Uly.me

cloud engineer

JQ on GitBash

JQ is a json processor. It’s for slicing and dicing data.

Download

To install on GitBash, unzip the file and copy the executable to /usr/bin.

mv jq-win64.exe to /usr/bin/jq.exe

Create an alias. Edit ~/.bashrc.

alias jq='/usr/bin/jq.exe'

Using JQ.

jq --version
jq '.selfLink' vm.json

Change DNS Records in Route 53 via CLI

How to change DNS records in Route 53 via AWS CLI.

  • Assuming AWS CLI is already configured
  • Uses Route53 change-resource-record-sets to update DNS records
  • Substitute with your own hosted-zone-id
  • Uses JSON files containing record sets
  • See JSON file examples below 
cd /path/to/scripts/
# the command to switch to the elb
aws route53 change-resource-record-sets --hosted-zone-id xxxxxxxxxxxxxx --change-batch file://elb.json
# the command to switch to standard site
aws route53 change-resource-record-sets --hosted-zone-id xxxxxxxxxxxxxx --change-batch file://live.json

elb.json = points to AWS ELB (elastic load balancer)

{
   "Comment": "back to elb",
   "Changes": [
      {
         "Action": "UPSERT",
         "ResourceRecordSet": {
            "Name": "yourdomain.com",
            "Type": "A",
            "AliasTarget": {
               "HostedZoneId": "xxxxxxxxxxxxxx",
               "EvaluateTargetHealth": false,
               "DNSName": "xxxxxxxxxxxxx.us-east-1.elb.amazonaws.com."
            }
         }
      }
   ]
}

live.json = points to your standard site. Value is your IP Address.

{
   "Comment": "back to live",
   "Changes": [
      {
         "Action": "UPSERT",
         "ResourceRecordSet": {
            "Name": "yourdomain.com",
            "Type": "A",
            "TTL": 60,
            "ResourceRecords": [
               {
                  "Value": "xxx.xxx.xxx.xxx"
               }
            ]
         }
      }
   ]
}

AWS CLI Bucket Lifecycle Configuration

I was banging my head against the wall (not quite literally, but it was close) trying to come up with a S3 lifecycle configuration from scratch. I needed a JSON file that I can run in a bash script, so I can apply the lifecycle rules to a few dozen S3 buckets. Obviously, trying to create one from scratch wasn’t the wisest choice in my part. As it turns out, you can setup a temporary bucket and use the console to recreate the lifecycle, then export the lifecycle JSON file. Duh! Genius! Here’s the command to export the lifecycle configuration.

aws s3api get-bucket-lifecycle-configuration \
--bucket bucket-name

The output would be in a JSON format similar to this:

{
    "Rules": [
        {
            "Status": "Enabled",
            "NoncurrentVersionExpiration": {
                "NoncurrentDays": 90
            },
            "NoncurrentVersionTransitions": [
                {
                    "NoncurrentDays": 7,
                    "StorageClass": "INTELLIGENT_TIERING"
                }
            ],
            "Filter": {
                "Prefix": ""
            },
            "Expiration": {
                "ExpiredObjectDeleteMarker": true
            },
            "AbortIncompleteMultipartUpload": {
                "DaysAfterInitiation": 7
            },
            "ID": "EFS S3 Backup Lifecycle Rules"
        }
    ]
}