Continuous integration and Continuous delivery

How to design and implement CI and CD.

CI

Run in a premade container or install OS packages
Display environment information
Set access credentials
Version control
- Git committer
- Commit message
- PR title
Cache OS and programming language library packages
Check programming language and framework version compatibility
Check package management configuration (validate & normalize)
Check outdated packages and known security vulnerabilities
Build code
Configure application
0️⃣ Byte-level
- Check execute file mode bit
- Look for non-ASCII characters (non-English alphabets, whitespace characters, control characters)
1️⃣ Syntax errors
- Check source code for syntax errors
- Check template files for syntax errors
2️⃣ Run unit and functional tests
3️⃣ Static Analysis
- Run static analysis: PHPStan
- Magic Number Detector
- Copy-Paste Detector
4️⃣ Coding Standards
- Check coding style
- Adhere to EditorConfig
Measure code coverage
Check route methods (controllers of routes)
Check list of distributed files
Check spelling: Codespell
Custom checks and warnings
Display logs in CI output or upload logs as artifacts
Start CD by SSH-ing to own server (restrict,command in authorized_keys and DenyUsers in sshd.conf)
Wipe sensitive data

Possible constrains:
- successful tests
- do not run on PR-s
- our repo
- specific branch
- tag in commit message [deploy:prod]
- deploy head commit only
- optional manual start (GitLab manual actions)
Do not run as root user
Keep deploy configuration in a file
Log every output to a file, log start and finish to syslog
Limit execution time of time-consuming steps (timeout)
Optionally back up project files before starting to deploy
Create a bot user on the server for git access with SSH key (@companybot)
List changes in current project files
Check for maintenance mode, Turn on maintenance mode php artisan down covering static resource, page, AJAX and API requests
Clear caches (configuration, routes, application, template etc.)
Wait for to finish and disable cron jobs and background workers after clearing caches (email piped to a program)
Identify git repository and branch
Checkout by commit hash (not by branch HEAD)
At least lint the source code
Don't deploy testing packages
Enable production optimizations in package manager
Build code
Run database migrations
Turn off maintenance mode
Populate caches (application, OPcache, wp rewrite flush)
Run at least 1 basic functional or unit test (e.g. log in or display dashboard)
Check HTML output
Special sudo configuration for reloading PHP-FPM or Cachetool
Alert on failure
"Was down for X seconds"
Send email, Slack, Trello or Google Hangouts notification