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Resolving UnsupportedCharsetException: gzip in AppKit and Fusion 5.9.x

Updated

Issue

When connecting AppKit or TwigKit 4.11.0 to Fusion 5.9.15, search requests fail with a character set exception. This typically occurs after an upgrade to Fusion 5.9.x or when deploying into Kubernetes environments where response compression is enabled by default.

The following error is observed in the AppKit logs:

java.nio.charset.UnsupportedCharsetException: gzip
at org.apache.commons.io.Charsets.toCharset(Charsets.java:111)
at org.apache.solr.client.solrj.impl.HttpSolrClient.executeMethod(HttpSolrClient.java:586)
at twigkit.search.solr.SolrPlatform.search(SolrPlatform.java:141)

 

Diagnosis

  1. The AppKit HttpSolrClient (based on an older version of SolrJ) sends an Accept-Encoding: gzip header to Fusion.

  2. The Fusion api-gateway or the Kubernetes Ingress controller (Nginx) honors this header and compresses the response.

  3. The response is returned with a Content-Encoding: gzip header.

  4. The legacy SolrJ client incorrectly attempts to parse the string "gzip" as a character set (Charset) rather than a compression format, leading to the UnsupportedCharsetException.

 

Environment

  • Fusion: 5.9.x

  • AppKit/TwigKit: 4.11.0

  • Solr: 9.x

  • Infrastructure: Kubernetes (AKS, EKS, GKE) with Nginx Ingress Controller

 

Cause

The issue is caused by a compatibility gap between older SolrJ clients used in AppKit and modern Kubernetes Ingress configurations. While the client requests compression, it lacks the logic to properly handle the resulting GZIP-encoded stream, mistakenly passing the encoding type to the character set validator.

 

Resolution

To resolve this, you must disable GZIP compression at the Ingress level specifically for the Fusion api-gateway service. This ensures that the response sent back to AppKit remains uncompressed.

Disable Compression via Ingress Annotation

  1. Locate the configuration for the api-gateway Ingress in your Fusion deployment repository (typically found in global-values.yaml or a specific service override file).

  2. Add the following annotation to the api-gateway Ingress metadata:

nginx.ingress.kubernetes.io/enable-compression: "false"

  1. Apply the changes using Helm:

helm upgrade <release-name> lucidworks/fusion -f my-values.yaml

  1. Verify the change by checking the Ingress resource in Kubernetes:

kubectl get ingress <release-name>-api-gateway -o yaml

 

This configuration selectively disables compression for the API Gateway route while maintaining default compression settings for other Fusion services.

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