jsonwatch — like watch -d but for JSON

jsonwatch is a command line utility with which you can track changes in JSON data delivered by a shell command or a web (HTTP/HTTPS) API. jsonwatch requests data from the designated source repeatedly at a set interval and displays the differences when the data changes. It is similar but not isomorphic in its behavior to how watch(1) with the -d switch works for plain-text data.

It has been tested on Debian 10, Ubuntu 18.04, and Windows 7.

The two previous versions of jsonwatch are preserved in the branch python and haskell.

Installation

Prebuilt Linux and Windows binaries are available. They are attached to releases on the Releases page.

Building on Debian and Ubuntu

Follow the instructions to build a static Linux binary of jsonwatch from source on recent Debian and Ubuntu.

1. Install Rustup. Through Rustup add the stable MUSL target for your CPU.

rustup target add x86_64-unknown-linux-musl

2. Install the build and testing dependencies.

sudo apt install build-essential expect musl-tools tcl

3. Clone this repository. Build and install the binary.

git clone https://github.com/dbohdan/jsonwatch
cd jsonwatch
make test
make release
sudo make install "BUILD_USER=$USER"

Cross-compiling for Windows

Follow the instructions to build a 32-bit Windows binary of jsonwatch on recent Debian and Ubuntu.

1. Install Rustup. Through Rustup add the i686 GNU ABI Windows target.

rustup target add i686-pc-windows-gnu

2. Install the build dependencies.

sudo apt install build-essential mingw-w64

3. Configure Cargo for cross-compilation. Put the following in ~/.cargo/config.

[target.i686-pc-windows-gnu]
linker = "/usr/bin/i686-w64-mingw32-gcc"

4. Fix the crt2.o issue.

cd ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/
mv crt2.o crt2.o.bak
cp /usr/i686-w64-mingw32/lib/crt2.o .

5. Clone this repository. Build the binary.

git clone https://github.com/dbohdan/jsonwatch
cd jsonwatch
RUSTFLAGS="-C panic=abort -C lto" make release TARGET=i686-pc-windows-gnu
cp "/tmp/$USER/cargo/jsonwatch/i686-pc-windows-gnu/release/jsonwatch.exe" .

Use examples

Commands

*nix

Testing jsonwatch.

$ jsonwatch -n 1 -c "echo '{ \"filename\": \"'\$(mktemp -u)'\"}'"

{
  "filename": "/tmp/tmp.dh3Y7LJTaK"
}
2020-01-19T18:52:19+0000 .filename: "/tmp/tmp.dh3Y7LJTaK" -> "/tmp/tmp.i4s56VENEJ"
2020-01-19T18:52:20+0000 .filename: "/tmp/tmp.i4s56VENEJ" -> "/tmp/tmp.zzMUSn45Fc"
2020-01-19T18:52:21+0000 .filename: "/tmp/tmp.zzMUSn45Fc" -> "/tmp/tmp.Jj1cKt6VLr"
2020-01-19T18:52:22+0000 .filename: "/tmp/tmp.Jj1cKt6VLr" -> "/tmp/tmp.1LGk4ok8O2"
2020-01-19T18:52:23+0000 .filename: "/tmp/tmp.1LGk4ok8O2" -> "/tmp/tmp.wWulyho8Qj"

Docker process information.

$ jsonwatch -c 'docker ps -a "--format={{json .}}"' -n 1

2020-01-19T18:57:20+0000
    + .Command: "\"bash\""
    + .CreatedAt: "2020-01-19 18:57:20 +0000 UTC"
    + .ID: "dce7fb2194ed"
    + .Image: "i386/ubuntu:latest"
    + .Labels: ""
    + .LocalVolumes: "0"
    + .Mounts: ""
    + .Names: "dreamy_edison"
    + .Networks: "bridge"
    + .Ports: ""
    + .RunningFor: "Less than a second ago"
    + .Size: "0B"
    + .Status: "Created"
2020-01-19T18:57:21+0000 .RunningFor: "Less than a second ago" -> "1 second ago"
2020-01-19T18:57:23+0000
    .RunningFor: "1 second ago" -> "3 seconds ago"
    .Status: "Created" -> "Up 1 second"
2020-01-19T18:57:24+0000
    .RunningFor: "3 seconds ago" -> "4 seconds ago"
    .Status: "Up 1 second" -> "Up 2 seconds"
2020-01-19T18:57:25+0000
    .RunningFor: "4 seconds ago" -> "5 seconds ago"
    .Status: "Up 2 seconds" -> "Up 3 seconds"

Windows

On Windows -c executes cmd.exe commands.

> jsonwatch -c "type tests\weather1.json"

{
  "clouds": {
    "all": 92
  },
  "name": "Kiev",
  "coord": {
    "lat": 50.43,
    "lon": 30.52
  },
  "sys": {
    "country": "UA",
    "message": 0.0051,
    "sunset": 1394985874,
    "sunrise": 1394942901
  },
  "weather": [
    {
      "main": "Snow",
      "id": 612,
      "icon": "13d",
      "description": "light shower sleet"
    },
    {
      "main": "Rain",
      "id": 520,
      "icon": "09d",
      "description": "light intensity shower rain"
    }
  ],
  "rain": {
    "3h": 2
  },
  "base": "cmc stations",
  "dt": 1394979003,
  "main": {
    "pressure": 974.8229,
    "humidity": 91,
    "temp_max": 277.45,
    "temp": 276.45,
    "temp_min": 276.15
  },
  "id": 703448,
  "wind": {
    "speed": 10.27,
    "deg": 245.507
  },
  "cod": 200
}
2020-01-19T18:51:04+0000 + .test: true
2020-01-19T18:51:10+0000 .test: true -> false
2020-01-19T18:51:23+0000 - .test: false

URLs

Watching a URL works identically on *nix and on Windows.

Weather tracking.

$ jsonwatch -u http://api.openweathermap.org/data/2.5/weather\?q\=Kiev,ua --no-initial-values -n 300

2014-03-17T23:06:19.073790
    + .rain.1h: 0.76
    - .rain.3h: 0.5
    .dt: 1395086402 -> 1395089402
    .main.temp: 279.07 -> 278.66
    .main.temp_max: 279.82 -> 280.15
    .main.temp_min: 277.95 -> 276.05
    .sys.message: 0.0353 -> 0.0083

Geolocation. (Try this on a mobile device.)

$ jsonwatch -u https://ipinfo.io/ --no-initial-values -n 300

dbohdan/jsonwatch

dbohdan

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