Before a long run, you want to know what it will do. --dry answers
without running anything: every task in the graph, whether the cache
would answer it, its key, and how long it took last time.
$ vx run test --all --dry would run: ▶ @demo/api#test cache miss — would exec 62269624 ~213ms ▶ @demo/api#build cache miss — would exec 10361de3 ~326ms ◉ @demo/docs#test cache hit (local) 067839a7 ◉ @demo/docs#build cache hit (local) b5134b6e ◉ @demo/ui#build cache hit (local) 6a36fb4c ◉ @demo/ui#test cache hit (local) d5097182 ◉ @demo/web#test cache hit (local) a5787dc7 ◉ @demo/web#build cache hit (local) 731116aa 8 task(s) planned, 6 cache hits (6 local), 2 would run. predicted: ~539ms wall · ~539ms total execution One edit to api: two tasks would run, six come from the cache.
Real keys, real predictions
A dry run derives the same keys a real run would and asks the same
cache. A "hit" in the plan is a hit in the run. The time next to each
task is what it took the last time it ran. The wall prediction lays
those times on the graph: api#test waits for api#build, so the two
run one after the other, ~539 ms.
For scripts and agents
--dry=json prints the same plan as JSON: tasks, keys, hit or miss,
predicted times. An agent can decide whether a run is worth starting,
or show a reviewer what a change will rebuild.
vx run build --affected --dry=json The graph itself
--graph writes the task graph as Graphviz DOT, to stdout or a file:
vx run build --all --graph=graph.dot dot -Tsvg graph.dot > graph.svg Learn more: Plan before you run and
the CLI reference.
Originally published on the vx blog. vx is an MIT task runner and build cache for JS monorepos: github.com/vznjs/vx.
Written with AI assistance.
