Variable substitution in DataLinks does not URL encode unsafe characters

[yanscalyr]

What happened:
When following a DataLink that contains a variable, the variable will be substituted in without being encoded, which can result in unsafe characters being present in the URL.
Some safe characters will also be backslash escaped automatically which adds additional unsafe characters, and is probably unnecessary in a URL.

Unsafe characters can result in the server rejecting the request.

What you expected to happen:
Variable values would be encoded and not backslash escaped in the URL.

How to reproduce it (as minimally and precisely as possible):

1. Create a variable with a value containing a backslash \
2. Create a datalink that references the above variable (for full effect point it to a server using a recent version of Apache Tomcat, as this is how I ran into this issue)
3. Use the DataLink

Anything else we need to know?:
Depending on where your DataLink is pointing to, some servers encode unsafe values when received, or do not reject the request.

Environment:

• Grafana version: v6.5.2
• Data source type & version:
• OS Grafana is installed on: MacOS Catalina Version 10.15.3
• User OS & Browser: MacOS Catalina Version 10.15.3, Chrome
• Grafana plugins:
• Others:

[sakjur]

This is similar to #22125, so I'm closing this as a duplicate of that. Would be great if you could add a comment there to put emphasis that it's not about more characters than # 🙂