Add logs for queries and mutations

[paolochiodi]

When a fastify + mercurius application receives a request with a query or a mutation, only the original fastify http request is logged.
Unfortunately this is not very useful as everything will be logged as a POST /graphql.

It would be great if mercurius could instead:

• log the name of the mutation or query
• extend the logger passed to the resolvers to include informations about the query or mutation
• (optional) suppress default fastify logs

I guess what I'm saying is that it would be great to have some mercurius logging that works the way fastify logging works.

I understand this is feature request that will need some thinking / designing. Let me know if I can help.

[mcollina]

I think this should be implemented logging the query source right before

mercurius/index.js

Line 511 in 5760b06

// Parse, with a little lru

as a new logging value at a debug level.

[paolochiodi]

But what should be logged? I.e. I send multiple named queries like

query Query1 {
  currentUser {
    id
  }
}

query Query2 {
  categories {
    id
    name
  }
}

Will both queries be logged separately? Will it log the query name or the actual query?

[mcollina]

If you check in the actual code, it's just the source that is sent by the user before parsing it.

[Eomm]

I have created a plugin for this issue:
https://github.com/Eomm/mercurius-logging

[mcollina]

Could you add a link in the docs?