proto v0.59 - Java support, a new version parser, improved OpenTelemetry, and more

In this release, we're shipping one of our most requested tools to date, Java, alongside a ground-up rewrite of our version parsing layer that makes it possible.

Java support

Java has been requested since proto's early days, but between the sheer number of vendors, distributions, and packaging formats, it was never a simple plugin to write. Until now, the closest workaround was the asdf backend, which doesn't work on Windows. That changes today, as proto now ships with a built-in Java plugin, powered by the foojay.io Disco API!

The plugin is available through 3 tool identifiers: java or jdk for the full development kit, and jre for the slimmer runtime-only package.

$ proto install java
$ proto install jre 21

On top of installing Java itself (with shims for java, javac, and jar), the plugin will detect versions from .java-version and .sdkmanrc files (easing migration from other version managers), and will export JAVA_HOME for activated shells.

Choosing a distribution

Java isn't a single tool with a single publisher — it's an ecosystem of vendors, each shipping their own builds. By default, the plugin installs the openjdk distribution (Oracle OpenJDK builds), but you can choose another by prefixing the version with a scope:

jdk = "temurin-21"

Over 30 distributions are supported through the Disco API, including Temurin, Zulu, Corretto, Liberica, GraalVM, Microsoft, SapMachine, Semeru, Kona, Dragonwell, and more. Common SDKMAN! shorthands (tem, amzn, librca, etc) are also accepted, both in version specifications and in .sdkmanrc files.

And lastly, if you need early access builds instead of general availability, or want to route through a self-hosted Disco API, the plugin supports both:

[tools.java]
api-url = "https://custom-foojay.hosted.com/disco/v3.0"
release-type = "ea"

A new version specification parser

Since its inception, proto has parsed versions with the semver crate, wrapped in layers of regex and string munging to squeeze in everything that crate wasn't designed for — calendar versions, partial versions, and tool-specific quirks. This approach has been a constant source of edge cases, so in this release, we threw it all away and wrote a custom grammar-based parser designed for how proto actually consumes versions.

What does this unlock? For starters, first-class version scopes: a named prefix attached to a version or requirement, such as openjdk-21.0.2, zulu-26, or pypy-2.1. Scopes are what power Java distributions above, are passed through the WASM plugin API for any plugin to consume, and remote version lists are now cached per scope.

Beyond scopes, the new parser brings consistency to both versioning schemes:

• Semantic versions and calendar versions now support the same features: pre-releases, build metadata (+123), leading v prefixes, and requirements and ranges (^, ~, comparison operators, wildcards, &&, ||).
• Calendar versions are parsed with dash separators exclusively, so ambiguous values like 24.12 are always treated as semantic versions.
• Better error messages when a version fails to parse, instead of cryptic semver errors.

OpenTelemetry improvements

We introduced OpenTelemetry support in the last release, with traces, metrics, and logs exported over gRPC. In this release, we've expanded the implementation:

• Added experimental HTTP transport support, enabled with OTEL_EXPORTER_OTLP_PROTOCOL=http/protobuf.
• Added experimental TLS support for both HTTP and gRPC transports.
• Added support for the standard OTEL_SERVICE_NAME, OTEL_*_EXPORTER, OTEL_EXPORTER_OTLP_*_PROTOCOL, and OTEL_EXPORTER_OTLP_*_ENDPOINT environment variables (including their signal-specific variants).

If your environment already configures OTEL exporters through these variables, proto will now respect them out of the box.

Smarter PATH handling in shims

This release fixes two long-standing PATH issues in proto run and shim executions:

• When a tool requires another tool to function (npm requires node), the required tool's paths were placed before the paths of the tool being ran. For example, npm run scripts that execute npm would resolve node's bundled npm, instead of the npm version managed by proto. The tool being ran now takes precedence.
• When falling back to a global executable on PATH, proto could recursively execute forever if that executable was itself a proto shim from another store (typically caused by HOME or PROTO_HOME changing, or symlinked paths). We now skip shims from foreign stores during the lookup, and detect and error on the loop instead of hanging.

Breaking changes

Calendar version build segments

As part of the new parser, the proto-specific "micro" build segment (dot or underscore separated) has been removed from calendar versions. Use standard build metadata instead.

2024-02-26.123          ->  2024-02-26+123
2024-02-26_123-alpha.0  ->  2024-02-26-alpha.0+123

Other changes

View the official release for a full list of changes.

• Added bzip2, xz, and z codec support for self-compressed binaries (not packed with tar or zip), as well as .tar.Z (LZW) archive support.
• Updated archive unpacking to be streamed when applicable, reducing memory usage.
• Updated offline detection to take AI agent firewall policies into account. If networking is disabled, we mark as offline, otherwise if it's open or filtered, we mark it as online.
• Fixed an issue where proto clean would not recursively clean certain directories.
• Fixed an issue where we didn't check for an internet connection when downloading a plugin from an OCI registry or GitHub.
• Updated Rust to v1.97.