Panic in CLI during file parsing when using environment variables inside HCL templates

[the-maldridge]

Nomad version

$ nomad version
Nomad v1.0.4 (a480eed0815c54612856d9115a34bb1d1a773e8c)

Operating system and Environment details

Void Linux on amd64.

Issue

Trying to run the provided job file causes a panic.

Reproduction steps

Load the file provided, run it, observe the panic.

Expected Result

No panic.

Actual Result

Nomad panics.

Job file (if appropriate)

job "redis" {
  type = "service"

  group "app" {
    network {
      mode = "bridge"
      port "redis" { to = 6379 }
    }

    service {
      name = "redis"
      port = "redis"
      check {
        type = "tcp"
        interval = "10s"
        timeout = "2s"
        address_mode = "host"
      }
    }

    task "redis" {
      driver = "docker"

      config {
        image = "redis:6-alpine"
        ports = ["redis"]
      }
    }

    task "memset" {
      driver = "docker"
      lifecycle {
        hook = "poststart"
      }
      config {
        image = "redis:6-alpine"
        entrypoint = ["/usr/local/bin/redis-cli"]
        args = [
          "-h", "${env["NOMAD_IP_app_redis"]}",
          "-p", "${env["NOMAD_PORT_app_redis"]}",
          "CONFIG SET maxmemory 285MB",
        ]
      }
    }
  }
}

Nomad Client logs (if appropriate)

$ nomad job plan redis.nomad 
panic: interface conversion: hcl.Traverser is hcl.TraverseIndex, not hcl.TraverseAttr

goroutine 1 [running]:
github.com/hashicorp/hcl/v2.Traversal.toStringValue(0xc000425660, 0x2, 0x2, 0x3, 0x4c81a00)
	/builddir/nomad-1.0.4/vendor/github.com/hashicorp/hcl/v2/traversal.go:140 +0x566
github.com/hashicorp/hcl/v2.Traversal.TraverseAbs(0xc000425660, 0x2, 0x2, 0xc0006931e0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/builddir/nomad-1.0.4/vendor/github.com/hashicorp/hcl/v2/traversal.go:94 +0x9e5
github.com/hashicorp/hcl/v2/hclsyntax.(*ScopeTraversalExpr).Value(0xc0005207e0, 0xc0006931e0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
	/builddir/nomad-1.0.4/vendor/github.com/hashicorp/hcl/v2/hclsyntax/expression.go:109 +0x65
github.com/hashicorp/hcl/v2/hclsyntax.(*TemplateWrapExpr).Value(0xc000216500, 0xc0006931e0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
	/builddir/nomad-1.0.4/vendor/github.com/hashicorp/hcl/v2/hclsyntax/expression_template.go:224 +0x42
github.com/hashicorp/hcl/v2/hclsyntax.(*TupleConsExpr).Value(0xc000439680, 0xc0006931e0, 0xc000115fc0, 0xc00030176c, 0xc000680000, 0x419cfb, 0xc000115fc0, 0xc0004ff848, 0x10)
	/builddir/nomad-1.0.4/vendor/github.com/hashicorp/hcl/v2/hclsyntax/expression.go:712 +0xf0
github.com/hashicorp/nomad/jobspec2.decodeInterface(0x7fb1dc3f4480, 0xc000439680, 0xc0006931e0, 0x2902d01, 0x27dfb00, 0xc0000d1680, 0x2a5eda0, 0xc000115fc0)
	/builddir/nomad-1.0.4/jobspec2/parse_map.go:65 +0x59
github.com/hashicorp/nomad/jobspec2.(*walker).Map(0xc000693200, 0x2af37a0, 0xc000303a58, 0x195, 0xc000693200, 0x2b84201)
	/builddir/nomad-1.0.4/jobspec2/parse_map.go:52 +0x20a
github.com/mitchellh/reflectwalk.walkMap(0x2af37a0, 0xc000303a58, 0x195, 0x2b5ce20, 0xc000693200, 0x3727f00, 0x2af37a0)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:205 +0x586
github.com/mitchellh/reflectwalk.walk(0x2af37a0, 0xc000303a58, 0x195, 0x2b5ce20, 0xc000693200, 0x0, 0x2af37a0)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:182 +0x43a
github.com/mitchellh/reflectwalk.walkStruct(0x319d880, 0xc000303a20, 0x199, 0x2b5ce20, 0xc000693200, 0x100, 0x0)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:386 +0x3ed
github.com/mitchellh/reflectwalk.walk(0x2e776e0, 0xc00007f538, 0x196, 0x2b5ce20, 0xc000693200, 0xc00007f500, 0x196)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:188 +0x4e5
github.com/mitchellh/reflectwalk.walkSlice(0x2879680, 0xc000360130, 0x197, 0x2b5ce20, 0xc000693200, 0x3727f00, 0x2879680)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:284 +0x211
github.com/mitchellh/reflectwalk.walk(0x2879680, 0xc000360130, 0x197, 0x2b5ce20, 0xc000693200, 0x0, 0x2879680)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:185 +0x3ab
github.com/mitchellh/reflectwalk.walkStruct(0x31757c0, 0xc0003600f0, 0x199, 0x2b5ce20, 0xc000693200, 0x100, 0x412590)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:386 +0x3ed
github.com/mitchellh/reflectwalk.walk(0x2e777a0, 0xc000208918, 0x196, 0x2b5ce20, 0xc000693200, 0xc000208900, 0x196)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:188 +0x4e5
github.com/mitchellh/reflectwalk.walkSlice(0x2879780, 0xc000102800, 0x197, 0x2b5ce20, 0xc000693200, 0x3727f00, 0x2879780)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:284 +0x211
github.com/mitchellh/reflectwalk.walk(0x2879780, 0xc000102800, 0x197, 0x2b5ce20, 0xc000693200, 0x0, 0x2879780)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:185 +0x3ab
github.com/mitchellh/reflectwalk.walkStruct(0x31bc4a0, 0xc000102780, 0x199, 0x2b5ce20, 0xc000693200, 0x100, 0x0)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:386 +0x3ed
github.com/mitchellh/reflectwalk.walk(0x27b6640, 0xc00044a390, 0x16, 0x2b5ce20, 0xc000693200, 0x7464fc7ce3d82500, 0x0)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:188 +0x4e5
github.com/mitchellh/reflectwalk.Walk(0x27b6640, 0xc00044a390, 0x2b5ce20, 0xc000693200, 0x2af37a0, 0x36e8280)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/reflectwalk/reflectwalk.go:92 +0x18f
github.com/hashicorp/nomad/jobspec2.decodeMapInterfaceType(0x27b6640, 0xc00044a390, 0xc0006931e0, 0x0, 0x0, 0x0)
	/builddir/nomad-1.0.4/jobspec2/parse_map.go:21 +0x7f
github.com/hashicorp/nomad/jobspec2.decode(0xc00044a380, 0xc00044a380, 0x31f9415)
	/builddir/nomad-1.0.4/jobspec2/parse.go:108 +0x71b
github.com/hashicorp/nomad/jobspec2.ParseWithConfig(0xc0004fc4d0, 0xc0004fc4d0, 0x2b, 0xc000208c40)
	/builddir/nomad-1.0.4/jobspec2/parse.go:44 +0xa8
github.com/hashicorp/nomad/command.(*JobGetter).ApiJobWithArgs(0xc0003b4800, 0x7ffc73f8848e, 0xb, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/builddir/nomad-1.0.4/command/helpers.go:455 +0x41f
github.com/hashicorp/nomad/command.(*JobPlanCommand).Run(0xc0003b4750, 0xc00004e0f0, 0x1, 0x1, 0xc0001143b0)
	/builddir/nomad-1.0.4/command/job_plan.go:145 +0x3e5
github.com/mitchellh/cli.(*CLI).Run(0xc0003e4000, 0xc0003e4000, 0xc000204ec0, 0x37)
	/builddir/nomad-1.0.4/vendor/github.com/mitchellh/cli/cli.go:260 +0x1cf
main.RunCustom(0xc00004e0d0, 0x3, 0x3, 0xc00005a0b8)
	/builddir/nomad-1.0.4/main.go:142 +0x4a5
main.Run(...)
	/builddir/nomad-1.0.4/main.go:87
main.main()
	/builddir/nomad-1.0.4/main.go:83 +0x65

[notnoop]

Thanks @the-maldridge for reporting it. I just pushed a fix for this panic in #10326, which should be out in the next release . For now, I'd suggest using --hcl1 flag (e.g. nomad job run --hcl1 file.hcl) to fallback to using the hcl1 parser.

[the-maldridge]

slick! I think it might be worth creating a patch to the documentation as well until the next release. This page is what led me to believe that this syntax would work.

[notnoop]

Good points. Will update the upgrade guide too.

[the-maldridge]

This was released as part of 1.1.0 iirc.

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