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First Blog Posts (#391)
* Add new blog section to website * Add a blog on simple HA Signed-off-by: Derek Nola <derek.nola@suse.com>
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‎blog/2025-03-09-hello-blog.md‎

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---
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title: "Hello Blog"
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description: This is the first blog post on k3s.io
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authors: dereknola # Fill out your info in the authors.yml file
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# tags: ["example-tag"]
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---
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This is the first post on blog.k3s.io
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<!-- everything above is seen in the snippet on the main blog page. The truncate tag below hides the rest -->
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<!-- truncate -->
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We will explore aspects of K3s, Kubernetes, and other related topics. These long form posts will be written by the K3s team and help illuminate aspects of the project that are not easily covered in the documentation.
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Stay tuned for more posts in the future.

‎blog/2025-03-10-simple-ha.md‎

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---
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title: "The Basic HA Cluster"
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description: Creating the simplest High Availability cluster with LB and upgrading
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authors: dereknola # Fill out your info in the authors.yml file
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hide_table_of_contents: true
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---
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While we have more [detailed docs](/datastore/ha-embedded/) on setting up a High Availability (HA) cluster, this post will cover the simplest HA cluster you can create.
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<!-- truncate -->
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## Baseline HA Cluster 💻🖥️💻
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Whenever we get a question around HA, this is the cluster configuration I start with. It provides a solid foundation when deploying beyond a single server.
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Our cluster will have:
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- 4 nodes or VMs:
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- 1 load balancer
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- 3 servers
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- A k3s-upgrade plan that will automatically update the cluster to the latest patch version of a given minor.
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## Cluster Setup 🌐🔧
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I'm using `vagrant` to provision 4 Ubuntu 24.04 VMs for this setup, all on a flat network. Setup of nodes is left as an exercise for the reader 😅.
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My nodes are configured with the following names and IPs:
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| Name | IP |
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|------|----|
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| lb-0 | 10.10.10.100 |
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| server-0 | 10.10.10.50 |
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| server-1 | 10.10.10.51 |
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| server-2 | 10.10.10.52 |
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### Load Balancer
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I'm using [haproxy](https://www.haproxy.org/) as it supports later expansion to multiple LB nodes (via keepalived).
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SSH into the load balancer and install haproxy:
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```bash
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sudo apt install haproxy
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```
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The haproxy config is simple, just forward traffic to the servers:
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```
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#/etc/haproxy/haproxy.cfg
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frontend k3s
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bind *:6443
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mode tcp
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default_backend k3s
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backend k3s
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mode tcp
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option tcp-check
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balance roundrobin
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server server-0 10.10.10.50:6443 check
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server server-1 10.10.10.51:6443 check
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server server-2 10.10.10.52:6443 check
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```
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Restart haproxy to apply the config:
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```bash
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systemctl restart haproxy
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```
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### Install K3s on first server
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On the first server, install K3s with embedded etcd and a known token:
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```bash
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curl -sfL https://get.k3s.io | INSTALL_K3S_CHANNEL=v1.31 sh -s - \
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--cluster-init --token k3sblog --tls-san 10.10.10.100
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```
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We pass the `--tls-san` flag adds the load balancer IP as a Subject Alternative Name (SAN) for the certificate.
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### Join the other servers
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On the other servers, join the cluster via the load balancer:
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```bash
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curl -sfL https://get.k3s.io | INSTALL_K3S_CHANNEL=v1.31 sh -s - \
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--server https://10.10.10.100:6443 --token k3sblog
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```
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### Grab the kubeconfig
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Now that the cluster is up, we can grab the kubeconfig from the first server:
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```bash
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scp server-0:/etc/rancher/k3s/k3s.yaml k3s.yaml
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```
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Modify it to access the cluster via the load balancer:
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```bash
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sed -i 's/127.0.0.1/10.10.10.100/' k3s.yaml
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```
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No we can manage the cluster from our local machine:
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```bash
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export KUBECONFIG=$(pwd)/k3s.yaml
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kubectl get nodes
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```
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## Upgrade Plan 🏗️📝📐
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The plan I'm using will keep k3s updated to the latest patch version of the channel we give. In this case I'm using the `v1.31` channel, the same channel used above. Kubernetes v1.31.4 just released at time of writing this post, so with this plan we have stable upgrades handled for the next 10-12 months (depending on how many patch releases this minor gets).
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### Install the system-upgrade-controller
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The upgrade plan is managed by the system-upgrade-controller. Install it:
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```bash
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kubectl apply -f https://github.com/rancher/system-upgrade-controller/releases/latest/download/system-upgrade-controller.yaml
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kubectl apply -f https://github.com/rancher/system-upgrade-controller/releases/latest/download/crd.yaml
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```
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### Create the upgrade plan
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```yaml
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#server-plan.yaml
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apiVersion: upgrade.cattle.io/v1
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kind: Plan
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metadata:
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name: server-plan
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namespace: system-upgrade
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spec:
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concurrency: 1
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cordon: true
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nodeSelector:
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matchExpressions:
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- key: node-role.kubernetes.io/control-plane
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operator: In
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values:
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- "true"
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serviceAccountName: system-upgrade
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upgrade:
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image: rancher/k3s-upgrade
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channel: https://update.k3s.io/v1-release/channels/v1.31
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```
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```bash
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kubectl apply -f server-plan.yaml
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```
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See the [automated upgrade docs](/upgrades/automated) for more details.
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## Conclusion 🚀
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![kubectl summary](kubectl.png)
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We now have a high-availability cluster, accessible via a single IP. Upgrades are handled for the next year. This is a great starting point to:
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- Add agent nodes to expand our workload capacity
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- Add another load-balancer for additional redundancy

‎blog/authors.yml‎

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# No names, just github icons and links
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dereknola:
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title: K3s maintainer
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image_url: https://github.com/dereknola.png
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url: https://github.com/dereknola
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name: Derek Nola

‎blog/kubectl.png‎

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‎docusaurus.config.js‎

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docsRouteBasePath: "/",
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hashed: true,
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highlightSearchTermsOnTargetPage: true,
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indexBlog: false,
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indexBlog: true,
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ignoreFiles: [/release-notes\/.*/],
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}),
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],
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type: "localeDropdown",
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position: "right",
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},
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{
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to: 'blog',
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label: 'Blog',
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position: 'right',
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className: 'navbar__icon navbar__blog',
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},
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{
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to: 'https://github.com/k3s-io/k3s/',
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label: 'GitHub',
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position: 'right',
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className: 'navbar__github btn',
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className: 'navbar__icon navbar__github',
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},
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],
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},
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showLastUpdateTime: true,
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editUrl: 'https://github.com/k3s-io/docs/edit/main/',
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},
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blog: false, // Optional: disable the blog plugin
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blog: {
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blogTitle: 'k3s blog',
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showReadingTime: false,
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blogSidebarTitle: 'All our posts',
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blogSidebarCount: 'ALL',
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},
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// ...
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theme: {
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customCss: [require.resolve("./src/css/custom.css")],

‎src/css/custom.css‎

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* bundles Infima by default. Infima is a CSS framework designed to
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* work well for content-centric websites.
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*/
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@import "icon_dropdown.css";
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/* Import fonts. */
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/* poppins */
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height: 40px;
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}
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.btn.navbar__github {
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font-weight: 400;
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color: #fff!important;
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text-align: center;
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user-select: none;
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background-color: #384745;
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border: 2px solid transparent;
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padding: 8px 20px 7px 47px;
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font-size: 1rem;
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line-height: 1.66;
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border-radius: 3px;
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transition: color .15s ease-in-out,background-color .15s ease-in-out,border-color .15s ease-in-out,box-shadow .15s ease-in-out;
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border-color: #384745;
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box-shadow: inset 0 1px rgb(255 255 255 / 15%), 0 1px 1px rgb(0 0 0 / 8%);
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position: relative;
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font-family: poppins,sans-serif;
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text-decoration: none;
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}
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.clear-btn {
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padding: 100px;
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}
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a.btn.navbar__github:hover {
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color: #fff;
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background-color: #273230;
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border-color: #222a29;
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}
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a.btn.navbar__github::before {
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content: "";
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background-image: url("data:image/svg+xml,%3Csvg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 20.5 20%22%3E%3Cdefs/%3E%3Cpath fill=%22%23fff%22 d=%22M10.3.0C4.6.0.0 4.6.0 10.3c0 4.4 2.8 8.3 7 9.7.5.1.7-.2.7-.5v-1.9c-2.6.5-3.2-.6-3.4-1.2-.2-.6-.6-1.1-1-1.5-.4-.2-.9-.7.0-.7.7.1 1.3.5 1.6 1 .6 1.1 1.9 1.4 3 .8.0-.5.3-1 .7-1.4-2.3-.3-4.7-1.1-4.7-5.1.0-1 .4-2 1.1-2.8-.5-.6-.5-1.6-.1-2.5.0.0.9-.3 2.8 1.1 1.7-.5 3.4-.5 5.1.0 2-1.3 2.8-1.1 2.8-1.1.4.9.5 1.9.2 2.8.7.7 1.1 1.7 1.1 2.8.0 3.9-2.4 4.8-4.7 5.1.5.5.7 1.2.7 1.9v2.8c0 .3.2.6.7.5 5.4-1.8 8.3-7.6 6.5-13C18.6 2.8 14.7.0 10.3.0z%22/%3E%3C/svg%3E");
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width: 20px;
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position: absolute;
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left: 15px;
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top: 10px;
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}
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.header-github-link::before {
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content: '';
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width: 24px;
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height: 24px;
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display: flex;
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background: url("data:image/svg+xml,%3Csvg viewBox='0 0 24 24' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M12 .297c-6.63 0-12 5.373-12 12 0 5.303 3.438 9.8 8.205 11.385.6.113.82-.258.82-.577 0-.285-.01-1.04-.015-2.04-3.338.724-4.042-1.61-4.042-1.61C4.422 18.07 3.633 17.7 3.633 17.7c-1.087-.744.084-.729.084-.729 1.205.084 1.838 1.236 1.838 1.236 1.07 1.835 2.809 1.305 3.495.998.108-.776.417-1.305.76-1.605-2.665-.3-5.466-1.332-5.466-5.93 0-1.31.465-2.38 1.235-3.22-.135-.303-.54-1.523.105-3.176 0 0 1.005-.322 3.3 1.23.96-.267 1.98-.399 3-.405 1.02.006 2.04.138 3 .405 2.28-1.552 3.285-1.23 3.285-1.23.645 1.653.24 2.873.12 3.176.765.84 1.23 1.91 1.23 3.22 0 4.61-2.805 5.625-5.475 5.92.42.36.81 1.096.81 2.22 0 1.606-.015 2.896-.015 3.286 0 .315.21.69.825.57C20.565 22.092 24 17.592 24 12.297c0-6.627-5.373-12-12-12'/%3E%3C/svg%3E")
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no-repeat;
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}
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[data-theme='dark'] .header-github-link::before {
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background: url("data:image/svg+xml,%3Csvg viewBox='0 0 24 24' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath fill='white' d='M12 .297c-6.63 0-12 5.373-12 12 0 5.303 3.438 9.8 8.205 11.385.6.113.82-.258.82-.577 0-.285-.01-1.04-.015-2.04-3.338.724-4.042-1.61-4.042-1.61C4.422 18.07 3.633 17.7 3.633 17.7c-1.087-.744.084-.729.084-.729 1.205.084 1.838 1.236 1.838 1.236 1.07 1.835 2.809 1.305 3.495.998.108-.776.417-1.305.76-1.605-2.665-.3-5.466-1.332-5.466-5.93 0-1.31.465-2.38 1.235-3.22-.135-.303-.54-1.523.105-3.176 0 0 1.005-.322 3.3 1.23.96-.267 1.98-.399 3-.405 1.02.006 2.04.138 3 .405 2.28-1.552 3.285-1.23 3.285-1.23.645 1.653.24 2.873.12 3.176.765.84 1.23 1.91 1.23 3.22 0 4.61-2.805 5.625-5.475 5.92.42.36.81 1.096.81 2.22 0 1.606-.015 2.896-.015 3.286 0 .315.21.69.825.57C20.565 22.092 24 17.592 24 12.297c0-6.627-5.373-12-12-12'/%3E%3C/svg%3E")
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no-repeat;
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}
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background-color: rgb(72, 77, 91);
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display: block;

‎src/css/icon_dropdown.css‎

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.navbar__icon {
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font-family: poppins,sans-serif;
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font-size: 16px;
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display: flex;
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}
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.navbar__icon:before {
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content: "";
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display: inline-flex;
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height: 20px;
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width: 35px;
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margin-right: 4px;
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padding-bottom: 7px;
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background-color: var(--ifm-navbar-link-color);
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}
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.navbar__icon:hover:before {
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background-color: var(--ifm-link-color);
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}
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.navbar__github{
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font-size: 16px;
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}
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.navbar__github:before {
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mask: url(/static/img/icon-github.png) no-repeat 100% 100%;
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mask-size: cover;
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height: 19px;
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width: 22px;
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padding-right: 1px;
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padding-bottom: 4px;
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}
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.navbar__blog:before {
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mask: url(/static/img/icon-notebook.png) no-repeat 100% 100%;
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mask-size: cover;
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height: 19px;
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width: 22px;
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padding-right: 1px;
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padding-bottom: 4px;
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}
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/* Used on mobile for icon only links */
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.header__link:before {
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content: '';
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width: 24px;
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height: 24px;
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display: flex;
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background-color: var(--ifm-navbar-link-color);
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}
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.header__link:hover:before {
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background-color: var(--ifm-link-color);
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}
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.header__github:before {
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mask: url(/static/img/icon-github.png) no-repeat 100% 100%;
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mask-size: cover;
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}
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.header__blog:before {
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mask: url(/static/img/icon-notebook.png) no-repeat 100% 100%;
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mask-size: cover;
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}

‎src/theme/Navbar/MobileSidebar/Header/index.js‎

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return (
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<div className="navbar-sidebar__brand">
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<NavbarLogo />
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<a
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href="blog"
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target="_blank"
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rel="noopener noreferrer"
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className="margin-right--md header__link header__blog"
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/>
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<a
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href="https://github.com/k3s-io/k3s"
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target="_blank"
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rel="noopener noreferrer"
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className="margin-right--md header-github-link"
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className="margin-right--md header__link header__github"
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/>
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<NavbarColorModeToggle className="margin-right--md" />
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<CloseButton />

‎static/img/icon-github.png‎

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‎static/img/icon-notebook.png‎

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