act_runner/DEVELOPMENT.md

Development

Job log line format

Gitea stores one log row per line and its web UI decodes the payload, so getting the encoding wrong never fails a test here, it only shows up in the browser.

A row cannot contain a real newline. FormatLog rewrites \n to a literal backslash-n and truncates at 64 KiB on a byte boundary.

The payload of a line starting with a recognised prefix is decoded, with the escape set depending on the prefix:

prefix	decodes
##[error] ##[warning] ##[notice] ##[debug] ##[group] ##[endgroup] ##[add-matcher]	%25 %0D %0A %3B %5D
::error:: ::warning:: ::notice:: ::debug:: (with or without key=value properties), ::group:: ::endgroup:: ::add-matcher::	%25 %0D %0A
##[command] [command], or no recognised prefix	nothing

Rules

• Emitting a command line? Escape the payload with runner.EscapeCommandData. One escaper covers both forms: it escapes % first, so a literal %3B becomes %253B that the extra ##[…] rules cannot match, and a raw ; or ] is never decoded. It is also what makes multi-line work, \n becomes %0A and the UI turns it back into a line break.
• Forwarding a command from step output? Leave the payload alone, it arrived escaped and is decoded once. Decoding here double-decodes and destroys multi-line.
• No prefix? Do not escape, and split multi-line values into one row each.
• Interpolating a secret? Masking runs after escaping, so AppendSecretMasker registers the encoded forms too.
• Command properties also escape %3A and %2C, which the UI never decodes, so the command handler folds an annotation's location into its decoded message and escapes the result again.

Logging

Log through act/common/logging; the linter rejects importing log/slog elsewhere. A job's logger comes from common.Logger(ctx); code with no job uses the package functions (logging.Infof, logging.With). Both take printf-style messages, and With("key", value) adds fields.

• The process-wide logger masks the secrets of every live task, the job logger masks its own. Going around either leaks them.
• The job logger's output can reach the job log workflow authors see, the process-wide logger's stays on the runner host, so keep operator-only detail (host paths, internal addresses) off the job logger.
• Libraries that log through slog's global logger are forwarded to the process-wide one, so they follow its level and masking too. Avoid dependencies that log through logrus, nothing forwards it.
• Tests read what was logged with logtest.NewLogger(), or logtest.SetDefault(t) for the package functions.

Built-in actions

Each lives in internal/pkg/action/<name> and is registered in builtinActions in act/runner/step_action_builtin.go.

End-to-end compatibility tests

make test-e2e runs the runner against E2E_GITEA_IMAGE. It defaults to the nightly image. It requires Docker and is excluded from make test. CI runs stable and nightly variants in parallel.

The cli_* scenarios build the binary and drive register and daemon as a user would, including --once, --labels and shutdown with a running job. failure_paths covers failed, skipped, tolerated and timed-out jobs. label_routing and capacity cover scheduling, reconnect drops the connection to Gitea through a proxy, and host_mode and reusable_workflow cover host labels and workflow_call.

The suite shares one Gitea and regular runner. Cache and ephemeral scenarios use isolated repository runners. A run path is <workflow>@<ref> and a log row is <timestamp>Z <payload>.