Windows Azure Diagnostics

Andy Cross

Overview

• Diagnostics in Windows Azure

– Application Level

– Service Level

– Operating System Level

App• Things your application chooses to log

Service• Things logged by what runs your application

OS• Things logged by OS container

Example Log Usage

• Application:

– Error: Cannot save Order

• Service:

– Error: IO Exception

• OS:

– Error: Disk is full

What’s special?

• Familiar diagnostic challenges– Already solved on premises

• Massively scalable– No request affinity

– Unpredictable application topology

• Where do the logs go?!– Centralised Logging approach

What you need

• Hosted Service:

– Compute capacity within Windows Azure

• Storage Account:

– Storage capacity within Windows Azure

• Table

• Blobs

Windows Azure Diagnostics

• Each Role– Configurable Diagnostics Monitor– Each Instance inherits configuration

Instances

Role

Hosted Service My Azure App

Web Role

IN_0 IN_1

Worker Role

IN_0

Example Trace Points

• Application– .net application Tracing– custom

• Files written via nLog, log4net etc

– Windows Event Log

• Service– IIS Logs– IIS Failed Request Logs– Azure Diagnostics Infrastructure Logs

• Metalog

– Performance Counters

• Operating System– Windows Event Log– Custom (any known file log)

Configuration

• Set options on types– Directories– Logs– Performance Counters

• Storage Options– Some types allow a configurable destination

• Transfer Period• Maximum Buffer Size

Transfer

• Two distinct methods of transfer

– Same underlying result

• On Demand Transfer

• Scheduled Transfer

Output formats

Type Description Destination

Trace With Trace Listener Table WADLogsTable

IIS Logs W3svc format Blob

Windows Event Logs Table WADWindowsEventLogsTable

Windows Performance Counters

Table WADPerformanceCountersTable

Custom Logs File based Blob

Crash Dump Blob

Diagnostic Infrastructure Log

Metalog Table WADDiagnosticInfrastructureLogsTable

Methodologies

• .net Tracing

– Add Trace Listener

– Configure WAD

– View Result:

Logging per Instance

• Logs on Instance Basis:

– RoleInstance:

• deployment(526).MultipleTraceSources.Host_IN_0

– DeploymentId.Role.Instance

• Allows for per instance diagnosis

Configure Windows Azure Diagnostics

• Setup Storage Account

• Create Role Instance Diagnostics Manager

• Get and update a configuration from Manager

• Set Current Configuration

Example Code

Extended Code

Verbosity

• Code is building XML WADCFG

– Structure based on XML Schema

• Not necessarily intuitive

Fluent Diagnostics

• Attempts to curtail verbosity

Windows Azure Role Lifecycle

• Each Role runs – OnStart

– Run

– OnStop

• Setup Diagnostics OnStart – always correct for that role

• But if you change the config, another OnStartwill undo your changes

Change at Runtime

• WAPPSCmdlets

PowerShell cmdlets available at wappowershell.codeplex.comExample courtesy of michaelwasham.com

Diagnostics Lifecycle

OnStart Run Redeploy OnStop OnStart Run

Diagnostics A

Diagnostics B

Diagnostics A

Scenario A

Diagnostics Lifecycle

OnStart RunChange Instance

CountOnStart Run

Diagnostics A

Diagnostics B

Diagnostics A

Scenario B

Diagnostics Lifecycle

• Why do we see this behaviour?

– Increase Instance Count

– New Instance added by Fabric

– Instance goes through OnStart!

Fluent Diagnostics

• Allows you to use programmatic approach still

– Uses Marker XML

– Prevents further updates for a deployment

Diagnostics Lifecycle

OnStart RunChange Instance

CountOnStart Run

Diagnostics A

Diagnostics B

Diagnostics A

Fluent Diagnostics Scenario B

Marker File Added

How to view Diagnostics

• Raw in Tables, as shown before.

• Cerebrata Azure Diagnostics Manager

Q&A

• Many thanks.

• Check out my blog:http://blog.bareweb.eu

• Questions and Answers session