[receiver/prometheusreceiver] Configuring httpSD http client from TAs…

… clienthttp (open-telemetry#34035)

**Description:** 
Translating relevant fields from TargetAllocator's confighttps to be
used in the service discovery http client config
This assures that the relevant config defiend for the TA is used by the
service discovery jobs in addition to the scrape configs (as solved by
open-telemetry#31449)

**Link to tracking Issue:** Resolves
open-telemetry#33370

**Testing:**
Added unit tests.

**Documentation:**

.chloggen/httpSD-client-config-from-TA-confighttp.yaml

@@ -0,0 +1,28 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: prometheusreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Ensure Target Allocator's confighttp is used in the receiver's service discovery
+
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [33370]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

receiver/prometheusreceiver/go.mod

@@ -17,6 +17,8 @@ require (
 	go.opentelemetry.io/collector/component v0.107.1-0.20240816132030-9fd84668bb02
 	go.opentelemetry.io/collector/component/componentstatus v0.107.1-0.20240816132030-9fd84668bb02
 	go.opentelemetry.io/collector/config/confighttp v0.107.1-0.20240816132030-9fd84668bb02
+	go.opentelemetry.io/collector/config/configopaque v1.13.1-0.20240816132030-9fd84668bb02
+	go.opentelemetry.io/collector/config/configtls v1.13.1-0.20240816132030-9fd84668bb02
 	go.opentelemetry.io/collector/confmap v0.107.1-0.20240816132030-9fd84668bb02
 	go.opentelemetry.io/collector/confmap/provider/fileprovider v0.107.1-0.20240816132030-9fd84668bb02
 	go.opentelemetry.io/collector/consumer v0.107.1-0.20240816132030-9fd84668bb02
@@ -168,10 +170,8 @@ require (
 	go.opentelemetry.io/collector/component/componentprofiles v0.107.1-0.20240816132030-9fd84668bb02 // indirect
 	go.opentelemetry.io/collector/config/configauth v0.107.1-0.20240816132030-9fd84668bb02 // indirect
 	go.opentelemetry.io/collector/config/configcompression v1.13.1-0.20240816132030-9fd84668bb02 // indirect
-	go.opentelemetry.io/collector/config/configopaque v1.13.1-0.20240816132030-9fd84668bb02 // indirect
 	go.opentelemetry.io/collector/config/configretry v1.13.1-0.20240816132030-9fd84668bb02 // indirect
 	go.opentelemetry.io/collector/config/configtelemetry v0.107.1-0.20240816132030-9fd84668bb02 // indirect
-	go.opentelemetry.io/collector/config/configtls v1.13.1-0.20240816132030-9fd84668bb02 // indirect
 	go.opentelemetry.io/collector/config/internal v0.107.1-0.20240816132030-9fd84668bb02 // indirect
 	go.opentelemetry.io/collector/connector v0.107.1-0.20240816132030-9fd84668bb02 // indirect
 	go.opentelemetry.io/collector/consumer/consumerprofiles v0.107.1-0.20240816132030-9fd84668bb02 // indirect

receiver/prometheusreceiver/metrics_receiver.go

@@ -6,6 +6,7 @@ package prometheusreceiver // import "github.com/open-telemetry/opentelemetry-co
 import (
 	"bytes"
 	"context"
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"hash/fnv"
@@ -16,6 +17,7 @@ import (
 	"reflect"
 	"regexp"
 	"sort"
+	"strings"
 	"sync"
 	"time"
 	"unsafe"
@@ -174,6 +176,80 @@ func getScrapeConfigHash(jobToScrapeConfig map[string]*config.ScrapeConfig) (uin
 	return hash.Sum64(), err
 }
 
+// ConvertTLSVersion converts a string TLS version to the corresponding config.TLSVersion value in prometheus common.
+func convertTLSVersion(version string) (commonconfig.TLSVersion, error) {
+	normalizedVersion := "TLS" + strings.ReplaceAll(version, ".", "")
+
+	if tlsVersion, exists := commonconfig.TLSVersions[normalizedVersion]; exists {
+		return tlsVersion, nil
+	}
+	return 0, fmt.Errorf("unsupported TLS version: %s", version)
+}
+
+// configureSDHTTPClientConfig configures the http client for the service discovery manager
+// based on the provided TargetAllocator configuration.
+func configureSDHTTPClientConfigFromTA(httpSD *promHTTP.SDConfig, allocConf *TargetAllocator) error {
+	httpSD.HTTPClientConfig.FollowRedirects = false
+
+	httpSD.HTTPClientConfig.TLSConfig = commonconfig.TLSConfig{
+		InsecureSkipVerify: allocConf.TLSSetting.InsecureSkipVerify,
+		ServerName:         allocConf.TLSSetting.ServerName,
+		CAFile:             allocConf.TLSSetting.CAFile,
+		CertFile:           allocConf.TLSSetting.CertFile,
+		KeyFile:            allocConf.TLSSetting.KeyFile,
+	}
+
+	if allocConf.TLSSetting.CAPem != "" {
+		decodedCA, err := base64.StdEncoding.DecodeString(string(allocConf.TLSSetting.CAPem))
+		if err != nil {
+			return fmt.Errorf("failed to decode CA: %w", err)
+		}
+		httpSD.HTTPClientConfig.TLSConfig.CA = string(decodedCA)
+	}
+
+	if allocConf.TLSSetting.CertPem != "" {
+		decodedCert, err := base64.StdEncoding.DecodeString(string(allocConf.TLSSetting.CertPem))
+		if err != nil {
+			return fmt.Errorf("failed to decode Cert: %w", err)
+		}
+		httpSD.HTTPClientConfig.TLSConfig.Cert = string(decodedCert)
+	}
+
+	if allocConf.TLSSetting.KeyPem != "" {
+		decodedKey, err := base64.StdEncoding.DecodeString(string(allocConf.TLSSetting.KeyPem))
+		if err != nil {
+			return fmt.Errorf("failed to decode Key: %w", err)
+		}
+		httpSD.HTTPClientConfig.TLSConfig.Key = commonconfig.Secret(decodedKey)
+	}
+
+	if allocConf.TLSSetting.MinVersion != "" {
+		minVersion, err := convertTLSVersion(allocConf.TLSSetting.MinVersion)
+		if err != nil {
+			return err
+		}
+		httpSD.HTTPClientConfig.TLSConfig.MinVersion = minVersion
+	}
+
+	if allocConf.TLSSetting.MaxVersion != "" {
+		maxVersion, err := convertTLSVersion(allocConf.TLSSetting.MaxVersion)
+		if err != nil {
+			return err
+		}
+		httpSD.HTTPClientConfig.TLSConfig.MaxVersion = maxVersion
+	}
+
+	if allocConf.ProxyURL != "" {
+		proxyURL, err := url.Parse(allocConf.ProxyURL)
+		if err != nil {
+			return err
+		}
+		httpSD.HTTPClientConfig.ProxyURL = commonconfig.URL{URL: proxyURL}
+	}
+
+	return nil
+}
+
 // syncTargetAllocator request jobs from targetAllocator and update underlying receiver, if the response does not match the provided compareHash.
 // baseDiscoveryCfg can be used to provide additional ScrapeConfigs which will be added to the retrieved jobs.
 func (r *pReceiver) syncTargetAllocator(compareHash uint64, allocConf *TargetAllocator, baseCfg *PromConfig) (uint64, error) {
@@ -208,7 +284,13 @@ func (r *pReceiver) syncTargetAllocator(compareHash uint64, allocConf *TargetAll
 		}
 		escapedJob := url.QueryEscape(jobName)
 		httpSD.URL = fmt.Sprintf("%s/jobs/%s/targets?collector_id=%s", allocConf.Endpoint, escapedJob, allocConf.CollectorID)
-		httpSD.HTTPClientConfig.FollowRedirects = false
+
+		err = configureSDHTTPClientConfigFromTA(&httpSD, allocConf)
+		if err != nil {
+			r.settings.Logger.Error("Failed to configure http client config", zap.Error(err))
+			return 0, err
+		}
+
 		scrapeConfig.ServiceDiscoveryConfigs = discovery.Configs{
 			&httpSD,
 		}

receiver/prometheusreceiver/metrics_receiver_target_allocator_test.go

@@ -7,9 +7,11 @@ package prometheusreceiver
 
 import (
 	"context"
+	"encoding/base64"
 	"encoding/json"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -24,6 +26,8 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.opentelemetry.io/collector/component/componenttest"
+	"go.opentelemetry.io/collector/config/configopaque"
+	"go.opentelemetry.io/collector/config/configtls"
 	"go.opentelemetry.io/collector/consumer/consumertest"
 	"go.opentelemetry.io/collector/receiver/receivertest"
 )
@@ -776,3 +780,51 @@ func TestTargetAllocatorJobRetrieval(t *testing.T) {
 		})
 	}
 }
+
+func TestConfigureSDHTTPClientConfigFromTA(t *testing.T) {
+	ta := &TargetAllocator{}
+	ta.TLSSetting = configtls.ClientConfig{
+		InsecureSkipVerify: true,
+		ServerName:         "test.server",
+		Config: configtls.Config{
+			CAFile:     "/path/to/ca",
+			CertFile:   "/path/to/cert",
+			KeyFile:    "/path/to/key",
+			CAPem:      configopaque.String(base64.StdEncoding.EncodeToString([]byte("test-ca"))),
+			CertPem:    configopaque.String(base64.StdEncoding.EncodeToString([]byte("test-cert"))),
+			KeyPem:     configopaque.String(base64.StdEncoding.EncodeToString([]byte("test-key"))),
+			MinVersion: "1.2",
+			MaxVersion: "1.3",
+		},
+	}
+	ta.ProxyURL = "http://proxy.test"
+
+	httpSD := &promHTTP.SDConfig{RefreshInterval: model.Duration(30 * time.Second)}
+
+	err := configureSDHTTPClientConfigFromTA(httpSD, ta)
+
+	assert.NoError(t, err)
+
+	assert.Equal(t, false, httpSD.HTTPClientConfig.FollowRedirects)
+	assert.Equal(t, true, httpSD.HTTPClientConfig.TLSConfig.InsecureSkipVerify)
+	assert.Equal(t, "test.server", httpSD.HTTPClientConfig.TLSConfig.ServerName)
+	assert.Equal(t, "/path/to/ca", httpSD.HTTPClientConfig.TLSConfig.CAFile)
+	assert.Equal(t, "/path/to/cert", httpSD.HTTPClientConfig.TLSConfig.CertFile)
+	assert.Equal(t, "/path/to/key", httpSD.HTTPClientConfig.TLSConfig.KeyFile)
+	assert.Equal(t, "test-ca", httpSD.HTTPClientConfig.TLSConfig.CA)
+	assert.Equal(t, "test-cert", httpSD.HTTPClientConfig.TLSConfig.Cert)
+	assert.Equal(t, commonconfig.Secret("test-key"), httpSD.HTTPClientConfig.TLSConfig.Key)
+	assert.Equal(t, commonconfig.TLSVersions["TLS12"], httpSD.HTTPClientConfig.TLSConfig.MinVersion)
+	assert.Equal(t, commonconfig.TLSVersions["TLS13"], httpSD.HTTPClientConfig.TLSConfig.MaxVersion)
+
+	parsedProxyURL, _ := url.Parse("http://proxy.test")
+	assert.Equal(t, commonconfig.URL{URL: parsedProxyURL}, httpSD.HTTPClientConfig.ProxyURL)
+
+	// Test case with empty TargetAllocator
+	emptyTA := &TargetAllocator{}
+	emptyHTTPSD := &promHTTP.SDConfig{RefreshInterval: model.Duration(30 * time.Second)}
+
+	err = configureSDHTTPClientConfigFromTA(emptyHTTPSD, emptyTA)
+
+	assert.NoError(t, err)
+}