How to make custom RestTemplate to instrument with standard Spring Boots' Prometheus RestTemplate metrics when using SimpleClientHttpRequestFactory?

Question

According to the docs , the standard http client metrics are grabbed if the RestTemplate is created using RestTemplateBuilder and then injected. However, we have a custom RestTemplate bean initialization that uses no RestTeplateBuilder, but instead RestTemplate is initiated with new and the SimpleClientHttpRequestFactory is passed as the parameter.

@Bean(name = "RestTemplateWithoutTimeOut")
    public RestTemplate restTemplateWithoutTimeOut() {
        SimpleClientHttpRequestFactory simpleClientHttpRequestFactory = new SimpleClientHttpRequestFactory();
        int timeout = 5 * 60 * 1000;
        simpleClientHttpRequestFactory.setConnectTimeout(timeout);
        simpleClientHttpRequestFactory.setReadTimeout(timeout);
        RestTemplate restTemplate = new RestTemplate(simpleClientHttpRequestFactory);
        restTemplate.setErrorHandler(new ErrorHandler());
        List<ClientHttpRequestInterceptor> interceptors = restTemplate.getInterceptors();
        interceptors.add(new LoggingInterceptor());
        interceptors.add(new SecureInterceptor());
        return restTemplate;
    }

How can we inject metrics collector (the same metrics as are collected by default) for that kind of RestTemplate initialization?

Answer 1

The RestTemplateBuilder exposes methods for customizing essentially every knob that's available on RestTemplate . You can just call requestFactory and pass your customized factory, then build a RestTemplate instance that has all of the usual instrumentation.