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Tag Filter ​

The Tag Filter can be used in multiple Terramate features:

The filter returns a list of stacks containing tags which satisfies the filter query. The query language is best explained with some examples but a formal definition can be found here.

Let's say the project has multiple stacks and some of them having the tag abc, others having the tag xyz and some having of them having both.

Then:

  • abc selects the stacks containing the tag abc.
  • xyz selects the stacks containing the tag xyz.
  • abc:xyz selects the stacks containing both abc and xyz tags.
  • abc,xyz selects the stacks containing abc or xyz tags.

The : character defines the AND operation and the , character the OR operation. They can be freely combined but no explicit grouping is supported (yet).

Examples:

  • tf,pulumi,cfn selects the stacks containing the tags tf or pulumi or cfn.
  • app:k8s:frontend selects only stacks containing the three tags: app && k8s && frontend.
  • app:k8s,app:nomad selects only stacks containing the both the tags app AND k8s or stacks containing both the tags app AND nomad.

Filter Grammar ​

Below is the formal grammar definition:

ebnf
query         ::= or_term {',' or_term}
or_term       ::= and_term {':' and_term}
and_term      ::= tagname
tagname       ::= ident
ident         ::= allowedchars { allowedchars } | allowedchars
allowedchars  ::= lowercase | digit | '-' | '_'
digit         ::= '0' ... '9'
lowercase     ::= 'a' | 'b' | ... | 'z'

The ident definition is a simplification and you should refer to stack.tags for the correct definition (in prose) for the expected declaration of tag names.