Fabian Lee : Software Engineer

Ubuntu: resolving systemd error, “Start request repeated too quickly”

December 5, 2023
Categories: Linux

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”

Bash: schedule a command that will be run at reboot using cron

November 30, 2023
Categories: Linux

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

Docker: installing Docker CE on Ubuntu

September 14, 2023
Categories: Containers, Linux

Ubuntu: ‘Connection to the Snap Store failed’ during upgrade from Ubuntu 20 to 22

March 24, 2023
Categories: Linux

If you are upgrading from Ubuntu 20 to Ubuntu 22 using ‘do-release-upgrade’ and get a fatal error ‘Connection to the the Snap Store failed’, this may be resolved by removing the ‘lxd’ package which is a lightweight container supervisor. sudo /etc/init.d/lxd stop sudo rm -fr /var/lib/lxd sudo dpkg –force depends -P lxd; sudo dpkg –force … Ubuntu: ‘Connection to the Snap Store failed’ during upgrade from Ubuntu 20 to 22

Ubuntu: fixing apt NO_PUBKEY errors by converting deprecated keyring to signed-by attribute

January 15, 2023
Categories: Linux

If apt update throws warnings about invalid signature verification and NO_PUBKEY, you may need to migrate from using the deprecated system keyring to using a ‘signed-by’ attribute in your apt repo definition file. Here are examples of errors you might see when doing an ‘apt update’. W: An error occurred during the signature verification. The … Ubuntu: fixing apt NO_PUBKEY errors by converting deprecated keyring to signed-by attribute

Ubuntu: fix apt warning for Dropbox with key in legacy keyring

December 21, 2022
Categories: Linux

If you have Dropbox installed on your Linux desktop and have recently started seeing this warning message from apt: http://linux.dropbox.com/ubuntu/dists/disco/Release.gpg: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details This can be resolved by adding the Dropbox PGP key to the ‘signed-by’ of the apt repo definition (as … Ubuntu: fix apt warning for Dropbox with key in legacy keyring

GoLang: Running a Go binary as a systemd service on Ubuntu 22.04

October 29, 2022
Categories: Development, Linux

The Go language with its simplicity, concurrency support, rich package ecosystem, and ability to compile down to a single binary is an attractive solution for writing services on Ubuntu. However, the Go language does not natively provide a reliable way to daemonize itself. In this article I will describe how to take a couple of simple Go language programs … GoLang: Running a Go binary as a systemd service on Ubuntu 22.04

GoLang: Installing the Go Programming language on Ubuntu 22.04

October 29, 2022
Categories: Development, Linux

Update Sept 2024: changed the page parsed for latest version, validated installation of go1.23.1 on Ubuntu22.04 The Go programming language consistently ranks as one of the most popular languages in developer surveys. In fact, Kubernetes as well as most of the CNF projects are written in Go. And it compiles down to machine code, which … GoLang: Installing the Go Programming language on Ubuntu 22.04

Terraform: creating an Ubuntu 22 template and then guest VM in vCenter

October 12, 2022
Categories: Linux, Virtualization

In this article I will demonstrate how to create an Ubuntu 22 template in vCenter. Then use Terraform to create a vSphere VM based on this template. The VM template creation is done by manually stepping through the Ubuntu server ISO installation wizard, followed by a set of preparation steps. Then Terraform is used to … Terraform: creating an Ubuntu 22 template and then guest VM in vCenter

GoLang: Installing the Go Programming language on Ubuntu 20.04

August 22, 2022
Categories: Development

See the newer version of this article, “Installing the Go Programming language on Ubuntu 22.04“. The Go programming language consistently ranks as one of the most popular languages in developer surveys. In fact, Kubernetes as well as most of the CNF projects are written in Go. And it compiles down to machine code, which has … GoLang: Installing the Go Programming language on Ubuntu 20.04

Ubuntu: Installing .NET SDK 6 on Ubuntu 20.04

August 21, 2022
Categories: Development, Linux

The Microsoft .NET SDK is an open-source development platform for developing applications across multiple architectures and operating systems. In this article, I will show you how to install the .NET SDK on Ubuntu 20.04 and then create/compile/run a simple web application. Ubuntu 22 will have the dotnet-sdk available in the default Ubuntu apt repositories, but … Ubuntu: Installing .NET SDK 6 on Ubuntu 20.04

Buildah: Installing buildah and podman on Ubuntu 20.04

August 2, 2022
Categories: Containers

buildah is a tool that can create OCI compatible (Docker) images without the Docker daemon. podman can run these images without the need for a Docker daemon. The buildah and podman packages are available on the Debian Bullseye testing branch, but are not available from an Ubuntu 20.04 LTS release because these test packages could … Buildah: Installing buildah and podman on Ubuntu 20.04

Helm: Installing Helm on Ubuntu

January 16, 2022
Categories: Containers, DevOps

Update Aug 2023: using newer ‘signed-by’ attribute for apt signing keys. Installing Helm using apt is a straight-forward procedure and documented on the official site. Coming straight from the official helm documentation, here are the commands for Ubuntu 22. curl https://baltocdn.com/helm/signing.asc | gpg –dearmor | sudo tee /usr/share/keyrings/helm.gpg > /dev/null sudo chmod 644 /usr/share/keyrings/helm.gpg sudo … Helm: Installing Helm on Ubuntu

Docker: Installing Docker CE on Ubuntu focal 20.04

December 10, 2021
Categories: Containers, Linux

Docker is a container platform that streamlines software delivery and provides isolation, scalability, and efficiency with less overhead than OS level virtualization. These instructions are taken directly from the official Docker for Ubuntu page, but I wanted to reiterate those tasks essential for installing the Docker Community Edition on Ubuntu focal 20.04. If you want … Docker: Installing Docker CE on Ubuntu focal 20.04

KVM: Deploying a nested version of VMware ESXi 7.0 on KVM

November 18, 2021
Categories: Linux, Virtualization

If you are running KVM on an Ubuntu server, you already have an excellent Type 1 virtualization engine. Luckily, if you need to test something specific to VMware you can always run ESXi 7.0 nested inside a KVM virtual machine. In this article, I’ll be using a bare metal server running Ubuntu and KVM as … KVM: Deploying a nested version of VMware ESXi 7.0 on KVM

Terraform: creating an Ubuntu 20 Focal template and then guest VM in vCenter

August 16, 2021
Categories: Linux, Virtualization

In this article I will demonstrate how to create an Ubuntu 20 Focal template in vCenter. Then use Terraform to create a vSphere VM based on this template. The VM template creation is done by manually stepping through an installation using the minimal Ubuntu server ISO followed by a set of preparation steps. Then Terraform … Terraform: creating an Ubuntu 20 Focal template and then guest VM in vCenter

Ansible: Ubuntu alternatives using the community.general collection

June 20, 2021
Categories: Automation

In a previous article, I showed how to manually setup Alternatives so that different versions of a binary could co-exist on a target machine. In that step-by-step example, we used the Terraform binary as an example, and placed two independent versions in /usr/local/bin, and then set the priority so that terraform14 was preferred. To do … Ansible: Ubuntu alternatives using the community.general collection

Ansible: installing the latest Ansible on Ubuntu

May 31, 2021
Categories: Automation

Update Sep 2023: Installing ansible-core at user level (not system) with pip Ansible is an agentless configuration management tool that helps operations teams manage installation, patching, and command execution across a set of servers. In this article I’ll describe how to install the latest release of Ansible.

Ubuntu: WireGuard VPN for Ubuntu servers, with a Windows client

May 30, 2021
Categories: Linux

WireGuard aims to be the successor to IPsec and more performant than OpenVPN. It is a general purpose VPN that is secure enough for servers, yet light enough to run on embedded devices. In this article, I will show how to install WireGuard on an Ubuntu server and then access it using a Windows client. … Ubuntu: WireGuard VPN for Ubuntu servers, with a Windows client

Terraform: using update-alternatives to manage multiple terraform binaries

May 24, 2021
Categories: DevOps, Scripting

If you have multiple terraform projects, it can be necessary to support multiple versions of the terraform binary to match module and provider dependencies. Instead of creating a custom solution of binary copies and links, this can be done using the Alternatives concept which handles these symbolic links in a standard way using links in … Terraform: using update-alternatives to manage multiple terraform binaries

Ubuntu: Adding a root certificate authority

March 27, 2020
Categories: Linux

If your backend components or application servers use a custom CA (Certificate Authority), then you may need to add it to the system trusted root certificate store so that the standard tools and other utilities trust the TLS communication.

KVM: Testing cloud-init locally using KVM for an Ubuntu cloud image

February 23, 2020
Categories: Linux, Virtualization

The ability to quickly stand up a guest OS with cloud-init is most often associated with deployment of virtual machines in an IaaS like EC2 or Azure. But cloud-init is not just for remote cloud providers, and using cloud-init for local images that can be quickly deployed in KVM works great for local development and … KVM: Testing cloud-init locally using KVM for an Ubuntu cloud image

KVM: Terraform and cloud-init to create local KVM resources

February 22, 2020
Categories: Linux, Virtualization

Terraform is a popular tool for provisioning infrastructure on cloud provider such as EC2 and Azure, but there is also a provider written for local KVM libvirt resources. Using the libvirt provider, we can use standard Terraform constructs to create local VMs, networks, and disks.

GoLang: Installing the Go Programming language on Ubuntu

January 24, 2020
Categories: Development

The Go programming language has gotten considerable momentum, and the fact that it compiles down to a single statically linked binary has made it popular in containers, where a single executable binary fits the execution model perfectly. This article will detail installation on Ubuntu with the standard hello world validation.

Docker: Installing Docker CE on Ubuntu bionic 18.04

September 28, 2019
Categories: Containers, Linux

Update Dec 2021: I have written an updated article for installing Docker on focal 20.04 Docker is a container platform that streamlines software delivery and provides isolation, scalability, and efficiency with less overhead than OS level virtualization. These instructions are taken directly from the official Docker for Ubuntu page, but I wanted to reiterate those … Docker: Installing Docker CE on Ubuntu bionic 18.04

Kubernetes: running Minikube locally on Ubuntu using KVM

February 11, 2019
Categories: Containers, Kubernetes

Updated Aug 2023: tested on Ubuntu 22 with QEMU 6.2.0/libvirt 8.0.0 and with Minikube v1.31.2 Minikube is a tool that runs a full Kubernetes stack on a host, making it ideal for local development and experimentation. We are taking it one step further by placing Minikube into a virtual machine run by the KVM virtualization … Kubernetes: running Minikube locally on Ubuntu using KVM

Ubuntu: apt-get error, yarn signature verification

January 13, 2019
Categories: Linux

If you attempt an “apt-get update” and get a signature verification error from “dl.yarnpkg.com”, the problem is most likely an expired key. This can be resolved by reloading the new public key from the site: # add latest key curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add – # try refresh again sudo apt-get update Below … Ubuntu: apt-get error, yarn signature verification

AWS: Installing the AWS SDK for Python on Ubuntu

January 2, 2019
Categories: Automation, Python

Amazon EC2 provides a web interface for managing IaaS, but for repeatable infrastructure deployment what you really want is the ability to deploy and manage this infrastructure using an API or command line tool. The AWS SDK for Python (Boto3) provides a lower level as well as resource level API for managing and creating infrastructure. This … AWS: Installing the AWS SDK for Python on Ubuntu

AWS: Installing the AWS CLI on Ubuntu

December 16, 2018
Categories: Automation

Amazon EC2 provides a web interface for managing IaaS, but for repeatable infrastructure deployment what you really want is the ability to deploy and manage this infrastructure using an API or command line tool. In this article we want to focus on the CLI (command line interface), which shields us from the API innards and … AWS: Installing the AWS CLI on Ubuntu

Linux: Copy a directory preserving ownership, permissions, and modification date

October 15, 2018
Categories: Linux

File copying is about more than just content – the metadata for user ownership, permissions, and timestamps is often critical to retrieval and function. Below are the relevant switches for metadata preservation when using cp, rsync, and tar. These typically need sudo in order to work.

Ubuntu: X11 forwarding to view GUI applications running on server hosts

October 14, 2018
Categories: Linux

Although server hosts typically have no graphical desktop and only serve console-based clients, these machines still have the ability to serve a GUI display screen to a remote desktop if necessary. The X11 protocol makes it possible to send the graphical display to a remote graphical desktop. Beyond the ability to run GUI utilities on … Ubuntu: X11 forwarding to view GUI applications running on server hosts

Ubuntu: Gathering hardware and BIOS details

September 23, 2018
Categories: Linux

Whether you need to flash the BIOS or check hardware compatibility for a virtualization engine, it is often necessary to gather details on your current hardware, BIOS, and CPU/DRAM feature set. In this article I’ll provide a starting list of commands you can use to gather this information.

KVM: Deploying a nested version of VMware ESXi 6.7 inside KVM

September 19, 2018
Categories: Linux, Virtualization

Update Nov 2021: I have written a newer article that deploys ESXi 7.0U1. If you are running KVM on an Ubuntu server, you already have an excellent Type 1 virtualization engine. Luckily, if you need to test something specific to VMware you can always run ESXi 6.7 nested inside a KVM virtual machine. In this … KVM: Deploying a nested version of VMware ESXi 6.7 inside KVM

Ubuntu: Using iptables to forward tcp and udp requests

September 17, 2018
Categories: Linux

In previous articles I have described how to use a Squid proxy as a bridge to outside services such as http and ftp. Having hosts in your private networks use a single access point to services in the outside world institutes the type of control often required in production data centers. Having a single host … Ubuntu: Using iptables to forward tcp and udp requests

KVM: Bare metal virtualization on Ubuntu with KVM

August 27, 2018
Categories: Linux, Virtualization

Update September 2022: Validated these instructions on Ubuntu 22.04 If you are running an Ubuntu host, you have multiple choices for a virtualization hypervisor. I have written up several articles on using VirtualBox, but now let’s consider a bare metal hypervisor like KVM. KVM is a type 1 hypervisor implemented as a Linux kernel module … KVM: Bare metal virtualization on Ubuntu with KVM

SaltStack: salt-ssh for agentless automation on Ubuntu

July 1, 2018
Categories: Automation, DevOps

Configuration Management tools like SaltStack are invaluable for managing infrastructure at scale. Even in the growing world of containerization, there is the need for bulk automation. This article will detail installation of Salt SSH which leverages the power of SaltStack without the requirements for an agent install.

SaltStack: Installing a Salt Master on Ubuntu Xenial

June 25, 2018
Categories: Automation, DevOps

Configuration Management tools like SaltStack are invaluable for managing infrastructure at scale. Even in the growing world of containerization where immutable image deployment is the norm, those images need to be built in a repeatable and auditable fashion. This article will detail installation of the SaltStack master on Ubuntu Xenial 16.04, with validation using a single Minion. Note that … SaltStack: Installing a Salt Master on Ubuntu Xenial

GoLang: Installing the Go Programming language on Ubuntu 16.04

May 9, 2018
Categories: Development

Update: For the latest version of this article compatible with Ubuntu 22.04 and Go 1.19, see my newer article here. The Go programming language has gotten considerable momentum, and the fact that it compiles down to machine code has made it popular in containers like Docker where a single executable binary fits the execution model perfectly. This article … GoLang: Installing the Go Programming language on Ubuntu 16.04

Ubuntu: Resizing Nautilus window after it has been maximized

May 6, 2018
Categories: Linux

If you have issues with the Nautilus default file browser window not being resizable after it has been maximized, first try holding down “alt” while holding down the mouse button and dragging inside the window. If that does not work, you can use “wmctrl” from the console to fix the issue.

Java: Spring Boot application as a service using SysV on Ubuntu 14.04

April 17, 2018
Categories: Java, Linux

Although in modern architectures you typically see Spring Boot executable jars running as the primary process of a container, there are still many deployment scenarios where running the jar as a service at boot time is required. With Ubuntu 14.04, we can use SysV to run a Spring Boot application at boot time. This will … Java: Spring Boot application as a service using SysV on Ubuntu 14.04