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169 lines
9.2 KiB
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169 lines
9.2 KiB
Markdown
---
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title: "Deployments"
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keywords: 'KubeSphere, Kubernetes, Deployments, workload'
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description: 'Kubernetes Deployments'
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weight: 2230
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---
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A Deployment controller provides declarative updates for Pods and ReplicaSets. You describe a desired state in a Deployment object, and the Deployment controller changes the actual state to the desired state at a controlled rate. As a Deployment runs a number of replicas of your application, it automatically replaces instances that go down or malfunction. This is how Deployments make sure app instances are available to handle user requests.
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For more information, see the [official documentation of Kubernetes](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/).
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## Prerequisites
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- You need to create a workspace, a project and an account (`project-regular`). Please refer to [Create Workspace, Project, Account and Role](../../../quick-start/create-workspace-and-project) if they are not ready yet.
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- You need to sign in with the `project-admin` account and invite `project-regular` to the corresponding project. Please refer to [these steps to invite a member](../../../quick-start/create-workspace-and-project#task-3-create-a-project).
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## Create a Deployment
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### Step 1: Open Dashboard
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Log in the console as `project-regular`. Go to **Workloads** of a project, choose **Deployments** and click **Create**.
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### Step 2: Input Basic Information
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Specify a name for the Deployment (e.g. `demo-deployment`) and click **Next** to continue.
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### Step 3: Set Image
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1. Before you set an image, define the number of replicated Pods in **Pod Replicas** by clicking the **plus** or **minus** icon, which is indicated by the `.spec.replicas` field in the manifest file.
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{{< notice tip >}}
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You can see the Deployment manifest file in YAML format by enabling **Edit Mode** in the top right corner. KubeSphere allows you to edit the manifest file directly to create a Deployment. Alternatively, you can follow the steps below to create a Deployment via the dashboard.
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{{</ notice >}}
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2. Click the **Add Container Image** area.
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3. You can input an image name to use the image from public Docker Hub or select an image from a private repository you want to use. For example, input `nginx` in the search bar and press **Enter**.
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{{< notice note >}}
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- Remember to press **Enter** on your keyboard after you input an image name in the search bar.
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- If you want to use your private image repository, you should create a Docker Hub secret first in **Secrets** under **Configurations**.
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{{</ notice >}}
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4. Set requests and limits for CPU and memory resources based on your needs. For more information, see [Resource Request and Resource Limit in Container Image Settings](../container-image-settings/#add-container-image).
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5. Click **Use Default Ports** for **Port Settings** or you can customize **Protocol**, **Name** and **Container Port**.
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6. Select a policy for image pulling from the drop-down menu. For more information, see [Image Pull Policy in Container Image Settings](../container-image-settings/#add-container-image).
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7. For other settings (**Health Checker**, **Start Command**, **Environment Variables**, **Container Security Context** and **Sync Host Timezone**), you can configure them on the dashboard as well. For more information, see detailed explanations of these properties in [Container Image Settings](../container-image-settings/#add-container-image). When you finish, click **√** in the bottom right corner to continue.
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8. Select an update strategy from the drop-down menu. It is recommended you choose **RollingUpdate**. For more information, see [Update Strategy](../container-image-settings/#update-strategy).
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9. Select a deployment mode. For more information, see [Deployment Mode](../container-image-settings/#deployment-mode).
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10. Click **Next** to go to the next step when you finish setting the container image.
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### Step 4: Mount Volumes
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You can add a volume directly or mount a ConfigMap or Secret. Alternatively, click **Next** directly to skip this step.
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- **Add Volume**: Support EmptyDir and PersistentVolumeClaim.
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In **Add Volume** there are 3 kinds of volumes:
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- **Existing Volume**: Use *PVC* to mount.
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Persistent storage volumes can be used to save users' persistent data. You need to create volumes in advance so that you can choose an existing volume from the list.
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- **Temporary Volume**: Use *emptyDir* to mount.
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The temporary storage volume represents [emptyDir](https://kubernetes.cn/docs/concepts/storage/volumes/#emptydir), which is first created when a Pod is assigned to a node, and exists as long as that Pod is running on that node. When a Pod is removed from a node for any reason, the data in the emptyDir is deleted forever.
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- **HostPath**: Use *HostPath* to mount.
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A HostPath volume mounts a file or directory from the host node's filesystem into your Pod. This is not something that most Pods will need, but it offers a powerful escape hatch for some applications.
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- **Mount ConfigMap or Secret**: Support key-value pairs in ConfigMap or Secret.
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A secret volume is used to pass sensitive information, such as passwords, to Pods. Secret volumes are backed by tmpfs (a RAM-backed filesystem) so they are never written to non-volatile storage.
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A ConfigMap is used to store configuration data in the form of key-value pairs. The ConfigMap resource provides a way to inject configuration data into Pods. The data stored in a ConfigMap object can be referenced in a volume of type ConfigMap and then consumed by containerized applications running in a Pod. ConfigMaps are often used in the following cases:
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- Set the value of the environment variable.
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- Set command parameters in the container.
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- Create a config file in the volume.
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For more information about volumes, please visit [Volumes](../../storage/volumes).
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{{< notice note >}}
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Deployments can't use the volume template, which is different from StatefulSets.
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{{</ notice>}}
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### Step 5: Configure Advanced Settings
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You can set a policy for node scheduling and add metadata in this section. When you finish, click **Create** to complete the whole process of creating a Deployment.
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- **Set Node Scheduling Policy**
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You can allow Pod replicas to run on specified nodes. It is specified in the field `nodeSelector`.
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- **Add Metadata**
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Additional metadata settings for resources such as **Labels** and **Annotations**.
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## Check Deployment Details
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### Detail Page
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1. After a Deployment is created, it displays in the list as below. You can click the three dots on the right and select the operation from the menu to modify a Deployment.
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- **Edit**: View and edit the basic data.
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- **Edit YAML**: View, upload, download, or update the YAML file.
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- **Redeploy**: Redeploy the Deployment.
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- **Delete**: Delete the Deployment.
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2. Click the name of the Deployment and you can go to its detail page.
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3. Click **More** to display what operations about this Deployment you can do.
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- **Revision Rollback**: Select the revision to roll back.
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- **Horizontal Pod Autoscaling**: Autoscale the replicas according to CPU and memory usage. If both CPU and memory are specified, replicas are added or deleted if any of the conditions is met.
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- **Edit Config Template**: Configure update strategies, containers and volumes.
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- **Edit YAML**: View, upload, download, or update the YAML file.
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- **Redeploy**: Redeploy this Deployment.
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- **Delete**: Delete the Deployment, and return to the Deployment list page.
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4. Click the **Resource Status** tab to view the port and Pod information of a Deployment.
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- **Replica Status**: Click the arrow in the image to increase or decrease the number of Pod replicas.
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- **Pod detail**
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- The Pod list provides detailed information of the Pod (status, node, Pod IP and resource usage).
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- You can view the container information by clicking a Pod item.
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- Click the container log icon to view output logs of the container.
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- You can view the Pod detail page by clicking the Pod name.
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### Revision Records
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After the resource template of workload is changed, a new log will be generated and Pods will be rescheduled for a version update. The latest 10 versions will be saved by default. You can implement a redeployment based on the change log.
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