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"
        }
    ]
}

Convert JSON to YAML

JSON, or JavaScript Object Notation, is a minimal, readable format for structuring data. It is used primarily to transmit data between a server and web application, as an alternative to XML. YAML is a flexible, human readable file format that is ideal for storing object trees. YAML stands for “YAML Ain’t Markup Language”. It is easier to read than JSON, and can contain richer meta data. If you would like to switch formats, for example from JSON to YAML or vice versa, there are numerous website out there that can convert your code from one format to another. Check out this json2yaml converter.