hashicorp
HCL2 `split` function doesn't evaluate its parameters
Nomad version
1.2.3
Operating system and Environment details
Ubuntu 20.04 LTS
Issue
With meta.variants_comma_separated being set to "base,uhd", using HCL2, the output doesn't appear to be split properly. For example,
join(":", [for v in split(",", meta.variants_comma_separated) : "/mnt/media-variant-${v}"]) returns /mnt/media-variant-base,uhd
However, if the value is hardcoded
join(":", [for v in split(",", "base,uhd") : "/mnt/media-variant-${v}"]) returns /mnt/media-variant-base:/mnt/media-variant-uhd
Reproduction steps
/etc/nomad.d/nomad.hcl
client {
enabled = true
meta {
variants_comma_separated = "base,uhd"
}
}
with job file
job "issue" {
datacenters = ["dc1"]
group "issue" {
task "issue" {
driver = "raw_exec"
env {
VARIANTS_COMMA_SEPARTED = "${meta.variants_comma_separated}"
VARIANT_PATHS_1 = join(":", formatlist("/mnt/media-variant-%s", split(",", "base,uhd")))
VARIANT_PATHS_2 = join(":", [for v in split(",", "base,uhd") : "/mnt/media-variant-${v}"])
META_VARIANT_PATHS_1 = join(":", formatlist("/mnt/media-variant-%s", split(",", meta.variants_comma_separated)))
META_VARIANT_PATHS_2 = join(":", [for v in split(",", meta.variants_comma_separated) : "/mnt/media-variant-${v}"])
}
config {
command = "/bin/bash"
args = ["${NOMAD_TASK_DIR}/test.sh"]
}
template {
data = <<-EOF
#!/bin/bash
echo $VARIANTS_COMMA_SEPARTED
echo $VARIANT_PATHS_1
echo $VARIANT_PATHS_2
echo $META_VARIANT_PATHS_1
echo $META_VARIANT_PATHS_2
# Keep script running
tail -f /dev/null
EOF
destination = "local/test.sh"
}
}
}
}
Expected Result
STDOUT should return
base,uhd
/mnt/media-variant-base:/mnt/media-variant-uhd
/mnt/media-variant-base:/mnt/media-variant-uhd
/mnt/media-variant-base:/mnt/media-variant-uhd
/mnt/media-variant-base:/mnt/media-variant-uhd
Actual Result
STDOUT instead returns
base,uhd
/mnt/media-variant-base:/mnt/media-variant-uhd
/mnt/media-variant-base:/mnt/media-variant-uhd
/mnt/media-variant-base,uhd
/mnt/media-variant-base,uhd
Nomad Server logs (if appropriate)
Nomad Client logs (if appropriate)
Hey @axsuul
Thanks for finding this! We'll have to look into this and see if it's an issue with HCL or the nomad parser 🤔 . We'll keep this issue updated with what we find
Hi @axsuul there's no need to bump issues. We'll update when there's an update to be had. Thanks.
I'm also experiencing an issue where the split function isn't working as expected, so I'm adding the details of this scenario here...
Nomad version
1.6.0-beta.1
Operating system and Environment details
Manjaro Ultima Thule 23.0.0 Kernel: 6.1.31-2
Issue
Using a template to read key -> value pairs from a nomad variable into environment variables and then splitting one of the string ENV VARs on a comma doesn't work.
Reproduction steps
Define a nomad variable that contains multiple key value pairs, with one of them being:
{
"extra_hosts": "extra-host:172.17.0.1,demo.extra-host:172.17.0.1"
}
job "job-name-same-as-var-name" {
group "group1" {
task "task1" {
template {
change_mode = "restart"
error_on_missing_key = true
destination = "${NOMAD_SECRETS_DIR}/.env"
env = true
data = <<EOT
{{- with nomadVar (env "NOMAD_JOB_NAME") -}}
EXTRA_HOSTS = {{ .extra_hosts }}
{{- end -}}
EOT
}
driver = "docker"
config {
image = "path.to/image:tag"
extra_hosts = flatten(["hard-coded-host:123.45.67.8", split(",", EXTRA_HOSTS)])
}
}
}
}
Expected result
EXTRA_HOSTS to be split and returned as an array:
[
"extra-host:172.17.0.1",
"demo.extra-host:172.17.0.1"
]
Actual result
Driver Failure: failed to create container: API error (400): invalid IP address in add-host: "172.17.0.1,demo.extra-host:172.17.0.1"
Hi @axsuul there's no need to bump issues. We'll update when there's an update to be had. Thanks.
Doing a bit of issue cleanup and dug into the syntax used here. I've tried this jobspec with a couple of variations:
jobspec
locals {
variants = "${meta.variants}"
}
job "example" {
group "issue" {
task "issue" {
driver = "raw_exec"
env {
VARIANTS_COMMA_SEPARTED = "${meta.variants}"
VARIANT_PATHS_1 = join(":", formatlist("/mnt/media-variant-%s", split(",", "base,uhd")))
VARIANT_PATHS_2 = join(":", [for v in split(",", "base,uhd") : "/mnt/media-variant-${v}"])
META_VARIANT_PATHS_1 = join(":", formatlist("/mnt/media-variant-%s", split(",", "${meta.variants}")))
META_VARIANT_PATHS_2 = join(":", [for v in split(",", "${meta.variants}") : "/mnt/media-variant-${v}"])
META_VARIANT_PATHS_3 = join(":", formatlist("/mnt/media-variant-%s", split(",", "${local.variants}")))
META_VARIANT_PATHS_4 = join(":", [for v in split(",", "${local.variants}") : "/mnt/media-variant-${v}"])
OTHER_FUNCTIONS = join(":", ["${meta.variants}", local.variants])
}
config {
command = "/bin/bash"
args = ["${NOMAD_TASK_DIR}/test.sh"]
}
template {
data = <<-EOF
#!/bin/bash
echo $VARIANTS_COMMA_SEPARTED
echo $VARIANT_PATHS_1
echo $VARIANT_PATHS_2
echo $META_VARIANT_PATHS_1
echo $META_VARIANT_PATHS_2
echo $META_VARIANT_PATHS_3
echo $META_VARIANT_PATHS_4
echo $OTHER_FUNCTIONS
# Keep script running
tail -f /dev/null
EOF
destination = "local/test.sh"
}
}
}
}
That returns:
$ nomad alloc logs eda8f9fa
base,uhd
/mnt/media-variant-base:/mnt/media-variant-uhd
/mnt/media-variant-base:/mnt/media-variant-uhd
/mnt/media-variant-base,uhd
/mnt/media-variant-base,uhd
/mnt/media-variant-base,uhd
/mnt/media-variant-base,uhd
base,uhd:base,uhd
It looks like the parameters of the split function (specifically) simply aren't being evaluated. This looks like it might be a HCL2 bug rather than a Nomad bug.
I'm going to re-title this for clarity and mark it for roadmapping. The issue will be updated when someone is working on it.
For @heatzync's report:
Using a template to read key -> value pairs from a nomad variable into environment variables and then splitting one of the string ENV VARs on a comma doesn't work.
Correct. See the HCL Parsing Context docs. The value you're trying to interpolate into extra_hosts only exists on the client, whereas the HCL2 evaluation is being done on your command line client. That's working as intended.