Preflight

A swiss army knife for CI and container checks. Single binary, zero dependencies.

Stop copying brittle shell scripts and installing a variety of tools for container validation. Preflight is a small, dependency-free binary that handles service readiness, health checks, environment validation, file verification, and more.

COPY --from=ghcr.io/vertti/preflight:latest /preflight /usr/local/bin/preflight

RUN preflight cmd myapp --min 2.0
RUN preflight env MODEL_PATH --match '^/models/'
RUN preflight file /app/config.yaml --not-empty
RUN preflight tcp postgres:5432

Use it for:

• Docker builds – verify binaries, configs, and paths during image build
• Container startup – wait for databases and services before your app starts
• CI pipelines – validate environments, check connectivity, verify checksums
• Health checks – HTTP and TCP checks without curl or netcat

Clear output, CI-friendly exit codes:

Every check tells you exactly what passed or failed—no more guessing why your build broke.

[OK] cmd: node
     path: /usr/local/bin/node
     version: 20.10.0

[OK] file: /app/config.yaml
     size: 1.2KB
     mode: -rw-r--r--

[FAIL] cmd: python
       version 3.9.0 < minimum 3.11

[FAIL] tcp: postgres:5432
       connection refused

Exit code 0 on success, 1 on failure. Works with set -e, Docker RUN, and CI pipelines out of the box.

Install

Dockerfiles (recommended):

COPY --from=ghcr.io/vertti/preflight:latest /preflight /usr/local/bin/preflight

Want to keep your final image lean? See Keeping Containers Clean for multi-stage builds and external validation.

Shell:

curl -fsSL https://raw.githubusercontent.com/vertti/preflight/main/install.sh | sh

Other install methods

Usage

See the full usage guide for all commands and options.

Check commands

Like which, but actually runs the binary to verify it works.

preflight cmd node                            # exists and runs
preflight cmd node --min 18.0                 # version constraint
preflight cmd ffmpeg --version-cmd -version   # custom version flag

All cmd options

Check environment variables

preflight env DATABASE_URL                       # exists and non-empty
preflight env MODEL_PATH --match '^/models/'     # matches pattern
preflight env APP_ENV --one-of dev,staging,prod  # allowed values

All env options

Check files and directories

preflight file /models/bert.onnx --not-empty   # file exists and has content
preflight file /var/log/app --dir --writable   # directory is writable
preflight file /app/entrypoint.sh --executable # script is executable

All file options

Check HTTP endpoints

Health checks for services without requiring curl or wget in your container.

preflight http http://localhost:8080/health         # basic health check
preflight http https://api.example.com --status 204 # custom status code
preflight http http://localhost/ready --retry 3     # retry on failure

All http options

Verify file checksums

Supply chain security - verify downloaded binaries match expected hashes.

preflight hash --sha256 67574ee...2cf myfile.tar.gz  # verify SHA256
preflight hash --checksum-file SHASUMS256.txt app.tar.gz  # from checksum file

All hash options

Run checks from a file

Create a .preflight file in your project to define all checks in one place:

# .preflight
file /etc/localtime --not-empty
cmd myapp --min 2.0
cmd go
env HOME

Run all checks:

preflight run                             # finds .preflight automatically
preflight run --file /path/to/.preflight  # specify file explicitly

File format, discovery, and hashbang support

Full usage guide

License

Apache 2.0