Scripts and Templates are very much alike. There are only two main differences between them when it comes to watcher:
1. The template doesn't have a language type - it's always mustache.
2. Templates are often used to render xcontent (json/yaml). So there's build in support for content type in it
Traditionally, in es core, the configuration of the scripts and templates was always a bit of a mess. There was no consistency between the two and when it comes to the templates configuration, they're even not future proof (future additions to the search requests body can break the templates).
After a long discussion, we've decided that we need to change the way users configure templates & scripts in es core... and align the two. These changes will only come in es 2.0. That said, it's important that watcher will be aligned with es core in how templates and scripts are configured and therefore we need to change it for that purpose.
Watcher will come with support for the scripts & templates configuration format of es 2.0. We want to future proof the configuration from day one.
here are the configuration:
Inline:
```
{
"inline" : "script here",
"lang" : "lang here",
"params" : { parameters here }
}
```
File:
```
{
"file" : "file name here",
"lang" : "language here",
"params" : { parameters here }
}
```
Indexed:
```
{
"id" : "template id here",
"lang" : "language here",
"params" : { parameters here }
}
```
For templates it's the same configuration except there is no `lang` field. Also, for templates, there's native support for xcontent:
```
{
"inline" : { "key" : "{{param1}}" },
"params" : { "param1" : "value1" }
}
}
```
Original commit: elastic/x-pack-elasticsearch@4a31114f35
a06303a894