watcher

watcher 👀

Compare runtime environments across servers — fast, read-only, and CI-friendly.

Watcher is a lightweight CLI that detects and compares runtimes (Java, Python, Node.js, Go, Docker, etc.) across local and remote servers over gRPC. It gives operators and SREs reliable answers to:

“Why does this server behave differently from that one?”
“Are all environments actually running the same versions?”

⭐ If this tool helps you inspect or debug infrastructure, consider giving it a star — it really helps.

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Why Watcher?

• Read-only, safe to run on production boxes
• Fast comparisons across many hosts
• Extensible detector registry for new runtimes
• Friendly to CI pipelines and automation
• API-key authentication for remote access

Watcher observes; it never mutates target machines. Run it on prod nodes, CI runners, or anywhere you need version truth.

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What it does

• Detects installed runtimes and versions:
  • Java, Python, Node.js, Go, Docker
  • MySQL/MariaDB, Redis, Nginx
• Collects data locally or remotely via gRPC
• Compares versions across multiple servers
• Outputs results as tables, JSON, or YAML

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Example

Multi-server comparison

┌─────────┬───────────┬───────────┬─────────┐
│ RUNTIME │ SERVER-1  │ SERVER-2  │ STATUS  │
├─────────┼───────────┼───────────┼─────────┤
│ python  │ 3.10.12   │ 3.10.12   │ SAME    │
│ go      │ 1.25.5    │ 1.25.5    │ SAME    │
│ node    │ x         │ 20.18.0   │ PARTIAL │
│ docker  │ x         │ 27.5.1    │ PARTIAL │
│ java    │ x         │ 17.0.17   │ PARTIAL │
└─────────┴───────────┴───────────┴─────────┘

Environment drift becomes instantly visible.

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Installation

Quick install

go install github.com/binaryarc/watcher/cmd/wctl@latest
go install github.com/binaryarc/watcher/cmd/wsctl@latest

Ensure $GOPATH/bin is on your PATH.

Build from source

git clone https://github.com/binaryarc/watcher.git
cd watcher
make build

This produces:

• wctl — client CLI
• wsctl — server CLI

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Usage

Local runtime check

wctl get runtimes
wctl get runtime java

Example output for wctl get runtimes:

Observing local runtimes...

┌─────────┬─────────┬──────────────────────────────────────────┐
│ RUNTIME │ VERSION │                   PATH                   │
├─────────┼─────────┼──────────────────────────────────────────┤
│ java    │ 17.0.17 │ /opt/java/bin/java                      │
│ python  │ 3.10.12 │ /usr/bin/python3                        │
│ node    │ 20.18.0 │ /opt/node/bin/node                      │
│ go      │ 1.25.5  │ /usr/local/go/bin/go                    │
│ docker  │ 27.5.1  │ /usr/bin/docker                         │
└─────────┴─────────┴──────────────────────────────────────────┘

Total: 5 runtime(s) detected

Remote runtime check

On each target server:

wsctl run --port 9090

From your client:

wctl get runtimes --host 192.168.1.100:9090
wctl get runtime java --host server.example.com:9090 -o json

Compare multiple servers

wctl compare runtimes --hosts server1:9090,server2:9090,server3:9090

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Authentication & API keys

Watcher uses shared API keys for every remote RPC.

Client side

Generate and store a key:

wctl key gen

Print the currently saved key:

wctl get key

Keys load automatically in this order:

1. --api-key flag
2. WATCHER_API_KEY environment variable
3. File at ~/.watcher/keys/default

Server side

Register keys and start the server:

wsctl add key <api-key> "CI pipeline token"
wsctl run --port 9090

Manage keys:

wsctl get keys
wsctl delete key --name <api-key>
wsctl clear keys

For quick tests you can disable auth:

wsctl run --disable-auth

(Not recommended for production.)

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How it works

wctl (client) --- gRPC ---> wsctl (server)
                           |
                     runtime detectors

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Supported runtimes

• Java
• Python
• Node.js
• Go
• Docker
• MySQL / MariaDB
• Redis
• Nginx

Detection relies on standard version commands (java -version, python3 --version, ...).

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Project structure

cmd/
  wctl/           CLI client
  wsctl/          gRPC server CLI
internal/
  detector/       runtime detection logic
  grpcclient/     client wrapper
  grpcserver/     server implementation
proto/            gRPC definitions

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Roadmap

• Binary releases (Linux/macOS) — first tag: v0.1.0
• One-line install script
• Shell auto-completion (bash/zsh/fish)
• Baseline comparison (--baseline)
• CI mode with exit codes (--ci)
• Snapshot & diff support

Ideas, bug reports, and feature requests are welcome.

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Contributing

Watcher is evolving. Issues and pull requests are encouraged.

If this fits your workflow, a ⭐ on the repository makes a big difference.

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License

Watcher is distributed under the MIT License. See LICENSE for details.