systems k6 runtime

k6 runtime

Active contributors: Douwe de Vries

Purpose

The k6 runtime generates executable k6 inputs, resolves the k6 binary, launches a child process, streams output and metrics, parses final summaries, and cleans up run artifacts. Most of this behavior lives in src-tauri/src/k6/process/runtime.rs.

Directory layout

src-tauri/src/importing/script.rs
src-tauri/src/importing/runtime.rs
src-tauri/src/k6/process/runtime.rs
src-tauri/src/k6/process/live_metrics.rs
src-tauri/src/k6/process/state.rs
src-tauri/src/k6/summary.rs
src-tauri/src/k6/report.rs
scripts/install-k6.sh

Key abstractions

Abstraction	File	Description
Generated script	src-tauri/src/importing/script.rs	Embeds collection requests and k6 option logic
K6BinaryResolution	src-tauri/src/k6/process/runtime.rs	k6 executable path and source
RunTempArtifacts	src-tauri/src/k6/process/runtime.rs	Private temp directory with script.js, summary.json, and metrics.json
LiveMetricsAggregator	src-tauri/src/k6/process/live_metrics.rs	Converts JSON metric lines into live snapshots
CompletionRecord	src-tauri/src/k6/process/state.rs	Data stored when a run reaches a terminal state

How it works

graph TD
    Options[K6Options] --> Env[Environment variables]
    Script[Generated script] --> Temp[Private run artifacts]
    Env --> Command[k6 run]
    Temp --> Command
    Command --> Output[stdout/stderr forwarders]
    Command --> Metrics[metrics.json forwarder]
    Command --> Summary[summary.json parser]
    Output --> Events[k6:output]
    Metrics --> Events2[k6:metrics]
    Summary --> Events3[k6:complete]

Loading

start_k6_process in src-tauri/src/k6/process/runtime.rs serializes variable overrides, selected request IDs, and request weights into JSON environment variables. It also passes VUs, duration, ramp-up settings, thresholds, auth token, base URL, traffic mode, and advanced options.

k6 resolution checks LOADRIFT_K6_BIN, Tauri resources, executable directories, manifest bin, working directory, and PATH. scripts/install-k6.sh installs the bundled binary used by development and packaged builds.

Artifact lifecycle

Run artifacts are created with private permissions. The marker file identifies Load Rift-owned k6 artifact directories. Artifacts are normally deleted after completion, but LOADRIFT_PRESERVE_K6_ARTIFACTS=true keeps them for debugging. Startup cleanup only removes stale marker-owned directories after safety checks.

Integration points

The runtime receives requests from Tauri backend, emits events through Command API bridge, and feeds Results and reporting.

Entry points for modification

Change generated k6 behavior in src-tauri/src/importing/script.rs. Change binary lookup, env vars, child process handling, or artifact cleanup in src-tauri/src/k6/process/runtime.rs. Change live metrics in src-tauri/src/k6/process/live_metrics.rs.

Key source files

File	Purpose
src-tauri/src/importing/script.rs	k6 JavaScript generation
src-tauri/src/k6/process/runtime.rs	k6 launch, stop, completion, and artifact lifecycle
src-tauri/src/k6/process/live_metrics.rs	Live metrics aggregation
src-tauri/src/k6/process/state.rs	Runtime state transitions
src-tauri/src/k6/summary.rs	Final summary parsing and fallback results