StackTrac

StackTrac is a lightweight CLI SRE diagnostic tool that accepts a trace via --file, --string, --url or stdin, extracts the most likely offending stack frame, and returns the probable file and line number plus a search link (default: StackOverflow). The CLI also returns the exception message when available.

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• Node >= 18 (the CLI falls back to node-fetch if built-in fetch is unavailable).

Global install: npm install -g stacktrac

Local/dev install: npm install --save-dev stacktrac

From a file: stacktrac --file path/to/trace.txt

From an inline string: stacktrac --string "Exception: Something went wrong: null pointer\n\tat com.example.Foo(Foo.java:12)"

From a URL: stacktrac --url "https://example.com/log.txt"

From stdin: cat trace.txt | stacktrac

Machine-readable output: stacktrac --file path/to/trace.txt --json

• -f, --file <path> — read trace from path
• -s, --string <text> — pass trace as a string
• -u, --url <url> — fetch trace from a URL
• -j, --json — output JSON
  If no input option is given the CLI reads from stdin when piped.

Human readable: Exception: java.lang.NullPointerException: Attempt to read property 'id' of null Exception message: Attempt to read property 'id' of null Probable frame: at com.example.service.UserService.getUser(UserService.java:87) File: UserService.java:87 Search: https://stackoverflow.com/search?q=java.lang.NullPointerException+UserService.getUser

JSON (--json): { "found": true, "exception": "java.lang.NullPointerException: Attempt to read property 'id' of null", "exceptionMessage": "Attempt to read property 'id' of null", "frameString": "at com.example.service.UserService.getUser(UserService.java:87)", "file": "UserService.java", "line": 87, "function": "com.example.service.UserService.getUser", "link": "https://stackoverflow.com/search?q=java.lang.NullPointerException+UserService.getUser" }

Notes:

• exception contains the exception header and message when present. exceptionMessage is provided for easy access to the message text.

• If the parser cannot extract a message, exceptionMessage may be omitted or empty.

• Accepts raw logs and traces and extracts trace blocks (Java, Node, Python heuristics).

• Chooses the most likely user frame by ignoring common framework/internal packages.

• Returns exception (header plus message when available), exceptionMessage (message only), file, line, frameString, function and a link to search results.
  Extend lib/parser.js to improve message extraction or add languages.

Optional environment variables:

• STACKTRAC_IGNORE_PACKAGES — comma-separated package prefixes to ignore.
• STACKTRAC_SO_BASE — base search URL (defaults to StackOverflow search).
• STACKTRAC_JSON — force JSON output when set to 1.

Main files:

• package.json
• bin/stacktrac.js
• lib/parser.js

Local testing and linking: git clone cd npm install npm link

Run tests: npm test

• Fork, add tests, follow existing style and open a PR.
• Use the issue tracker for bug reports and feature requests.

Distributed under the MIT License. See LICENSE for details.

written by [email protected] Wed Nov 5 09:38:17 MST 2025