Category: Software

Go template that properly renders delimiters for a slice of structs

Posted on by rchapin

It is common to write go text/templates that range over a slice of objects to write out a list or array of items that are separated by some delimiter defined in the template.

In the case of a JSON array of objects, the cleanest output would be a , separating each object without a leading or trailing comma.

Because go template if statements are falsey in that a 0 value will evaluate to false you can write a template as → Continue reading “Go template that properly renders delimiters for a slice of structs”

How to set up a locally hosted git server and create new repositories

Posted on by rchapin

You may have code and configurations that are required to stay on premise. As a result, you will need to setup your own git server and create and manage repositories locally. Following is an overview of how to set that up.

We will leave aside server setup, configuration, and networking and assume that we have a machine on which we will host the repos, git-server, and machines that will clone, pull, and push updates, clients.

Setting up the

→ Continue reading “How to set up a locally hosted git server and create new repositories”

Setting up software RAID on Debian with mdadm

Posted on by rchapin

Software RAID has come a long way. Unless you have some very high-rate, high-volume, I/O workloads with SLAs that will otherwise cost you money, for the most part a software RAID will perform just fine. One of the primary benefits of using software RAID is the portability of your disks/data. If a box on which you have a software RAID dies somehow and at least some (depending on your RAID configuration) of drives survive, you can easily resurrect the RAID → Continue reading “Setting up software RAID on Debian with mdadm”

[SOLVED] debsig-verify for Failed verification error, “signatures using the SHA1 algorithm are rejected” and “Can’t check signature: Invalid digest algorithm”

Posted on by rchapin

If you are using debsig-verify for the verification of a downloaded .deb file and are unable to verify it, run it with the -d option to get more information. If you see the following two lines

gpg: Note: signatures using the SHA1 algorithm are rejected
gpg: Can't check signature: Invalid digest algorithm

It is likely that the PGP signature used to sign the package uses the SHA1 algorithm which has been deprecated in most of the recent Linux distros. If → Continue reading “[SOLVED] debsig-verify for Failed verification error, “signatures using the SHA1 algorithm are rejected” and “Can’t check signature: Invalid digest algorithm””

LVM Resize – reduce the size of one logical volume to enable expanding another

Posted on by rchapin

I’m running an Ubuntu workstation and when setting it up simply went the “next-next-next” route when setting up the encrypted disk via LVM. The default is to create a 1G swap partition which is just not enough when you attempt to run too many things and locks up and/or crashes the machine.

My goal was to reduce my /root partition and then use that space to extend my swap partition.

Ensure that you back up your data first! There is → Continue reading “LVM Resize – reduce the size of one logical volume to enable expanding another”

Convert a Slice of Any Type to a CSV in Go

Posted on by rchapin

There are times, mostly for logging and debugging, when you have a slice of a given type that you would like to print to a log file or just convert to a CSV of values.

A quick and easy way to convert a slice to a CSV in Golang is to use the json module to Marshal it a JSON encoded array.

For example

package main

import (
	"encoding/json"
	"fmt"
)

func main() {
	ints := []int64{1, 2, 3,
→ Continue reading “Convert a Slice of Any Type to a CSV in Go”

Earthly Cheat Sheet

Posted on by rchapin

I have just recently started using Earthly and the following is a list of commands that I want to keep track of

Caching

Completely clearing the cache: Earthly stores artifacts in docker volumes. If you want to completely flush that data and start fresh run the following

docker stop earthly-buildkitd && \
docker rm earthly-buildkitd && \
docker volume rm earthly-cache
→ Continue reading “Earthly Cheat Sheet”

git Cheat Sheet

Posted on by rchapin

A handful of handy git commands that I don’t use all that often but want to keep track of:

Stashing

Stash a single file

git stash push -m 'message here' -- path/to/file

Drop a specific stash

First figure out the id of the stash you want to drop with git stash list, then issue the following command

git stash drop stash@{n}

Editing Commits

Changing author of already pushed commit

If you need to change the author of a commit → Continue reading “git Cheat Sheet”

Use printf to join an array in Bash

Posted on by rchapin

If you would like to join an array of elements with a defined delimiter in Bash there is an easy way to go about it by using printf. Following is an example

#!/bin/bash

declare -a arr=()

for i in `seq 1 5`
do
  arr=("${arr[@]}" $i)
done

# Generate a single string joined by a comma.  The printf string can contain
# any arbitrary delimiter.
printf -v joined '%s,' "${arr[@]}"

# Print out the string minus the trailing comma
echo
→ Continue reading “Use printf to join an array in Bash”

Specifying a commit in go.mod instead of a local replace for development

Posted on by rchapin

Sometimes you are making changes to a dependency in another of your go projects and instead of adding a replace command in the go.mod file you want to update that entry in go.mod to point to a specific commit in the repo.

To do so, all that you need to do is:

  1. Get the git commit that you want included in your build
  2. Change directories to the same directory that your project’s go.mod file resides in which you want to
→ Continue reading “Specifying a commit in go.mod instead of a local replace for development”
© 2005 Ryan Chapin