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      Rancher

      How to Deploy Kubernetes on Linode with Rancher 2.2


      Updated by Linode Written by Linode

      Rancher title graphic.

      What is Rancher?

      Rancher is a web application that provides an interactive and easy-to-use GUI for creating and managing Kubernetes clusters. Rancher has plugins for interacting with multiple cloud hosts, including Linode, and you can manage clusters across different hosting providers.

      Rancher also maintains a curated list of apps that offer simple configuration options and a click-to-deploy interface. If you prefer to deploy your apps from a Helm chart, you can do that too.

      Guide Outline

      This guide will show how to:

      • Install Rancher on a Linode

      • Deploy a Kubernetes cluster on Linode using Rancher

      • Deploy an app from the Rancher app library to your cluster

      • Take advantage of the Linode CCM and CSI for Kubernetes via Rancher.

      If you are not familiar with Kubernetes and container deployments, we recommend that you review our other guides on these subjects first.

      Caution

      This guide’s example instructions will create several billable resources on your Linode account. If you do not want to keep using the example cluster that you create, be sure to remove it when you have finished the guide.

      If you remove the resources afterward, you will only be billed for the hour(s) that the resources were present on your account.

      If You Already Run Rancher

      If you already run Rancher and would like to start creating clusters on Linode, you can skip to the Activate the Linode Node Driver and Deploy a Kubernetes Cluster sections. The Deploy an App section will show how you can take advantage of the Linode CCM and CSI.

      You may need to update your local Rancher installation to see the Linode node driver as an option.

      Before You Begin

      The Rancher web application will run on a Linode in your Cloud Manager account. Create and prepare the Linode that will run Rancher:

      1. Create a Linode running Ubuntu 18.04 in the data center of your choice. Follow the Getting Started guide for instructions on setting up your server. It is recommended that you create a 2GB Linode or larger.

        Note

        You will be able to create Kubernetes clusters in any Linode data center from the Rancher UI, even if your Rancher Linode is located in a different region.

      2. The Rancher web application is run inside a Docker container, so you will also need to install Docker CE on your Linode. Follow the instructions for installing Docker CE on Ubuntu 18.04 and then return to this guide.

      You will also need to generate an API token and prepare a domain zone:

      1. Rancher will need a Linode APIv4 token from your Linode account in order to create your cluster. Review the instructions from the Getting Started with the Linode API guide to get a token.

      2. The Set Up DNS section of this guide will assign an address to this guide’s example app. In order to do so, you must already have a domain zone created in the Linode Cloud Manager. If you do not have a zone created, review the instructions from our DNS Manager guide.

        Note

        If you haven’t purchased a domain name, then you can read along with the DNS section of this guide without implementing it in your own cluster.

      Install Rancher

      After you have your Linode up and running with Docker, you can then install and run Rancher:

      1. Log in to your Linode via SSH:

        ssh your_user@192.0.2.0
        
      2. Create a rancher directory inside /opt; this folder will hold settings and keys for Rancher:

        sudo mkdir -p /opt/rancher
        
      3. Run Rancher:

        docker run -d -p 80:80 -p 443:443 
          --restart=unless-stopped 
          -v /opt/rancher:/var/lib/rancher 
          rancher/rancher:latest
        
        • The --restart option ensures that the application will be restarted if the Linode is ever rebooted.
        • The -v option binds the /opt/rancher directory on the Linode to the container so that the application can persist its data.
      4. Visit your Linode’s IP address in your browser. Your browser will display an SSL certificate warning, but you can bypass it.

        Note

        If you are interested in setting up an SSL certificate with Rancher, you may consider also creating an NGINX container with an SSL certificate that proxies traffic to the Rancher container.

      5. You should see a welcome screen from Rancher. Enter a new password for the default administrative user for Rancher (which is named admin) and click Continue:

        Rancher first load screen

      6. The server URL entry form will appear, which should already show your Rancher server’s IP address. Click the Save URL button to continue:

        Rancher enter server URL screen

      7. The default home page for your Rancher app will appear. This page normally displays a list of all of your Kubernetes clusters. Since you have not created a cluster yet, a placeholder image is shown instead:

        Rancher enter server URL screen

        Note

        The main interface for navigating Rancher is via the blue navigation bar that spans the top of the page. The items in this navigation bar will change when you view different parts of the application.

      8. Before you can create your first cluster, you will need to enable Linode’s integration with Rancher. Proceed to the Activate the Linode Node Driver for Rancher section.

      Activate the Linode Node Driver for Rancher

      Rancher includes two kinds of integrations with hosting providers:

      • A cluster driver allows Rancher to create and administer a cloud host-launched Kubernetes cluster. In a host-launched Kubernetes cluster, your hosting platform operates the new cluster’s control plane and etcd components, while you provision and configure your worker nodes (via Rancher as well).

      • A node driver allows Rancher to create and administer a Rancher-launched Kubernetes cluster. Rancher will directly provision your control plane and etcd nodes along with your worker nodes. Your cloud host does not manage your control plane and etcd components.

      Rancher is shipped with a node driver for Linode, but it is inactive by default. To activate the Linode node driver:

      1. Click on Tools from the main navigation bar and select Drivers from the dropdown menu.

        Rancher Drivers menu option highlighted

      2. Click on the Node Drivers tab:

        Rancher Node Drivers tab highlighted

      3. Scroll down to Linode’s driver. Click the corresponding more options ellipsis and click on the Activate item in the dropdown menu that appears:

        Rancher activate Linode node driver

      4. Activating the Linode node driver does not install the Linode CCM and CSI for your new clusters. Further instructions for enabling these features are listed in the Deploy a Kubernetes Cluster section. You should wait until the node driver is listed as Active before moving on.

        What are the Linode CCM and CSI?

        The CCM (Cloud Controller Manager) and CSI (Container Storage Interface) are Kubernetes addons published by Linode. These addons provide additional integrations with the Linode cloud platform. Specifically, you can use them to create NodeBalancers, DNS records, and Block Storage Volumes.

      Deploy a Kubernetes Cluster

      Add a Node Template

      Node templates are used by Rancher to provision cluster nodes. When you create a node template, you can specify configuration parameters, like the region, instance type, and Linux image that should be used for any node in the cluster. You can set different templates for different clusters, which allows you to choose the right resources for your different workloads.

      Before provisioning your cluster, you will need to add the node template it will use. To add a node template:

      1. Click on your User Avatar icon in the upper right-hand corner and select Node Templates.

        Click on the User Avatar icon

      2. On the Node Templates page, click on the Add Template button in the upper right-hand corner.

      3. The Add Node Template dialog will appear, select Linode from the list of providers and enter in your Linode APIv4 token in the API Token field.

        Add Node Template dialog window

      4. Click on the Next: Configure Instances button.

      5. Another dialog will appear which accepts options for your new node template. Under the Instance Options section, set the preferred region, instance type, and Linux image for your nodes, along with any Cloud Manager tags you’d like to apply to your nodes.

        Rancher Add Node Template form - Linode options

        Note

        We recommend that you choose a Linode 2GB or higher for the nodes in a Kubernetes cluster. The Block Storage service has not been deployed to our Atlanta (US-Southeast) data center. Since this guide will use Block Storage Volumes in its example cluster, please choose a different region when creating your node template.

      6. Enter a name for your template. This can be arbitrary, but it’s helpful to call it something that will help you remember the options you set in the template form, like newark-linode8gb-ubuntu1804.

        Rancher Add Node Template form - template name

      7. When finished with the form, click the Create button.

        Note

        All other node template settings are optional and will not be used in this guide. You do not need to set a password for the nodes created through this template; Rancher will generate one automatically. As well, Rancher provides command-line access to the Kubernetes API for your cluster, so logging into your nodes generally isn’t needed.

      8. You will be returned to the Node Templates page where your node template will be visible.

        Rancher Node Template list page

      Provision a Cluster

      1. Return to the home page by hovering over the Global dropdown menu in the main navigation bar and then clicking the Global menu item:

        Rancher return to the global view

      2. Click on the Add Cluster button. The Add Cluster form will appear.

      3. Select the Linode driver from the From nodes in an infrastructure provider section:

        Rancher Add Cluster form - Linode node driver selected

      4. Enter a name for your cluster in the Cluster Name field. The name for our example cluster will be example-cluster.

      5. In the Node Pools section, under the Template column, you should see the node template you created in the previous section of this guide. Set a value for the Name Prefix field. For each Linode that Rancher creates for that node pool, the Linode will be prefixed according to the name you set (e.g. if the name prefix is example-cluster-, then your Linodes will be named example-cluster-1, example-cluster-2, etc.

        Rancher Add Cluster form - Add Node Template button highlighted

        • A node pool is Rancher’s method for creating the nodes (Linodes) that form your cluster. You specify how many nodes should be in a node pool, along with the node template for those nodes in that pool. If Rancher later detects that one of the nodes has lost connectivity with the cluster, it will automatically create a new one.

        • When configuring a node pool, you also specify which of your cluster’s components operate on the nodes in the pool. For example, you can have one pool that only runs your cluster’s etcd database, another pool which only runs your control plane components (the Kubernetes API server, scheduler, and controller manager), and a third pool which runs your application workloads.

      6. Set the value for the Count field to 3. Rancher will create 3 Linodes for the node pool.

      7. Toggle on the checkboxes for etcd, Control Plane, and Worker. In our example cluster, the nodes for this node pool will run each of these components. Your configured form should look like the following:

        Rancher Add Node Template form - single node pool configuration

        Note

        When you set up a cluster for production, avoid having a node pool that runs your workloads alongside your etcd or control plane components. An example node pool configuration which splits the etcd and control plane components from your workloads would look like the following:

        Rancher Add Node Template form - example production node pool configuration

        Review Rancher’s Production Ready Cluster documentation for more guidance on setting up production clusters.

      8. The last part in creating your cluster is to configure Linode’s CCM and CSI. In the Cluster Options section, toggle on the Custom option for the Cloud Provider field, then click on the Edit as YAML button above the section.

        Rancher Add Node Template form - example production node pool configuration

      9. A text editor will appear:

        Rancher Add Cluster form - YAML editor

      10. Insert the following snippet before the first line in the editor (above the addon_job_timeout declaration):

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        addons_include:
          - https://linode.github.io/rancher-ui-driver-linode/releases/v0.2.0/linode-addons.yml
        addons: |-
          ---
          apiVersion: v1
          kind: Secret
          metadata:
            name: linode
            namespace: kube-system
          stringData:
            token: "..."
            region: "..."
          ---
      11. Insert your Linode APIv4 token in the token field from this snippet. Also, enter the label for your node template’s data center in the region field. This label should be lower-case (e.g. us-east instead of US-East).

      12. Scroll down in the editor to the services section. Remove the existing services section and replace it with this snippet:

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        services:
          etcd:
            backup_config:
              interval_hours: 12
              retention: 6
            creation: "12h"
            extra_args:
              heartbeat-interval: 500
              election-timeout: 5000
            retention: "72h"
            snapshot: true
          kube-api:
            always_pull_images: false
            pod_security_policy: false
            service_node_port_range: "30000-32767"
            extra_args:
              feature-gates: "PersistentLocalVolumes=true,VolumeScheduling=true,CSINodeInfo=true,CSIDriverRegistry=true,BlockVolume=true,CSIBlockVolume=true"
          kubelet:
            fail_swap_on: false
            extra_args:
              cloud-provider: "external"
              feature-gates: "PersistentLocalVolumes=true,VolumeScheduling=true,CSINodeInfo=true,CSIDriverRegistry=true,BlockVolume=true,CSIBlockVolume=true"
          kube-controller:
            extra_args:
              cloud-provider: "external"
      13. After you finish with both of these steps, your YAML should resemble this completed snippet.

        Note

        Avoid copying and pasting the entire completed snippet example, as it has some variable values outside of the addons_include, addons, and services sections that may not match your deployment (e.g. the kubernetes_version setting).

        Instead, compare your YAML file with the completed example to ensure you have inserted the addons_include, addons, and services sections in the right places.

      14. Click the Create button below the YAML editor. You will be returned to the global home page, and your new cluster will be listed (in the Provisioning state):

        Rancher Global home page with new cluster listed

      15. If you visit the list of your Linodes in the Linode Cloud Manager, you will see the new nodes in your cluster:

        Linode Cloud Manager - new cluster nodes

        Note

        If your nodes do not not appear in the Linode Cloud Manager as expected, then you may have run into a limit on the number of resources allowed on your Linode account. Contact Linode Support if you believe this may be the case.

      Explore the New Cluster

      1. To inspect your new cluster, click on its name in the global list of clusters:

        Rancher home page - new cluster highlighted

        Or, hover over the Global menu and then select the name of the new cluster:

        Rancher cluster selection menu

      2. Your cluster’s dashboard will appear. If it is still provisioning, it will display a placeholder graphic:

        Rancher cluster dashboard

      3. Note that the items in the main navigation bar will change when viewing a cluster:

        Rancher navigation bar - cluster mode

      4. Click on the Nodes main menu item:

        Rancher cluster navigation bar - Nodes highlighted

      5. A list of your cluster’s nodes will appear. If they are still provisioning, they will be labelled with the most recent step in the provisioning sequence:

        Rancher cluster nodes list - provisioning

        When the nodes finish provisioning, the Active label will be displayed:

        Rancher cluster nodes list - active

      6. When your nodes have finished provisioning, click the Cluster item in the navigation bar to navigate back to the dashboard. A summary of the cluster’s resource usage is displayed:

        Rancher cluster dashboard

      Load the Kubectl Command Line

      In addition to managing your cluster via Rancher’s interactive UI, Rancher also provides command-line access to your cluster’s Kubernetes API:

      • From your cluster’s dashboard, click the Launch kubectl button:

        Rancher cluster dashboard - kubectl button highlighted

        A new dialog will appear with a command-line prompt. You are able to use kubectl to interact with your cluster:

        Rancher kubectl web CLI

      • Alternatively, you can use the kubectl CLI from your local computer if you have it installed. From your cluster’s dashboard in Rancher, click on the Kubeconfig File button:

        Rancher cluster dashboard - kubeconfig button highlighted

        A new dialog will appear with the correct kubeconfig for your cluster. Copy the contents of the configuration to a file on your computer. Then, pass it as an option when using the CLI:

        kubectl --kubeconfig /path/to/your/local/kube.config get pods
        

      Rancher Projects

      Rancher introduces an organizational concept called projects. Projects group together Kubernetes namespaces and allows you to perform actions across all namespaces in a project, like adjusting administrative access to them.

      1. To view your cluster’s projects, click on the cluster selection menu in Rancher’s navigation bar, then hover over your cluster in the dropdown menu’s Clusters list:

        Rancher cluster selection menu - list of projects

        A new cluster created through Rancher will have a Default project and a System project.

      2. Options for creating new projects are exposed under the navigation bar’s Projects/Namespaces item:

        Rancher cluster navigation bar - Projects/Namespaces highlighted

        However, this guide will deploy its example app to the Default project.

      3. Navigate to the Default project. Click on the cluster selection menu in Rancher’s navigation bar, then hover over your cluster in the dropdown menu’s Clusters list, and then click on the Default item that appears:

        Rancher cluster selection menu - Default project highlighted

      4. The Workloads view for the project will appear, but it will be empty, as no apps have been deployed yet. Also, note that the items in the navigation bar will change when viewing a project:

        Rancher navigation bar - project mode

      Deploy an App from the Rancher App Library

      Rancher provides a library of apps which offer easy setup through Rancher’s UI. The apps in this curated library are based on existing Helm charts.

      A Helm chart is a popular format for describing Kubernetes resources. Rancher extends the Helm chart format with some additional configuration files, and this extended packaging is referred to as a Rancher chart. The additional information in the Rancher chart format is used to create interactive forms for configuring the app through the Rancher UI.

      Note

      It is possible to enable more app catalogs than just Rancher’s curated library, including a catalog of stable Helm charts. These other apps will not feature Rancher’s easy setup forms and will instead require manual entry of configuration options.

      To test out deploying an app on your new cluster, launch the WordPress app from the Rancher library. This app will also take advantage of Linode’s Block Storage, NodeBalancer, and DNS services (via the CCM and CSI):

      1. From the Default project in your new cluster, click on the Apps item in the navigation bar:

        Rancher project navigation bar - Apps highlighted

      2. The Apps view for your project will appear, but it will show a placeholder image because no apps have been deployed yet. Click on this view’s Launch button.

      3. A list of apps will appear. Scroll down to the WordPress app and click its View Details button:

        WordPress app in Rancher app library catalog

      4. The setup form for the WordPress app will appear. In the WordPress Settings section, enter a username, password, and email for your WordPress admin user:

        Rancher WordPress setup form - WordPress Settings

        Note

        Avoid using symbols in the password you enter, as some symbols can cause syntax errors for this Rancher chart.

      5. In the Database Settings section, enter a password for WordPress’ database user. Then set MariaDB Persistent Volume Enabled to True and select the linode-block-storage option from the Default StorageClass for MariaDB dropdown menu:

        Rancher WordPress setup form - Database Settings

        These settings will result in your database deployment keeping its data in a Linode Block Storage Volume.

        Note

        The default value for the MariaDB Volume Size field is 8GiB, but the minimum size for a Block Storage Volume is 10Gib. The Linode CSI will automatically upgrade any persistent volume claims that are smaller than 10GiB to 10GiB.

      6. In the Services and Load Balancing section, set Expose app using Layer 7 Load Balancer to False, then choose the L4 Balancer option from the WordPress Service Type dropdown menu:

        Rancher WordPress setup form - Services and Load Balancing Settings

        Selecting the L4 Balancer option will result in the creation of a Linode NodeBalancer.

      7. Click the Launch button at the bottom of the form.

      8. You will be directed back to the project’s Apps view, where your new WordPress app will be listed. The listing will show a red bar with the number 2 below it. 2 represents the number of pods in the app, and the red color indicates that they are not available yet.

      9. Click on the name of the app:

        Rancher deployed apps list - WordPress app in middle of provisioning

      10. A detail view for the app will appear. The Workloads section will show the MariaDB and WordPress deployments for your app. They may still be in the middle of provisioning:

        Rancher app detail view - Workloads section

        When the deployments finish provisioning, they will display the Active label and the red bars under the Scale column will turn green.

      11. The Endpoints section displays the address of the NodeBalancer that was created for your app. After your deployments have finished provisioning, click on the HTTP NodeBalancer endpoint:

        Rancher app detail view - NodeBalancer HTTP endpoint highlighted

        Your WordPress site should open in a new browser tab.

      12. Visit the wp-login.php page on your site (e.g. at http://your-nodebalancer-name.newark.nodebalancer.linode.com/wp-login.php). You should be able to login with the WordPress admin username and password you specified earlier in the app’s form.

        Note

        If you view the Volumes and NodeBalancers areas of the Linode Cloud Manager, you should see the new Volume and NodeBalancer that were created for this app. They will have random alphanumeric names like pvc77e0c083490411e9beabf23c916b1.

      Set Up DNS for the WordPress App

      You can currently visit your new app from the NodeBalancer’s generic subdomain. With the Linode CCM, it’s also possible to assign a custom domain or subdomain to your app:

      1. In the detail view for your WordPress app, scroll down to the Services section.

      2. Click on the more options ellipsis for the wordpress-wordpress service, then click on the View/Edit YAML item in the dropdown menu that appears:

        Rancher Services section - View/Edit YAML option highlighted

      3. A YAML editor for the service will appear. Find the annotations section under the metadata sections, then insert this line:

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        metadata:
          annotations:
            external-dns.alpha.kubernetes.io/hostname: wordpress.example.com

        Replace wordpress.example.com with the address you want to use for your app. As a reminder, example.com needs to exist as a domain zone on your Linode account. If you’re not sure if you’ve inserted the new line in the right location, compare your YAML with this snippet of an updated metadata section.

      4. Click the Save button below the YAML editor.

      5. The Linode CCM will create a DNS record in your domain’s zone and automatically assign the IP of your NodeBalancer to it. If you visit the domain’s zone in the Linode Cloud Manager, the new A record should appear.

      6. It may take some time for Linode’s DNS database to update, so if you don’t see the record show up in the Cloud Manager immediately, try refreshing it after a few minutes.

        After the record becomes visible in the Cloud Manager, it can also take time for the DNS change to propagate to your local ISP. After the DNS change has propagated, you should be able to view your WordPress app by navigating to the address you set up.

      Scaling your Cluster and App

      Rancher makes it easy to scale the number of nodes in your cluster and to scale the number of replica pods in your app’s deployments.

      Scale your Cluster

      Caution

      The example instructions in this section will add nodes to your cluster, which will add further billable services to your account. You can read these instructions without performing them on your own account if you prefer.

      1. Return to the home page by hovering over the Global dropdown menu in the main navigation bar and then clicking the Global menu item:

        Rancher return to the global view

      2. Your cluster will show up on the page that appears. Click on the more options ellipsis corresponding to the cluster and then click on the Edit item from the dropdown menu:

        Rancher global list of clusters - Edit option highlighted

      3. The same form that you completed when creating your cluster will appear. In the Node Pools section, increase the count of your pool:

        Rancher edit cluster form - node pool count highlighted

        Note

        Your example cluster’s nodes all run etcd, so you can only scale the node pool to a count of 1, 3, or 5. If you had a separate node pool for your workloads, you could scale it freely to any count.

      4. Click the Save button at the bottom of the form. You will be redirected to the dashboard for the cluster.

      5. The dashboard will report that the cluster is updating. When the new nodes have finished provisioning and are registered with Kubernetes, the dashboard will show that all components and nodes are responding normally.

      Scale your App

      Rancher also provides an easy way to scale your app’s deployments:

      1. Navigate to the Default project of your cluster:

        Rancher cluster selection menu - Default project highlighted

      2. Click on the Apps item in the navigation bar:

        Rancher project navigation bar - Apps highlighted

      3. Click on the name of the WordPress app:

        Rancher deployed apps list - WordPress app completed provisioning

      4. In the Workloads section, click on the wordpress-wordpress link in the Name column for that deployment:

        Rancher WordPress workloads - deployment name highlighted

      5. A detail view for the deployment will appear. In the Config Scale section at the top, click on the + button to increase the replica count for the deployment by one (to a total of 2):

        Rancher WordPress deployment detail view - config scale highlighted

      6. A second pod will appear in the Pods section on this page, and there will be an Updating label at the top of the page. You may see a series of warning messages about the new pod not being available. Eventually, the new pod will be labelled as Running.

      Set Up GitHub Authentication

      In addition to manually creating users that can access your Rancher application, you can also enable GitHub authentication and then invite GitHub users:

      1. From the Global home page, click on the Security item in the navigation bar and then select Authentication from the dropdown menu:

        Rancher Security navigation bar item - Authentication highlighted

      2. Choose GitHub from the authentication options listed:

        Rancher Authentication page - GitHub option selected

      3. In a new browser window, visit the developer settings of your account on the GitHub website. Click the Register a new application button under the OAuth Apps section.

      4. Fill out the form that appears. Use the values that Rancher lists under the Authentication page that you have open in your original browser window, then click the Register application button:

        Rancher generated GitHub OAuth form values

      5. You will be directed to the detail view for your new OAuth application. Copy the ClientID and Client Secret values displayed on this page. Paste these into the form at the bottom of Rancher’s Authentication page:

        Rancher Authentication page - Client ID and Secret form

      6. Click the Authenticate with GitHub button. A new browser window will appear that asks you to confirm the access request.

      7. Confirm the access request. Rancher will show a new page with further options for controlling access to your Rancher site.

      8. To invite GitHub users to your Rancher site, enter them in the search field in the Site Access section and select the correct user from the search results. Then, click the Save button:

        Rancher Authentication page - search for and add GitHub users

      Removing the Cluster

      To remove the cluster:

      1. Navigate to the Global home page.

      2. Click on the more options ellipsis for your cluster, then select the Delete option from the dropdown menu that appears:

        Rancher global cluster list - delete option highlighted

      3. Confirm in the Linode Cloud Manager that all the Linodes, Volumes, NodeBalancers, and DNS records from the cluster are deleted.

      More Information

      You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.

      Find answers, ask questions, and help others.

      This guide is published under a CC BY-ND 4.0 license.



      Source link

      How To Set Up Multi-Node Deployments With Rancher 2.1, Kubernetes, and Docker Machine on Ubuntu 18.04


      The author selected Code Org to receive a donation as part of the Write for DOnations program.

      Introduction

      Rancher is a popular open-source container management platform. Released in early 2018, Rancher 2.X works on Kubernetes and has incorporated new tools such as multi-cluster management and built-in CI pipelines. In addition to the enhanced security, scalability, and straightforward deployment tools already in Kubernetes, Rancher offers a graphical user interface that makes managing containers easier. Through Rancher’s GUI, users can manage secrets, securely handle roles and permissions, scale nodes and pods, and set up load balancers and volumes without needing a command line tool or complex YAML files.

      In this tutorial, you will deploy a multi-node Rancher 2.1 server using Docker Machine on Ubuntu 18.04. By the end, you’ll be able to provision new DigitalOcean Droplets and container pods via the Rancher UI to quickly scale up or down your hosting environment.

      Prerequisites

      Before you start this tutorial, you’ll need a DigitalOcean account, in addition to the following:

      • A DigitalOcean Personal Access Token, which you can create following the instructions in this tutorial. This token will allow Rancher to have API access to your DigitalOcean account.

      • A fully registered domain name with an A record that points to the IP address of the Droplet you create in Step 1. You can learn how to point domains to DigitalOcean Droplets by reading through DigitalOcean’s Domains and DNS documentation. Throughout this tutorial, substitute your domain for example.com.

      Step 1 — Creating a Droplet With Docker Installed

      To start and configure Rancher, you’ll need to create a new Droplet with Docker installed. To accomplish this, you can use DigitalOcean’s Docker image.

      First, log in to your DigitalOcean account and choose Create Droplet. Then, under the Choose an Image section, select the Marketplace tab. Select Docker 18.06.1~ce~3 on 18.04.

      Choose the Docker 18.06 image from the One-click Apps menu

      Next, select a Droplet no smaller than 2GB and choose a datacenter region for your Droplet.

      Finally, add your SSH keys, provide a host name for your Droplet, and press the Create button.

      It will take a few minutes for the server to provision and for Docker to download. Once the Droplet deploys successfully, you’re ready to start Rancher in a new Docker container.

      Step 2 — Starting and Configuring Rancher

      The Droplet you created in Step 1 will run Rancher in a Docker container. In this step, you will start the Rancher container and ensure it has a Let’s Encrypt SSL certificate so that you can securely access the Rancher admin panel. Let’s Encrypt is an automated, open-source certificate authority that allows developers to provision ninety-day SSL certificates for free.

      Log in to your new Droplet:

      To make sure Docker is running, enter:

      Check that the listed Docker version is what you expect. You can start Rancher with a Let's Encrypt certificate already installed by running the following command:

      • docker run -d --restart=unless-stopped -p 80:80 -p 443:443 -v /host/rancher:/var/lib/rancher rancher/rancher --acme-domain example.com

      The --acme-domain option installs an SSL certificate from Let's Encrypt to ensure your Rancher admin is served over HTTPS. This script also instructs the Droplet to fetch the rancher/rancher Docker image and start a Rancher instance in a container that will restart automatically if it ever goes down accidentally. To ease recovery in the event of data loss, the script mounts a volume on the host machine (at /host/rancher) that contains the Rancher data.

      To see all the running containers, enter:

      You'll see output similar to the following (with a unique container ID and name):

      Output

      CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 7b2afed0a599 rancher/rancher "entrypoint.sh" 12 seconds ago Up 11 seconds 0.0.0.0:80->80/tcp, 0.0.0.0:443->443/tcp wizardly_fermat

      If the container is not running, you can execute the docker run command again.

      Before you can access the Rancher admin panel, you'll need to set your admin password and Rancher server URL. The Rancher admin interface will give you access to all of your running nodes, pods, and secrets, so it is important that you use a strong password for it.

      Go to the domain name that points to your new Droplet in your web browser. The first time you visit this address, Rancher will let you set a password:

      Set your Rancher password using the prompt

      When asked for your Rancher server URL, use the domain name pointed at your Droplet.

      You have now completed your Rancher server setup, and you will see the Rancher admin home screen:

      The Rancher admin home screen

      You're ready to continue to the Rancher cluster setup.

      Step 3 — Configuring a Cluster With a Single Node

      To use Rancher, you'll need to create a cluster with at least one node. A cluster is a group of one or more nodes. This guide will give you more information about the Kubernetes Architecture. In this tutorial, nodes correspond to Droplets that Rancher will manage. Pods represent a group of running Docker containers within the Droplet. Each node can run many pods. Using the Rancher UI, you can set up clusters and nodes in an underlying Kubernetes environment.

      By the end of this step, you will have set up a cluster with a single node ready to run your first pod.

      In Rancher, click Add Cluster, and select DigitalOcean as the infrastructure provider.

      Select DigitalOcean from the listed infrastructure providers

      Enter a Cluster Name and scroll down to the Node Pools section. Enter a Name Prefix, leave the Count at 1 for now, and check etcd, Control Plane, and Worker.

      • etcd is Kubernetes' key value storage system for keeping your entire environment's state. In order to maintain high availability, you should run three or five etcd nodes so that if one goes down your environment will still be manageable.
      • Control Plane checks through all of the Kubernetes Objects — such as pods — in your environment and keeps them up to date with the configuration you provide in the Rancher admin interface.
      • Workers run the actual workloads and monitoring agents that ensure your containers stay running and networked. Worker nodes are where your pods will run the software you deploy.

      Create a Node Pool with a single Node

      Before creating the cluster, click Add Node Template to configure the specific options for your new node.

      Enter your DigitalOcean Personal Access Token in the Access Token input box and click Next: Configure Droplet.

      Next, select the same Region and Droplet Size as Step 1. For Image, be sure to select Ubuntu 16.04.5 x64 as there's currently a compatibility issue with Rancher and Ubuntu 18.04. Hit Create to save the template.

      Finally, click Create at the Add Cluster page to kick off the provisioning process. It will take a few minutes for Rancher to complete this step, but you will see a new Droplet in your DigitalOcean Droplets dashboard when it's done.

      In this step, you've created a new cluster and node onto which you will deploy a workload in the next section.

      Step 4 — Deploying a Web Application Workload

      Once the new cluster and node are ready, you can deploy your first pod in a workload. A Kubernetes Pod is the smallest unit of work available to Kubernetes and by extension Rancher. Workloads describe a single group of pods that you deploy together. For example, you may run multiple pods of your webserver in a single workload to ensure that if one pod slows down with a particular request, other instances can handle incoming requests. In this section, you're going to deploy a Nginx Hello World image to a single pod.

      Hover over Global in the header and select Default. This will bring you to the Default project dashboard. You'll focus on deploying a single project in this tutorial, but from this dashboard you can also create multiple projects to achieve isolated container hosting environments.

      To start configuring your first pod, click Deploy.

      Enter a Name, and put nginxdemos/hello in the Docker Image field. Next, map port 80 in the container to port 30000 on the host nodes. This will ensure that the pods you deploy are available on each node at port 30000. You can leave Protocol set to TCP, and the next dropdown as NodePort.

      Note: While this method of running the pod on every node's port is easier to get started, Rancher also includes Ingress to provide load balancing and SSL termination for production use.

      The input form for deploying a Workload

      To launch the pod, scroll to the bottom and click Launch.

      Rancher will take you back to the default project home page, and within a few seconds your pod will be ready. Click the link 30000/tcp just below the name of the workload and Rancher will open a new tab with information about the running container's environment.

      Server address, Server name, and other output from the running NGINX container

      The Server address and port you see on this page are those of the internal Docker network, and not the public IP address you see in your browser. This means that Rancher is working and routing traffic from http://first_node_ip:30000/ to the workload as expected.

      At this point, you've successfully deployed your first workload of one pod to a single Rancher node. Next, you'll see how to scale your Rancher environment.

      Step 5 — Scaling Nodes and Pods

      Rancher gives you two ways to scale your hosting resources: increasing the number of pods in your workload or increasing the number of nodes in your cluster.

      Adding pods to your workload will give your application more running processes. This will allow it to handle more traffic and enable zero-downtime deployments, but each node can handle only a finite number of pods. Once all your nodes have hit their pod limit, you will have to increase the number of nodes if you want to continue scaling up.

      Another consideration is that while increasing pods is typically free, you will have to pay for each node you add to your environment. In this step, you will scale up both nodes and pods, and add another node to your Rancher cluster.

      Note: This part of the tutorial will provision a new DigitalOcean Droplet automatically via the API, so be aware that you will incur extra charges while the second node is running.

      Navigate to the cluster home page of your Rancher installation by selecting Cluster: your-cluster-name from the top navigation bar. Next click Nodes from the top navigation bar.

      Use the top navbar dropdown to select your Cluster

      This page shows that you currently have one running node in the cluster. To add more nodes, click Edit Cluster, and scroll to the Node Pools section at the bottom of the page. Click Add Node Pool, enter a prefix, and check the Worker box. Click Save to update the cluster.

      Add a Node Pool as a Worker only

      Within 2–5 minutes, Rancher will provision a second droplet and indicate the node as Active in the cluster's dashboard. This second node is only a worker, which means it will not run the Rancher etcd or Control Plane containers. This allows the Worker more capacity for running workloads.

      Note: Having an uneven number of etcd nodes will ensure that they can always reach a quorum (or consensus). If you only have one etcd node, you run the risk of your cluster being unreachable if that one node goes down. In a production environment it is a better practice to run three or five etcd nodes.

      When the second node is ready, you will be able to see the workload you deployed in the previous step on this node by navigating to http://second_node_ip:30000/ in your browser.

      Scaling up nodes gives you more Droplets to distribute your workloads on, but you may also want to run more instances of each pod within a workload. To add more pods, return to the Default project page, press the arrow to the left of your hello-world workload, and click + twice to add two more pods.

      Running three Hello World Pods in a Workload

      Rancher will automatically deploy more pods and distribute the running containers to each node depending on where there is availability.

      You can now scale your nodes and pods to suit your application's requirements.

      Conclusion

      You've now set up multi-node deployments using Rancher 2.1 on Ubuntu 18.04, and have scaled up to two running nodes and multiple pods within a workload. You can use this strategy to host and scale any kind of Docker container that you need to run in your application and use Rancher's dashboard and alerts to help you maximize the performance of your workloads and nodes within each cluster.



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