prog893 · April 10, 2018 07:08 · Apr 10, 2018 · Apr 10, 2018 · Mar 6, 2018
diff --git a/README.md b/README.md
@@ -6,7 +6,6 @@ Inspired by: https://stackoverflow.com/questions/45020323/ecs-asg-scaling-down-p
 Ignores ecs-agent and dd-agent when counting running containers. You can add more in `containers_running` in the script below.
 
 ## Prerequisites
-- awk
 - jq
 - awscli
 - run as root

diff --git a/ecs_instance_scalein_protector.sh b/ecs_instance_scalein_protector.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # inspired by https://stackoverflow.com/questions/45020323/ecs-asg-scaling-down-policy-recommendations
-# needs awk, jq, awscli, root, IAM autoscaling:DescribeAutoScalingInstances, SetInstanceProtection
+# needs jq, awscli, root, IAM autoscaling:DescribeAutoScalingInstances, SetInstanceProtection
 
 echo "--------------------------------"
 echo "[$(date)] Starting script "
@@ -18,11 +18,10 @@ region=${az:0:${#az} - 1}
 asg_name=$(aws autoscaling describe-auto-scaling-instances --region $region --instance-ids $instance_id | jq .AutoScalingInstances[].AutoScalingGroupName -r)
 
 ## number of containers running (except ecs-agent and dd-agent)
-containers_running=$(docker ps | awk '{print $2}' | tail -n+2 | grep -v "amazon/amazon-ecs-agent" | grep -v "datadog/docker-dd-agent" | wc -l)
+containers_running=$(docker ps --format "{{.Image}}" | grep -v "amazon/amazon-ecs-agent" | grep -v "datadog/docker-dd-agent" | wc -l)
 
 ## current protection state
 scale_protection=$(aws autoscaling describe-auto-scaling-instances --region ${region} --instance-ids ${instance_id} | jq '.AutoScalingInstances[].ProtectedFromScaleIn' -r)
-# scale_protection=$(aws autoscaling describe-auto-scaling-instances --region ap-northeast-1 --instance-ids i-0d24aa0f9d1b5558f --output text | awk '{print tolower($8)}')
 
 if [ ${containers_running} -ge 1 ]; then
     if [ ${scale_protection} == "true" ]; then

diff --git a/README.md b/README.md
@@ -7,6 +7,7 @@ Ignores ecs-agent and dd-agent when counting running containers. You can add mor
 
 ## Prerequisites
 - awk
+- jq
 - awscli
 - run as root
 - cron (opt.)

diff --git a/ecs_instance_scalein_protector.sh b/ecs_instance_scalein_protector.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # inspired by https://stackoverflow.com/questions/45020323/ecs-asg-scaling-down-policy-recommendations
-# needs awk, awscli, root, IAM autoscaling:DescribeAutoScalingInstances, SetInstanceProtection
+# needs awk, jq, awscli, root, IAM autoscaling:DescribeAutoScalingInstances, SetInstanceProtection
 
 echo "--------------------------------"
 echo "[$(date)] Starting script "

diff --git a/README.md b/README.md
@@ -0,0 +1,20 @@
+# ECS Container Instance scale-in protector
+
+Protect container instance with containers running from scale-in. Uses aws-cli [set-instance-protection](https://docs.aws.amazon.com/ja_jp/autoscaling/ec2/userguide/as-instance-termination.html#instance-protection). 
+Inspired by: https://stackoverflow.com/questions/45020323/ecs-asg-scaling-down-policy-recommendations
+
+Ignores ecs-agent and dd-agent when counting running containers. You can add more in `containers_running` in the script below.
+
+## Prerequisites
+- awk
+- awscli
+- run as root
+- cron (opt.)
+- Permissions for EC2 IAM role
+  - autoscaling:DescribeAutoScalingInstances
+  - autoscaling:SetInstanceProtection
+
+## Example crontab
+```
+*/5 * * * * root /usr/local/bin/scale_in_protection.sh
+```
diff --git a/ecs_instance_scalein_protector.sh b/ecs_instance_scalein_protector.sh
@@ -0,0 +1,47 @@
+#!/bin/bash
+
+# inspired by https://stackoverflow.com/questions/45020323/ecs-asg-scaling-down-policy-recommendations
+# needs awk, awscli, root, IAM autoscaling:DescribeAutoScalingInstances, SetInstanceProtection
+
+echo "--------------------------------"
+echo "[$(date)] Starting script "
+
+set -x
+## self EC2 instance ID
+instance_id=$(curl -s http://169.254.169.254/latest/meta-data/instance-id)
+
+## self region
+az=$(curl -s http://169.254.169.254/latest/meta-data/placement/availability-zone)
+region=${az:0:${#az} - 1}
+
+## self ASG ID
+asg_name=$(aws autoscaling describe-auto-scaling-instances --region $region --instance-ids $instance_id | jq .AutoScalingInstances[].AutoScalingGroupName -r)
+
+## number of containers running (except ecs-agent and dd-agent)
+containers_running=$(docker ps | awk '{print $2}' | tail -n+2 | grep -v "amazon/amazon-ecs-agent" | grep -v "datadog/docker-dd-agent" | wc -l)
+
+## current protection state
+scale_protection=$(aws autoscaling describe-auto-scaling-instances --region ${region} --instance-ids ${instance_id} | jq '.AutoScalingInstances[].ProtectedFromScaleIn' -r)
+# scale_protection=$(aws autoscaling describe-auto-scaling-instances --region ap-northeast-1 --instance-ids i-0d24aa0f9d1b5558f --output text | awk '{print tolower($8)}')
+
+if [ ${containers_running} -ge 1 ]; then
+    if [ ${scale_protection} == "true" ]; then
+        echo "Containers are running and scale protection is on. Doing nothing."
+    else
+        aws autoscaling set-instance-protection --region ${region} --instance-ids ${instance_id} --auto-scaling-group-name ${asg_name} --protected-from-scale-in
+        echo "Containers are running and scale protection is off. Enabling scale-in protection"
+    fi
+elif  [ ${containers_running} == 0 ]; then
+    if [ ${scale_protection} == "true" ]; then
+        echo "No containers running and scale protection is on. Disabling scale-in protection."
+        aws autoscaling set-instance-protection --region ${region} --instance-ids ${instance_id} --auto-scaling-group-name ${asg_name} --no-protected-from-scale-in
+    else
+        echo "No containers running and scale protection is off. Doing nothing."
+    fi
+fi
+
+set +x
+
+echo "[$(date)] Script finished running successfully."
+echo "--------------------------------"
+echo