Jettison not logging as JSON

[peterlabuschagne]

Hi

The readme suggests that jettison/log provides structured JSON logging, but when I use both
log.Info(ctx, "entering the example function", jettison.WithKeyValueString("key", "value"))
and
log.Error(nil, err, jettison.WithKeyValueString("another_key", "another_value"))
neither prints the error to stdout as JSON. I also can't find configurable options to specify that the output JSON.

Below is an example of the output I receive when running jettison/example:

`I 15:59:02.085 g/l/j/e/serverclient/client.go:39: serverclient: Performing a hop to another server[ctx_key=ctx_value,ctx_key2=ctx_value2,ctx_key3=ctx_value3,hops=2]
I 15:59:02.086 g/l/j/e/serverclient/server.go:30: serverclient: Received a Hop request from a client[ctx_key=ctx_value,ctx_key2=ctx_value2,ctx_key3=ctx_value3]
I 15:59:02.086 g/l/j/e/serverclient/client.go:39: serverclient: Performing a hop to another server[ctx_key=ctx_value,ctx_key2=ctx_value2,ctx_key3=ctx_value3,hops=1]
I 15:59:02.086 g/l/j/e/serverclient/server.go:30: serverclient: Received a Hop request from a client[ctx_key=ctx_value,ctx_key2=ctx_value2,ctx_key3=ctx_value3]
E 15:59:02.086 example/example.go:33: serverclient: error hopping: serverclient: run out of hops[hops=1,hops=0]
example: []
example:

• github.com/luno/jettison/example/serverclient/server.go:38
• github.com/luno/jettison/example/examplepb/example.pb.go:153
• github.com/luno/jettison/interceptors/interceptors.go:48
• github.com/luno/jettison/example/examplepb/example.pb.go:155
• google.golang.org/[email protected]/server.go:999
• google.golang.org/[email protected]/server.go:1279
• google.golang.org/[email protected]/server.go:717
• runtime/asm_amd64.s:1374
  example:
• github.com/luno/jettison/example/serverclient/server.go:33
• github.com/luno/jettison/example/examplepb/example.pb.go:153
• github.com/luno/jettison/interceptors/interceptors.go:48
• github.com/luno/jettison/example/examplepb/example.pb.go:155
• google.golang.org/[email protected]/server.go:999
• google.golang.org/[email protected]/server.go:1279
• google.golang.org/[email protected]/server.go:717
• runtime/asm_amd64.s:1374`