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How to Mock Docker Image Non-Root User in Python
This Python class simulates Docker image layers and inspects whether the final user is a non-root user, returning UID, GID, and security status.
from pathlib import Path
class DockerImageMock:
def __init__(self, name, tag):
self.name = name
self.tag = tag
self.layers = []
self.user = "root"
def add_file(self, path, content):
self.layers.append({"file": path, "content": content})
def set_user(self, usernam…How to Mock Multi-Stage Docker Builds in Python
Simulate a multi-stage Docker build in pure Python using classes and temp directories to understand how build stages copy artifacts into a final image.
# Simulate multi-stage Docker build with pure Python
from pathlib import Path
import tempfile
import shutil
class BuildContext:
"""Mimics a Docker build context with stages."""
def __init__(self, name):
self.name = name
self.files = {}
def add_file(self, dest, content):
s…How to Mock Terraform Plan and Apply in Python
This code provides a lightweight Python mock of Terraform's plan and apply commands, helping you simulate infrastructure changes without real cloud resources.
class MockTerraform:
def __init__(self):
self.plans = [
{"id": 1, "action": "create", "resource": "aws_instance.web"},
{"id": 2, "action": "update", "resource": "aws_s3_bucket.data"},
{"id": 3, "action": "destroy", "resource": "aws_iam_user.legacy"}
]
sel…How to Mock a CI Pipeline with Build, Test, and Deploy Stages in Python
Simulate a three-stage CI pipeline (build, test, deploy) in Python with random pass/fail logic, early exit on failure, and measured stage durations.
import time
import random
from dataclasses import dataclass
@dataclass
class StageResult:
name: str
status: str
duration: float
def run_stage(name: str, success_chance: float = 0.9) -> StageResult:
"""Simulate a pipeline stage with random success/failure."""
start = time.time()
time.sleep(r…How to Mock a Container Registry in Python
Build an in-memory container registry mock with push, tag listing, and manifest retrieval logic for testing deployment tooling.
import json
from collections import defaultdict
class MockRegistry:
def __init__(self):
self.repositories = defaultdict(dict)
def push_image(self, repo: str, tag: str, layers: list[str]) -> None:
self.repositories[repo][tag] = {
"layers": layers,
"size": sum(len(layer…How to Mock a Dependency for Readiness Probe in Python
Use unittest.mock.Mock to simulate a dependency's readiness check response for testing a service's is_ready method without hitting a real connection.
import time
import unittest
from unittest.mock import Mock
class Service:
def __init__(self, dependency):
self.dependency = dependency
def is_ready(self):
try:
result = self.dependency.check()
return result == "ready"
except Exception:
return False
…How to Mock a Dockerfile Multi-Stage Build in Python
Simulate a Dockerfile multi-stage build process in Python using dataclasses to validate stage ordering and file availability before you write the real Dockerfile.
from dataclasses import dataclass
from pathlib import Path
@dataclass
class BuildStage:
name: str
base_image: str
files: list[str]
commands: list[str]
def run_build(stage: BuildStage, context_dir: Path):
print(f"=== Stage: {stage.name} (base: {stage.base_image}) ===")
for file in stage.file…How to Mock a Feature Flag Rollout Percentage in Python
Simulate a percentage-based feature flag rollout by hashing a user ID to deterministically enable features for a subset of users.
import random
from dataclasses import dataclass
@dataclass
class FeatureFlag:
name: str
rollout_percentage: int
def is_feature_enabled(feature_flag: FeatureFlag, user_id: str) -> bool:
hashed_id = hash(user_id) % 100
return hashed_id < feature_flag.rollout_percentage
if __name__ == "__main__":
…How to Mock a GitHub Actions Workflow in Python
Build a dataclass-based model of a GitHub Actions workflow and simulate its execution to validate steps and outputs before deployment.
import json
from dataclasses import dataclass, asdict
from typing import List, Dict, Any
@dataclass
class Step:
name: str
run: str
@dataclass
class Job:
name: str
steps: List[Step]
runs_on: str = "ubuntu-latest"
@dataclass
class Workflow:
name: str
jobs: List[Job]
def to_github_a…How to Mock a Kubernetes Rolling Update with maxSurge in Python
Simulate a Kubernetes rolling update with maxSurge policy, tracking peak and final replica counts during roll transitions.
from collections import deque
class RollingUpdateMaxSurge:
def __init__(self, replicas, max_surge):
self.replicas = replicas
self.max_surge = max_surge
self.available = replicas
self.history = deque()
def roll(self, desired_replicas):
"""
Simulate a rolling upd…How to Mock a SIGTERM Handler in Python
Create a graceful shutdown handler for SIGTERM and SIGINT signals, then test it by simulating a signal delivery without terminating the process.
import signal
import time
class Service:
def __init__(self):
self.running = True
def shutdown(self, signum, frame):
print(f"Received signal {signum}, shutting down gracefully...")
self.running = False
def run(self):
signal.signal(signal.SIGTERM, self.shutdown)
sig…How to Mock a Slow Startup Probe for Fast Testing in Python
This code shows how to replace a slow startup probe's initialization with a mock to make tests run fast and reliably.
import time
from unittest.mock import Mock, patch
class StartupProbe:
def __init__(self, init_time):
self.init_time = init_time
self.ready = False
def initialize(self):
time.sleep(self.init_time)
self.ready = True
return self.ready
def run_startup_probe(probe):
…How to Mock an Ingress TLS Certificate Manager in Python
Build a mock TLS certificate manager for ingress that issues, checks, and renews certificates with expiry tracking — useful for testing deployment workflows before touching real infrastructure.
import ssl
import socket
from datetime import datetime, timedelta
class TLSCertManager:
def __init__(self, hostname):
self.hostname = hostname
self.certificates = {}
def request_certificate(self, domain, days_valid=90):
"""Mock a certificate issuance request that stores a cert with e…How to Mock time.sleep in a Python PreStop Hook
This code simulates a Kubernetes PreStop hook that delays shutdown, then mocks time.sleep to verify the hook logic without real delay.
import subprocess
import sys
import time
from unittest.mock import patch
def pre_stop_hook():
"""Simulate a Kubernetes PreStop hook that sleeps before shutdown."""
print("PreStop hook started: delaying shutdown")
time.sleep(3)
print("PreStop hook completed: ready to shutdown")
if __name__ == "__main_…How to Replace Fields in an Immutable Dataclass in Python
Create a new copy of a frozen dataclass with selected fields changed, leaving the original unchanged.
from dataclasses import dataclass, replace
@dataclass(frozen=True)
class ServerConfig:
name: str
cpu: int = 2
ram: int = 4096
tags: tuple = ()
original = ServerConfig("web-01", cpu=4, tags=("env:prod",))
updated = replace(original, ram=8192, tags=("env:prod", "region:us-east"))
print("Original:", …How to Roll Back to a Previous Image Tag in Python
A dataclass-based mock registry that tracks image tag history and rolls back to the previous tag, useful for deployment rollback logic.
"""Demonstrates a rollback pattern for a Docker-style image tag registry."""
from dataclasses import dataclass, field
@dataclass
class ImageRegistry:
"""A minimal mock registry tracking current tags per image."""
tags: dict[str, list[str]] = field(default_factory=dict)
def push(self, image: str, tag: …How to Simulate a Packer AMI Build in Python
A simple Python class that mimics a Packer AMI build lifecycle — creates a build object, transitions its state to completed, and prints a JSON snapshot.
import json
class PackerBuildMock:
def __init__(self, name, ami_id, region="us-east-1", state="pending"):
self.name = name
self.ami_id = ami_id
self.region = region
self.state = state
def build(self):
if self.state == "pending":
self.state = "completed"
…How to build a maintenance mode page in Python
Mock a service maintenance status page that computes remaining downtime and lists affected features from a simple class.
from datetime import datetime
class MaintenanceMode:
"""Mock a maintenance mode status page for a service."""
def __init__(self, service_name: str, scheduled_end: str):
self.service_name = service_name
self.scheduled_end = datetime.fromisoformat(scheduled_end)
self.affected_featur…How to hide incomplete mock features with a Python feature toggle
A simple decorator-based feature toggle that returns a placeholder when a mock feature is disabled, so incomplete code can ship safely.
import functools
class FeatureToggle:
def __init__(self, enabled=False):
self.enabled = enabled
def feature(self, func=None):
"""Decorator to conditionally enable a feature."""
if func is None:
return self.feature
@functools.wraps(func)
def wrapper(*args,…How to mock resource request limits in Python
A Python class that simulates CPU and memory limit checks for resource requests, returning clear acceptance or rejection messages.
class ResourceLimits:
def __init__(self, cpu_limit, memory_limit):
self.cpu_limit = cpu_limit
self.memory_limit = memory_limit
def check_request(self, cpu, memory):
if cpu > self.cpu_limit:
return "CPU limit exceeded: {cpu} > {limit}".format(cpu=cpu, limit=self.cpu_limit)
…How to simulate GitLab CI stages in Python
Build a lightweight Python mock of GitLab CI pipeline stages to test job sequencing and output locally.
def mock_gitlab_ci_stages():
stages = ["build", "test", "deploy"]
stage_status = {}
for stage in stages:
jobs = []
if stage == "build":
jobs = ["compile", "package"]
elif stage == "test":
jobs = ["unit", "integration", "e2e"]
elif stage == "deploy":…How to simulate a Jenkins pipeline in Python
Simulate a Jenkins-style pipeline in Python by running sequential stages and checking aggregate success.
def run_stage(name, duration, fn):
print(f"[Pipeline] Running stage: {name}")
result = fn()
print(f"[Pipeline] Stage '{name}' completed in {duration}s -> {result}")
return result
def build_project():
print(" compiling source...")
return "BUILD_OK"
def run_tests():
print(" executing unit…How to simulate a database migration init container mock in Python
A mock init container that runs environment checks and a staged database migration job before the main application starts, printing progress to stdout.
```python
class MigrationJob:
def __init__(self, name, steps):
self.name = name
self.steps = steps
self.current_step = 0
self.status = "pending"
def run(self):
print(f"Initializing migration job: {self.name}")
for step in self.steps:
self.current_ste…Browse by section
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