Azure Functions Flashcards
1
Q
What is serverless and what are serverless service charateristics?
A
- Fully managed cloud services
- Abstracts away underlying infrastructure
- Billed based on the execution of your business task
- Can scale-to-zero meaning when not in use the serverless resources cost nothing
- Highly elastic and scalable
- Highly available
- Highly durable
- Secure by default
2
Q
What is Function as a Service and FaaS characteristics?
A
- Category of cloud computing service that allows developers to focus on just writing pieces of code (functions) and not worry about maintaining the underlying computing infrastructure
- Event-driven integration trigger functions based on event data or to emit event data
- Generally multiple functions can be orchestrated together to create a serverless app
- Generally only run when needed
- Is not serverless on its own - FaaS is only serverless if its fully-managed and scales to zero
3
Q
What are Azure Functions and their properties?
A
- FaaS offering that allows developers to focus on just writing pieces of code (functions) and not worry about maintaining the underlying computing infrastructure
- Lightweight and can be serverless
- Easier to write and deploy
4
Q
What is a Function App?
A
- Function App defines the underlying configuration for a collection of functions such as Hosting, Runtime and other global configurations and the compute for a collection of functions.
- Requires a storage account to operate
5
Q
What are the storage considerations for Azure Function - Function Apps?
A
- Storage Account
- Blob Storage - maintain bindings state and function keys
- Azure Files - File share used to store and run your function app code in a Consumption Plan and Premium Plan. Set up by default, can create an app without Azure Files under certain conditions
- Queue Storage - used by task hubs in Durable Functions
- Table Storage - used by task hubs in Durable Functions
6
Q
What core files can be found in an Azure Function?
A
- function.json - configuration of a single functions bindings
- index.js / Code - code for your function
- .funcignore - files to ignore
- host.json - global configuration of all functions at the function app level
- Local Project - a place to locally store code
7
Q
What are Azure Function authorization levels and features of the different Azure Function authorization levels?
A
- Determines what keys, if any, need to be present on the request in order to invoke the function
- Anonymous - No API key required
- Function - Function-specific API key is required
- Admin - Master API key is required
- Can be changed after creation in the portal
- Set on the trigger of the function
8
Q
How can you debug Azure Functions?
A
- Enable streaming logs for Azure Functions to see near real time logging when an error occurs
9
Q
How do you view a stream of log files being generated by Azure Functions?
A
- Azure Monitor
- Built-in log streaming - Via App Service platform
- Live Metrics Stream - In Azure Portal when connected to Application Insights
10
Q
Why are Azure Functions fast to execute?
A
- No large application, startup time, initialisation, and other events fired before code is executed
11
Q
What are the infrastructure and maintenance costs of Azure Functions?
A
- No infrastructure and maintenance costs
12
Q
How are Azure functions executed?
A
- Event-Driven
- Execution is triggered when an event is fired and can emit event data
13
Q
How do Azure functions communicate?
A
- Using industry standard protocols with other APIs, databases, and libraries
14
Q
How much do Azure Functions cost?
A
- Pay while your functions are running
- Automatically scale to meet the demand of traffic - underneath Azure will provision more serverless containers
- Can Scale-to-Zero cost
15
Q
How is CI/CD handled for Azure Functions?
A
- Built in CI/CD via Azure DevOps
16
Q
What are example Business Azure Function Use-Cases?
A
- Scheduled Tasks
- Reminders and Notifications
- Lightweight Web API
- Sending background emails
- Running background backup tasks
- Doing backend calculations
17
Q
What are example Techincal Azure Function Use-Cases?
A
- Sending emails
- Starting backup
- Order processing
- Task scheduling (database cleanup, sending notifications, messages, IoT data processing)
18
Q
What type of of apps are Azure Functions best suited for?
A
- Smaller apps that have events that can work independently of other websites
19
Q
What are output bindings?
A
- One or more data sinks that will receive outputted data from a function on successful execution
20
Q
Requirements for working with Azure Functions (VSCode)
A
- Install Azure Functions extension
- Use Azure icon in the Activity Bar with a Side Bar drawer called Functions
21
Q
What is an Application Runtime?
A
- An application runtime, is compute environment configured with the necessary software and system configuration to run a specific type of application code.
22
Q
What hosting options do Azure Function Apps have?
A
- Windows
- Linux
23
Q
What function templates does Azure provide and what triggers them?
A
- HTTP - triggered by an HTTP request and returns HTTP
- Timer - triggered based on a schedule
- Blob Storage - triggered when files are uploaded/updated in a Blob storage container.
- Cosmos DB - triggered when processing a new/modified Cosmos DB documents.
- Queue Storage - triggered by Azure Storage queue messages.
- Event Grid (serverless event bus integrated with Azure services that mane Azure services can use to trigger a function) - triggered by event from Event Grid
- Event Hub – triggered by Event Hub event. (streaming)
- Service Bus Queue – triggered by a message in a Bus Queue (messaging)
- Service Bus Topics – triggered by an event from Bus Topic (pub/sub)
- SendGrid — triggered by an email event in third-party service SendGrid
24
Q
What are the 3 types of Azure Function Plans?
A
- Consumption Plan (Serverless) - Cold Starts
- Premium Plan (Functions Premium) - Pre-Warmed
- Dedicated Plan (App Service Plan) - VM Sharing, optimal when you have underutilized VMs
25
Q
What is a trigger?
A
- Causes function to run
- Defines how function is invoked
- Function must have one trigger
- Can have associated data provided as the payload of the function
- Direction property in the function.json file is always In
26
Q
What is a binding?
A
- Define if your function is connected to another service
- Functions can have multiple input and output bindings
- Direction property in the function.json file can be In, Out, or Inout
- Can use binding expressions that resolve to values from various sources
27
Q
6 Types of Binding Expressions
A
- App Settings
- Trigger filename
- Trigger metadata
- JSON Payloads
- New GUID
- Current Date and Time
28
Q
Local Settings File name and contents?
A
- local.settings.json
- IsEncrypted - encrypt with local machine key
- Values - Application settings
- Host - Functions host process
- ConnectionStrings
29
Q
What do Azure Functions Core Tools let you do?
A
- Develop and test your functions on your local computer
30
Q
Azure Functions Core Tools Top-Level Commands and Azure Functions Core Tools Command Groups
A
- func init
- func logs
- func new
- func run
- func start
- func azure
- func durable
- func extensions
- func kubernetes
- func settings
- func templates
31
Q
What are Azure Functions Custom Handlers and their requirements?
A
- Lightweight web servers that receive events from the Functions host
- Must be written in a language that supports HTTP primitives
- Used for language not supported by an existing Azure runtime - Go, Rust or Ruby etc. or runtime environment configured for specific technology - Ruby on Rails etc.
- Triggers, input and output bindings are used via extension bundles
- Must have a host.json file, a local.settings.json file, a function.json file for each function (inside folder matching the function name), a command, script, or executable which runs a web server
/MyQueueFunction
| function.json
| host.json
| local.settings.json
| handler.exe
32
Q
What Application runtimes does Azure support?
A
- .NET
- Java
- Node.js
- PowerShell Core
- Python
33
Q
Reasons an Azure Function is unreachable?
A
- Storage account was deleted
- Storage account app settings deleted
- Storage account credentials invalid
- Storage account inaccessible
- Daily execution quota is full
- App behind firewall
34
Q
What are Durable Functions, what two types of functions does it introduce, what languages are supported, and requirements to use?
A
- Serverless compute extension of Azure Functions that allows you to write stateful functions
- Orchestrator function - define stateful workflows
- Entity function - manage the state of an entity
- They define workflows in code, no JSON schemas or designers needed
- They call other functions synchronously and asynchronously
- They automatically checkpoint their progress whenever the function awaits
- C#, JavaScript, Python, F#, PowerShell, PowerShell 7
- Must install a library specific to your language (npm install durable-functions)
35
Q
Patterns of Durable Functions
A
- Function chaining
- Fan-out/fan-in - execute multiple functions in parallel then wait for them all to finish
- Fan out - functions sends multiple messages to a queue
- Fan in - Track when the queue-triggered functions end and store the outputs.
- Async HTTP API - have an HTTP call trigger the long-running action, then redirect the client to a status endpoint that they can poll to learn when the operation is complete
- Monitor pattern - flexible recurring process e.g. polling until certain conditions are met
- Human Interaction - using timeouts and compensation logic
- Aggregator (stateful entities) - group event data into a single entity
