Add haproxy controller code.

WIP -- testing currently incomplete.

pkg/haproxy/faccess.go

+/*
+ * Copyright (c) 2020 UPLEX Nils Goroll Systemoptimierung
+ * All rights reserved
+ *
+ * Author: Geoffrey Simmons <geoffrey.simmons@uplex.de>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+package haproxy
+
+import (
+	"net/http"
+	"net/url"
+)
+
+type FaccessError struct {
+	Status int
+	PEM    string
+}
+
+func (err FaccessError) Error() string {
+	return err.PEM + ": " + http.StatusText(err.Status)
+}
+
+type FaccessClient struct {
+	baseURL *url.URL
+	client  *http.Client
+}
+
+func NewFaccessClient(host string) *FaccessClient {
+	return &FaccessClient{
+		baseURL: &url.URL{
+			Scheme: "http",
+			Host:   host,
+		},
+		client: http.DefaultClient,
+	}
+}
+
+func (client *FaccessClient) getHost() string {
+	return client.baseURL.Host
+}
+
+func (client *FaccessClient) PEMExists(spec Spec) (bool, error) {
+	relPath := &url.URL{Path: spec.CertName()}
+	url := client.baseURL.ResolveReference(relPath)
+	req, err := http.NewRequest(http.MethodHead, url.String(), nil)
+	if err != nil {
+		return false, err
+	}
+
+	resp, err := client.client.Do(req)
+	if err != nil {
+		return false, err
+	}
+	defer drainAndClose(resp.Body)
+
+	switch resp.StatusCode {
+	case http.StatusNoContent:
+		return true, nil
+	case http.StatusNotFound:
+		return false, nil
+	default:
+		return false, &FaccessError{
+			Status: resp.StatusCode,
+			PEM:    spec.CertName(),
+		}
+	}
+}