Git: send patch using send-email & Gmail

01 Aug 2019

Github revolutionized how we contribute to Open Source. All my past contribution was through Github pull requests. As a break from that recently I got a opportunity to contribute a minor patch to wireguard-android which is outside of github ecosystem.

Since wireguard follows linux way of accepting patches via email I have to setup the git send-email command to send my patch. This post is about my learning on setting up git and use my Gmail to send the patch.

This post is based on Ubuntu and expect you already have git installed setup on your machine

Installation

We will get started with installing the required package from apt-get. git-email is the package we required to send the patch via email. We can install this by running the command below.

sudo apt-get install git-email

Once the installation is success we can configure the sendmail smtp configuration.

Configuration

Add the following to your global/local git config as per your need. Since I am planning to use this only for wireguard repo I added these into local config.

#.git/config
[sendemail]
    smtpserver = smtp.googlemail.com
    smtpencryption = tls
    smtpserverport = 587
    smtpuser = youremail@gmail.com

Please remember to replace youremail@gmail.com with your original email which you indent to use. That email should have post access to the email group to which we are sending the patch to.

Also remember not to use alias email if you are using gmail co-orporate account.

Create a application password on gmail

In Gmail instead of using your main password, you can generate different passwords for different application. Goto app passwords in your google account and generate the new password for git-email and keep it handy. I recommend using a password managers since you need this password everytime you need to send the patch.

Create the patch

Next let’s generate the patch files for all the commits which we need to send.

git format-patch --to=to@list.email.com HEAD~..HEAD

The above command will generate patch only for the latest commit. if you have to send patches of last 2 commits instead of HEAD~..HEAD use HEAD~2..HEAD.

This will create .patch file in the current directory. Please remember to update the --to with actual email address.

Send patch as email

Once we have the .patch files we can initiate send.

git send-email *.patch

This command will initial the send and will ask for the to email and cc emails before the gmail password prompt.

password prompt

Please make sure to provide only the app password we generated a while ago.

Once the correct password is entered we will get the success message.

success

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