invoke

Documentation

Overview

Package invoke implements the process of invoking a 'luciexe' compatible subprocess, but without setting up any of the 'host' requirements (like a Logdog Butler or LUCI Auth).

See go.chromium.org/luci/luciexe for details on the protocol.

Index

• type Options
• type Subprocess
  • func Start(ctx context.Context, luciexePath string, input *bbpb.Build, opts *Options) (*Subprocess, error)
  • func (s *Subprocess) Wait() (*bbpb.Build, error)

Types

type Options

type Options struct {
	// This should be in Build.Step.Name format, i.e. "parent|parent|leaf".
	//
	// Namespace is used as:
	//   * The Step name of the enclosing Build Step.
	//   * Generating the new LOGDOG_NAMESPACE in the environment for the
	//     subprocess. Non-StreamName characters are replaced with '_',
	//     and if the first character of a segment is not a character, "s_" is
	//     prpended. i.e. if the current LOGDOG_NAMESPACE is "u", and this
	//     namespace is "x|!!cool!!|z", then LOGDOG_NAMESPACE for the
	//     subprocess will be "u/x/s___cool__/z".
	//     * The LUCI Executable host process will assert that all logdog stream
	//       names mentioned in the subprocess's Build are relative to this.
	//   * The basis for the stdout/stderr Logdog streams for the subprocess.
	//   * The LUCI Executable host process will adjust the subprocess's step
	//     names to be relative to this. i.e. if the subprocess emits a step "a|b"
	//     and the Namespace is "x|y|z", then the step will show up as "x|y|z|a|b"
	//     on the overall Build.
	//
	// TODO(iannucci): Logdog stream names are restricted because they show up in
	// URLs on the logdog service. If the logdog service instead uses URL encoding
	// of the stream name, then StreamName could be expanded to allow all
	// characters except for "/". At some later point we could potentially change
	// the separator from "/" to "|" to match Buildbucket semantics.
	//
	// TODO(iannucci): Find a way to have logdog stream name namespacing be more
	// transparent (i.e. without needing explicit cooperation from the logdog
	// client library via LOGDOG_NAMESPACE envvar).
	//
	// Default: The Namespace is empty. This is ONLY useful when writing
	// a transparent wrapper for a luciexe which doesn't, itself, implement the
	// luciexe protocol. If Namespace is empty, then Subprocess.Step will be
	// `nil`.
	Namespace string

	// Absolute path to the cache base directory. This must exist and be
	// a directory.
	//
	// Default: If LUCI_CONFIG['lucictx']['cache_dir'] is set, it will be passed
	// through unchanged. Otherwise a new empty directory is allocated which will
	// be destroyed on the subprocess's completion.
	CacheDir string

	// If set, the subprocess's final Build message will be collected and returned
	// from Wait.
	//
	// If CollectOutput is specified, but CollectOutputPath is not, a temporary
	// path will be seleceted and destroyed on the subprocess's completion.
	CollectOutput bool

	// If set, will be used as the path to output the subprocess's final Build
	// state. Must end with one of {'.pb', '.json', '.textpb'}. This must be
	// a path to a non-existent file (i.e. parent must be a directory).
	//
	// If CollectOutputPath is specified, but CollectOutput is not, the subprocess
	// will be instructed to dump the result to this path, but we won't attempt to
	// parse or validate it in any way, and Wait will return a nil `output`.
	CollectOutputPath string

	// A replacement environment for the Options.
	//
	// If this is not specified, the current process's environment is inherited.
	//
	// The following environment variables will be ignored from this `Env`:
	//   * LOGDOG_NAMESPACE
	//   * LUCI_CONTEXT
	Env environ.Env
}

Options represents settings to use when Start'ing a luciexe.

All values here have defaults, so Start can accept `nil`.

type Subprocess

type Subprocess struct {
	Step *bbpb.Step
	// contains filtered or unexported fields
}

Subprocess represents a running luciexe.

func Start

func Start(ctx context.Context, luciexePath string, input *bbpb.Build, opts *Options) (*Subprocess, error)

Start launches a binary implementing the luciexe protocol and returns immediately with a *Subprocess.

Args:

• ctx will be used for deadlines/cancellation of the started luciexe.
• luciexePath must be the full absolute path to the luciexe binary.
• input must be the Build message you wish to pass to the luciexe binary.
• opts is optional (may be nil to take all defaults)

Callers MUST call Wait and/or cancel the context or this will leak handles for the process' stdout/stderr.

This assumes that the current process is already operating within a "host application" environment. See "go.chromium.org/luci/luciexe" for details.

The caller SHOULD immediately take Subprocess.Step, append it to the current Build state, and send that (e.g. using `exe.BuildSender`). Otherwise this luciexe's steps will not show up in the Build.

func (*Subprocess) Wait

func (s *Subprocess) Wait() (*bbpb.Build, error)

Wait waits for the subprocess to terminate.

If Options.CollectOutput (default: false) was specified, this will return the final Build message, as reported by the luciexe.

If you wish to cancel the subprocess (e.g. due to a timeout or deadline), make sure to pass a cancelable/deadline context to Start().

Calling this multiple times is OK; it will return the same values every time.