Every log line starts with <nil> (with default logger config)

[mkilchhofer]

Description

Without configuring any logging options (eg. setting NEBRASKA_LOG_FORMAT to json), every log line starts with <nil>

<nil> DBG Unknown format context=api logFormat=
<nil> DBG Unknown format context=nebraska logFormat=
<nil> DBG Unknown format context=auth logFormat=
<nil> DBG Unknown format context=omaha logFormat=
<nil> DBG Unknown format context=nebraska logFormat=
<nil> DBG Unknown format context=nebraska logFormat=
<nil> DBG Unknown format context=syncer logFormat=

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⇨ http server started on [::]:8000
<nil> INF processEvent eventError 0 appID=(REDACTED) context=omaha event="update complete.success reboot" group=(REDACTED) machineId=(REDACTED) previousVersion=
<nil> ERR getInstances - getting instances params {(REDACTED) (REDACTED) 0  0 0    } error="invalid duration param null" context=nebraska

Impact

Either we should hide the timestamp field or we should instantiate zerolog with .With().Timestamp().xyz: https://github.com/flatcar/nebraska/blob/3f95eeb9ded93d96a00586331b3eb213c6ec9fbc/backend/pkg/util/log.go#L30-L33

or configure the writer to exclude the timestamp field: https://github.com/flatcar/nebraska/blob/3f95eeb9ded93d96a00586331b3eb213c6ec9fbc/backend/pkg/util/log.go#L26

Environment and steps to reproduce

Either using the default logging settings of the helm chart or starting the backends main.go in VSCode.

Expected behavior

No <nil>'s in every log line

Additional information

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