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intelsdi-x / snap

The open telemetry framework
http://snap-telemetry.io
Apache License 2.0
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Handle empty configuration without panic or fatal error. #1746

Closed cce closed 6 years ago

cce commented 6 years ago

I noticed a panic if a configuration section contains an empty block after the all:, and fatal errors in other cases (shown in the test case). Ideally Snap will ignore empty configuration sections and process them as if no configuration was supplied. This PR logs a warning and moves on if empty configuration sections exist, rather than a crash or fatal error.

Here is the panic, taken from a recent build from the Intel Snap releases Github page:

panic: runtime error: invalid memory address or nil pointer dereference [recovered]
    panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x2533a2]

goroutine 1 [running]:
panic(0x7182e0, 0xc42000e100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/runtime/panic.go:500 +0x1a1
encoding/json.(*encodeState).marshal.func1(0xc420191238)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:272 +0x1b9
panic(0x7182e0, 0xc42000e100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/runtime/panic.go:458 +0x243
github.com/intelsdi-x/snap/core/cdata.(*ConfigDataNode).MarshalJSON(0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/travis/gopath/src/github.com/intelsdi-x/snap/core/cdata/node.go:59 +0x22
encoding/json.marshalerEncoder(0xc42029c420, 0x798d80, 0xc420320940, 0x16, 0xc420320100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:431 +0xb1
encoding/json.(*mapEncoder).encode(0xc42022c2e8, 0xc42029c420, 0x711640, 0xc4202d5c20, 0x195, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:646 +0x542
encoding/json.(*mapEncoder).(encoding/json.encode)-fm(0xc42029c420, 0x711640, 0xc4202d5c20, 0x195, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:662 +0x64
encoding/json.(*structEncoder).encode(0xc42030fce0, 0xc42029c420, 0x746b60, 0xc4202d5c20, 0x199, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:601 +0x253
encoding/json.(*structEncoder).(encoding/json.encode)-fm(0xc42029c420, 0x746b60, 0xc4202d5c20, 0x199, 0xc4202d0100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:615 +0x64
encoding/json.(*ptrEncoder).encode(0xc42022c2f8, 0xc42029c420, 0x6af560, 0xc4202b9958, 0x196, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:742 +0xe3
encoding/json.(*ptrEncoder).(encoding/json.encode)-fm(0xc42029c420, 0x6af560, 0xc4202b9958, 0x196, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:747 +0x64
encoding/json.(*structEncoder).encode(0xc42030fbc0, 0xc42029c420, 0x78ab80, 0xc4202b9950, 0x199, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:601 +0x253
encoding/json.(*structEncoder).(encoding/json.encode)-fm(0xc42029c420, 0x78ab80, 0xc4202b9950, 0x199, 0xc4202b0100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:615 +0x64
encoding/json.(*ptrEncoder).encode(0xc42022c310, 0xc42029c420, 0x779980, 0xc4202ac100, 0x196, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:742 +0xe3
encoding/json.(*ptrEncoder).(encoding/json.encode)-fm(0xc42029c420, 0x779980, 0xc4202ac100, 0x196, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:747 +0x64
encoding/json.(*structEncoder).encode(0xc42030faa0, 0xc42029c420, 0x7d3c00, 0xc4202ac0c0, 0x199, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:601 +0x253
encoding/json.(*structEncoder).(encoding/json.encode)-fm(0xc42029c420, 0x7d3c00, 0xc4202ac0c0, 0x199, 0xc4202a0100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:615 +0x64
encoding/json.(*ptrEncoder).encode(0xc42022c3a0, 0xc42029c420, 0x779800, 0xc4202c0b18, 0x196, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:742 +0xe3
encoding/json.(*ptrEncoder).(encoding/json.encode)-fm(0xc42029c420, 0x779800, 0xc4202c0b18, 0x196, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:747 +0x64
encoding/json.(*structEncoder).encode(0xc42030fa70, 0xc42029c420, 0x7bbca0, 0xc4202c0af0, 0x199, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:601 +0x253
encoding/json.(*structEncoder).(encoding/json.encode)-fm(0xc42029c420, 0x7bbca0, 0xc4202c0af0, 0x199, 0xc4202c0100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:615 +0x64
encoding/json.(*ptrEncoder).encode(0xc42022c478, 0xc42029c420, 0x707e20, 0xc4202c0af0, 0x16, 0x700100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:742 +0xe3
encoding/json.(*ptrEncoder).(encoding/json.encode)-fm(0xc42029c420, 0x707e20, 0xc4202c0af0, 0x16, 0xc4202c0100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:747 +0x64
encoding/json.(*encodeState).reflectValue(0xc42029c420, 0x707e20, 0xc4202c0af0, 0x16, 0x100)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:307 +0x82
encoding/json.(*encodeState).marshal(0xc42029c420, 0x707e20, 0xc4202c0af0, 0x6d0100, 0x0, 0x0)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:280 +0xb8
encoding/json.Marshal(0x707e20, 0xc4202c0af0, 0xc420245180, 0xc4203067e0, 0x65, 0xc420304120, 0x120)
    /home/travis/.gimme/versions/go1.7.3.linux.amd64/src/encoding/json/encode.go:145 +0x8f
main.action(0xc420245180, 0x0, 0x0)
    /home/travis/gopath/src/github.com/intelsdi-x/snap/snapteld.go:252 +0x166
github.com/intelsdi-x/snap/vendor/github.com/urfave/cli.HandleAction(0x6ef820, 0x86a788, 0xc420245180, 0xc420236960, 0x0)
    /home/travis/gopath/src/github.com/intelsdi-x/snap/vendor/github.com/urfave/cli/app.go:485 +0xd4
github.com/intelsdi-x/snap/vendor/github.com/urfave/cli.(*App).Run(0xc42005ab60, 0xc42000a330, 0x3, 0x3, 0x0, 0x0)
    /home/travis/gopath/src/github.com/intelsdi-x/snap/vendor/github.com/urfave/cli/app.go:259 +0x74f
main.main()
    /home/travis/gopath/src/github.com/intelsdi-x/snap/snapteld.go:231 +0x705
dancyding commented 6 years ago

Thanks for your contribution, which help the code more robust.

cce commented 6 years ago

Glad to help! Great!