I’m revamping our CICD process with Salesforce DX and Bitbucket Pipeline with the following initial setup which will only a delta deployment

Authentication method – authorize an org and grab the sfdxurl to be stored as repository variable in Bitbucket

sfdx force:auth:web:login 
sfdx force:org:display --verbose

There would be two token types

force://<refreshToken>@<instanceUrl> 
or 
force://<clientId>:<clientSecret>:<refreshToken>@<instanceUrl>

Copy the SFDX Auth URL which will be the second type. Create a repository variable AUTH_URL in Bitbucket and store the copied value.

Echo the AUTH_URL to a file then authenticate with with sfdxurl:store

echo $AUTH_URL >> /tmp/sfdx_auth.txt
sfdx force:auth:sfdxurl:store -f /tmp/sfdx_auth.txt -s -a dxpipeline

Grab the latest sfdx tool and install.

wget https://developer.salesforce.com/media/salesforce-cli/sfdx-linux-amd64.tar.xz 
mkdir sfdx-cli 
tar xJf sfdx-linux-amd64.tar.xz -C sfdx-cli --strip-components 1 
./sfdx-cli/install

Next, to compare delta files – there is node tool available in github that does delta comparison between hash commit or branch. Install the sfdx-git-delta app

npm install sfdx-git-delta@latest -g

Finally I incorporated these to my git workflow

On a Pull Request – I want to run a delta comparison and do an empty check only that my delta files changes are deployable and does break any unit tests.

First checkout a temporary branch from the feature branch

git checkout -b some-pr-branch

Next, run the tool to create a delta comparison from that branch to the target branch.

sgd --to some-pr-branch --from origin/staging --repo . --output .

The tool should create a package.xml/destructiveChange.xml file based on the diff on their respective directory.

Next convert the source format to mdapi so we can run a transactional deploy.

sfdx force:source:convert --manifest=package/package.xml --outputdir=convert

After conversion, do an empty check deploy and run the unit test

sfdx force:mdapi:deploy --deploydir=convert -c -l RunLocalTests -w 30

Below is the complete Pull Request script.

image: atlassian/default-image:2

pipelines:
  pull-requests:
    'feature/*': # Pull request from feature branch to Staging
      - step:
          name: "Staging Pull Request Validate Package"
          script:
            - echo "QA Pull Request Validation"
            - wget https://developer.salesforce.com/media/salesforce-cli/sfdx-linux-amd64.tar.xz
            - mkdir sfdx-cli
            - tar xJf sfdx-linux-amd64.tar.xz -C sfdx-cli --strip-components 1
            - ./sfdx-cli/install
            - echo $AUTH_URL >> /tmp/sfdx_auth.txt
            - sfdx force:auth:sfdxurl:store -f /tmp/sfdx_auth.txt -s -a dxpipeline
            - npm install sfdx-git-delta@latest -g
            - git checkout -b some-pr-branch          
            - git --no-pager diff --name-status some-pr-branch  origin/staging
            - sgd --to some-pr-branch  --from origin/staging --repo . --output .
            - echo "--- package.xml generated with added and modified metadata ---"
            - cat package/package.xml
            - sfdx force:source:convert --manifest=package/package.xml --outputdir=convert 
            - echo "---- Validating delta package  ----"
            - sfdx force:mdapi:deploy --deploydir=convert -c -l RunLocalTests -w 30

On Push to the branch – I ran similar steps with the only exception that I compare the current branch to the staging branch and not do an empty check or run the test classes as I already ran them.

Below is the complete Push script.

image: atlassian/default-image:2

pipelines:
  pushs:
    staging: 
      - step:
          name: "Deploy to Staging"
          script:
            - echo "Deploy to Staging"
            - wget https://developer.salesforce.com/media/salesforce-cli/sfdx-linux-amd64.tar.xz
            - mkdir sfdx-cli
            - tar xJf sfdx-linux-amd64.tar.xz -C sfdx-cli --strip-components 1
            - ./sfdx-cli/install
            - echo $AUTH_URL >> /tmp/sfdx_auth.txt
            - sfdx force:auth:sfdxurl:store -f /tmp/sfdx_auth.txt -s -a dxpipeline
            - npm install sfdx-git-delta@latest -g
            - git checkout -b dev          
            - git --no-pager diff --name-status some-pr-branch  origin/staging
            - sgd --to dev  --from origin/staging --repo . --output .
            - echo "--- package.xml generated with added and modified metadata ---"
            - cat package/package.xml
            - sfdx force:source:convert --manifest=package/package.xml --outputdir=convert 
            - echo "---- Validating delta package  ----"
            - sfdx force:mdapi:deploy --deploydir=convert -w 30

Hope you find this useful. Hit me up on the comments below for any questions.