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We have a springboot app deployed in kubernetes (using latest azure-cosmos jar files) This app connects to cosmosdb and it all works fine for a while when we use it continuously. When the app is left untouched for a while (or sometimes first time use) and we try hitting it, we notice UnknownHostException and it will retry 3 times or so and then gives the results from cosmos. It is able to make connection eventually, but not sure why this exception happens before making connection(or if kept idle) intermittently
WARN 1 --- [or-http-epoll-1] c.a.c.i.WebExceptionRetryPolicy : Received retriable web exception, will retry
springboot-app
com.azure.cosmos.CosmosException: {"innerErrorMessage":null,"cosmosDiagnostics":{"userAgent":"azsdk-java-cosmos/4.45.1 Linux/4.15.0-173-generic JRE/17.0.7 az-sd-cos/3.19.0","activityId":null,"requestLatencyInMs":5009,"requestStartTimeUTC":"2023-06-02T22:23:26.115499944Z","requestEndTimeUTC":"2023-06-02T22:23:31.125221458Z","responseStatisticsList":[],"supplementalResponseStatisticsList":[],"addressResolutionStatistics":{},"regionsContacted":["west us 2"],"retryContext":{"statusAndSubStatusCodes":null,"retryLatency":0,"retryCount":0},"metadataDiagnosticsContext":{"metadataDiagnosticList":null},"serializationDiagnosticsContext":{"serializationDiagnosticsList":null},"gatewayStatistics":{"sessionToken":null,"operationType":"QueryPlan","resourceType":"Document","statusCode":503,"subStatusCode":10001,"requestCharge":0.0,"requestTimeline":[{"eventName":"connectionAcquired","startTimeUTC":"2023-06-02T22:23:26.115929088Z","durationInMilliSecs":5009.249658},{"eventName":"connectionConfigured","startTimeUTC":null,"durationInMilliSecs":0.0},{"eventName":"requestSent","startTimeUTC":null,"durationInMilliSecs":0.0},{"eventName":"transitTime","startTimeUTC":null,"durationInMilliSecs":0.0},{"eventName":"received","startTimeUTC":null,"durationInMilliSecs":0.0}],"partitionKeyRangeId":null,"exceptionMessage":null,"exceptionResponseHeaders":"{x-ms-substatus=10001}","responsePayloadSizeInBytes":0},"samplingRateSnapshot":1.0,"systemInformation":{"usedMemory":"66301 KB","availableMemory":"187139 KB","systemCpuLoad":"(2023-06-02T22:23:03.201816571Z 0.7%), (2023-06-02T22:23:08.201829869Z 3.8%), (2023-06-02T22:23:13.201827491Z 1.2%), (2023-06-02T22:23:18.201819737Z 1.6%), (2023-06-02T22:23:23.201822475Z 2.2%), (2023-06-02T22:23:28.201820864Z 2.4%)","availableProcessors":1},"clientCfgs":{"id":1,"machineId":"uuid:4197750d-5682-4cc1-8ef5-18166feefcf8","connectionMode":"DIRECT","numberOfClients":1,"clientEndpoints":{"https://<REMOVED FOR SECURITY>:443/":1},"connCfg":{"rntbd":"(cto:PT15S, nrto:PT5S, icto:PT15S, ieto:PT1H, mcpe:130, mrpc:30, cer:true)","gw":"(cps:1000, nrto:PT1M, icto:PT1M, p:false)","other":"(ed: true, cs: true, rv: true)"},"consistencyCfg":"(consistency: Session, mm: true, prgns: [westus2])","proactiveInit":null}}}
springboot-app
at com.azure.cosmos.BridgeInternal.createCosmosException(BridgeInternal.java:462) ~[azure-cosmos-4.45.1.jar!/:4.45.1]
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To troubleshoot and resolve this issue, you can try the following steps:
Verify DNS settings: Ensure that the DNS settings in your Kubernetes cluster are correctly configured. Check if the DNS service is running and functioning properly. You may also want to check the DNS configuration within your Azure Cosmos DB account to ensure it is set up correctly.
Check network connectivity: Ensure that your Spring Boot application and Kubernetes cluster have proper network connectivity to Azure Cosmos DB. Check if there are any network issues or firewall restrictions that could be affecting the DNS resolution.
Configure DNS cache settings: You can adjust the DNS cache settings in your Kubernetes environment to reduce the chances of DNS resolution failures. For example, you can lower the DNS cache TTL (Time-to-Live) value to reduce the time it takes for DNS records to expire and be refreshed.
Enable DNS resolution logging: Enable DNS resolution logging in your Spring Boot application and Kubernetes cluster to gather more information about the DNS resolution process. This can help in identifying any specific issues or patterns that may be causing the intermittent UnknownHostException.
Use IP address instead of hostname: As a workaround, you can try using the IP address of your Azure Cosmos DB instance instead of the hostname in your Spring Boot application's configuration. This bypasses the DNS resolution process and can help determine if the issue is related to DNS resolution or some other factor.
If the issue persists after trying these steps, it would be best to reach out to the Azure support team for further assistance. They can analyze the specific details of your environment and provide guidance based on your configuration.
Remember to provide any relevant logs, error messages, or other diagnostic information when contacting support to help them understand the issue better.
I hope this helps you resolve the intermittent UnknownHostException when connecting to Azure Cosmos DB from your Spring Boot application.
Could you please share the code snippet of what's throwing the error.
How are you querying, and what SKU (R/Us) you configured in your instance.
Regards,
Oury
Could you please share the code snippet of what's throwing the error.
How are you querying, and what SKU (R/Us) you configured in your instance.
Regards,
Oury
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@cosmosdbuser Do you have some news about your problem? I am also facing this issue in Azure Container Apps and really don't see how this is happening. (not with cosmos db but with any other host in a very sporadic manner)
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Do you use coredns?
Do you netty for your springboot? Check if you running into this bug https://github.com/reactor/reactor-netty/issues/1431