thanos-io/thanos · error

parsing http config YAML

Error message

parsing http config YAML

What it means

After obtaining the raw content, the sidecar converts it into a client-go style HTTPClientConfig via clientconfig.NewHTTPClientConfigFromYAML(httpConfContentYaml). If the content is not valid YAML or doesn't match the HTTPClientConfig schema (e.g. unknown tls_config fields), startup aborts with "parsing http config YAML".

Solutions

1. Paste the config content into a YAML linter/parser to catch syntax errors (tabs vs spaces, stray characters).
2. Validate keys against the prometheus/common config HTTPClientConfig schema (http_headers, tls_config with ca_file/cert_file/key_file, bearer_token, etc.).
3. Read the wrapped unmarshal error in the message — it names the offending key and line.
4. Start from a known-good minimal config like `{}` or `{"tls_config": {"insecure_skip_verify": true}}` and add fields incrementally.

Example fix

// before
{"tls_config": {"certificate_file": "/certs/tls.crt"}}
// after
{"tls_config": {"cert_file": "/certs/tls.crt", "key_file": "/certs/tls.key"}}

func validHTTPClientYAML(y string) error {
    var cfg clientconfig.HTTPClientConfig
    return yaml.UnmarshalStrict([]byte(y), &cfg) // same strict decode the sidecar performs
}

null

httpClientConfig, err := clientconfig.NewHTTPClientConfigFromYAML(httpConfContentYaml)
if err != nil {
    return fmt.Errorf("parsing http config YAML: %w (check keys against prometheus/common HTTPClientConfig schema)", err)
}

When it happens

Trigger: Passing an HTTP client config whose content is invalid YAML (tabs, bad indentation) or contains unknown/mistyped keys (e.g. tls_config.certificate_file instead of cert_file), so NewHTTPClientConfigFromYAML fails at cmd/thanos/sidecar.go:78.

Common situations: Hand-written YAML with indentation/tab errors; Prometheus-format TLS blocks copied incorrectly; JSON passed where strict YAML decoding rejects duplicate or unknown keys; schema drift between client-go versions.

Related errors

• getting http client config
• Improper http client config
• unable to parse objstore config
• parsing config YAML file
• unable to unmarshal config content

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/9b51b616434b4ad1. Report an issue: GitHub.

Appendix: source

Thrown at cmd/thanos/sidecar.go:79

func registerSidecar(app *extkingpin.App) {
	cmd := app.Command(component.Sidecar.String(), "Sidecar for Prometheus server.")
	conf := &sidecarConfig{}
	conf.registerFlag(cmd)
	cmd.Setup(func(g *run.Group, logger log.Logger, reg *prometheus.Registry, tracer opentracing.Tracer, _ <-chan struct{}, _ bool) error {

		grpcLogOpts, logFilterMethods, err := logging.ParsegRPCOptions(conf.reqLogConfig)

		if err != nil {
			return errors.Wrap(err, "error while parsing config for request logging")
		}

		httpConfContentYaml, err := conf.prometheus.httpClient.Content()
		if err != nil {
			return errors.Wrap(err, "getting http client config")
		}
		httpClientConfig, err := clientconfig.NewHTTPClientConfigFromYAML(httpConfContentYaml)
		if err != nil {
			return errors.Wrap(err, "parsing http config YAML")
		}

		httpClient, err := clientconfig.NewHTTPClient(*httpClientConfig, "thanos-sidecar")
		if err != nil {
			return errors.Wrap(err, "Improper http client config")
		}

		opts := reloader.Options{
			HTTPClient:    *httpClient,
			CfgFile:       conf.reloader.confFile,
			CfgOutputFile: conf.reloader.envVarConfFile,
			WatchedDirs:   conf.reloader.ruleDirectories,
			WatchInterval: conf.reloader.watchInterval,
			RetryInterval: conf.reloader.retryInterval,
		}

		switch conf.reloader.method {
		case HTTPReloadMethod:

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