Fix Cannot View AnalysisRun Result In UI Not A Valid JSON

Jul 18, 2025 by gitftunila 58 views

Introduction

This article addresses a common issue encountered when using Argo Rollouts and Kargo together: the "Cannot view AnalysisRun result in UI - not a valid JSON" error. This problem arises when an AnalysisTemplate, particularly one using the web provider, receives a non-JSON response from a webhook. While Argo Rollouts can sometimes handle plain text responses, Kargo UI expects a JSON format, leading to this error. This article delves into the root cause of the issue, provides a detailed explanation, and suggests potential solutions and workarounds. Understanding this issue is crucial for effectively using Argo Rollouts and Kargo for progressive delivery and automated rollouts. Let's explore the intricacies of this problem and how to resolve it.

Understanding the Problem

When integrating Argo Rollouts with Kargo for advanced deployment strategies, the AnalysisRun resource plays a vital role in verifying the health and stability of new application versions. The core of the issue lies in the interaction between Kargo UI and the responses from webhooks used in AnalysisTemplate definitions. Specifically, Kargo UI expects these webhooks to return data in JSON format. However, there are scenarios where webhooks might return plain text or other non-JSON formats. This discrepancy leads to the "Cannot view AnalysisRun result in UI - not a valid JSON" error within the Kargo UI, preventing users from effectively monitoring and managing their deployments. This error highlights the importance of understanding the data format expectations of Kargo UI when working with AnalysisRun results.

The Scenario: Plain Text Responses from Webhooks

Consider a scenario where an AnalysisTemplate is configured to use the web provider to ping a URL for health checks. The expectation is that the webhook at this URL should return a JSON payload. However, in some cases, the webhook might be designed to return a simple plain text response, such as "PASS" or "FAIL". This can occur due to various reasons, such as legacy systems, simplicity of the health check endpoint, or a misunderstanding of the required response format. While Argo Rollouts itself might be configured to handle such plain text responses under certain conditions, Kargo UI, which is designed to interpret AnalysisRun results, strictly expects a JSON format. When Kargo UI encounters a plain text response, it fails to parse the data, resulting in the "Cannot view AnalysisRun result in UI - not a valid JSON" error. This scenario underscores the need for careful consideration of webhook response formats when integrating Argo Rollouts and Kargo.

Technical Details: AnalysisTemplate and Kargo UI Interaction

To fully grasp the issue, it's essential to understand the technical details of how AnalysisTemplate resources interact with Kargo UI. An AnalysisTemplate in Argo Rollouts defines a set of metrics and providers used to evaluate the health and performance of a rollout. The web provider is commonly used to make HTTP requests to external endpoints, such as health check URLs. When an AnalysisRun is executed based on an AnalysisTemplate, the web provider fetches data from the specified URL. The response is then evaluated against predefined success and failure conditions. Kargo UI, as a visual interface for managing Argo Rollouts deployments, displays the results of these AnalysisRun executions. It parses the data returned by the providers to present a clear and concise view of the analysis results. However, Kargo UI's parsing logic is specifically designed to handle JSON data. If the response from the web provider is not in JSON format, the parsing process fails, leading to the "Cannot view AnalysisRun result in UI - not a valid JSON" error. This technical limitation highlights the importance of ensuring that all webhooks used in AnalysisTemplate definitions return JSON-formatted responses to maintain compatibility with Kargo UI.

Reproducing the Bug

To effectively address this issue, it's crucial to understand how to reproduce it. Here’s a step-by-step guide to replicating the "Cannot view AnalysisRun result in UI - not a valid JSON" error, along with the specific configurations and code snippets involved.

Step-by-Step Instructions

Define a Simple AnalysisTemplate:

Start by creating an AnalysisTemplate that uses the web provider. This template will ping a URL that returns plain text instead of JSON. Here’s an example AnalysisTemplate:
```
apiVersion: argoproj.io/v1alpha1
kind: AnalysisTemplate
metadata:
  name: healthcheck
spec:
  args:
    - name: url
  metrics:
    - name: diags
      count: 4
      failureLimit: 2
      initialDelay: 30s
      interval: 30s
      successCondition: result == "PASS"
      provider:
        web:
          url: "{{ args.url }}"
```
This AnalysisTemplate defines a metric named diags that pings a URL specified by the args.url parameter. The success condition is set to `result ==