Elastic Beanstalk terminating and recreating instances frantically - amazon-web-services

Question

Elastic Beanstalk is adding & removing instances one after the other. Googling around points to checking the "State transition message" which is coming up as "Client.UserInitiatedShutdown: User initiated shutdown" for which https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/troubleshooting-launch.html#troubleshooting-launch-internal states some possible reasons but none of these apply. No one has touched any setting, etc. Any ideas?
UPDATE: Did a bit more digging and found out that app deployment is failing. Relevant log errors are below:
eb-engine.log
2021/08/05 15:46:29.272215 [INFO] Executing instruction: PreBuildEbExtension
2021/08/05 15:46:29.272220 [INFO] Starting executing the config set Infra-EmbeddedPreBuild.
2021/08/05 15:46:29.272235 [INFO] Running command /bin/sh -c /opt/aws/bin/cfn-init -s arn:aws:cloudformation:us-east-1:345470085661:stack/awseb-e-mecfm5qc8z-stack/317924c0-a106-11ea-a8a3-12498e67507f -r AWSEBAutoScalingGroup --region us-east-1 --configsets Infra-EmbeddedPreBuild
2021/08/05 15:50:44.538818 [ERROR] An error occurred during execution of command [app-deploy] - [PreBuildEbExtension]. Stop running the command. Error: EbExtension build failed. Please refer to /var/log/cfn-init.log for more details.
2021/08/05 15:50:44.540438 [INFO] Executing cleanup logic
2021/08/05 15:50:44.581445 [INFO] CommandService Response: {"status":"FAILURE","api_version":"1.0","results":[{"status":"FAILURE","msg":"Engine execution has encountered an error.","returncode":1,"events":[{"msg":"Instance deployment failed. For details, see 'eb-engine.log'.","timestamp":1628178644,"severity":"ERROR"}]}]}
2021/08/05 15:50:44.620394 [INFO] Platform Engine finished execution on command: app-deploy
2021/08/05 15:51:22.196186 [ERROR] An error occurred during execution of command [self-startup] - [PreBuildEbExtension]. Stop running the command. Error: EbExtension build failed. Please refer to /var/log/cfn-init.log for more details.
2021/08/05 15:51:22.196215 [INFO] Executing cleanup logic
eb-cfn-init.log
[2021-08-05T15:42:44.199Z] Completed executing cfn_init.
[2021-08-05T15:42:44.226Z] finished _OnInstanceReboot
+ RESULT=1
+ [[ 1 -ne 0 ]]
+ sleep_delay
+ (( 2 < 3600 ))
+ echo Sleeping 2
Sleeping 2
+ sleep 2
+ SLEEP_TIME=4
+ true
+ curl https://elasticbeanstalk-platform-assets-us-east-1.s3.amazonaws.com/stalks/eb_php74_amazon_linux_2_1.0.1153.0_20210728213922/lib/UserDataScript.sh
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
100 4627 100 4627 0 0 24098 0 --:--:-- --:--:-- --:--:-- 24098
+ RESULT=0
+ [[ 0 -ne 0 ]]
+ SLEEP_TIME=2
+ /bin/bash /tmp/ebbootstrap.sh 'https://cloudformation-waitcondition-us-east-1.s3.amazonaws.com/arn%3Aaws%3Acloudformation%3Aus-east-1%3A345470085661%3Astack/awseb-e-mecfm5qc8z-stack/317924c0-a106-11ea-a8a3-12498e67507f/AWSEBInstanceLaunchWaitHandle?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20200528T171102Z&X-Amz-SignedHeaders=host&X-Amz-Expires=86399&X-Amz-Credential=AKIAIIT3CWAIMJYUTISA%2F20200528%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=57c7da0aec730af1b425d1aff68517c333cf9d5432c984d775419b415cac8513' arn:aws:cloudformation:us-east-1:345470085661:stack/awseb-e-mecfm5qc8z-stack/317924c0-a106-11ea-a8a3-12498e67507f 65c52bb7-0376-4d43-b304-b64890a34c1c https://elasticbeanstalk-health.us-east-1.amazonaws.com '' https://elasticbeanstalk-platform-assets-us-east-1.s3.amazonaws.com/stalks/eb_php74_amazon_linux_2_1.0.1153.0_20210728213922 us-east-1
[2021-08-05T15:46:07.683Z] Started EB Bootstrapping Script.
[2021-08-05T15:46:07.739Z] Received parameters:
TARBALLS =
EB_GEMS =
SIGNAL_URL = https://cloudformation-waitcondition-us-east-1.s3.amazonaws.com/arn%3Aaws%3Acloudformation%3Aus-east-1%3A345470085661%3Astack/awseb-e-mecfm5qc8z-stack/317924c0-a106-11ea-a8a3-12498e67507f/AWSEBInstanceLaunchWaitHandle?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20200528T171102Z&X-Amz-SignedHeaders=host&X-Amz-Expires=86399&X-Amz-Credential=AKIAIIT3CWAIMJYUTISA%2F20200528%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=57c7da0aec730af1b425d1aff68517c333cf9d5432c984d775419b415cac8513
STACK_ID = arn:aws:cloudformation:us-east-1:345470085661:stack/awseb-e-mecfm5qc8z-stack/317924c0-a106-11ea-a8a3-12498e67507f
REGION = us-east-1
GUID =
HEALTHD_GROUP_ID = 65c52bb7-0376-4d43-b304-b64890a34c1c
HEALTHD_ENDPOINT = https://elasticbeanstalk-health.us-east-1.amazonaws.com
PROXY_SERVER =
HEALTHD_PROXY_LOG_LOCATION =
PLATFORM_ASSETS_URL = https://elasticbeanstalk-platform-assets-us-east-1.s3.amazonaws.com/stalks/eb_php74_amazon_linux_2_1.0.1153.0_20210728213922
Is this some corrupted AMI?

Answer 1

Turned out that there was a config script in the .ebextension directory that was not behaving.