Context

After upgrading LangSmith in a self-hosted environment managed by ArgoCD, the Fleet interface appears completely blank. Users may also encounter HTTP 405 "Method Not Allowed" errors when trying to interact with agent-builder functionality. This issue typically occurs when ArgoCD continuously reconciles the ingress configuration, removing the dynamic paths that the LangGraph Platform operator adds for agent-builder services.

Answer

This issue occurs because ArgoCD removes the /lgp/ paths that the LangGraph Platform operator dynamically adds to the ingress configuration. When these paths are missing, POST requests to agent-builder endpoints hit the frontend nginx service instead of the proper backend services, resulting in 405 errors and a blank Fleet interface.

To resolve this issue, you need to configure ArgoCD to ignore changes to the ingress paths:

1. Add the following ignoreDifferences section to your ArgoCD Application spec:

   spec:
     ignoreDifferences:
       - group: networking.k8s.io
         kind: Ingress
         name: agentic-studio-ls-ingress
         jsonPointers:
           - /spec/rules/0/http/paths

2. Sync the ArgoCD Application to apply the changes

3. Restart the LangSmith operator pod to force it to re-add the missing paths:

   kubectl rollout restart deployment agentic-studio-ls-operator -n langsmith

4. Verify that the paths were successfully added by checking the ingress configuration:

   kubectl get ingress agentic-studio-ls-ingress -n langsmith -o jsonpath='{.spec.rules[0].http.paths[*].path}'

You should see /lgp/agent-builder-* paths alongside the / path in the output. Once these paths are present, the Fleet interface should load properly and function as expected.

This configuration prevents ArgoCD from removing the dynamically added paths while still allowing it to manage other aspects of the ingress resource.