non-admin users can't run USE in the CLI

[beckettsean]

Bug report

System info: [Include InfluxDB version, operating system name, and other relevant details]

InfluxDB 0.12.1, Ubuntu 14.04, not a fresh install (upgraded from 0.10 over time)

Steps to reproduce:

1. enable authentication in the config file
2. create an admin user
3. create a non-admin user with ALL privileges to an existing database

Expected behavior: [What you expected to happen]

non-admin user with ALL privs can USE <database>

Actual behavior: [What actually happened]

non-admin user gets an auth error

Connecting directly to the database works:

# influx -username 'mydb' -password 'mmydb' -database 'mydb'
Visit https://enterprise.influxdata.com to register for updates, InfluxDB server management, and monitoring.
Connected to http://localhost:8086 version 0.12.1
InfluxDB shell 0.12.1
> show measurements
name: measurements
------------------
name
ambiguous
cpu
string1
strings

However, the mydb user cannot issue a USE command, because the CLI has a behind the scenes SHOW DATABASES command that fails:

# influx -username 'mydb' -password 'mmydb'
Visit https://enterprise.influxdata.com to register for updates, InfluxDB server management, and monitoring.
Connected to http://localhost:8086 version 0.12.1
InfluxDB shell 0.12.1
> use mydb
ERR: error authorizing query: mydb not authorized to execute statement 'SHOW DATABASES', requires admin privilege

[jsternberg]

@beckettsean should we allow non-admins to use SHOW DATABASES? What should the required privileges be?

[beckettsean]

If non-admins can run SHOW DATABASES it would be important that the command only return a list of the databases to which they have at least one read or write privilege. If there are 10 databases on the instance and a user only has read access to one, they should not be able to retrieve the entire list of databases.

Alternately we could remove the SHOW DATABASES command from the CLI on USE. I think we're only doing that so we can give a meaningful "no database found" error when someone runs USE against a non-existent database.

I think it warrants a more involved discussion. @jwilder @pauldix @gunnaraasen your thoughts?

[gunnaraasen]

I agree we should allow non-admin users to see only databases where they have either read or write privileges. Looks like this is a duplicate of #4785.

[katiitak]

This would be useful for the Admin UI also. As right you can't query data with non-admin user, as it can't get the list of databases.

[jsternberg]

Closing this in favor of #4785 since they are duplicates. A hack has already been included to get around this right now, so now we just need to fix the underlying problem.