How to troubleshoot with resource logs

This how-to guide provides an overview of Azure Web PubSub resource logs and some tips for using the logs to troubleshoot certain problems. Logs can be used for issue identification, connection tracking, message tracing, HTTP request tracing, and analysis.

What are resource logs?

There are three types of resource logs: Connectivity, Messaging, and HTTP requests.

  • Connectivity logs provide detailed information for Azure Web PubSub hub connections. For example, basic information (user ID, connection ID, and so on) and event information (connect, disconnect, and so on).
  • Messaging logs provide tracing information for the Azure Web PubSub hub messages received and sent via Azure Web PubSub service. For example, tracing ID and message type of the message.
  • HTTP requests logs provide tracing information for HTTP requests to the Azure Web PubSub service. For example, HTTP method and status code. Typically the HTTP request is recorded when it arrives at or leave from service.

Capture resource logs by using the live trace tool

The Azure Web PubSub service live trace tool has ability to collect resource logs in real time, which is helpful for troubleshooting problems in your development environment. The live trace tool can capture connectivity logs, messaging logs, and HTTP request logs.

Note

The following considerations apply to using the live trace tool:

  • The real-time resource logs captured by live trace tool will be billed as messages (outbound traffic).
  • The live trace tool does not currently support Azure Active Directory authentication. You must enable access keys to use live trace. Under Settings, select Keys, and then enable Access Key.
  • The Azure Web PubSub service Free Tier instance has a daily limit of 20,000 messages (outbound traffic). Live trace can cause you to unexpectedly reach the daily limit.

Launch the live trace tool

  1. Go to the Azure portal and your Web PubSub service.

  2. On the left menu, under Monitoring, select Live trace settings.

  3. On the Live trace settings page, select Enable Live Trace.

  4. Choose the log categories to collect.

  5. Select Save and then wait until the settings take effect.

  6. Select Open Live Trace Tool.

    Screenshot of launching the live trace tool.

Capture the resource logs

The live trace tool provides functionality to help you capture the resource logs for troubleshooting.

  • Capture: Begin to capture the real-time resource logs from Azure Web PubSub.
  • Clear: Clear the captured real-time resource logs.
  • Log filter: The live trace tool lets you filter the captured real-time resource logs with one specific key word. The common separators (for example, space, comma, semicolon, and so on) will be treated as part of the key word.
  • Status: The status shows whether the live trace tool is connected or disconnected with the specific instance.

Screenshot of capturing resource logs with live trace tool.

The real-time resource logs captured by live trace tool contain detailed information for troubleshooting.

Name Description
Time Log event time
Log Level Log event level, can be [Trace | Debug | Informational | Warning | Error]
Event Name Operation name of the event
Message Detailed message for the event
Exception The run-time exception of Azure Web PubSub service
Hub User-defined hub name
Connection ID Identity of the connection
User ID User identity
IP Client IP address
Route Template The route template of the API
Http Method The Http method (POST/GET/PUT/DELETE)
URL The uniform resource locator
Trace ID The unique identifier to the invocation
Status Code The Http response code
Duration The duration between receiving the request and processing the request
Headers The additional information passed by the client and the server with an HTTP request or response

Capture resource logs with Azure Monitor

How to enable resource logs

Currently Azure Web PubSub supports integration with Azure Storage.

  1. Go to Azure portal.

  2. On Diagnostic settings page of your Azure Web PubSub service instance, select + Add diagnostic setting. Screenshot of viewing diagnostic settings and create a new one

  3. In Diagnostic setting name, input the setting name.

  4. In Category details, select any log category you need.

  5. In Destination details, check Archive to a storage account.

    Screenshot of configuring diagnostic setting detail

  6. Select Save to save the diagnostic setting.

Note

The storage account should be in the same region as Azure Web PubSub service.

Archive to an Azure Storage Account

Logs are stored in the storage account that's configured in the Diagnostics setting pane. A container named insights-logs-<CATEGORY_NAME> is created automatically to store resource logs. Inside the container, logs are stored in the file resourceId=/SUBSCRIPTIONS/XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX/RESOURCEGROUPS/XXXX/PROVIDERS/MICROSOFT.SIGNALRSERVICE/SIGNALR/XXX/y=YYYY/m=MM/d=DD/h=HH/m=00/PT1H.json. The path is combined by resource ID and Date Time. The log files are split by hour. The minute value is always m=00.

All logs are stored in JavaScript Object Notation (JSON) format. Each entry has string fields that use the format described in the following sections.

Archive log JSON strings include elements listed in the following tables:

Format

Name Description
time Log event time
level Log event level
resourceId Resource ID of your Azure SignalR Service
location Location of your Azure SignalR Service
category Category of the log event
operationName Operation name of the event
callerIpAddress IP address of your server or client
properties Detailed properties related to this log event. For more detail, see the properties table below

Properties Table

Name Description
collection Collection of the log event. Allowed values are: Connection, Authorization and Throttling
connectionId Identity of the connection
userId Identity of the user
message Detailed message of log event
hub User-defined Hub Name
routeTemplate The route template of the API
httpMethod The Http method (POST/GET/PUT/DELETE)
url The uniform resource locator
traceId The unique identifier to the invocation
statusCode The Http response code
duration The duration between the request is received and processed
headers The additional information passed by the client and the server with an HTTP request or response

The following code is an example of an archive log JSON string:

{
  "properties": {
    "message": "Connection started",
    "collection": "Connection",
    "connectionId": "LW61bMG2VQLIMYIVBMmyXgb3c418200",
    "userId": null
  },
  "operationName": "ConnectionStarted",
  "category": "ConnectivityLogs",
  "level": "Informational",
  "callerIpAddress": "167.220.255.79",
  "resourceId": "/SUBSCRIPTIONS/XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX/RESOURCEGROUPS/MYGROUP/PROVIDERS/MICROSOFT.SIGNALRSERVICE/WEBPUBSUB/MYWEBPUBSUB",
  "time": "2021-09-17T05:25:05Z",
  "location": "westus"
}

Archive to Azure Log Analytics

To send logs to a Log Analytics workspace:

  1. On the Diagnostic setting page, under Destination details, select **Send to Log Analytics workspace.
  2. Select the Subscription you want to use.
  3. Select the Log Analytics workspace to use as the destination for the logs.

To view the resource logs, follow these steps:

  1. Select Logs in your target Log Analytics.

    Log Analytics menu item

  2. Enter WebPubSubConnectivity, WebPubSubMessaging or WebPubSubHttpRequest, and then select the time range to query the log. For advanced queries, see Get started with Log Analytics in Azure Monitor.

    Query log in Log Analytics

To use a sample query for SignalR service, follow the steps below.

  1. Select Logs in your target Log Analytics.
  2. Select Queries to open query explorer.
  3. Select Resource type to group sample queries in resource type.
  4. Select Run to run the script. Sample query in Log Analytics

Archive log columns include elements listed in the following table.

Name Description
TimeGenerated Log event time
Collection Collection of the log event. Allowed values are: Connection, Authorization and Throttling
OperationName Operation name of the event
Location Location of your Azure SignalR Service
Level Log event level
CallerIpAddress IP address of your server/client
Message Detailed message of log event
UserId Identity of the user
ConnectionId Identity of the connection
ConnectionType Type of the connection. Allowed values are: Server | Client. Server: connection from server side; Client: connection from client side
TransportType Transport type of the connection. Allowed values are: Websockets | ServerSentEvents | LongPolling

Troubleshoot with the resource logs

If you find unexpected changes in the number of connections, either increasing or decreasing, you can take advantage of resource logs to troubleshoot the problem. Typical issues are often about connections' unexpected quantity changes, connections reach connection limits, and authorization failure.

Unexpected changes in number of connections

Unexpected connection dropping

If a connection disconnects, the resource logs will record the disconnection event with ConnectionAborted or ConnectionEnded in operationName.

The difference between ConnectionAborted and ConnectionEnded is that ConnectionEnded is an expected disconnection that is triggered by the client or server side. While the ConnectionAborted is usually an unexpected connection dropping event, and the reason for disconnection will be provided in message.

The abort reasons are listed in the following table:

Reason Description
Connection count reaches limit Connection count reaches limit of your current price tier. Consider scale up service unit
Service reloading, reconnect Azure Web PubSub service is reloading. You need to implement your own reconnect mechanism or manually reconnect to Azure Web PubSub service
Internal server transient error Transient error occurs in Azure Web PubSub service, should be auto recovered

Unexpected increase in connections

When the number of client connections unexpectedly increases, the first thing you need to do is to filter out the superfluous connections. Add a unique test user ID to your test client connection. Then check the resource logs; if you see more than one client connection has the same test user ID or IP, then it's likely the client is creating more connections than expected. Check your client code to find the source of the extra connections.

Authorization failure

If you get 401 Unauthorized returned for client requests, check your resource logs. If you find Failed to validate audience. Expected Audiences: <valid audience>. Actual Audiences: <actual audience>, it means all audiences in your access token are invalid. Try to use the valid audiences suggested in the log.

Throttling

If you find that you can't establish client connections to Azure Web PubSub service, check your resource logs. If you see Connection count reaches limit in the resource log, you established too many connections to Azure Web PubSub service and reached the connection count limit. Consider scaling up your Azure Web PubSub service instance. If you see Message count reaches limit in the resource log and you're using the Free tier, it means you used up the quota of messages. If you want to send more messages, consider changing your Azure Web PubSub service instance to Standard tier. For more information, see Azure Web PubSub service Pricing.