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Go banana!

Peter Mescalchin magnetikonline

Go banana!
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magnetikonline / workflow.yaml
Created Mar 24, 2021
Simple form passing artefacts between GitHub Actions workflow jobs.
View workflow.yaml
name: Workflow
- main
runs-on: ubuntu-latest
magnetikonline /
Created Mar 4, 2021
Remove an existing AWS CloudFormation stack, but retain the managed resources.

Delete CloudFormation stack - retaining resources

How to remove an existing CloudFormation stack, but retain the managed resources.

First step - we need the stack within a state of DELETE_FAILED, this can be achieve by attempting stack delete with a user that only has IAM rights to cloudformation:*. Create a new temporary IAM user with the following inline policy:

	"Version": "2012-10-17",
	"Statement": [
magnetikonline /
Last active Jan 19, 2021
Remove AWS network interfaces from given security group ID.

Remove AWS network interfaces from security group ID

Script has been handy to clean up security groups which have been used with VPC honed AWS Lambda functions and maintain an ENI association.

Why this is a problem:

  • New Lambda is created within the given VPC subnets and security group.
  • During deployment, AWS creates ENIs assigned to the security group and placed into the instructed subnets.
  • Next, change is made to Lambda involving new security group association. AWS now creates new ENIs - as ENI reuse between Lambdas is only for the same security group/subnet combination.
  • Finally, user wishes to clean up legacy security group - but can't as existing ENIs still use security group.
magnetikonline /
Last active Jan 17, 2021
List AWS Lambda@Edge log groups across regions.

List AWS Lambda@Edge log groups across regions

AWS Lambda@Edge functions, which run under CloudFront at multiple edge locations require associated Lambda functions to exist within each AWS region.

By design, this means CloudWatch Logs produced by Lambda@Edge functions will exist across these regions.

This Bash script will query for all log groups associated to Lambda@Edge functions for each enabled region of the current AWS account to hopefully help determine where logs are going/exist.

magnetikonline /
Created Jan 11, 2021
Delete all AWS S3 bucket versioned objects and delete markers.

Delete all S3 versioned objects and delete markers

Quick and dirty Bash script to iterate an S3 bucket and remove all object versions and delete markers.

Probably only usable on buckets with a few hundred version objects maximum, otherwise it might be more efficient and time effective to use a lifecycle rule to age out and remove objects in bulk.


magnetikonline /
Last active Dec 23, 2020
macOS - Install The Silver Searcher (`ag`) from source.

Install The Silver Searcher (ag) on macOS from source

A quick n' dirty bash script to install the following:

  • automake, pkg-config, PCRE, xz - all needed by ag configure.
  • ag - from source.

Requires as a minimum Xcode CLI tools (don't need a full Xcode install). Can be done via the following:

$ xcode-select --install
magnetikonline /
Last active Nov 28, 2020
Golang net/http middleware flow.

Golang net/http middleware flow

$ go run main.go
Called middleware03()
Called middleware02()
Called middleware01()
Called initial()
magnetikonline /
Created Nov 24, 2020
Access Golang private modules within a GitHub organization.

Golang private modules within a GitHub organization

You've got Golang modules within a private repository or an organization and would like to go get them.

For this example the GitHub organization will be spacely-sprockets.


Set GOPRIVATE (ideally placed in your .bashrc / dotfiles):

magnetikonline /
Created Nov 23, 2020
Find latest non beta/RC release for Docker CLI

Find latest non beta/RC release for Docker CLI

Using curl and jq to:

  • Pull list of GitHub release tags.
  • Filter out all that don't match vX.Y.Z (stripping beta/rc).
  • Finally return just the first entry (latest tag).
curl --silent \
magnetikonline /
Last active Nov 11, 2020
Creating a 'run once' systemd unit.

Creating a 'run once' systemd unit

A template for a systemd unit which calls a script exactly once on startup and keeps unit status active after script exits.

Unit file placed in /etc/systemd/system and enabled with:

$ sudo systemctl enable runonce.service
$ sudo systemctl start runonce.service