "boot_var=/tmp"]
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```
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1. Create a new file, `service.yaml` and copy the following Service definition
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into the file. Make sure to replace `{username}` with your Docker Hub
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username.
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```yaml
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apiVersion: serving.knative.dev/v1
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kind: Service
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metadata:
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name: helloworld-elixir
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namespace: default
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spec:
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template:
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spec:
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containers:
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- image: docker.io/{username}/helloworld-elixir
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env:
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- name: TARGET
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value: "elixir Sample v1"
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```
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# Building and deploying the sample
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The sample in this directory is ready to build and deploy without changes. You
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can deploy the sample as is, or use you created version following the directions
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above.
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1. Generate a new `secret_key_base` in the `config/prod.secret.exs` file.
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Phoenix applications use a secrets file on production deployments and, by
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default, that file is not checked into source control. We have provides
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shell of an example on `config/prod.secret.exs.sample` and you can use the
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following command to generate a new prod secrets file.
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```shell
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SECRET_KEY_BASE=$(elixir -e ":crypto.strong_rand_bytes(48) |> Base.encode64 |> IO.puts")
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sed "s|SECRET+KEY+BASE|$SECRET_KEY_BASE|" config/prod.secret.exs.sample >config/prod.secret.exs
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```
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1. Use Docker to build the sample code into a container. To build and push with
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Docker Hub, run these commands replacing `{username}` with your Docker Hub
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username:
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```shell
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# Build the container on your local machine
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docker build -t {username}/helloworld-elixir .
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# Push the container to docker registry
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docker push {username}/helloworld-elixir
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```
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1. After the build has completed and the container is pushed to docker hub, you
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can deploy the app into your cluster. Ensure that the container image value
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in `service.yaml` matches the container you built in the previous step.
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Apply the configuration using `kubectl`:
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```shell
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kubectl apply --filename service.yaml
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```
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1. Now that your service is created, Knative will perform the following steps:
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- Create a new immutable revision for this version of the app.
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- Network programming to create a route, ingress, service, and load balance
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for your app.
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- Automatically scale your pods up and down (including to zero active pods).
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1. To find the URL for your service, use
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```
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kubectl get ksvc helloworld-elixir --output=custom-columns=NAME:.metadata.name,URL:.status.url
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NAME URL
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helloworld-elixir http://helloworld-elixir.default.1.2.3.4.xip.io
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```
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1. Now you can make a request to your app to see the results. Replace
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`{IP_ADDRESS}` with the address you see returned in the previous step.
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```shell
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curl http://helloworld-elixir.default.1.2.3.4.xip.io
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...
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# HTML from your application is returned.
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```
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Here is the HTML returned from our deployed sample application:
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```HTML
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="utf-8">
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<meta http-equiv="X-UA-Compatible" content="IE=edge">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<meta name="description" content="">
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<meta name="author" content="">
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<title>Hello Knative</title>
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<link rel="stylesheet" type="text/css" href="/css/app-833cc7e8eeed7a7953c5a02e28130dbd.css?vsn=d">
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</head>
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```
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<body>
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<div class="container">
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<header class="header">
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<nav role="navigation">
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</nav>
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</header>
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<p class="alert alert-info" role="alert"></p>
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<p class="alert alert-danger" role="alert"></p>
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<main role="main">
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<div class="jumbotron">
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<h2>Welcome to Knative and Elixir</h2>
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<p>$TARGET = elixir Sample v1</p>
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</div>
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<h3>Environment</h3>
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<ul>
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<li>BINDIR = /opt/app/erts-9.3.2/bin</li>
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<li>DEST_SYS_CONFIG_PATH = /opt/app/var/sys.config</li>
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<li>DEST_VMARGS_PATH = /opt/app/var/vm.args</li>
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<li>DISTILLERY_TASK = foreground</li>
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<li>EMU = beam</li>
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<li>ERL_LIBS = /opt/app/lib</li>
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<li>ERL_OPTS = </li>
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<li>ERTS_DIR = /opt/app/erts-9.3.2</li>
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<li>ERTS_LIB_DIR = /opt/app/erts-9.3.2/../lib</li>
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<li>ERTS_VSN = 9.3.2</li>
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<li>HELLOWORLD_ELIXIR_00001_SERVICE_PORT = tcp://10.35.241.50:80</li>
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<li>HELLOWORLD_ELIXIR_00001_SERVICE_PORT_80_TCP = tcp://10.35.241.50:80</li>
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<li>HELLOWORLD_ELIXIR_00001_SERVICE_PORT_80_TCP_ADDR = 10.35.241.50</li>
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<li>HELLOWORLD_ELIXIR_00001_SERVICE_PORT_80_TCP_PORT = 80</li>
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<li>HELLOWORLD_ELIXIR_00001_SERVICE_PORT_80_TCP_PROTO = tcp</li>
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<li>HELLOWORLD_ELIXIR_00001_SERVICE_SERVICE_HOST = 10.35.241.50</li>
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<li>HELLOWORLD_ELIXIR_00001_SERVICE_SERVICE_PORT = 80</li>
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<li>HELLOWORLD_ELIXIR_00001_SERVICE_SERVICE_PORT_HTTP = 80</li>
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<li>HELLOWORLD_ELIXIR_PORT = tcp://10.35.253.90:80</li>
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<li>HELLOWORLD_ELIXIR_PORT_80_TCP = tcp://10.35.253.90:80</li>
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<li>HELLOWORLD_ELIXIR_PORT_80_TCP_ADDR = 10.35.253.90</li>
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<li>HELLOWORLD_ELIXIR_PORT_80_TCP_PORT = 80</li>
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<li>HELLOWORLD_ELIXIR_PORT_80_TCP_PROTO = tcp</li>
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<li>HELLOWORLD_ELIXIR_SERVICE_HOST = 10.35.253.90</li>
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<li>HELLOWORLD_ELIXIR_SERVICE_PORT = 80</li>
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<li>HELLOWORLD_ELIXIR_SERVICE_PORT_HTTP = 80</li>
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<li>HOME = /root</li>
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<li>HOSTNAME = helloworld-elixir-00001-deployment-84f68946b4-76hcv</li>
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<li>KUBERNETES_PORT = tcp://10.35.240.1:443</li>
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<li>KUBERNETES_PORT_443_TCP = tcp://10.35.240.1:443</li>
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<li>KUBERNETES_PORT_443_TCP_ADDR = 10.35.240.1</li>
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<li>KUBERNETES_PORT_443_TCP_PORT = 443</li>
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<li>KUBERNETES_PORT_443_TCP_PROTO = tcp</li>
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<li>KUBERNETES_SERVICE_HOST = 10.35.240.1</li>
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<li>KUBERNETES_SERVICE_PORT = 443</li>
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<li>KUBERNETES_SERVICE_PORT_HTTPS = 443</li>
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<li>LD_LIBRARY_PATH = /opt/app/erts-9.3.2/lib:</li>
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<li>MIX_ENV = prod</li>
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<li>NAME = hello@127.0.0.1</li>
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<li>NAME_ARG = -name hello@127.0.0.1</li>
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<li>NAME_TYPE = -name</li>
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<li>OLDPWD = /opt/app</li>
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<li>OTP_VER = 20</li>
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<li>PATH = /opt/app/erts-9.3.2/bin:/opt/app/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin</li>
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<li>PORT = 8080</li>
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<li>PROGNAME = opt/app/releases/0.0.1/hello.sh</li>
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<li>PWD = /opt/app</li>
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<li>RELEASES_DIR = /opt/app/releases</li>
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<li>RELEASE_CONFIG_DIR = /opt/app</li>
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<li>RELEASE_ROOT_DIR = /opt/app</li>
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<li>REL_NAME = hello</li>
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<li>REL_VSN = 0.0.1</li>
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<li>REPLACE_OS_VARS = true</li>
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<li>ROOTDIR = /opt/app</li>
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<li>RUNNER_LOG_DIR = /var/log</li>
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<li>RUN_ERL_ENV = </li>
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<li>SHLVL = 1</li>
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<li>SRC_SYS_CONFIG_PATH = /opt/app/releases/0.0.1/sys.config</li>
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<li>SRC_VMARGS_PATH = /opt/app/releases/0.0.1/vm.args</li>
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<li>SYS_CONFIG_PATH = /opt/app/var/sys.config</li>
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<li>TARGET = elixir Sample v1</li>
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<li>TERM = xterm</li>
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<li>VMARGS_PATH = /opt/app/var/vm.args</li>
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</ul>
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</main>
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</div> <!-- /container -->
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<script src="/js/app-930ab1950e10d7b5ab5083423c28f06e.js?vsn=d"></script>
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</body>
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</html>
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```
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## Removing the sample app deployment
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To remove the sample app from your cluster, delete the service record:
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```shell
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kubectl delete --filename service.yaml
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```
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