Contents

Commands

vakna fork

Note
This page is generated from a mock CLI, and its numbers are placeholders.

Verified against vakna 0.0.0-mock on · generated from the CLI's own definitions

vakna fork: fork a box n times from a snapshot and run a command in each. Proposed: the real CLI doesn't have this command yet.

Synopsis

sh
vakna fork <box> --count <n> -- <command>

Flags

Flag Default What it does
--count <n> 1 boxes to fork, up to 1000
--name <name> fork-<n> the task's name, shown on its receipt
--format <format> text text, or json: one JSON object per line
--json off the same as --format json
-h, --help off this help

Examples

Example

sh
vakna fork api --count 50 -- go test -run TestRetry ./retry/...
prints snapshot snp_eu1a_z7a8b9c0 taken 0.19s forked api ×50 from snapshot · 0.34s each task prove-flaky-retry tsk_eu1a_0k1m2n3p ran go test -run TestRetry ./retry/... in 50 boxes · 42 exit 0, 8 failed 2m 11s errors: 2 signatures assertion in retry_test.go:88 ×6 timeout after 30s ×2 receipt: prove-flaky-retry · 50 boxes · 8 failed · 2m 11s · $0.46 · mocked

Exit code 1.

Another example

sh
vakna fork api --count 1000 --name prove-hypothesis-42 -- pytest -k slow
prints snapshot snp_eu1a_z7a8b9c0 taken 0.19s forked api ×1,000 from snapshot · 0.34s each task prove-hypothesis-42 tsk_eu1a_4x5y6z7a ran pytest -k slow in 1,000 boxes · 994 exit 0, 6 failed 3m 20s errors: 3 signatures OOM in test runner ×3 port 5432 already in use ×2 timeout after 45s ×1 receipt: prove-hypothesis-42 · 1,000 boxes · 6 failed · 3m 20s · $4.12 · mocked

Exit code 1.

When it fails

sh
vakna fork api --count 5000 -- go test ./...
prints vakna: --count 5,000 is over the limit of 1,000 boxes per task hint: vakna fork --help # split it into tasks of 1,000 or fewer

Exit code 255.

Exit codes

Code Meaning
0 ok
1 vakna failed; under shell, run, try or fork, the command in the box failed
2 usage: a missing argument, an unknown flag or command
255 vakna failed under shell, run, try or fork

JSON output

With --format json (or --json) every line is one JSON object. v is the format's version; mocked marks numbers from the mock.

sh
vakna fork api --count 50 --json -- go test -run TestRetry ./retry/...
prints {"v":1,"event":"snapshot","box":"api","id":"sbx_eu1a_01JB7X9K3M4N5P6Q7R8S9T0V1W","snapshot":"snp_eu1a_01JB83S1T2V3W4X5Y6Z7A8B9C0","ms":190,"mocked":true} {"v":1,"event":"forked","box":"api","snapshot":"snp_eu1a_01JB83S1T2V3W4X5Y6Z7A8B9C0","count":50,"eachMs":341,"mocked":true} {"v":1,"event":"task","id":"tsk_eu1a_01JB7Y4D5E6F7G8H9J0K1M2N3P","name":"prove-flaky-retry","mocked":true} {"v":1,"event":"ran","task":"tsk_eu1a_01JB7Y4D5E6F7G8H9J0K1M2N3P","command":"go test -run TestRetry ./retry/...","boxes":50,"exit0":42,"failed":8,"ms":131000,"mocked":true} {"v":1,"event":"errors","task":"tsk_eu1a_01JB7Y4D5E6F7G8H9J0K1M2N3P","signatures":[{"signature":"e3b0c442","label":"assertion in retry_test.go:88","count":6},{"signature":"9f86d081","label":"timeout after 30s","count":2}],"mocked":true} {"v":1,"event":"receipt","receipt":{"kind":"task","id":"tsk_eu1a_01JB7Y4D5E6F7G8H9J0K1M2N3P","name":"prove-flaky-retry","startedAt":"2026-10-17T11:20:00Z","endedAt":"2026-10-17T11:22:11Z","boxes":50,"coldBoots":0,"forks":50,"forkEachMs":341,"medianReadyMs":346,"wallClockMs":4700000,"elapsedMs":131000,"suspendedMs":0,"passed":42,"failures":[{"signature":"e3b0c442","label":"assertion in retry_test.go:88","count":6},{"signature":"9f86d081","label":"timeout after 30s","count":2}],"costMicros":456944,"trial":false,"mocked":true},"mocked":true}

Errors

--help

This page and the help text come from one definition.

Output
vakna fork · fork a box n times from a snapshot and run a command in each Proposed: the real CLI doesn't have this command yet. usage vakna fork <box> --count <n> -- <command> flags --count <n> boxes to fork, up to 1000 (default: 1) --name <name> the task's name, shown on its receipt (default: fork-<n>) --format <format> text, or json: one JSON object per line (default: text) --json the same as --format json (default: off) -h, --help this help (default: off) examples vakna fork api --count 50 -- go test -run TestRetry ./retry/... vakna fork api --count 1000 --name prove-hypothesis-42 -- pytest -k slow exit codes 0 ok 1 vakna failed; under shell, run, try or fork, the command in the box failed 2 usage: a missing argument, an unknown flag or command 255 vakna failed under shell, run, try or fork

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