If you have a set of resources in Terraform that are conditionally included based on the same criteria, instead of appending a “count/for_each” on every resource definition, consider refactoring them into a module. The conditional can then be placed on the module definition instead of polluting each resource definition. For example, if you had several … Terraform: module for conditional include of related resources
The output of a Terraform child module is not shown by the root configuration/module. In order to have the child module output shown, you must explicitly define a root level output. For example, if you root had a child module defined like below, and you wanted to display the output of that child module, then … Terraform: enabling the output of a child module
If you are using awk with a relatively indexed NF variable (number of fields), and get an error like below, this is because the input being parsed does not have the number of fields expected. awk: run time error: negative field index $-1 The root problem is the awk expression was expecting a certain number … Bash: resolving awk run time error, negative field index
Istio Ambient mode is a data plane model that eliminates the need for an envoy sidecar proxy on each of your workloads. This reduces resource overhead, timing issues between sidecar lifecycle and your containers, and the need to restart your workloads to upgrade proxy versions. In this article, I will show you how to install … Minikube: Istio Ambient mode on Minikube
At the Bash command line interface, there is the concept of programmable completion and regular file/directory completion. This means that when you press the <TAB>, the alternatives can be provided by a custom program or the filesystem hierarchy. There is always the chance that a program may introduce undesirable behavior to your auto-completion, and if … Bash: falling back to file autocompletion if errors introduced by program autocompletion
Github Actions provide the ability to define a build workflow, and for projects that are building an OCI (Docker) image, there are custom actions available for running the Trivy container security scanner. In this article, I will show you how to modify your GitHub Action to run the Trivy security scanner against your image, and … Github: security scanning built into GitHub Actions image build
GitLab Pipelines provide the ability to define a build workflow, and for projects that are building an OCI (Docker) image, there is a convenient method for doing container security scanning as part of the build process. Include Container Scanning As described in the official documentation, add the following include to your .gitlab-ci.yml pipeline definition. include: … GitLab: security scanning built into GitLab Pipelines image build
Google Pub/Sub is a managed messaging platform providing a scalable, asynchronous, loosely-coupled solution for communication between application entities. It centers around the concept of a Topic (queue). A Publisher can put messages on the Topic, and a Subscriber can read messages from the Subscription on a Topic. In this article, I will first use the … GCP: publishing and reading from Google PubSub Topic using Python client libraries
KEDA is an open-source event-driven autoscaler that greatly enhances the abilities of the standard HorizontalPodAutoscaler. It can scale based on internal metrics as well as external Scaler sources. In this article, I will illustrate how to install KEDA on a GKE cluster that has Workload Identity enabled, and then how to configure KEDA scaling events … GCP: Installing KEDA on a GKE cluster with workload identity and testing Scalers
Although the simple ‘gcloud container operations list‘ command is the easiest way to find recent upgrade events on your GKE cluster or nodepool, it returns only the recent events and does not provide a historical record. If you need to look at historical events, you can use Logs Explorer web UI or use the ‘gcloud … GCP: historical log of GKE cluster and nodepool upgrades and scaling
Trivy is an open-source tool that can scan your containers and produce reports on known critical issues at the binary and OS package level. In this article, I will describe how to scan images directly from your local Debian/Ubuntu machine, whether you built the image locally or pulled it down remotely. Installation on Debian/Ubuntu Per … Kubernetes: Trivy for container scanning from CLI
If you find yourself low on disk space, check the size of the Systemd journal logs as a way to easily free up some space. $ sudo journalctl –disk-usage Archived and active journals take up 528.0M in the file system. # reduce size to 300 Mb sudo journalctl –vacuum-size=300M There are automatic jobs that trim … Linux: reducing disk usage of Systemd journal logs
The openssl utility can be used to show the details of a certificate, including its ‘Not After’ expiration date in string format. This can be transformed into “how many days till expiration” with a bit of Bash date math. Create test certificate and key Using a line provided by Diego Woitasen for non-interactive self-signed certification … Bash: calculating number of days till certificate expiration using openssl
GitLab pipelines are a convenient way to expose deployment/delivery tasks. But with their rudimentary web UI for variable input, it can be challenging for users to populate the required list of variables. One way of making it more convenient for end-users is to provide them a URL pre-populated with the specific branch and pipeline variable … GitLab: URL shortcut to override pipeline variable values
Terraform has now been open-source and forked with the OpenTofu project. The ‘tofu’ binary is a drop-in replacement for terraform, and this article will show you how to install on Debian/Ubuntu. After installation, we will then use the Debian/Ubuntu Alternatives concept to supersede existing calls to ‘terraform’ to instead invoke ‘tofu’. Setup OpenTofu apt repository … OpenTofu: installing OpenTofu on Debian/Ubuntu
If you are using Terraform as a way to provide infrastructure/services to outside teams, your Terraform definitions and variables may initially be owned by your team alone, with all “tf apply” operations done by trusted internal group members at the CLI. But once there is a certain amount of maturity in the solution, the Terraform … Terraform: external yaml file as a contribution model for outside teams
Base64 encoding a string may seem like a straight-forward operation, but there are a couple of gotchas even when dealing with just simple ASCII strings. Avoid embedding a new line character into the encoding If you use the most straight forward method of Base64 encoding shown below, you have to remember that echo by default … Bash: avoiding newline artifacts when Base64 encoding a string
Mike Farah’s yq yaml processor has a a rich set of operators and functions for advanced usage. In this article, I will illustrate how to update deeply nested elements in yaml. This can be done for both known paths as well as arbitrarily deep paths. Sample yaml We will use the following yaml files to … yq: updating deeply nested elements
Mike Farah’s yq yaml processor has a a full-featured validation command that is very detailed in its reporting, but the yaml specification itself is very lenient, which means yq may accept scenarios you did not expect (e.g. an empty file). yq -v file.yaml >/dev/null ; echo “final result = $?” Luckily, the yq tips-and-tricks section … yq: validate yaml syntax
Keeping the Ubuntu system-level Python version and modules independent from those desired at each project level is a difficult task best managed by a purpose-built tool. There are many solutions in the Python ecosystem, but one that stands out for simplicity is pyenv and pyenv-virtualenv. pyenv allows you to install and switch between different versions … Ubuntu: pyenv for managing multiple Python versions and environments
It is relatively easy to experiment with a base LLama2 model on Ubuntu, thanks to llama.cpp written by Georgi Gerganov. The llama.cpp project provides a C++ implementation for running LLama2 models, and works even on systems with only a CPU (although performance would be significantly enhanced if using a CUDA-capable GPU).
If you need to dig deeper into the dependencies that brew has installed on your Mac, you can show a complete dependency tree using: brew deps –tree –installed If you need to see who relies on a specific target Formulae: brew uses –installed <targetFormulae> REFERENCES brew.sh, deps command syntax apple.stackexchange, ‘brew deps’ showing all … Mac: list deep dependencies of Homebrew formulae
It is relatively easy to experiment with a base LLama2 model on M family Apple Silicon, thanks to llama.cpp written by Georgi Gerganov. The llama.cpp project provides a C++ implementation for running LLama2 models, and takes advantage of the Apple integrated GPU to offer a performant experience (see M family performance specs).
minikube makes it easy to spin up a local Kubernetes cluster on macOS, and adding an Ingress is convenient with its built-in Addons. In this article, I want to take it one step further and show how to expose the Ingress via TLS (secure https) using a custom key/certificate chain.
The Apple Virtualization Framework (AVF) provides the ability to run completely independent virtual machines on top of M family Apple Silicon. For example, you can run multiple versions of MacOS virtualized for validating an application or its dependencies against different environments. Additionally, cloning an existing VM (with little cost thanks to APFS copy-on-write) allows you … Mac: bare-metal virtualization on Apple Silicon with virtualbuddy
Although you could use brew to install Python directly, the cleaner way to manage Python versions and isolate Python virtual environments is by using pyenv and pyenv-virtualenv. pyenv allows you to install and switch between different versions of Python, while pyenv-virtualenv provides isolation of pip modules, for independence between projects.
If you are using ssh private/public keypair authentication, and get an almost immediate error like below: $ ssh -i id_rsa.pub myuser@a.b.c.d -p 22 Received disconnect from a.b.c.d port 22:2: Too many authentication failures Disconnected from a.b.c.d port 22 Then try again using the ‘IdentitiesOnly‘ option. ssh -o ‘IdentitiesOnly yes’ -i id_rsa.pub myuser@a.b.c.d -p 22 The … Bash: fixing “Too many authentication failures” for ssh with private key authentication
If you want a variable to reference another variable in Bash, that is possible using a concept called indirect reference. Below is a simple example where ‘varname’ contains the name of another variable ‘foo’. # our variable foo=bar # our reference varname=foo # the following syntax will ERROR and DOES NOT work !!! echo “${$varname}” … Bash: indirect reference to evaluate a variable value
If your systemd service is failing with the following error message: XXX.service: Start request repeated too quickly The first thing to do is fix any underlying issues. Use ‘systemctl status <service>’, ‘journalctl -u <service>’, and search any log files produced by the service to understand why the service failed multiple times and exceeded its StartLimitBurst. … Ubuntu: resolving systemd error, “Start request repeated too quickly”
The Vault Secrets Operator is a Vault integration that runs inside a Kubernetes cluster and synchronizes Vault-level secrets to Kubernetes-level secrets. This secret synchronization happens transparently to the running workloads, without any need to retrofit existing images or manifests. In this article, I will show how to: Install the Vault Secrets Operator (VSO) Configure the … Vault: synchronizing secrets from Vault to Kubernetes using Vault Secrets Operator
minikube makes it easy to spin up a local Kubernetes cluster, and adding an Ingress is convenient with its built-in Addons. In this article, I want to take it one step further and show how to use a custom key/certificate to expose a service using TLS (secure https).
If there is a command that needs to run on startup/reboot, you can use the @reboot directive in cron to schedule it. Here is a simple example of logging the date to a file at startup. (crontab -l 2>/dev/null; echo “@reboot date >> ~/startup.log”) | sort -u | crontab – The sort command avoids duplicate … Bash: schedule a command that will be run at reboot using cron
In this article, I will detail how to use Vault JWT auth mode to isolate the secrets of two different deployments in the same Kubernetes cluster. This will be done by using two different Kubernetes Service Accounts, each of which generates unique JWT that are tied to a different Vault role. JWT auth mode is … Vault: JWT authentication mode with multiple roles to isolate secrets
If you are getting the following error when invoking an Ansible playbook or any of the Ansible related utilities: ERROR! Invalid callback for stdout specified: yaml This means Ansible is attempting to use the new YAML callback plugin, but cannot find the Ansible Galaxy community.general module. This module is installed by the ‘ansible’ pip module, … Ansible: resolving error “Invalid callback for stdout specified: yaml”
HashiCorp Vault is a secret and encryption management system that allows your organization to secure sensitive information such as API keys, certificates, and passwords. In this article, I will show how a NodeJS Express web application deployed into a Kubernetes cluster can fetch a secret directly from the Vault server using the node-vault module. This … Vault: NodeJS Express web app using node-vault to fetch secrets
Getting the sum of a list of numbers is a common scenario on the command line, whether you are checking local filesystem utilization or parsing infrastructure reports for total cpu counts. There are multiple ways this can be done, but one of the simplest is to use awk. Let’s use a a sequence of numbers … Bash: calculate sum from a list of numbers
HashiCorp Vault is a secret and encryption management system that allows your organization to secure sensitive information such as API keys, certificates, and passwords. In this article, I will show how a Java Spring Boot web application deployed into a Kubernetes cluster can fetch a secret directly from the Vault server using the Spring Cloud … Vault: Spring Boot web app using Spring Cloud Vault to fetch secrets
HashiCorp Vault is a secret and encryption management system that allows your organization to secure sensitive information such as API keys, certificates, and passwords. It has tight integrations with Kubernetes that allows containers to fetch secrets without requiring hardcoding them into environment variables, files, or external services. The official docs already provide usage scenarios, so … Vault: HashiCorp Vault deployed into Kubernetes cluster for secret management
If ssh private/public keypair authentication is failing, check the logs on the server side for permission errors. On Debian/Ubuntu check for these errors in “/var/log/auth.log”. # error if authorized_keys file has too wide a permission for others Authentication refused: bad ownership or modes for file /home/myuser/.ssh/authorized_keys # error if .ssh directory has too wide a … Bash: fixing SSH authentication error “bad ownership or modes for file/directory”
GitLab Agent for Kubernetes is an integration for the GitLab CI/CD pipeline that provides kubectl access from pipeline jobs, allowing Continuous Deployment into a live Kubernetes Cluster. However, the default role for this Agent is cluster-admin when doing a basic Helm install, which is far too permissive and needs to be scoped down to only … GitLab: least privilege for Kube-API calls from GitLab Agent for Kubernetes