Re: Cpu Components
Amabella Tevebaugh
The worker node(s) host the Pods that arethe components of the application workload. Thecontrol plane manages the workernodes and the Pods in the cluster. In production environments, the control plane usuallyruns across multiple computers and a cluster usually runs multiple nodes, providingfault-tolerance and high availability.
The control plane's components make global decisions about the cluster (for example, scheduling),as well as detecting and responding to cluster events (for example, starting up a newpod when a Deployment'sreplicas field is unsatisfied).
Control plane components can be run on any machine in the cluster. However,for simplicity, setup scripts typically start all control plane components onthe same machine, and do not run user containers on this machine. SeeCreating Highly Available clusters with kubeadmfor an example control plane setup that runs across multiple machines.
Factors taken into account for scheduling decisions include:individual and collective resource requirements, hardware/software/policyconstraints, affinity and anti-affinity specifications, data locality,inter-workload interference, and deadlines.
The cloud-controller-manager only runs controllers that are specific to your cloud provider.If you are running Kubernetes on your own premises, or in a learning environment inside yourown PC, the cluster does not have a cloud controller manager.
As with the kube-controller-manager, the cloud-controller-manager combines several logicallyindependent control loops into a single binary that you run as a single process. You canscale horizontally (run more than one copy) to improve performance or to help tolerate failures.
The kubelet takes a set of PodSpecs thatare provided through various mechanisms and ensures that the containers described in thosePodSpecs are running and healthy. The kubelet doesn't manage containers which were not created byKubernetes.
Addons use Kubernetes resources (DaemonSet,Deployment, etc)to implement cluster features. Because these are providing cluster-level features, namespaced resourcesfor addons belong within the kube-system namespace.
Network plugins are softwarecomponents that implement the container network interface (CNI) specification. They are responsible forallocating IP addresses to pods and enabling them to communicate with each other within the cluster.
This is very similar to how we nest native HTML elements, but Vue implements its own component model that allows us to encapsulate custom content and logic in each component. Vue also plays nicely with native Web Components. If you are curious about the relationship between Vue Components and native Web Components, read more here.
The template is inlined as a JavaScript string here, which Vue will compile on the fly. You can also use an ID selector pointing to an element (usually native elements) - Vue will use its content as the template source.
We will be using SFC syntax for the rest of this guide - the concepts around components are the same regardless of whether you are using a build step or not. The Examples section shows component usage in both scenarios.
To use a child component, we need to import it in the parent component. Assuming we placed our counter component inside a file called ButtonCounter.vue, the component will be exposed as the file's default export:
It's also possible to globally register a component, making it available to all components in a given app without having to import it. The pros and cons of global vs. local registration is discussed in the dedicated Component Registration section.
In SFCs, it's recommended to use PascalCase tag names for child components to differentiate from native HTML elements. Although native HTML tag names are case-insensitive, Vue SFC is a compiled format so we are able to use case-sensitive tag names in it. We are also able to use /> to close a tag.
If you are authoring your templates directly in a DOM (e.g. as the content of a native element), the template will be subject to the browser's native HTML parsing behavior. In such cases, you will need to use kebab-case and explicit closing tags for components:
If we are building a blog, we will likely need a component representing a blog post. We want all the blog posts to share the same visual layout, but with different content. Such a component won't be useful unless you can pass data to it, such as the title and content of the specific post we want to display. That's where props come in.
Props are custom attributes you can register on a component. To pass a title to our blog post component, we must declare it in the list of props this component accepts, using the props optiondefineProps macro:
When a value is passed to a prop attribute, it becomes a property on that component instance. The value of that property is accessible within the template and on the component's this context, just like any other component property.
defineProps is a compile-time macro that is only available inside and does not need to be explicitly imported. Declared props are automatically exposed to the template. defineProps also returns an object that contains all the props passed to the component, so that we can access them in JavaScript if needed:
As we develop our component, some features may require communicating back up to the parent. For example, we may decide to include an accessibility feature to enlarge the text of blog posts, while leaving the rest of the page at its default size.
The button doesn't do anything yet - we want clicking the button to communicate to the parent that it should enlarge the text of all posts. To solve this problem, components provide a custom events system. The parent can choose to listen to any event on the child component instance with v-on or @, just as we would with a native DOM event:
Similar to defineProps, defineEmits is only usable in and doesn't need to be imported. It returns an emit function that is equivalent to the $emit method. It can be used to emit events in the section of a component, where $emit isn't directly accessible:
That's all you need to know about custom component events for now, but once you've finished reading this page and feel comfortable with its content, we recommend coming back later to read the full guide on Custom Events.
It should be noted that the limitations discussed below only apply if you are writing your templates directly in the DOM. They do NOT apply if you are using string templates from the following sources:
This is because the HTML spec only allows a few specific elements to omit closing tags, the most common being and . For all other elements, if you omit the closing tag, the native HTML parser will think you never terminated the opening tag. For example, the following snippet:
When used on native HTML elements, the value of is must be prefixed with vue: in order to be interpreted as a Vue component. This is required to avoid confusion with native customized built-in elements.
That's all you need to know about in-DOM template parsing caveats for now - and actually, the end of Vue's Essentials. Congratulations! There's still more to learn, but first, we recommend taking a break to play with Vue yourself - build something fun, or check out some of the Examples if you haven't already.
It's recommended (but not required) to also use the styled-components Babel plugin if you can. It offers many benefits like more legible class names, server-side rendering compatibility, smaller bundles, and more.
Let's say you want to create a simple and reusable component that you can use throughout your application. There should be a normal version and a big and primary version for the important buttons. This is what it should look like when rendered: (this is a live example, click on them!)
As you can see, styled-components lets you write actual CSS in your JavaScript. This means you can use all the features of CSS you use and love, including (but by far not limited to) media queries, all pseudo-selectors, nesting, etc.
The last step is that we need to define what a primary button looks like. To do that we also import css from styled-components and interpolate a function into our template literal, which gets passed the props of our component:
Dapr uses a modular design where functionality is delivered as a component. Each component has an interface definition. All of the components are interchangeable so that you can swap out one component with the same interface for another.
Name resolution components are used with the service invocation building block to integrate with the hosting environment and provide service-to-service discovery. For example, the Kubernetes name resolution component integrates with the Kubernetes DNS service, self-hosted uses mDNS and clusters of VMs can use the Consul name resolution component.
A workflow is custom application logic that defines a reliable business process or data flow. Workflow components are workflow runtimes (or engines) that run the business logic written for that workflow and store their state into a state store.
Dapr allows custom middleware to be plugged into the HTTP request processing pipeline. Middleware can perform additional actions on an HTTP request (such as authentication, encryption, and message transformation) before the request is routed to the user code, or the response is returned to the client. The middleware components are used with the service invocation building block.
Astro components are the basic building blocks of any Astro project. They are HTML-only templating components with no client-side runtime. You can spot an Astro component by its file extension: .astro.
Astro components are extremely flexible. Often, an Astro component will contain some reusable UI on the page, like a header or a profile card. At other times, an Astro component may contain a smaller snippet of HTML, like a collection of common tags that make SEO easy to work with. Astro components can even contain an entire page layout.
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