shell

README

args - Shell Arguments Appender Middleware

The args middleware appends the values provided under the args key to a shell command about to be executed. This is mostly for convenience and clarity - arguments can also be provided to the command string directly, although this often results in long execution strings that are harder to test and annotate with meaningful comments.

Note the difference between shell arguments (passed to the shell command) and pipe arguments (everything provided in the pipe invocation yaml, including the shell arguments under the args key).

Arguments

The args middleware expects an array of values, each in one of the following formats (mixing formats is fine).

Formats

Plain string

- some_pipeline:
    args:
      - string_argument

Long form options

For convenience, options of the common form --flag and --key=string_value can be provided as

- some_pipeline:
    args:
      - flag: true
      - unused_flag: false
      - key: string_value

This form is applied whenever the key does not start with a - and is not a single letter.

Short form options

If the key is a single letter, it will instead be appended to the shell command as -a (for boolean true value) or -cstring_value (for string value) without a space between key and value.

- some_pipeline:
    args:
      - a: true
      - b: false
      - c: string_value

Explicit form

Keys that start with a - will be appended as is, with the value concatenated.

- some_pipeline:
    args:
      - -a: string_value

results in -astring_value being appended.

This form can be used to enforce some custom formats:

- some_pipeline:
    args:
      - "-a ": string_value
      - "-b=": string_value
      - "--c": string_value
      - "--d ": string_value

results in -a string_value -b=string_value --string_value --d string_value being appended to the shell command.

Documentation

Overview

Package shell provides a middleware to execute commands in a shell

Index

• type Middleware
  • func NewMiddleware() Middleware
  • func NewMiddlewareWithExecutorCreator(executorCreator func() commandExecutor) Middleware
  • func (shellMiddleware Middleware) Apply(run *pipeline.Run, next func(pipelineRun *pipeline.Run), ...)
  • func (shellMiddleware Middleware) String() string

Types

type Middleware

type Middleware struct {
	ExecutorCreator func() commandExecutor
	// contains filtered or unexported fields
}

Middleware is a shell command runner

func NewMiddleware

func NewMiddleware() Middleware

NewMiddleware creates a new middleware instance

func NewMiddlewareWithExecutorCreator

func NewMiddlewareWithExecutorCreator(executorCreator func() commandExecutor) Middleware

NewMiddlewareWithExecutorCreator creates a new middleware instance with the specified executor creation function

func (Middleware) Apply

func (shellMiddleware Middleware) Apply(
	run *pipeline.Run,
	next func(pipelineRun *pipeline.Run),
	_ *middleware.ExecutionContext,
)

Apply is where the middleware's logic resides

It adapts the run based on its slice of the run's arguments. It may also trigger side effects such as executing shell commands or full runs of other pipelines. When done, this function should call next in order to continue unwinding the stack.

func (Middleware) String

func (shellMiddleware Middleware) String() string

String is a human-readable description