glanceapp/glance · error

parsing variable: %v

Error message

parsing variable: %v

What it means

Wraps any lower-level failure from parseConfigVariableOfType while expanding {{...}} variable references in glance.yml. The config loader regex-replaces variable expressions; if resolving a variable (env, secret, file-from-env) returns an error, it is wrapped as 'parsing variable: <cause>' and the whole config parse fails. The message deliberately prefixes context but keeps the inner error (e.g. 'environment variable FOO not found').

Source

Thrown at internal/glance/config.go:171

			// in the regex has been changed without updating the below code
			return match
		}

		prefix := string(groups[1])
		if prefix == `\` {
			if len(match) >= 2 {
				return match[1:]
			} else {
				return nil
			}
		}

		typeAsString, variableName := string(groups[2]), string(groups[3])
		variableType := ternary(typeAsString == "", configVarTypeEnv, typeAsString)

		parsedValue, returnOriginal, localErr := parseConfigVariableOfType(variableType, variableName)
		if localErr != nil {
			err = fmt.Errorf("parsing variable: %v", localErr)
			return nil
		}

		if returnOriginal {
			return match
		}

		return []byte(prefix + parsedValue)
	})

	if err != nil {
		return nil, err
	}

	return replaced, nil
}

// When the bool return value is true, it indicates that the caller should use the original value

View on GitHub (pinned to 91324e8de7)

Solutions

1. Read the inner error after 'parsing variable: ' — it names the exact variable and cause (env not found, secret read failure, etc.).
2. Export the missing environment variable or fix its name in the {{ env.X }} expression.
3. For {{ secret.X }}, ensure /run/secrets/X exists and is readable by the Glance process.
4. For {{ file-from-env.X }}, set X and verify the path it points to.
5. Note: only expressions whose name matches envVariableNamePattern are resolved; non-matching env names are left as-is, so check the pattern if the value isn't substituted.

Example fix

# before: APP_TOKEN not exported
$ glance --config glance.yml
# error: parsing variable: environment variable APP_TOKEN not found

# after
$ export APP_TOKEN=...
$ glance --config glance.yml

# Expand-and-check before starting Glance
for var in $(grep -oE '\{\{ *env\.[A-Za-z_][A-Za-z0-9_]* *\}\}' glance.yml | sed -E 's/.*env\.([A-Za-z0-9_]+).*/\1/'); do
  [ -n "${!var}" ] || { echo "missing env var: $var"; exit 1; }
done

// Running config programmatically (custom tooling):
err := cfg.Parse()
if err != nil {
    if strings.HasPrefix(err.Error(), "parsing variable: ") {
        cause := strings.TrimPrefix(err.Error(), "parsing variable: ")
        // cause names the variable and stage: env lookup, secret read, file read
        log.Fatalf("config variable problem: %s", cause)
    }
}

When it happens

Trigger: Any {{ env.FOO }}, {{ secret.foo }}, or {{ file-from-env.FOO }} expression in glance.yml whose resolution fails: missing env var, unreadable /run/secrets file, or file-from-env path problems. The outer regex match groups determine variableType and variableName passed to the resolver.

Common situations: Deploying to an environment missing variables referenced in the config template; Docker secrets not mounted at /run/secrets; typo'd variable names after refactor; renaming env vars without updating glance.yml.

Related errors

• readFileFromEnv: environment variable %s not found
• environment variable %s not found
• reading secret file: %v
• readFileFromEnv: file path %s is not absolute
• readFileFromEnv: reading file from %s: %v

AI-assisted analysis of glanceapp/glance@91324e8de7 (2026-08-15). Data as JSON: /api/errors/567e1fc694fd5f5f. Report an issue: GitHub.