This adds provisioning endpoints for downloading alert rules and alert rule groups in a
format that is compatible with file provisioning. Each endpoint supports both json and
yaml response types via Accept header as well as a query parameter
download=true/false that will set Content-Disposition to recommend initiating a download
or inline display.
This also makes some package changes to keep structs with potential to drift closer
together. Eventually, other alerting file structs should also move into this new file
package, but the rest require some refactoring that is out of scope for this PR.
This commit renames "Message templates" to "Notification templates"
in the user interface as it suggests that these templates cannot
be used to template anything other than the message. However, message
templates are much more general and can be used to template other fields
too such as the subject of an email, or the title of a Slack message.
* add depguard rule for ioutil
* replace ioutil.ReadDir with os.ReadDir
* use legacy option in depguard supported in golangci-lint v1.40
* replace ioutil.ReadDir with os.ReadDir
* return error for file info
