Continuing this short series of writing a simple echo service web API along with the docker and k8s requirements, we\u2019re now going to turn our attention to a Elixir implementation.<\/p>\n
Implementation<\/strong><\/p>\n I’m going to be using Visual Code and dev containers, so I created a folder echo_service which has a folder named .devcontainer with the following devcontainer.json<\/em><\/p>\n Next I opened Visual Code in the echo_service folder and it should detect the devtonainer and ask if you want to reopen in the devcontainer. To which we do.<\/p>\n I’m going to use Phoenix Server (phx), so I open the terminal in Visual Code and run the following<\/p>\n When this prompt appears, type y<\/p>\n Next we need to add a couple of controllers (well we could just use one but I’m going to create a Echo controller and a Health controller). So in lib\/echo_service_web\/controllers add the files echo_controller.ex and health_controller.ex<\/p>\n The echo_controller.ex looks like this<\/p>\n The health_controller.exe should look like this<\/p>\n In the parent folder (i.e. lib\/echo_service_web) edit the router.exe so it looks like this<\/p>\n Now we can run mix phx.server<\/em> again (ctrl+c twice to shut any existing running instance).<\/p>\n Dockerfile<\/strong><\/p>\n Next up we need to create our Dockerfile<\/p>\n Note: In Linux port 80 might be locked down, hence we use port 8080 – to override the default port in phx we also set the environment variable PORT.<\/p>\n To build this, run<\/p>\n Don\u2019t forget to change the name to your preferred name.<\/p>\n To test this, run<\/p>\n Kubernetes<\/strong><\/p>\n If all wen well we’ve not tested our application and see it working from a docker image, so now we need to create the deployment etc. for Kubernete’s. Let’s assume you’ve pushed you image to Docker or another container registry such as Azure – I’m call my container registry putridparrotreg<\/em>.<\/p>\n I’m also not going to use helm at this point as I just want a (relatively) simple yaml file to run from kubectl, so create a deployment.yaml file, we’ll store all the configurations, deployment, service and ingress in this one file jus for simplicity.<\/p>\n\r\n{\r\n "image": "elixir",\r\n "forwardPorts": [3000]\r\n}\r\n<\/pre>\n\n
\r\nmix archive.install hex phx_new\r\n<\/pre>\n<\/li>\n
\r\nmix phx.new echo_service --no-html --no-ecto --no-mailer --no-dashboard --no-assets --no-gettext\r\n<\/pre>\n
\r\nFetch and install dependencies? [Yn]\r\n<\/pre>\n<\/li>\n
\r\nmix phx.server\r\n<\/pre>\n<\/li>\n<\/ul>\n
\r\ndefmodule EchoServiceWeb.EchoController do\r\n use Phoenix.Controller, formats: [:html, :json]\r\n\r\n def index(conn, %{"text" => text}) do\r\n send_resp(conn, 200, "Elixir Echo: #{text}")\r\n end\r\nend\r\n<\/pre>\n\r\ndefmodule EchoServiceWeb.HealthController do\r\n use Phoenix.Controller, formats: [:html, :json]\r\n\r\n def livez(conn, _params) do\r\n send_resp(conn, 200, "Live")\r\n end\r\n\r\n def readyz(conn, _params) do\r\n send_resp(conn, 200, "Ready")\r\n end\r\nend\r\n<\/pre>\n
\r\ndefmodule EchoServiceWeb.Router do\r\n use EchoServiceWeb, :router\r\n\r\n pipeline :api do\r\n plug :accepts, ["json"]\r\n end\r\n\r\n scope "\/", EchoServiceWeb do\r\n # pipe_through :api\r\n get "\/echo", EchoController, :index\r\n get "\/livez", HealthController, :livez\r\n get "\/readyz", HealthController, :readyz\r\n end\r\nend\r\n<\/pre>\n
\r\nFROM elixir:latest\r\n\r\nRUN mkdir \/app\r\nCOPY . \/app\r\nWORKDIR \/app\r\n\r\nRUN mix local.hex --force\r\nRUN mix do compile\r\n\r\nENV PORT=8080\r\nEXPOSE 8080\r\n\r\nCMD ["mix", "phx.server"]\r\n<\/pre>\n
\r\ndocker build -t putridparrot.echo_service:v1 .\r\n<\/pre>\n
\r\ndocker run -p 8080:8080 putridparrot.echo_service:v1\r\n<\/pre>\n
\r\napiVersion: apps\/v1\r\nkind: Deployment\r\nmetadata:\r\n name: echo\r\n namespace: dev\r\n labels:\r\n app: echo\r\nspec:\r\n replicas: 1\r\n selector:\r\n matchLabels:\r\n app: echo\r\n template:\r\n metadata:\r\n labels:\r\n app: echo\r\n spec:\r\n containers:\r\n - name: echo\r\n image: putridparrotreg\/putridparrot.echo_service:v1\r\n ports:\r\n - containerPort: 8080\r\n resources:\r\n requests:\r\n memory: "100Mi"\r\n cpu: "100m"\r\n limits:\r\n memory: "200Mi"\r\n cpu: "200m"\r\n livenessProbe:\r\n httpGet:\r\n path: \/livez\r\n port: 8080\r\n initialDelaySeconds: 30\r\n periodSeconds: 10\r\n readinessProbe:\r\n httpGet:\r\n path: \/readyz\r\n port: 8080\r\n initialDelaySeconds: 5\r\n periodSeconds: 5\r\n\r\n---\r\napiVersion: v1\r\nkind: Service\r\nmetadata:\r\n name: echo_service\r\n namespace: dev\r\n labels:\r\n app: echo\r\nspec:\r\n type: ClusterIP\r\n selector:\r\n app: echo \r\n ports:\r\n - name: http\r\n port: 80\r\n targetPort: 8080\r\n protocol: TCP\r\n---\r\napiVersion: networking.k8s.io\/v1\r\nkind: Ingress\r\nmetadata:\r\n name: echo-ingress\r\n namespace: dev\r\n annotations:\r\n kubernetes.io\/ingress.class: "nginx"\r\n nginx.ingress.kubernetes.io\/rewrite-target: \/\r\nspec:\r\n rules:\r\n - host: mydomain.com\r\n http:\r\n paths:\r\n - path: \/\r\n pathType: Prefix\r\n backend:\r\n service:\r\n name: echo_service\r\n port:\r\n number: 80\r\n<\/pre>\n