Sensu-go: Creating tcp handler without socket should not be permitted

[webframp]

Expected Behavior

Since a tcp handler requires a socket attribute, I would expect sensuctl create to fail in some way, or for sensuctl handler list to report invalid configurations.

Current Behavior

I can create a handler that crashes sensuctl

Possible Solution

Add some error checking in sensuctl? (That's kind of naive suggestion not knowing this codebase well)

Steps to Reproduce (for bugs)

1. Create a json object file with the following spec, lacking socket attribute:

handler.json:

{
  "type": "handler",
  "spec": {
    "name": "tcp_handler",
    "environment": "default",
    "organization": "default",
    "timeout": 30,
    "type": "tcp"
  }
}

1. Create the object

# sensuctl create -f handler.json

1. Try to list it

# sensuctl handler list

1. Observe the panic

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x88f324]

goroutine 1 [running]:
github.com/sensu/sensu-go/cli/commands/handler.printToTable.func6(0x9a0760, 0xc420238000, 0x4, 0x4)
        /go/src/github.com/sensu/sensu-go/cli/commands/handler/list.go:102 +0x234
github.com/sensu/sensu-go/cli/elements/table.(*Table).writeRow(0xc42004fbd8, 0xc42021e040)
        /go/src/github.com/sensu/sensu-go/cli/elements/table/standard.go:90 +0xcb
github.com/sensu/sensu-go/cli/elements/table.(*Table).writeRows(0xc42004fbd8, 0x8f8da0, 0xc4201f4160)
        /go/src/github.com/sensu/sensu-go/cli/elements/table/standard.go:83 +0x24e
github.com/sensu/sensu-go/cli/elements/table.(*Table).Render(0xc42004fbd8, 0xa31400, 0xc420096008, 0x8f8da0, 0xc4201f4160)
        /go/src/github.com/sensu/sensu-go/cli/elements/table/standard.go:66 +0x82
github.com/sensu/sensu-go/cli/commands/handler.printToTable(0x8f8da0, 0xc4201f4160, 0xa31400, 0xc420096008)
        /go/src/github.com/sensu/sensu-go/cli/commands/handler/list.go:132 +0x30a
github.com/sensu/sensu-go/cli/commands/helpers.Print(0xc4201a3400, 0xc4200930f0, 0x7, 0x9f21d0, 0x8f8da0, 0xc4201f4160, 0x0, 0x0)
        /go/src/github.com/sensu/sensu-go/cli/commands/helpers/print.go:23 +0xb3
github.com/sensu/sensu-go/cli/commands/handler.ListCommand.func1(0xc4201a3400, 0xd14408, 0x0, 0x0, 0x0, 0x0)
        /go/src/github.com/sensu/sensu-go/cli/commands/handler/list.go:41 +0x252
github.com/sensu/sensu-go/vendor/github.com/spf13/cobra.(*Command).execute(0xc4201a3400, 0xd14408, 0x0, 0x0, 0xc4201a3400, 0xd14408)
        /go/src/github.com/sensu/sensu-go/vendor/github.com/spf13/cobra/command.go:753 +0x468
github.com/sensu/sensu-go/vendor/github.com/spf13/cobra.(*Command).ExecuteC(0xc420180280, 0xc4201b0f00, 0xc4201b2000, 0xc4201b2280)
        /go/src/github.com/sensu/sensu-go/vendor/github.com/spf13/cobra/command.go:843 +0x30a
github.com/sensu/sensu-go/vendor/github.com/spf13/cobra.(*Command).Execute(0xc420180280, 0xc4201473e0, 0xc4200d9628)
        /go/src/github.com/sensu/sensu-go/vendor/github.com/spf13/cobra/command.go:791 +0x2b
main.main()
        /go/src/github.com/sensu/sensu-go/cli/cmd/start.go:26 +0xbd

Context

How has this issue affected you? Minor pain, blurred vision, slight headache.
What are you trying to accomplish? Writing custom chef resources to manage this stuff.

Your Environment

• Sensu version used (sensuctl, sensu-backend, and/or sensu-agent): sensu-ctl version dev-nightly#9bba4cf, build 9bba4cf6af864bbabf0a3120ec2ad6d187552a8b, built 2018-05-06T09:24:10+0000
• Installation method (packages, binaries, docker etc.): nightly packages from packagecloud
• Operating System and version (e.g. Ubuntu 14.04): Ubuntu 16.04

[echlebek]

Nice find, thank you for reporting this.

The solution here is to add some logic to the Validate() method on the type. When handler.Type == "tcp", the handler should be well-specified. (valid host and port fields)

This will cause both the client and the server to reject attempts to create these broken handlers.

[echlebek]

After building sensuctl with PR 1488, users get the following error on invalid handlers:

$ echo '{"type":"handler","spec":{"name":"a","environment":"b","organization":"c","type":"tcp"}}' | sensuctl create
error validating resource 0 (/handlers/a): tcp and udp handlers need a valid socket
Error: resource validation failed