cmdprobe

cmdprobe runs shell commands or HTTP requests and checks their output with exact, regular-expression, JSON-subset, or JMESPath matchers.

Quick start

The repository includes a complete, runnable example configuration. It demonstrates multiple YAML documents, retries, captured variables, JSON matching, saved JMESPath values, and HTTP checks.

cargo install cmdprobe
cmdprobe --config-file ./cmdprobe.yaml

For local development, start the example HTTP service first:

docker compose up -d
RUST_LOG=cmdprobe=info cargo run -- --config-file ./cmdprobe.yaml

Configuration files may contain multiple YAML documents. Each document is one check, with a test_name and an ordered list of stages:

test_name: curl json check
stages:
  - name: get the JSON document
    check: 'curl http://localhost/json'
    matchers:
      - json:
          slideshow:
            slides:
              - title: "Wake up to WonderWidgets!"
        save:
          author: slideshow.slides[0].title

See cmdprobe.yaml for the full example and the available configuration shapes.

Usage

The config path defaults to cmdprobe.yaml and can also be set with CMDPROBE_CONFIG_FILE.

Each stage supports:

• check: a shell command string, or an HTTP request with url, method, and optional headers.
• matchers: exact, regex, json, or jmespath checks. JSON matchers check that the expected value is a subset of the response.
• max_retries, delay_before, and delay_after, with delays in seconds.
• {{ name }} and {{ 1 }} variable references populated by save or regex capture groups.

Shell commands and configuration are trusted input: shell checks are executed through sh -c.

StatsD metrics

StatsD output is disabled by default. Supply an address to emit metrics for the probe, check, and stage results:

cmdprobe --config-file /etc/cmdprobe.yml --statsd-address 127.0.0.1:8125

The following counters are emitted:

cmdprobe.probe.failed / cmdprobe.probe.passed
cmdprobe.check.failed / cmdprobe.check.passed
cmdprobe.stage.failed / cmdprobe.stage.passed

Development

cargo fmt --all -- --check
cargo check --all-targets --all-features
cargo test --all-targets --all-features
cargo clippy --all-targets --all-features -- -D warnings

Inspiration

I modelled this tool after Tavern so that my team would have an easy time understanding how to use it and migrate existing tests across.