[Feature Request] {{if isvalue "/key" "value"}} {{if containsvalue "/key/*" "value"}}

[blaggacao]

Situation:
Deploying host-specific config scripts for example for a metric gatherer, I'd like to make some code conditional on a flag's value. Well, querying it's existence is already possible with {{if exists}}, yet this feels somewhat incomplete.

Take:

• Rancher Server
• Service Type Labels: io.rancher.appname=nginx , io.rancher.appname=postgres

Want:

• conditional deploy of a metrics gatherer like:

{{ if containsvalue "/self/host/containers/*/services/*/labels/io.rancher.appname" "postgres"}}
# Read metrics from one or many postgresql servers
[[inputs.postgresql]]
  address = "host=localhost user= password= sslmode=disable dbname="
  # databases = ["app_production", "testing"]
{{ end }}

[okushchenko]

You can use builtin conditionals from Go text/template, e.g.

{{ if (eq (getv "/key") "value") }}
exists
{{ end }}