Andreas Auernhammer 6f764a8efd crypto: fix nil pointer dereference of vault secret (#7241)
This commit fixes a nil pointer dereference issue
that can occur when the Vault KMS returns e.g. a 404
with an empty HTTP response. The Vault client SDK
does not treat that as error and returns nil for
the error and the secret.

Further it simplifies the token renewal and
re-authentication mechanism by using a single
background go-routine.

The control-flow of Vault authentications looks
like this:
1. `authenticate()`: Initial login and start of background job
2. Background job starts a `vault.Renewer` to renew the token
3. a) If this succeeds the token gets updated
   b) If this fails the background job tries to login again
4. If the login in 3b. succeeded goto 2. If it fails
   goto 3b.
2019-02-13 15:25:32 -08:00
..
2018-12-14 13:35:48 -08:00