104 lines
4.1 KiB
Markdown
104 lines
4.1 KiB
Markdown
---
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title: Commit syncing across hosted GIT instances
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description: How I keep my commit graph alive
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date: 2022-05-18
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tags:
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- random
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- git
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draft: false
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extra:
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auto_center_images: true
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excerpt: This post covers how to keep your commit graph alive across multiple GIT
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instances by syncing your commit history to magic repos.
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aliases:
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- /blog/commit-sync
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---
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Since September of 2018 (3 and a half years ago) I have been roughly holding a streak of going no more than three days without making a commit to some project on GitHub.
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This is not entirely intentional, and I have broken it a few times:
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- June 7, 2019
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- August 8, 2019
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- September 27, 2019
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- November 3, 2021
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..but a streak is a streak. A few of my friends know about this and keep an eye on my commit graph and I do too. Recently, with most of my programming time allocated to work, my graph started looking like weeks of empty cells, implying I broke my streak for good.
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In reality, that couldn't be farther from the truth. I have been writing quite a lot of code actually, its just all tracked in a company GIT instance with a separate account.
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## Time for some trickery
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I happened to remember a little trick I used in a CI pipeline for [Raider Robotics](https://github.com/frc5024/) where you can backdate empty commits with arbitrary authors. I recall using this for some kind of version tagging system at some point.. idk.. the important part being it is possible to make "fake" commits with the right command-line flags.
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### The game plan
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My idea was as follows:
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1) Scrape all work repos for commits authored by one of my email addresses
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2) Keep track of the commit timestamps
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3) Make empty commits to a GitHub repo and backdate them to the timestamps from the last step
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4) Enjoy having my GitHub contributor graph synced to my work account
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*For anyone concerned with the security issue of leaking commit data, In my real implementation, dates are shuffled a bit. This also all happens in a private repo, so the public can only ever see its affect on my commit graph, and can't actually see the commits themselves.*
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### Scraping commits from repos
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The `git` command has a `log` subcommand for querying info about commits. In its simplest form, you can dump all commits for a repo with:
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```sh
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git -C /path/to/repo log --pretty=format:"%H"
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```
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An example output for the repo behind this website:
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```text
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...
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62d0c4833766671182ed0aeeb76bb16cc3f35174
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420b3cc4a9d61024e0dd6c32deafb57244d09433
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fed6fc374d02c2ae8f67bff837c8c8334760b303
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5a64788339afd750c3853468f89d275cf8fa49cd
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01992912951d80631fa5069fce7d9a3593bbcd39
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d894387400158d231ed6559636169f1464bb630d
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4a68456c7a5df699bc7620c9250b7a04aac5bd3c
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ff87809b9c14c5132ecd5a39921b1cf2118b12cc
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2b8797bbdcec61654540d995aaae67bcab8dc1c1
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c4d978c5d098846b8a0105c5b6d3f42b389c6ea7
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9791cdd979a17f0d5ebf9028d4778152ca07ae1d
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dda08261872d3c2301cc02108c0f466dedaacaca
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f408c1fa9785a40038e04b0ef017bd8d2897cdd6
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...
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```
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Its just a bunch of hashes.
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As a side note, if you are trying to replicate my work and also commit with multiple email addresses, you can chain `--author` flags together.
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```sh
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git -C /path/to/repo log --pretty=format:"%H" --author=ewpratten@example.com --author=evan@work.com
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```
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### Cloning commits
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If we iterate over our list of hashes, we can perform the rest of the steps. The main data point we care about is the timestamp.
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To fetch a commit timestamp from a repo, use the following, replacing `$COMMIT_HASH` with the hash in question:
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```sh
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git -C /path/to/repo show -s --format=%ci $COMMIT_HASH
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```
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And finally, with our timestamp (stored as `$DATE`) a new commit can be written to a target repo:
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```sh
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git -C /path/to/public/repo commit -m "A message." --date="$DATE" --no-edit --allow-empty
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```
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Importantly, the `--allow-empty` flag removes the requirement for any files to be contained in the commit, essentially allowing you to have a "zero size" repository.
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## Conclusion
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Uh, ya. Cool. With your scripting language of choice, you can chain these commands together, toss a `git push` in there, stick this in a cron job, and have yourself a nice, healthy commit graph.
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