chore(aws): revise and improve commands, add ecs

knowledge base/cloud computing/aws/ecs.md

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+# Elastic Container Service
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+   1. [Sources](#sources)
+
+## TL;DR
+
+<details>
+  <summary>Usage</summary>
+
+```sh
+# List services.
+aws ecs list-services --cluster 'clusterName'
+
+# Scale services.
+aws ecs update-service --cluster 'clusterName' --service 'serviceName' --desired-count '0'
+aws ecs update-service --cluster 'clusterName' --service 'serviceName' --desired-count '10'
+
+# Wait for services to be running.
+aws ecs wait services-stable --cluster 'clusterName' --services 'serviceName' …
+
+# Delete services.
+# Cannot really be deleted if scaled above 0.
+aws ecs delete-service --cluster 'clusterName' --service 'serviceName'
+aws ecs delete-service --cluster 'clusterName' --service 'serviceName' --force
+
+# List task definitions.
+aws ecs list-task-definitions --family-prefix 'familyPrefix'
+
+# Deregister task definitions.
+aws ecs deregister-task-definition --task-definition 'taskDefinitionArn'
+
+# Delete task definitions.
+# The task definition must be deregistered.
+aws ecs delete-task-definitions --task-definitions 'taskDefinitionArn' …
+
+# List tasks.
+aws ecs list-tasks --cluster 'clusterName'
+aws ecs list-tasks --cluster 'clusterName' --service-name 'serviceName'
+
+# Get information about tasks.
+aws ecs describe-tasks --cluster 'clusterName' --tasks 'taskIdOrArn' …
+
+# Wait for tasks to be running.
+aws ecs wait tasks-running --cluster 'clusterName' --tasks 'taskIdOrArn' …
+
+# Access shells on containers in ECS.
+aws ecs execute-command \
+  --cluster 'clusterName' --task 'taskId' --container 'containerName' \
+  --interactive --command '/bin/bash'
+```
+
+</details>
+
+<details>
+  <summary>Real world use cases</summary>
+
+```sh
+# Get the ARNs of tasks for specific services.
+aws ecs list-tasks --cluster 'testCluster' --service-name 'testService' --query 'taskArns' --output 'text'
+
+# Get the private IP Address of containers.
+aws ecs describe-tasks --output 'text' \
+  --cluster 'testCluster' --tasks 'testTask' \
+  --query "tasks[].attachments[].details[?(name=='privateDnsName')].value"
+
+# Connect to the private DNS name of containers in ECS.
+curl -fs "http://$(\
+  aws ecs describe-tasks --cluster 'testCluster' --tasks "$(\
+      aws ecs list-tasks --cluster 'testCluster' --service-name 'testService' --query 'taskArns' --output 'text' \
+  )" --query "tasks[].attachments[].details[?(name=='privateDnsName')].value" --output 'text' \
+):8080"
+
+# Delete services.
+aws ecs delete-service --cluster 'testCluster' --service 'testService' --force
+
+# Delete task definitions.
+aws ecs list-task-definitions --family-prefix 'testService' --output 'text' --query 'taskDefinitionArns' \
+| xargs -n '1' aws ecs deregister-task-definition --task-definition
+
+# Wait for tasks to be running.
+aws ecs list-tasks --cluster 'testCluster' --family 'testService' --output 'text' --query 'taskArns' \
+| xargs -p aws ecs wait tasks-running --cluster 'testCluster' --tasks
+while [[ $(aws ecs list-tasks --query 'taskArns' --output 'text' --cluster 'testCluster' --service-name 'testService') == "" ]]; do sleep 1; done
+```
+
+</details>
+
+## Further readings
+
+- [Amazon Web Services]
+- [Amazon ECS task lifecycle]
+- AWS' [CLI]
+- [Troubleshoot Amazon ECS deployment issues]
+
+### Sources
+
+<!--
+  Reference
+  ═╬═Time══
+  -->
+
+<!-- In-article sections -->
+<!-- Knowledge base -->
+[amazon web services]: README.md
+[cli]: cli.md
+
+<!-- Files -->
+<!-- Upstream -->
+[amazon ecs task lifecycle]: https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-lifecycle-explanation.html
+[troubleshoot amazon ecs deployment issues]: https://docs.aws.amazon.com/codedeploy/latest/userguide/troubleshooting-ecs.html
+
+<!-- Others -->