nomadVar in template error: expected string; got dependency.NomadVarItem

[lbt]

Nomad version

Nomad v1.11.0
BuildDate 2025-11-11T16:18:19Z
Revision 9103d93

Operating system and Environment details

DEBIAN_VERSION_FULL=13.3
Minimal VM with nomad from
deb [signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com trixie main

Issue

nomadVar is not evaluating properly in templates and results in dependency.NomadVarItem errors.

get:

Killing: Template failed: (dynamic): execute: template: :3:38: executing "" at <",">: wrong type for value; expected string; got dependency.NomadVarItem

from

{{ with nomadVar "nomad/jobs/templtest" }}
split varcsv len = {{ .varcsv | split "," | len }}
{{end}}

Reproduction steps

nomad agent -dev-connect

nomad var put -namespace default nomad/jobs/templtest var1=one var2=two varcsv=a,b,c

# Create jobfile as below

nomad job run templtest.nomad

Verify

Works well
Logs show:

My Conf

var1 = one
var2 = two

split $list len is 3

Case 1:

Replace data EOF with:

{{ $v := nomadVar "nomad/jobs/templtest" }}
var1 = {{$v.var1}}
var2 = {{$v.var2}}

Result:

Killing: Template failed: (dynamic): execute: template: :3:11: executing "" at <$v.var1>: nil pointer evaluating *dependency.NomadVarItems.var1 

Case 2:

Replace data EOF with:

My Conf
{{ with nomadVar "nomad/jobs/templtest" }}
split varcsv len = {{ .varcsv | split "," | len }}
{{end}}

Result:

Killing: Template failed: (dynamic): execute: template: :3:38: executing "" at <",">: wrong type for value; expected string; got dependency.NomadVarItem

Job file

cat <<EOJ > templtest.nomad
job "templtest" {
  type = "batch"

  group "ttg" {
    count = 1
    task "ttt" {
      driver = "exec"
      template {
        destination  = "etc/conf"
        data = <<-EOF
My Conf
{{ with nomadVar "nomad/jobs/templtest" }}
var1 = {{.var1}}
var2 = {{.var2}}
{{ $list := "1,2,3"}}
split $list len is {{ $list | split "," | len }}
{{ end }}
EOF
      }
      config {
        command = "/bin/cat"
        args    = ["etc/conf"]
      }
    }
  }
}
EOJ

[pkazmierczak]

Hi @lbt, thanks for reporting this. Here's what happens: nomadVar is, sadly, not a string, so you can't split it. What you could do instead:

data        = <<-EOF
My Conf
{{ with nomadVar "nomad/jobs/templtest" }}
.varcsv.Value | split "," | len
{{end}}
EOF

Our documentation is wrong misleading. I'll update it. Apologies and thanks for catching this.

[lbt]

So given . is assigned to from a nomadVar we have .varcsv accessing a NomadVarItem

That can't be used in a pipeline without a .Value (presumably because {{ }} invokes the String() interface and | doesn't as it allows any data type to be passed) - so yes this works:

{{ with nomadVar "nomad/jobs/templtest" }}
split varcsv len = {{ .varcsv.Value  | split "," | len }}
{{end}}

OK. Thanks :)

So what is $v in

{{ $v := nomadVar "nomad/jobs/templtest" }}

(I assume it's a NomadVarItems plural) and why does:

{{ $v.varcsv.Value }}

not access the varItem in $v when it does access it in "." ?

Does . have a mechanism to access the map entry "var1" which points to a NomadVarItem

{{ $v }}

is String()'ed to: "map[var1:one var2:two varcsv:a,b,c]" so clearly $v is not nil here.

But I can't seem to access $v["varcsv"] using index

Looking at the code snippet you mentioned I see some helper functions.

However {{ $v.ItemsMap }} does not work:

Template failed: (dynamic): execute: template: :2:10: executing "" at <$v.ItemsMap>: error calling ItemsMap: value method github.com/hashicorp/consul-template/dependency.NomadVarItems.ItemsMap called using nil *NomadVarItems pointer

and here it confirms that we're looking at a NomadVarItems but suggests that $v is a nil pointer?

Same for .Keys

[pkazmierczak]

I admit that I'm puzzled by this myself.

$v in {{ $v := nomadVar "nomad/jobs/templtest" }} is: map[var1:one var2:two varcsv:a,b,c], but assigning $v variable doesn't check for nil/zero objects the way with does. $v just captures the nomadVar response result. However, this should never be a nil response.

[pkazmierczak]

ah hold on @lbt, I think the problem is you're not using with at all in your example? so if you do:

{{ $v := nomadVar "nomad/jobs/templtest" }}
{{ $v.varcsv.Value }}

the second line is not in scope of the variable assignment. Instead, do:

{{ with $v := nomadVar "nomad/jobs/templtest" }}
{{ $v.varcsv.Value }} (or .ItemsMap)
{{ end }}

and then you get what you need. Does that make sense?