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How to use “describe-load-balancer” command in AWS CLI?

January 6, 20241 min read

Amazon Elastic Compute Cloud (EC2) allows users to create multiple instances that provide on-demand, secure, computing services to its users. However, managing and monitoring these multiple EC2 instances can be a daunting task. Therefore, AWS has introduced “Elastic Load Balancer”, The load balancer monitors traffic patterns and then distributes traffic according to deployed EC2 instances. Therefore, it improves the health and availability of applications, prevents server collapse and enhances performance.

learn more: Overview of different types of load balancers on AWS

quick outline

In this article we will know,

Access and management of these services and resources through the AWS CLI is just a few commands away. For load balancers, several commands are available to create, manage, or list them. One such command is “describe-load-balancer” Permission.

What is “describe-load-balancer” command in AWS CLI?

“describe-load-balancer” The command is a paged operation that returns specific or all load balancers for a given account. If no specific load balancer name is provided then the command displays all load balancers in the response by default. However, all data is retrieved in multiple API calls to the service.

How to use “describe-load-balancer” command in AWS CLI?

There are no required parameters for this command. However, it accepts various optional and global parameters. Such parameters allow the user to control the output while listing Load Balancers.

syntax

syntax of “describe-load-balancer” The order is given below:

aws alb describe-load-balancer <Option,

Option

Here's a brief description of the different options:

Option Description
-Name This option is of string data type and accepts the name of the load balancer.
-load-balancer-arn Load balancers can also be listed by specifying an ARN “-load-balancer-arn” Parameters. The ARN associated with AWS resources uniquely identifies them.
-page size This parameter specifies the page size to display details of the created load balancers. The smaller the page size, the more API calls to the service. Specifying the page size will not affect the multiple items returned in the command.
-initial-token This parameter inputs the value of NextToken which is a string data type. NextToken is generated in the output when there is more data to list. Providing value of NextToken to -initial-token Will display the remaining load balancer.
-max-items -max-items The parameter displays a limited number of load balancers in a single response. It accepts an integer value. This parameter will cause the command's output to include NextToken. NextToken indicates that there is more data to list.
-cli-input-json This parameter provides several instructions to the resource in JSON format. The value of this option will be overwritten by other options within the command.
-generate-cli-skeleton This parameter accepts a string value and creates a JSON skeleton or template. This template is provided to “cli-input-json” to specify directives.

Example

There are different types of load balancers provided by AWS. For this demo, we have already created two application load balancers. Examples are given below:

Example 1: How to describe all load balancers in AWS CLI?

The command below lists all load balancers for a given account:

aws elbv2 describe-load-balancer

Production

Example 2: How to describe a typical load balancer in the AWS CLI?

The following command lists a specific load balancer within the account:

aws elbv2 describe-load-balancer –Name myfirstalb

Comment: change value myfirstalb Within the command with the name of your load balancer.

Production

Example 3: How to display a limited number of load balancers in the output?

-max-items The option is used to display a limited number of load balancers in React. The value of this parameter is an integer that must be between 1 and 1000:

aws elbv2 describe-load-balancer –max-items 1

Comment: replace the 1 In -max-items With any numerical value of choice between 1 to 1000.

Production

provide value of nexttoken till -initial token To list the remaining load balancers. the output will not contain any nexttoken Field if all load balancers are described. The command below shows its usage -initial-token fields with describe-load-balancer Permission:

aws elbv2 describe-load-balancer –initial-token <nexttoken,

Comment: replace the <नेक्स्टटोकन> With the given NextToken value in the output of your command.

Production

Example 4: How to display load balancers in different output formats in AWS CLI?

To display data in tabular format, use the following commands:

aws elbv2 describe-load-balancer –Output table

Comment: User can also substitute value table In -Output Fields with other output formats i.e. text, YAML, or JSON.

Production

Example 5: How to describe load balancers without pagination in the AWS CLI?

“-no-page” The parameter disables pagination and retrieves all data in a single response. The order is given as follows:

aws elbv2 describe-load-balancer –no page

Production

Read more: How to disable pager in AWS CLI?

Example 6: How to display specific details of load balancers in AWS CLI?

in the output of “describe-load-balancer” There are many details like commands, security groups, IP addresses, zones, subnets, etc. user can use -Question Parameters to filter specific details of all load balancers use below command:

aws elbv2 describe-load-balancer –Question “loadbalancer[*],[Scheme],

Production

Similarly, the user can also filter the specific details of a particular load balancer. Currently, there are two load balancers configured within the account. By default, the array starts at 0. So, to get the details of the second load balancer, we have provided the value “1” within the array. This refers to the second load balancer:

aws elbv2 describe-load-balancer –Question “loadbalancer[1],[LoadBalancerArn],

Production

Example 7: How to describe load balancers in a specific region in the AWS CLI?

Describing load balancer within a specific region is also one of the functionality of this command. For this purpose, -Area Parameters are used. The command for this functionality is given below:

aws elbv2 describe-load-balancer –Area AP-Southeast-1

Comment: replace the ap-southeast-1 With the AWS region of your choice.

Production

Example 8: How to describe load balancers within a specific page size in the AWS CLI?

Smaller page sizes will result in more API calls to the service to access data. If page size is specified as 1, the output will contain “Next Marker” price. This value is to be provided “-marker” Option within the command to list the next load balancer within the specified page size. To describe the load balancer within a specific page size, use the following command.

aws elbv2 describe-load-balancer –page size 100

Production

Example 9: How to Describe Load Balancers by Specifying ARN in the AWS CLI?

To list all load balancers based on their ARN, provide the following command:

aws elbv2 describe-load-balancer –load-balancer-arn

Production

The following command lists specific details of a load balancer using ARN:

aws elbv2 describe-load-balancer –load-balancer-arn arn:aws:elasticloadbalancing:us-west-2,123456789012:weight balance,Application,my-load-balancer,50dc6c495c0c9188

Production

That's all from this guide.

General Exception: LoadBalancerNotFound

The following exception occurs because the user provided an incorrect name of the load balancer:

Solution: To resolve this error, double-check the given name and run the command again:

That's all from this guide.

conclusion

describe-load-balancer Commands in the AWS CLI detail specific or all load balancers for a given account. It accepts a variety of options for filtering, querying, or displaying data in multiple output formats. To use this command, log in to your AWS account through the AWS CLI and provide the above command to the terminal. This article discusses practical implementations and various examples of listing load balancers. describe-load-balancer Commands in AWS CLI.

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