README — asset-compress

Pre-compress static assets to Brotli (.br) and Gzip (.gz) variants. Minimal, non-root, CI-friendly. Base image: SUSE BCI Base

What it does

• Recursively scans your working directory (or supplied paths) for common static asset extensions.
• Emits sibling .br and .gz files beside each source when the source is newer than existing precompressed outputs.
• Operates safely in read-only-friendly environments by writing through temporary files before atomic renames.
• Ships with Brotli, gzip, and pigz CLIs so you can choose between single-threaded or multi-core gzip compression.
• Runs as a non-root user by default (UID/GID 65532:65532).

Requirements

• Docker (or a compatible container runtime).
• A directory containing assets to compress, mounted at /work.

CLI behavior

• Default command: precompress-static-assets.
• No args: scans /work recursively.
• With args: limits work to the provided files or directories (relative to /work).
• Automatically skips files whose extension is outside the configured allowlist and ignores existing .gz / .br artifacts.
• Timestamp-aware: only regenerates compressed outputs when the source file is newer or the outputs are missing.

Tuning (environment variables)

• BROTLI_QUALITY (default: 11) — Brotli compression level (0–11).
• GZIP_LEVEL (default: 9) — gzip/pigz compression level (1–9).
• PREFER_PIGZ (default: unset) — set to 1 to prefer pigz (parallel gzip). Otherwise the script uses the stock gzip binary.
• PIGZ_PROCESSES (default: 0) — when PREFER_PIGZ=1, controls the number of worker processes (0 = auto).
• ASSET_EXTENSIONS — comma-separated list of extensions to compress (overrides defaults).
• ADDITIONAL_EXTENSIONS — comma-separated list appended to the defaults or ASSET_EXTENSIONS list.

Pairing with a webserver

Run this container during build or deploy to pre-generate Brotli/Gzip artifacts that can be served directly by your webserver or CDN (e.g., via try_files rules that prefer .br and .gz when present).

Built-in helpers

The container bundles a minimal toolkit to support asset workflows:

• brotli — reference Brotli encoder.
• gzip — GNU gzip CLI.
• pigz — parallel gzip encoder for multi-core environments.
• find / gawk — used internally to discover assets and handle timestamp comparisons.

Publishing to Docker registries

Use publish-asset-compress.sh to build and push versioned tags that follow the x.y.z-bci-base-16.0-10.3 pattern. Populate release.env with your registry credentials and tagging preferences before running the script.

Versioning note

When publishing releases, tag images with MAJOR.MINOR.PATCH-bci-base-16.0-10.3 to communicate both the project version and SUSE base image revision.