You don’t need to create a new SSH public key for your robot user when using Codeship. Once you’ve completed the steps for CI Integration, set up Codeship as follows:

Step 1: Copy the public key from your Codeship project’s General Settings page, and add it as a new key for your robot user.

Step 2: Add a Custom Script deployment in Codeship with the following commands:

git fetch --depth=1000000

📘 In the above example,$ENVIRONMENT_HANDLE/$APP_HANDLE.git represents your App’s Git Remote.

Also, see My deploy failed with a git error referencing objects, trees, revisions or commits to understand why you need git fetch here.