Output predicates

Security

If your application logs includes in it's output data from remote hosts or other untrusted sources, it is likely that attackers will be able to manipulate output predicates. Attackers will likely be able to trigger retry or stop predicates in inappropriate situations. If you are using regex predicates, attackers may be able to mount denial of service attacks by supplying pathological inputs. Attackers may also launch denial of service attacks by causing the output to be large.

Avoid using output predicates in untrusted environments.

Performance

Output predicates are often more convinient than status predicates, and users are encouraged to use them when in circumstances when developer time is the greatest concern (such as in command lines and for throw-away scripts). However, they are discouraged in scripting or CI use.

Output predicates are the most expensive. They require additional system calls to retrieve the output and additional computation to search it. They are typically unstable across different versions of the child process.

Status predicates should be prefferred when possible. If output predicates are used, the more specific predicates (eg --retry-if-stdout-contains vs --retry-if-contains) should be preferred.

Regular expression syntax

The regular expression predicates use the regex crate's syntax.

Retry predicates

--retry-if-contains <STRING>

Retry if either stdout or stderr contains the specified string.

--retry-if-matches <REGEX>

Retry if either stdout or stderr matches the specified regular expression.

--retry-if-stdout-contains <STRING>

Retry if stdout contains the specified string.

--retry-if-stdout-matches <REGEX>

Retry if stdout matches the specified regular expression.

--retry-if-stderr-contains <STRING>

Retry if stderr contains the specified string.

--retry-if-stderr-matches <REGEX>

Retry if stderr matches the specified regular expression.

Stop predicates

--stop-if-contains <STRING>

Stop retrying if either stdout or stderr contains the specified string.

--stop-if-matches <REGEX>

Stop retrying if either stdout or stderr matches the specified regular expression.

--stop-if-stdout-contains <STRING>

Stop retrying if stdout contains the specified string.

--stop-if-stdout-matches <REGEX>

Stop retrying if stdout matches the specified regular expression.

--stop-if-stderr-contains <STRING>

Stop retrying if stderr contains the specified string.

--stop-if-stderr-matches <REGEX>

Stop retrying if stderr matches the specified regular expression.