helper script for jibri on ASG

jibri_cron.sh

#!/bin/bash

meta_url='http://169.254.169.254'

AWS_REGION=$(curl --silent $meta_url/latest/dynamic/instance-identity/document | jq -r .region)
INSTANCE_ID=$(curl --silent $meta_url/latest/meta-data/instance-id)
ASG_NAME=$(aws autoscaling describe-auto-scaling-instances \
               --instance-ids $INSTANCE_ID \
               --region $AWS_REGION \
               | jq -r '.[] | .[] | .AutoScalingGroupName')

# modified: jibri exposes metrics on 2222, tested on a docker container
JIBRI_STATUS=$(curl --silent "http://localhost:2222/jibri/api/v1.0/health"| jq -j '.status.busyStatus')
JIBRI_HEALTH=$(curl --silent "http://localhost:2222/jibri/api/v1.0/health"| jq -j '.status.health.healthStatus')

## set/unset instance protection flag for asg
## args: no-protected-from-scale-in, protected-from-scale-in
protect_instance(){
    protection_flag=$1
    aws autoscaling set-instance-protection \
        --instance-ids $INSTANCE_ID \
        --auto-scaling-group-name $ASG_NAME \
        --${protection_flag} \
        --region $AWS_REGION
}

## report custom metric to cloudwatch
## args: 0|1; 0-BUSY, 1-IDLE
report_to_coudwatch(){
    CLOUDWATCH_METRIC_NAME="jibri_available"
    aws cloudwatch put-metric-data \
        --metric-name  $CLOUDWATCH_METRIC_NAME \
        --dimensions app="jibri" \
        --namespace "Custom" \
        --value $1 \
        --region $AWS_REGION
}

function check_health(){
   # if jibri is unhealthy
    if [ "$JIBRI_HEALTH" = "UNHEALTHY" ] 
    then 
        logger "shutdown_server, jibri is unhealthy, might be dead, recycing server"
        # systemctl shutdown
        exit 1;
    fi
}

function main(){
    # check state
    if [ "$JIBRI_STATUS" = "IDLE" ] 
    then
        logger "reporting jibri is idle"
        report_to_coudwatch 1
        protect_instance no-protected-from-scale-in
    fi

    if [ "$JIBRI_STATUS" = "BUSY" ]
    then
        logger "reporting jibri is BUSY"
        report_to_coudwatch 0
        protect_instance protected-from-scale-in
    fi
}

check_health
main