EDAS Agent overview
EDAS Agent is the Daemon program installed on ECS instances to implement communication between the EDAS cluster and the applications deployed on the corresponding ECS instances. EDAS Agent functions as follows:
- Application management: Deploys, starts, and stops applications.
- Status reporting: Reports application viability status, health check results, and Ali-Tomcat container status.
- Information retrieval: Retrieves the monitoring information on ECS instances and containers.
In addition to these application-based management functions, EDAS Agent is also responsible for communication between the EDAS console and your applications. Here is a simple example. EDAS Agent obtains and submits the information about whether a service from an application is published on a given ECS instance correctly and promptly.
Note: The above functions are transparent to users. You only have to install the EDAS Agent.
EDAS deploys applications (including first-time installation and later on expansion) on ECS instances that are installed with EDAS Agent only. The nodes in the EDAS billing system refer to the ECS instances which are installed with EDAS Agent and deployed with applications. To use EDAS, you must install EDAS Agent while or after you purchase an ECS instance.
You can install EDAS Agent in three ways:
- Automatic installation by using EDAS base image when you buy ECS
- Automatic installation by importing ECS instance
- Manual installation by executing script
- JDK 8 is installed in EDAS Agent by default in the three ways. To use JDK 7 or other versions, you can manually execute the script for installation.
- To manually execute the script for installation, you must log on to the ECS instance as a root user.
- Currently, EDAS Agent can be installed and run on 64-bit CentOS 6.5/6.8/7.0/7.2 or 64-bit Ali-Linux 5.7 only.
- This script can be run repeatedly. Running the script overwrites the existing version of EDAS Agent installed on the instance. Therefore, to upgrade EDAS Agent, simply run the same script again.
- The script for installation is region specific. You must switch to the appropriate region before clicking Install EDAS Agent.
Automatic installation by using EDAS base image when you buy ECS
The simplest and easiest method for installing EDAS Agent is to use an EDAS base image when you purchase an ECS instance.
In the upper-right corner of the ECS Instance List page, click Create Instances to go to the ECS purchase page.
In the Choose the Operating System section of the purchase page, select Marketplace Image. Then, click Select from image market (including operating system).
Enter EDAS in the search box and click Search.
Select EDAS JAVA Environment (common ECS) in the results. The latest version is selected by default. Then, click Use to select it as the EDAS base image.
Click Buy Now to purchase the ECS instance.
Automatic installation by importing ECS instance
If you did not select any EDAS base image when purchasing an ECS instance, you can click Import ECS in the EDAS console to install EDAS Agent. The process is as follows:
In the left-side navigation pane of the EDAS console, select Resources > ECS. In the upper-right corner of the Instance List page, click Import ECS.
In the Select Cluster and ECS step, select the namespace and cluster that you want to import your ECS to, and then select the ECS instance and click Next.
- After you select a cluster, the system automatically displays the ECS instances available for this cluster.
- If you wish to create a new cluster, click Create Cluster.
Note: You can also select Switch to Manual Installation in the upper-right corner of the page and manually install EDAS Agent by executing the script.
On the Set New Password page, enter a new logon password for the ECS instance and click Next.
After you confirm the ECS import, the system clears all data on the ECS instance and uses the EDAS official image to reinstall the operating system. Make sure you remeber your new password.
In the Import ECS host dialog box, click Import.
It takes about five minutes to import an ECS instance. Then, following the prompts, click Back to go to the cluster details page under Cluster Management. In the Cluster Deployment Information area, you can view the import status and progress.
When the status of the ECS instance changes from Converting to Online, the ECS instance is imported successfully.
Manual installation by executing script
Log on to the EDAS console and choose Resources > ECS in the left-side navigation pane.
In the upper-left corner of the page, select the region where the ECS instance is, for example, “China East 1”.
Note: Make sure you select the correct region, otherwise EDAS Agent installation may fail.
On the ECS page, select the appropriate ECS instance and click Import ECS in the upper-right corner.
On the Import ECS page, click Switch to Manual Installation in the upper-right corner, then click Copy to copy the script.
Note: You can also click Switch to Image Installation In the upper-right corner of the page to install EDAS Agent by importing an ECS instance.
Log on to the ECS instance where you want to install EDAS Agent as a root user.
On the ECS instance, paste the copied command and execute it.
After installing EDAS Agent, select Resources > ECS in the left-side navigation pane of the EDAS console. On the Instance List page, select the appropriate region to view the Agent Status for instances in the region.
If EDAS Agent is installed successfully, its status is Online or Docker Online.
If EDAS Agent installation fails, its status is Exception.
The process for upgrading EDAS Agent is the same as that for installing it. Refer to Manual installation by executing script section for the detailed steps.
The script automatically reinstalls and restarts the EDAS Agent.