Helmfile: Parsing data to stdin on exec function doesn't seem to work

[ggillies]

The notes at https://github.com/roboll/helmfile/blob/master/README.md#L903 say that you can parse input to the exec function and it will get passed to the stdin of the command running in the exec function. However I can't seem to get this to work at all, the result always seems to come back as "null".

Example as follows

a.sh is a shell script that simply echos what is parsed to stdin

$ cat a.sh
#!/bin/bash
read var
echo $var

$ echo 'asdf' | ./a.sh
asdf

I use it in the following helmfile

$ cat helmfile.yaml
---
repositories:
# Kubernetes incubator repo of helm charts
- name: "kubernetes-incubator"
  url: "https://kubernetes-charts-incubator.storage.googleapis.com"

releases:
- name:  test
  chart: "kubernetes-incubator/raw"
  namespace: default
  version: "0.2.3"
  installed: true
  values:
    - resources:
      - apiVersion: v1
        kind: Secret
        metadata:
          name: test
        stringData:
          test: {{ "asdf" | (exec "./a.sh" (list "")) }}

And it produces the following

$ helmfile template
Adding repo kubernetes-incubator https://kubernetes-charts-incubator.storage.googleapis.com
"kubernetes-incubator" has been added to your repositories

Updating repo
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "kubernetes-incubator" chart repository
...Successfully got an update from the "cloudposse-incubator" chart repository
...Successfully got an update from the "gitlab" chart repository
...Successfully got an update from the "stable" chart repository
Update Complete.

Fetching kubernetes-incubator/raw
Templating release=test, chart=/tmp/122827334/test/0.2.3/kubernetes-incubator/raw/raw
---
# Source: raw/templates/resources.yaml

---
apiVersion: v1
kind: Secret
metadata:
  labels:
    app: raw
    chart: raw-0.2.3
    heritage: Tiller
    release: test
  name: test
stringData:
  test: null

I would expect the test value under stringData to be "asdf"

[ggillies]

Doing some debugging and testing I think I have successfully narrowed down some interaction with closing the writeErrs chan and when it's closed. If I comment out this line https://github.com/roboll/helmfile/blob/master/pkg/tmpl/context_funcs.go#L72 then everything works as expected.

[ggillies]

I'm no expert but I think what might be happening is nil is being read from writeErrs channel, trigiring the select statement to return it instead of bytes. If I change the code at line 105 to

    for {
        select {
        case bytes := <-cmdOuts:
            return string(bytes), nil
        case err, isErr := <-cmdErrs:
            if isErr {
              return "", err
            }
        case err, isErr := <-writeErrs:
            if isErr {
              return "", err
            }
        }
    }

It seems to work as expected

[mumoshu]

@ggillies Thanks for reporting! You're absolutely correct - this is a bug.

Fortunately, as I'm seemingly a better Go programmer than me who wrote this a year ago, I've managed to fix it in #1151.

Would you mind giving it a shot once the new Helmfille release with the fix is published?

[mumoshu]

v0.102.1 has been released with the fix

[ggillies]

@mumoshu thanks so much for looking at this! Just tested and v0.102.1 has fixed this for me!