Add documentation for JsonImporter

.gitignore

@@ -31,3 +31,5 @@ dist/
 venv/
 .tox/
 .docker/
+docs_sphinx/venv/
+docs_sphinx/build/

docs/JSON.md

@@ -0,0 +1,125 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements.  See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership.  The ASF licenses this file
+ to you under the Apache License, Version 2.0 (the
+ "License"); you may not use this file except in compliance
+ with the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing,
+ software distributed under the License is distributed on an
+ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ KIND, either express or implied.  See the License for the
+ specific language governing permissions and limitations
+ under the License.
+-->
+# JSON Data Source
+
+> **Tip**
+> See [examples/](../examples/) for sample configuration files.
+
+## Overview
+
+`JsonImporter` reads benchmark results from a local JSON file and feeds them into Otava for change-point analysis. It is a simple data source to set up — no external database or service is required.
+
+The importer caches parsed file content in memory, so a file is only read once per session even if multiple tests reference the same path.
+
+---
+
+## Expected JSON Format
+
+The input file must be a JSON array. Each element represents a single benchmark run.
+```json
+[
+  {
+    "timestamp": 1711929600,
+    "metrics": [
+      { "name": "throughput", "value": 4821.0 },
+      { "name": "p99_latency_ms", "value": 142.7 }
+    ],
+    "attributes": {
+      "branch": "main",
+      "commit": "a3f9c12"
+    }
+  },
+  {
+    "timestamp": 1712016000,
+    "metrics": [
+      { "name": "throughput", "value": 5013.0 },
+      { "name": "p99_latency_ms", "value": 138.2 }
+    ],
+    "attributes": {
+      "branch": "main",
+      "commit": "b7d2e45"
+    }
+  }
+]
+```
+
+---
+
+## Fields
+
+### `timestamp`
+
+- **Type:** integer (Unix epoch seconds)
+- **Required:** yes
+- Identifies when the commit was merged into the tracked branch. This timestamp should remain constant for the same commit, even if benchmarks are rerun multiple times.
+
+### `metrics`
+
+- **Type:** array of objects
+- **Required:** yes
+- Each object must have:
+  - `name` (string) — unique identifier for the metric within this result
+  - `value` (number) — the measured value
+- Metric names must be consistent across results for change-point analysis to be meaningful.
+
+> Note: A `unit` field (e.g., "ms") is not currently supported by JsonImporter.
+
+### `attributes`
+
+- **Type:** object (string → string)
+- **Required:** no
+- Arbitrary key-value pairs describing the run context (e.g. branch, commit, version).
+- The `branch` key is required only when using branch-based filtering.
+---
+
+## Configuration Example
+
+Add a test with `type: json` to your `otava.yaml`:
+```yaml
+tests:
+  my_benchmark:
+    type: json
+    file: otava/examples/json/data/sample.json
+    base_branch: main
+```
+
+| Field | Required | Description |
+|---|---|---|
+| `type` | yes | Must be `json` |
+| `file` | yes |  Path to the JSON file |
+| `base_branch` | no | If set, only runs from this branch are analyzed by default |
+
+---
+
+## Limitations
+
+- The entire file is read into memory at once. Very large files may cause high memory usage.
+- There is no schema validation. Missing or malformed fields will cause a `KeyError` at runtime.
+- The `branch` filter requires the key `"branch"` to exist inside `attributes` on every entry — if it is absent on any entry that would otherwise be included, the importer will raise a `KeyError`.
+- Attribute values are expected to be strings. No type coercion is performed.
+- The file path is resolved at config load time; a missing file raises a `TestConfigError` immediately.
+
+---
+
+## Example Usage
+
+Analyze test results stored in JSON format:
+```bash
+otava analyze my_benchmark --config otava/examples/json/config/otava.yaml
+```

docs/index.html

@@ -0,0 +1,100 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+    <meta charset="UTF-8">
+    <title>Apache Otava Documentation</title>
+
+    <style>
+        body {
+            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
+            margin: 0;
+            background-color: #f6f8fa;
+            color: #24292e;
+        }
+
+        .container {
+            max-width: 900px;
+            margin: 40px auto;
+            padding: 30px;
+            background: #ffffff;
+            border-radius: 10px;
+            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
+        }
+
+        h1 {
+            margin-bottom: 10px;
+            font-size: 28px;
+            color: #1f2328;
+        }
+
+        p {
+            color: #57606a;
+        }
+
+        h2 {
+            margin-top: 30px;
+            border-bottom: 1px solid #d0d7de;
+            padding-bottom: 5px;
+        }
+
+        ul {
+            padding-left: 20px;
+        }
+
+        li {
+            margin: 8px 0;
+        }
+
+        a {
+            color: #0969da;
+            text-decoration: none;
+            font-weight: 500;
+        }
+
+        a:hover {
+            text-decoration: underline;
+        }
+
+        .section {
+            margin-top: 20px;
+        }
+    </style>
+</head>
+
+<body>
+    <div class="container">
+
+        <h1>Apache Otava Documentation</h1>
+
+        <p>
+            Structured entry point to the Otava documentation, replacing the default directory listing.
+        </p>
+
+        <div class="section">
+            <h2>Documentation</h2>
+            <ul>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/GETTING_STARTED.md">Getting Started</a></li>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/INSTALL.md">Installation</a></li>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/BASICS.md">Basics</a></li>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/MATH.md">Mathematics</a></li>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/CSV.md">CSV</a></li>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/BIG_QUERY.md">BigQuery</a></li>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/POSTGRESQL.md">PostgreSQL</a></li>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/GRAFANA.md">Grafana</a></li>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/GRAPHITE.md">Graphite</a></li>
+            </ul>
+        </div>
+
+        <div class="section">
+            <h2>Project</h2>
+            <ul>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/CONTRIBUTING.md">Contributing</a></li>
+                <li><a href="https://github.com/apache/otava/blob/master/docs/RELEASE.md">Release Notes</a></li>
+            </ul>
+        </div>
+
+    </div>
+</body>
+
+</html>

docs_sphinx/Makefile

@@ -0,0 +1,20 @@
+# Minimal makefile for Sphinx documentation
+#
+
+# You can set these variables from the command line, and also
+# from the environment for the first two.
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
+SOURCEDIR     = source
+BUILDDIR      = build
+
+# Put it first so that "make" without argument is like "make help".
+help:
+	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+
+.PHONY: help Makefile
+
+# Catch-all target: route all unknown targets to Sphinx using the new
+# "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
+%: Makefile
+	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)

docs_sphinx/make.bat

@@ -0,0 +1,35 @@
+@ECHO OFF
+
+pushd %~dp0
+
+REM Command file for Sphinx documentation
+
+if "%SPHINXBUILD%" == "" (
+	set SPHINXBUILD=sphinx-build
+)
+set SOURCEDIR=source
+set BUILDDIR=build
+
+%SPHINXBUILD% >NUL 2>NUL
+if errorlevel 9009 (
+	echo.
+	echo.The 'sphinx-build' command was not found. Make sure you have Sphinx
+	echo.installed, then set the SPHINXBUILD environment variable to point
+	echo.to the full path of the 'sphinx-build' executable. Alternatively you
+	echo.may add the Sphinx directory to PATH.
+	echo.
+	echo.If you don't have Sphinx installed, grab it from
+	echo.https://www.sphinx-doc.org/
+	exit /b 1
+)
+
+if "%1" == "" goto help
+
+%SPHINXBUILD% -M %1 %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
+goto end
+
+:help
+%SPHINXBUILD% -M help %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
+
+:end
+popd

docs_sphinx/source/conf.py

@@ -0,0 +1,36 @@
+# Configuration file for the Sphinx documentation builder.
+import os
+import sys
+
+sys.path.insert(0, os.path.abspath('../..'))
+
+# For the full list of built-in configuration values, see the documentation:
+# https://www.sphinx-doc.org/en/master/usage/configuration.html
+
+# -- Project information -----------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information
+
+project = 'otava'
+copyright = '2026, Apache Otava'
+author = 'Apache Otava'
+release = '0.1'
+
+# -- General configuration ---------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
+
+extensions = ["myst_parser"]
+
+templates_path = ['_templates']
+exclude_patterns = []
+
+
+
+# -- Options for HTML output -------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#options-for-html-output
+
+html_theme = 'alabaster'
+source_suffix = {
+    ".rst": "restructuredtext",
+    ".md": "markdown",
+}
+html_static_path = ['_static']

docs_sphinx/source/index.rst

@@ -0,0 +1,18 @@
+Welcome to Apache Otava Documentation
+====================================
+
+.. toctree::
+   :maxdepth: 2
+
+   ../../docs/README.md
+   ../../docs/INSTALL.md
+   ../../docs/GETTING_STARTED.md
+   ../../docs/BASICS.md
+   ../../docs/CSV.md
+   ../../docs/BIG_QUERY.md
+   ../../docs/POSTGRESQL.md
+   ../../docs/GRAFANA.md
+   ../../docs/GRAPHITE.md
+
+
+This documentation is powered by Sphinx and supports Markdown via MyST.