Use of environment variables in sources yaml file

[poilade-de-coulemelle]

Hello pgwatch community,

If I understand well this line, it seems it is possible to use environment variables in the yaml file containing pgwatch sources.

I try to use an environment variable for my connection string but it seems pgwatch is not able to parse it.

/ # cat /pgwatch/sources.yaml 
- name: fakename
  conn_str: $PG_CONNEXION_STRING
  kind: postgres-continuous-discovery
  preset_metrics: exhaustive
  custom_metrics:
  preset_metrics_standby:
  custom_metrics_standby:
  include_pattern:
  exclude_pattern:
  is_enabled: true
  group: default 

I got the error below

2026-02-23 08:11:49.995 [ERROR] [error:cannot parse $PG_CONNEXION_STRING: failed to parse as keyword/value (invalid keyword/value)] could not resolve databases from sources

You could wonder why I do that.
I actually created a ConfigMap in Kubernetes hosting all the non secret configuration to make it easier to debug (visible in ArgoCD for developer). However, I cannot have the connection string in clear text inside the ConfigMap. So I used an environment variable inside the ConfigMap and inject the variable as a secret.

Do I do something wrong or it is just not possible ?

[pashagolub]

well, it's the idea behind it, yes. Just to be on a safe side, the PG_CONNEXION_STRING is defined, right?

[poilade-de-coulemelle]

Fair question.
I retry using a fake connection string and

• cat the file located on my pod
• the env var corresponding

I still get on version pgwatch:5.0.0-beta2
[error:cannot parse$PG_CONNEXION_STRING`: failed to parse as keyword/value (invalid keyword/value)] could not resolve databases from sources (reaper/reaper.go:403 reaper.(*Reaper).LoadSources)

See the screenshot with the information.

[0xgouda]

@pashagolub That's indeed a bug the expandEnvVars() function doesn't substitute the connection string field:

pgwatch/internal/sources/yaml.go

Lines 145 to 165 in 430bd14

	func (fcr *fileSourcesReaderWriter) expandEnvVars(md Source) Source {
	if strings.HasPrefix(string(md.Kind), "$") {
	md.Kind = Kind(os.ExpandEnv(string(md.Kind)))
	}
	if strings.HasPrefix(md.Name, "$") {
	md.Name = os.ExpandEnv(md.Name)
	}
	if strings.HasPrefix(md.IncludePattern, "$") {
	md.IncludePattern = os.ExpandEnv(md.IncludePattern)
	}
	if strings.HasPrefix(md.ExcludePattern, "$") {
	md.ExcludePattern = os.ExpandEnv(md.ExcludePattern)
	}
	if strings.HasPrefix(md.PresetMetrics, "$") {
	md.PresetMetrics = os.ExpandEnv(md.PresetMetrics)
	}
	if strings.HasPrefix(md.PresetMetricsStandby, "$") {
	md.PresetMetricsStandby = os.ExpandEnv(md.PresetMetricsStandby)
	}
	return md
	}

[0xgouda]

@poilade-de-coulemelle thanks for catching this, #1232 will fix it and will be available under the v5 release (coming in a few days)

[poilade-de-coulemelle]

Awesome, thank you very much for the quick fix !