wasmerio/wasmer · error

Could not parse app.yaml: {err:?}

Error message

Could not parse app.yaml: {err:?}

What it means

`get_app_config_from_dir_opt` reads `app.yaml` from a directory and parses it into `AppConfigV1`. If `AppConfigV1::parse_yaml` fails — malformed YAML or schema violations — the error is reformatted into this message. It indicates the app.yaml present on disk is not a valid Wasmer app config.

Source

Thrown at lib/cli/src/commands/app/util.rs:368

    env.client()
}

pub fn get_app_config_from_dir_opt(
    path: &Path,
) -> Result<Option<(AppConfigV1, std::path::PathBuf)>, anyhow::Error> {
    let app_config_path = path.join(AppConfigV1::CANONICAL_FILE_NAME);

    if !app_config_path.exists() || !app_config_path.is_file() {
        return Ok(None);
    }
    // read the app.yaml
    let raw_app_config = std::fs::read_to_string(&app_config_path)
        .with_context(|| format!("Could not read file '{}'", app_config_path.display()))?;

    // parse the app.yaml
    let config = AppConfigV1::parse_yaml(&raw_app_config)
        .map_err(|err| anyhow::anyhow!("Could not parse app.yaml: {err:?}"))?;

    Ok(Some((config, app_config_path)))
}

pub fn get_app_config_from_current_dir_opt()
-> Result<Option<(AppConfigV1, std::path::PathBuf)>, anyhow::Error> {
    let current_dir = std::env::current_dir()?;
    get_app_config_from_dir_opt(&current_dir)
}

pub fn get_app_config_from_dir(
    path: &Path,
) -> Result<(AppConfigV1, std::path::PathBuf), anyhow::Error> {
    get_app_config_from_dir_opt(path)?
        .with_context(|| {
            format!(
                "Could not find app.yaml in directory: '{}'.\nPlease specify an app like 'wasmer app get <namespace>/<name>' or 'wasmer app get <name>`'",
                path.display()

View on GitHub (pinned to 8c4b9ee9d3)

Solutions

1. Read the inner `err:?` detail in the message and fix the offending YAML field/indentation.
2. Validate against the current AppConfigV1 schema — run `wasmer app create` to regenerate a known-good app.yaml and compare.
3. Check for tabs, missing quotes, or trailing garbage in the file with a YAML linter.
4. Ensure your CLI and any CI tooling agree on the config schema version.

Example fix

# before (invalid: missing required field, bad indentation)
app_id: my-app
kind: wasmer.io/App.v0
owner: me
  name: extra
# after
app_id: my-app
kind: wasmer.io/App.v0
owner: me
name: my-app
description: ""
package: .

// validate before invoking CLI commands that read app.yaml
let raw = std::fs::read_to_string("app.yaml")?;
if raw.contains('\t') {
    eprintln!("app.yaml contains tabs; use spaces for indentation");
}
// optionally dry-run parse with serde_yaml + required-field checks before deploy

match get_app_config_from_current_dir_opt() {
    Ok(Some((config, path))) => config,
    Ok(None) => anyhow::bail!("no app.yaml found in this directory"),
    Err(e) if e.to_string().contains("Could not parse app.yaml") => {
        eprintln!("fix app.yaml: {e:#}");
        std::process::exit(1);
    }
    Err(e) => return Err(e),
}

When it happens

Trigger: Calling any command that auto-discovers app.yaml (`wasmer app deploy`, `wasmer app secrets`, etc.) from a directory whose `app.yaml` fails `AppConfigV1::parse_yaml`.

Common situations: Hand-edited app.yaml with wrong indentation; missing required fields like `app_id` or `kind`; using config keys from an older/newer CLI schema version; YAML tabs instead of spaces; truncated file.

Related errors

• could not parse YAML for format-preserving edit: {e}
• could not parse YAML semantically: {e}
• Stack size must be 1024-bit aligned
• Headless is not a valid runtime to instantiate directly
• config from file: {e}

AI-assisted analysis of wasmerio/wasmer@8c4b9ee9d3 (2026-09-01). Data as JSON: /api/errors/7fc06bfa86ae1bc5. Report an issue: GitHub.