How to install a certificate from ACM on ELB

This is Nakagawa from the System Solutions Department.
The other day, I encountered a problem where I couldn't successfully install a certificate on an AWS ELB using the usual procedure.
I often use the procedure of entering the certificate file from the listener of the target ELB and saving it.
This time, however, an error was displayed during the installation process, and I was unable to register it smoothly.
After registering the certificate from ACM and then editing the listener, I was able to install it, so I will explain that procedure.

What is ACM?

AWS Certificate Manager is an abbreviation.
It allows you to request the issuance of certificates (free of charge) that can be used with various AWS services, and to register existing certificates. It
also automatically renews issued certificates.
For more details, pleasethe official documentation.

Steps for installation

As a prerequisite, we assume that an ELB (Elastic Load Balancer) has already been created to route traffic to HTTPS.
The procedure is as follows:

1. Select ACM from the console and then select "Import Certificate."

2. Open each certificate file in the program, paste it into the appropriate field, and click "Review Import."

3. Check that the certificate information displayed on the review import screen is correct

If there are no problems, select "Import" to display the import completion screen.
Note down the identifier in the details section and install it into the ELB.

4. From EC2, select the ELB listener you want to set up and select "Edit"

5. Select "Select an existing certificate from ACM."

Confirm that the identifier noted in step 3 is displayed on the certificate, then save it

6. After saving, check the ELB management screen

If no errors are displayed after saving, the certificate should be installed successfully!
That completes the process.

As the next assignment

I had checked the integrity of the certificate beforehand, so there shouldn't be any problem with the certificate itself, but I
haven't been able to pinpoint the cause of the error using my usual methods.
This time, I gained experience installing the certificate using a different procedure than before, so
next time I'd like to investigate the root cause of the error and the mechanism of ACM, and write an article about it.