catch

README

catch - Error Handling Middleware

Arguments

Matching rules

Define error matching rules using the pattern argument. It expects a regex that matches each handled line in the StdErr output.

Any errors that occur will be matched against your rules, and the first match will be applied. Subsequent pipes will not see these errors.

- some_pipeline:
    catch:
      pattern: "^Error: ",

Handling rules

The ignore argument will cause all matched errors to be swallowed instead of being passed to subsequent pipelines. Use with caution.

- some_pipeline:
    catch:
      pattern: "^Error: ",
      ignore: true

Some errors are best treated as output. The divert-to-output argument prints the error message in StdOut and does not pass it on.

- some_pipeline:
    catch:
      pattern: "^Error: ",
      divert-to-output: true

Use the explain-error argument to wrap the error using a GoLang format string. The placeholder %w can be used to refer to the underlying error. Note that a handler will not swallow the error, unless combined with another argument, such as ignore.

- some_pipeline:
    catch:
      pattern: "^Error: ",
      explain-error: "failed to parse configuration file due to syntax error: %w"

Documentation

Overview

Package catch provides a middleware for graceful handling of stderr output

Index

• type Middleware
  • func NewMiddleware() Middleware
  • func (catchMiddleware Middleware) Apply(run *pipeline.Run, next func(*pipeline.Run), ...)
  • func (Middleware) String() string

Types

type Middleware

type Middleware struct {
}

Middleware implements a handler for stderr output

func NewMiddleware

func NewMiddleware() Middleware

NewMiddleware creates a new Middleware instance

func (Middleware) Apply

func (catchMiddleware Middleware) Apply(
	run *pipeline.Run,
	next func(*pipeline.Run),
	executionContext *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 (Middleware) String() string

String is a human-readable description