GitHub上のコミット履歴から機密情報を削除する

$ brew install bfg
$ bfg --version
bfg 1.14.0

$ mkdir bfg-sample
$ cd bfg-sample
$ git init
$ echo 'password123' > secret.txt
$ git add secret.txt
$ git commit -m 'Add secret'

$ git remote add origin git@github.com:nyshk97/bfg-sample.git
$ git branch -M main
$ git push -u origin main

$ cd ..
$ git clone --mirror git@github.com:nyshk97/bfg-sample.git
$ bfg --delete-files secret.txt bfg-sample.git

Using repo : /Users/hoge/dev/bfg-sample.git

Found 2 objects to protect
Found 2 commit-pointing refs : HEAD, refs/heads/main

Protected commits
-----------------

These are your protected commits, and so their contents will NOT be altered:

 * commit 06de1b9c (protected by 'HEAD') - contains 1 dirty file : 
	- secret.txt (12 B )

WARNING: The dirty content above may be removed from other commits, but as
the *protected* commits still use it, it will STILL exist in your repository.

Details of protected dirty content have been recorded here :

/Users/hoge/dev/bfg-sample.git.bfg-report/2023-07-26/12-54-34/protected-dirt/

If you *really* want this content gone, make a manual commit that removes it,
and then run the BFG on a fresh copy of your repo.
       

Cleaning
--------

Found 1 commits
Cleaning commits:       100% (1/1)
Cleaning commits completed in 19 ms.

BFG aborting: No refs to update - no dirty commits found??

$ cd bfg-sample
$ rm -f secret.txt
$ git add -A
$ git commit -m 'Remove secret.txt'
$ git push origin main

$ cd ..
$ rm -rf bfg-sample.git
$ rm -rf bfg-sample.git.bfg-report # bfgの実行時に生成される、レポートのディレクトリ
$ git clone --mirror git@github.com:nyshk97/bfg-sample.git
$ bfg --delete-files secret.txt bfg-sample.git

Using repo : /Users/hoge/dev/bfg-sample.git

Found 1 objects to protect
Found 2 commit-pointing refs : HEAD, refs/heads/main

Protected commits
-----------------

These are your protected commits, and so their contents will NOT be altered:

 * commit 2357094b (protected by 'HEAD')

Cleaning
--------

Found 2 commits
Cleaning commits:       100% (2/2)
Cleaning commits completed in 25 ms.

Updating 1 Ref
--------------

	Ref               Before     After   
	-------------------------------------
	refs/heads/main | 2357094b | f5a165e6

Updating references:    100% (1/1)
...Ref update completed in 27 ms.

Commit Tree-Dirt History
------------------------

	Earliest      Latest
	|                  |
	    D         m     

	D = dirty commits (file tree fixed)
	m = modified commits (commit message or parents changed)
	. = clean commits (no changes to file tree)

	                        Before     After   
	-------------------------------------------
	First modified commit | 06de1b9c | 371366ef
	Last dirty commit     | 06de1b9c | 371366ef

Deleted files
-------------

	Filename     Git id          
	-----------------------------
	secret.txt | ad366d9e (12 B )


In total, 3 object ids were changed. Full details are logged here:

	/Users/hoge/dev/bfg-sample.git.bfg-report/2023-07-26/13-29-27

BFG run is complete! When ready, run: git reflog expire --expire=now --all && git gc --prune=now --aggressive

$ cd bfg-sample.git
$ git reflog expire --expire=now --all && git gc --prune=now --aggressive
Enumerating objects: 3, done.
Counting objects: 100% (3/3), done.
Delta compression using up to 8 threads
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), done.
Building bitmaps: 100% (2/2), done.
Total 3 (delta 1), reused 1 (delta 0), pack-reused 0

$ git push --force
Enumerating objects: 3, done.
Writing objects: 100% (3/3), 252 bytes | 252.00 KiB/s, done.
Total 3 (delta 0), reused 0 (delta 0), pack-reused 3
remote: Resolving deltas: 100% (1/1), done.
To github.com:nyshk97/bfg-sample.git
 + 2357094...f5a165e main -> main (forced update)

$ mv app-name app-name-old
$ git clone git@github.com:user-name/app-name.git
# cloneできたら、READMEを参考に環境構築をやり直す。

$ git clone --mirror git@github.com:organization/app-name.git
$ bfg --delete-files hoge.txt app-name.git
$ cd app-name.git
$ git push --force