Open TomekTrzeciak opened 3 years ago
oliver-sanders
commented
3 years ago Support for Bash substitutions might be the easiest way to achieve this:
[env]
FOO=${FOO:-default}Bash vars are already parsed out of the config using some logic in metomi.rose.env.
TomekTrzeciak
commented
3 years ago Support for Bash substitutions might be the easiest way to achieve this:
[env] FOO=${FOO:-default}Bash vars are already parsed out of the config using some logic in
metomi.rose.env.
That would do the trick, I just don't know how to alter regular expressions in metomi.rose.env in a robust way (default value could in principle contain any characters). OTOH, my suggestion above would be straightforward to implement in env config processor (metomi.rose.config_processors.env).
oliver-sanders
commented
3 years ago I just don't know how to alter regular expressions in metomi.rose.env in a robust way
^
(?P<head>.*?)
(?P<escape>\\*)
(?P<symbol>
\$
(?P<brace_open>\{)?
(?P<name>[A-z_]\w*)
(:-(?P<default>\w*))?
(?(brace_open)\})
)
(?P<tail>.*)
$
# should match
${FOO}
${FOO:-bar}
# shouldn't match
${FOO/a/b}
${FOO:bar}OTOH, my suggestion above would be straightforward to implement in env config processor (metomi.rose.config_processors.env)
I wouldn't want to go adding a new type of definition because it's not just about supporting that in the config processor but also internally handling a new type of definition and then presenting that throughout the CLI and GUI.
oliver-sanders
commented
3 years ago This allows substitutions so long as they aren't nested.
^
\${
(?P<key>\w+)
(
:-
(?P<default>
# don't allow nested substitutions
(?!\$)
(
# allow any chars within single quotes
(?:'[^']*')?
# allow any chars within double quotes (except dollar)
(?:\"[^"\$]*\")?
# ignore escaped braces
(?:\\})?
# match up to the closing brace
(?:[^}'\"]+)?
)+
)
)?
}
$# these all match
${FOO}
${FOO:-bar}
${FOO:-}
${FOO:-\}}
${FOO:-''}
${FOO:-'}'}
${FOO:-'}'"}"'"}"'}
# don't allow nested substitutions
${FOO:-${BAR}}
# don't allow nested expressions in double quotes
${FOO:-"${BAR}"}
# don't allow fancy bash syntax
${FOO/a/b}Encountered another use case for this.
I would find it quite useful if there was some way to specify default values for environment variables in rose apps, something like:
MY_VARwould be then set todefaultonly if it is not already set in the environment. The only way I can think of to override the env definition currently is to use a command line definerose task-run -D[env]MY_VAR=override, which is far less convenient to use.