Tracing API Requests and Responses

package main

import (
        "fmt"
        "net/http"
        "net/http/httputil"
        "os"

        buildv1client "github.com/openshift/client-go/build/clientset/versioned/typed/build/v1"

        metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
        corev1client "k8s.io/client-go/kubernetes/typed/core/v1"
        "k8s.io/client-go/tools/clientcmd"
)

// Tracer implements http.RoundTripper.  It prints each request and
// response/error to os.Stderr.  WARNING: this may output sensitive information
// including bearer tokens.
type Tracer struct {
        http.RoundTripper
}

// RoundTrip calls the nested RoundTripper while printing each request and
// response/error to os.Stderr on either side of the nested call.  WARNING: this
// may output sensitive information including bearer tokens.
func (t *Tracer) RoundTrip(req *http.Request) (*http.Response, error) {
        // Dump the request to os.Stderr.
        b, err := httputil.DumpRequestOut(req, true)
        if err != nil {
                return nil, err
        }
        os.Stderr.Write(b)
        os.Stderr.Write([]byte{'\n'})

        // Call the nested RoundTripper.
        resp, err := t.RoundTripper.RoundTrip(req)

        // If an error was returned, dump it to os.Stderr.
        if err != nil {
                fmt.Fprintln(os.Stderr, err)
                return resp, err
        }

        // Dump the response to os.Stderr.
        b, err = httputil.DumpResponse(resp, req.URL.Query().Get("watch") != "true")
        if err != nil {
                return nil, err
        }
        os.Stderr.Write(b)
        os.Stderr.Write([]byte{'\n'})

        return resp, err
}

func main() {
        // Instantiate loader for kubeconfig file.
        kubeconfig := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
                clientcmd.NewDefaultClientConfigLoadingRules(),
                &clientcmd.ConfigOverrides{},
        )

        // Determine the namespace referenced by the current context in the
        // kubeconfig file.
        namespace, _, err := kubeconfig.Namespace()
        if err != nil {
                panic(err)
        }

        // Get a rest.Config from the kubeconfig file.  This will be passed into all
        // the client objects we create.
        restconfig, err := kubeconfig.ClientConfig()
        if err != nil {
                panic(err)
        }

        // Wrap the default RoundTripper with an instance of Tracer.
        restconfig.WrapTransport = func(rt http.RoundTripper) http.RoundTripper {
                return &Tracer{rt}
        }

        // Create a Kubernetes core/v1 client.
        coreclient, err := corev1client.NewForConfig(restconfig)
        if err != nil {
                panic(err)
        }

        // Create an OpenShift build/v1 client.
        buildclient, err := buildv1client.NewForConfig(restconfig)
        if err != nil {
                panic(err)
        }

        // List all pods in our current namespace.
        pods, err := coreclient.Pods(namespace).List(metav1.ListOptions{})
        if err != nil {
                panic(err)
        }

        fmt.Printf("Pods in namespace %s:\n", namespace)
        for _, pod := range pods.Items {
                fmt.Printf("  %s\n", pod.Name)
        }

        // List all builds in our current namespace.
        builds, err := buildclient.Builds(namespace).List(metav1.ListOptions{})
        if err != nil {
                panic(err)
        }

        fmt.Printf("Builds in namespace %s:\n", namespace)
        for _, build := range builds.Items {
                fmt.Printf("  %s\n", build.Name)
        }
}