Completely Removing Secrets from Git History

What I Learned

Sensitive information (API keys, private keys, configuration files, etc.) that has been accidentally committed continues to remain in Git’s history even with normal deletion. By using git filter-repo, you can rewrite Git history and completely remove sensitive information. However, removing from history does not make already leaked credentials safe, so you must always revoke and reissue the relevant credentials.

Details

Background

Previously, methods using git filter-branch were introduced, but warnings are now issued in the official documentation, and when creating new procedures, the use of git filter-repo is recommended.

Local-Only Git Workflow Guide

What I Learned

I organized a workflow for using Git solely locally, without using remotes like GitHub, aimed at Git beginners and individual developers. Since Git inherently keeps all history locally, understanding local Git before learning about remotes makes it easier to handle and less confusing. Backups (pseudo-remote/mirror) are possible even within local environments.

Details

Benefits of Using Git Locally Only

• Fewer concepts to learn, easier to study
• No risk of bothering others
• Can focus on Git’s essence (managing change history)

1. Basic Operations and Workflow

1-1. Repository Creation and Status Checks

1git init
2git status

1-2. Recording Changes Flow

1git add .
2git commit -m "work description"

1-3. Checking Status and History

1git diff
2git log --oneline --graph --decorate

1-4. Branch Operations

1git switch -c feature
2git switch main
3git branch -d feature

2. Reverting to Past Versions (Recovery Commands)

2-1. Restore Files Only

1git restore filename

2-2. Undo the Last Commit (Keep Work Contents)

1git reset --soft HEAD^

2-3. Rewind Commits and Changes (Destructive)

1git reset --hard HEAD^

2-4. Revert to a Specific Commit

1git reset --hard <commit-id>

2-5. Undo Without Breaking History

1git revert <commit-id>

2-6. Reference Past State

1git switch --detach <commit-id>

3. Backup (Local Pseudo-Remote + Mirror)

Git “remotes” don’t have to be URLs; you can register local folders as remotes.

Setting Up a Development Environment with WSL2 + Ubuntu + Git

What I Learned

I usually develop on a Mac, but recently I’ve had more opportunities to teach development to Windows users. So I organized the procedure for setting up a development environment on Windows. With the combination of WSL2 + Ubuntu + Git + VS Code, you can build a comfortable Linux development environment on Windows similar to Mac. It’s lighter than virtual machines and file sharing with Windows is smooth.

How to Fix Unwanted File Changes in a GitHub PR

What I Learned

I learned how to remove unwanted file changes from a specific commit in a Pull Request. By combining git rebase -i and git commit --amend, you can pinpoint and modify past commits while keeping the history clean.

Details

The Problem

When creating a PR and checking the diff, I found that a certain commit had unintentionally changed a file:

D  example/config.yaml    (deleted)

It’s common to accidentally include unrelated changes such as configuration files or documentation in commits. This prevents the PR from being properly reviewed, so I needed to fix only that specific commit.

Git Rebase Interactive

What I Learned

Git’s interactive rebase (git rebase -i) is a powerful tool for cleaning up commit history before pushing changes. It allows you to reorder, squash, edit, or remove commits.

Details

Interactive rebase opens an editor with a list of commits and commands:

1git rebase -i HEAD~3

Available commands:

• pick - use commit as-is
• reword - change commit message
• edit - stop for amending
• squash - combine with previous commit
• fixup - like squash but discard commit message
• drop - remove commit

Example workflow: