Removing sensitive data from a repository

The git filter-repo tool and the BFG Repo-Cleaner rewrite your repository's history, which changes the SHAs for existing commits that you alter and any dependent commits. Changed commit SHAs may affect open pull requests in your repository. We recommend merging or closing all open pull requests before removing files from your repository.

You can remove the file from the latest commit with git rm. For information on removing a file that was added with the latest commit, see "About large files on GitHub."

Purging a file from your repository's history

You can purge a file from your repository's history using either the git filter-repo tool or the BFG Repo-Cleaner open source tool.

Using the BFG

The BFG Repo-Cleaner is a tool that's built and maintained by the open source community. It provides a faster, simpler alternative to git filter-branch for removing unwanted data.

For example, to remove your file with sensitive data and leave your latest commit untouched, run:

$ bfg --delete-files YOUR-FILE-WITH-SENSITIVE-DATA

To replace all text listed in passwords.txt wherever it can be found in your repository's history, run:

$ bfg --replace-text passwords.txt

After the sensitive data is removed, you must force push your changes to GitHub. Force pushing rewrites the repository history, which removes sensitive data from the commit history. If you force push, it may overwrite commits that other people have based their work on.

$ git push --force

See the BFG Repo-Cleaner's documentation for full usage and download instructions.

Using git filter-repo

To illustrate how git filter-repo works, we'll show you how to remove your file with sensitive data from the history of your repository and add it to .gitignore to ensure that it is not accidentally re-committed.

1. Install the latest release of the git filter-repo tool. You can install git-filter-repo manually or by using a package manager. For example, to install the tool with HomeBrew, use the brew install command.

   brew install git-filter-repo
   

   For more information, see INSTALL.md in the newren/git-filter-repo repository.

2. If you don't already have a local copy of your repository with sensitive data in its history, clone the repository to your local computer.

   $ git clone https://github.com/YOUR-USERNAME/YOUR-REPOSITORY
   > Initialized empty Git repository in /Users/YOUR-FILE-PATH/YOUR-REPOSITORY/.git/
   > remote: Counting objects: 1301, done.
   > remote: Compressing objects: 100% (769/769), done.
   > remote: Total 1301 (delta 724), reused 910 (delta 522)
   > Receiving objects: 100% (1301/1301), 164.39 KiB, done.
   > Resolving deltas: 100% (724/724), done.

3. Navigate into the repository's working directory.

   $ cd YOUR-REPOSITORY

4. Run the following command, replacing PATH-TO-YOUR-FILE-WITH-SENSITIVE-DATA with the path to the file you want to remove, not just its filename. These arguments will:

   • Force Git to process, but not check out, the entire history of every branch and tag
   • Remove the specified file, as well as any empty commits generated as a result
   • Remove some configurations, such as the remote URL, stored in the .git/config file. You may want to back up this file in advance for restoration later.
   • Overwrite your existing tags

     $ git filter-repo --invert-paths --path PATH-TO-YOUR-FILE-WITH-SENSITIVE-DATA
       Parsed 197 commits
       New history written in 0.11 seconds; now repacking/cleaning...
       Repacking your repo and cleaning out old unneeded objects
       Enumerating objects: 210, done.
       Counting objects: 100% (210/210), done.
       Delta compression using up to 12 threads
       Compressing objects: 100% (127/127), done.
       Writing objects: 100% (210/210), done.
       Building bitmaps: 100% (48/48), done.
       Total 210 (delta 98), reused 144 (delta 75), pack-reused 0
       Completely finished after 0.64 seconds.

   Note: If the file with sensitive data used to exist at any other paths (because it was moved or renamed), you must run this command on those paths, as well.

5. Add your file with sensitive data to .gitignore to ensure that you don't accidentally commit it again.

   $ echo "YOUR-FILE-WITH-SENSITIVE-DATA" >> .gitignore
   $ git add .gitignore
   $ git commit -m "Add YOUR-FILE-WITH-SENSITIVE-DATA to .gitignore"
   > [main 051452f] Add YOUR-FILE-WITH-SENSITIVE-DATA to .gitignore
   >  1 files changed, 1 insertions(+), 0 deletions(-)

6. Double-check that you've removed everything you wanted to from your repository's history, and that all of your branches are checked out.

7. Once you're happy with the state of your repository, force-push your local changes to overwrite your repository on GitHub.com, as well as all the branches you've pushed up. A force push is required to remove sensitive data from your commit history.

   $ git push origin --force --all
   > Counting objects: 1074, done.
   > Delta compression using 2 threads.
   > Compressing objects: 100% (677/677), done.
   > Writing objects: 100% (1058/1058), 148.85 KiB, done.
   > Total 1058 (delta 590), reused 602 (delta 378)
   > To https://github.com/YOUR-USERNAME/YOUR-REPOSITORY.git
   >  + 48dc599...051452f main -> main (forced update)

8. In order to remove the sensitive file from your tagged releases, you'll also need to force-push against your Git tags:

   $ git push origin --force --tags
   > Counting objects: 321, done.
   > Delta compression using up to 8 threads.
   > Compressing objects: 100% (166/166), done.
   > Writing objects: 100% (321/321), 331.74 KiB | 0 bytes/s, done.
   > Total 321 (delta 124), reused 269 (delta 108)
   > To https://github.com/YOUR-USERNAME/YOUR-REPOSITORY.git
   >  + 48dc599...051452f main -> main (forced update)

Fully removing the data from GitHub

After using either the BFG tool or git filter-repo to remove the sensitive data and pushing your changes to GitHub, you must take a few more steps to fully remove the data from GitHub.

1. Contact GitHub Support, asking them to remove cached views and references to the sensitive data in pull requests on GitHub. Please provide the name of the repository and/or a link to the commit you need removed.

2. Tell your collaborators to rebase, not merge, any branches they created off of your old (tainted) repository history. One merge commit could reintroduce some or all of the tainted history that you just went to the trouble of purging.

3. After some time has passed and you're confident that the BFG tool / git filter-repo had no unintended side effects, you can force all objects in your local repository to be dereferenced and garbage collected with the following commands (using Git 1.8.5 or newer):

   $ git for-each-ref --format="delete %(refname)" refs/original | git update-ref --stdin
   $ git reflog expire --expire=now --all
   $ git gc --prune=now
   > Counting objects: 2437, done.
   > Delta compression using up to 4 threads.
   > Compressing objects: 100% (1378/1378), done.
   > Writing objects: 100% (2437/2437), done.
   > Total 2437 (delta 1461), reused 1802 (delta 1048)

   Note: You can also achieve this by pushing your filtered history to a new or empty repository and then making a fresh clone from GitHub.

Avoiding accidental commits in the future

There are a few simple tricks to avoid committing things you don't want committed:

• Use a visual program like GitHub Desktop or gitk to commit changes. Visual programs generally make it easier to see exactly which files will be added, deleted, and modified with each commit.
• Avoid the catch-all commands git add . and git commit -a on the command line—use git add filename and git rm filename to individually stage files, instead.
• Use git add --interactive to individually review and stage changes within each file.
• Use git diff --cached to review the changes that you have staged for commit. This is the exact diff that git commit will produce as long as you don't use the -a flag.

Further reading

• git filter-repo man page
• Pro Git: Git Tools - Rewriting History
• "About Secret scanning"