# Git sha compare

### Idea

When committing to a branch, then compare the original master commit of the branch.

When committing to master, then compare to the previous master commit.

### Environment variables

`CURRENT_SHA = <Codebuild will provide this>`
`CURRENT_BRANCH = <Codebuild will provide this>`

`ACTUAL_IMAGES_SHA = CURRENT_SHA`
`EXPECTED_IMAGES_SHA`

### Logic:

if (CURRENT_BRANCH == 'origin/dev') {
    // Set the expected sha to the last master commit
    EXPECTED_IMAGES_SHA = git rev-list -n 1 --skip 1 $CURRENT_SHA
} else {
    // Set the expected sha to the original master commit of the branch
    EXPECTED_IMAGES_SHA = git merge-base origin/dev origin/$CURRENT_BRANCH
}