Initialize logging with default info

[tejal29]

In c-s-t we are seeing errors https://github.com/GoogleContainerTools//issues/135

/bazel-bin/linux_amd64_pure_stripped/container_structure_test  --image gcr.io/google-appengine/debian8 --config tests/debian_failure_test.yaml  -verbose=debug

ERRO[0000] runtime error: invalid memory address or nil pointer dereference 
tejaldesai@tejaldesai~/go/src/github.com/GoogleContainerTools/container-structure-test: (fix_invalid_flags)$ 

This is because, we --image is not a valid arg for root command container_structure_test. The conbra.OnInitialize registered function initLogging is only called when the command is parsed correctly.
Hence, this diff initialize the logging with info log level.

[tejal29]

On C-S-T after applying this diff.

tejaldesai@tejaldesai~/go/src/github.com/GoogleContainerTools/container-structure-test: (fix_invalid_flags)$ git diff
diff --git a/vendor/github.com/GoogleCloudPlatform/runtimes-common/ctc_lib/container_tool_command_base.go b/vendor/github.com/GoogleCloudPlatform/runtimes-common/ctc_lib/container_tool_command_base.go
index 8903986..9590039 100644
--- a/vendor/github.com/GoogleCloudPlatform/runtimes-common/ctc_lib/container_tool_command_base.go
+++ b/vendor/github.com/GoogleCloudPlatform/runtimes-common/ctc_lib/container_tool_command_base.go
@@ -24,6 +24,7 @@ import (
        "github.com/GoogleCloudPlatform/runtimes-common/ctc_lib/flags"
        "github.com/GoogleCloudPlatform/runtimes-common/ctc_lib/logging"
        "github.com/GoogleCloudPlatform/runtimes-common/ctc_lib/types"
+       log "github.com/sirupsen/logrus"
        "github.com/spf13/cobra"
        "github.com/spf13/viper"
 )
@@ -48,6 +49,15 @@ func (ctb *ContainerToolCommandBase) toolName() string {
 }
 
 func (ctb *ContainerToolCommandBase) Init() {
+       // Init Logging with info level with colors disabled since initLogging gets called
+       // only after arguments are pass.
+       Log = logging.NewLogger(
+               viper.GetString(config.LogDirConfigKey),
+               ctb.Name(),
+               log.InfoLevel,
+               false,
+       )
+
        cobra.OnInitialize(initConfig, ctb.initLogging)
        ctb.AddFlags()
        ctb.AddSubCommands()
tejaldesai@tejaldesai~/go/src/github.com/GoogleContainerTools/container-structure-test: (fix_invalid_flags)$

Run c-s-t

./bazel-bin/linux_amd64_pure_stripped/container_structure_test  --image gcr.io/google-appengine/debian8 --config tests/debian_failure_test.yaml  -verbose=debug

ERRO[0000] unknown flag: --image                        

[nkubala]

@tejal29 thanks for looking into this one. Can we also display the usage when someone provides an invalid flag? This will make it easier for them to figure out what flag they actually want, and save them the time of typing the help command.

[tejal29]

Working around the bug in cobra spf13/cobra#340 where RunE always displays usage.

[nkubala]

one nit but otherwise LGTM

[nkubala]

nit: s/"Donot"/"Do not"