Add http/protobuf support for Coralogix exporter (open-telemetry#43219)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

<!-- Issue number (e.g. #1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes open-telemetry#43216 

<!--Describe what testing was performed and which tests were added.-->
#### Testing

Tested with:
```yaml
receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317
      http:
        endpoint: 0.0.0.0:4318

exporters:
  debug:
  coralogix:
    protocol: http
    application_name: otel
    application_name_attributes:
      - service.name
      - k8s.namespace.name
      - service.namespace
    domain: eu2.coralogix.com
    subsystem_name: k8s-saas
    subsystem_name_attributes:
      - subsystem.name
    private_key: ${env:CORALOGIX_PRIVATE_KEY}

service:
  pipelines:
    traces:
      receivers: [otlp]
      exporters: [coralogix, debug]
    metrics:
      receivers: [otlp]
      exporters: [coralogix, debug]
    logs:
      receivers: [otlp]
      exporters: [coralogix, debug]
```

And
```yaml
receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317
      http:
        endpoint: 0.0.0.0:4318

exporters:
  debug:
  coralogix:
    application_name: otel
    application_name_attributes:
      - service.name
      - k8s.namespace.name
      - service.namespace
    domain: eu2.coralogix.com
    subsystem_name: k8s-saas
    subsystem_name_attributes:
      - subsystem.name
    private_key: ${env:CORALOGIX_PRIVATE_KEY}

service:
  pipelines:
    traces:
      receivers: [otlp]
      exporters: [coralogix, debug]
    metrics:
      receivers: [otlp]
      exporters: [coralogix, debug]
    logs:
      receivers: [otlp]
      exporters: [coralogix, debug]
```

Also did some tests with proxy.

<!--Describe the documentation added.-->
#### Documentation
- Changes done in `README.md`.

Signed-off-by: Israel Blancas <[email protected]>

Author: iblancasa

.chloggen/43216.yaml

@@ -0,0 +1,30 @@
+# 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: exporter/coralogix
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add HTTP/protobuf protocol support alongside existing gRPC transport.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [43216]
+
+# (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: |
+  The exporter now supports both gRPC (default) and HTTP/protobuf protocols for sending telemetry data.
+  HTTP transport enables proxy support and provides an alternative for environments where gRPC is restricted.
+  Configure using the `protocol` field with values "grpc" or "http".
+
+# 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: []

exporter/coralogixexporter/README.md

@@ -34,6 +34,9 @@ exporters:
     # Your Coralogix private key is sensitive
     private_key: "xxx"
 
+    # (Optional) Protocol to use for communication: "grpc" (default) or "http"
+    protocol: "grpc"
+
     # (Optional) Ordered list of Resource attributes that are used for Coralogix
     # AppName and SubSystem values. The first non-empty Resource attribute is used.
     # Example: application_name_attributes: ["k8s.namespace.name", "service.namespace"]
@@ -43,7 +46,7 @@ exporters:
     subsystem_name_attributes:
     - "service.name"
 
-    # Traces, Metrics and Logs emitted by this OpenTelemetry exporter 
+    # Traces, Metrics and Logs emitted by this OpenTelemetry exporter
     # are tagged in Coralogix with the default application and subsystem constants.
     application_name: "MyBusinessEnvironment"
     subsystem_name: "MyBusinessSystem"
@@ -52,13 +55,50 @@ exporters:
     sending_queue:
       sizer: bytes
       batch:
-        min_size: 4194304 
+        min_size: 4194304
         max_size: 8388608
 
     # (Optional) Timeout is the timeout for every attempt to send data to the backend.
     timeout: 30s
 ```
 
+### Transport Protocol
+
+The Coralogix exporter supports two transport protocols:
+- **gRPC** (default): Uses gRPC for efficient binary communication
+- **HTTP**: Uses HTTP with protobuf encoding, useful for proxy support or environments where gRPC is restricted
+
+To use HTTP protocol:
+```yaml
+exporters:
+  coralogix:
+    protocol: "http"
+    domain: "coralogix.com"
+```
+
+#### Using HTTP Protocol with Proxy
+
+When using HTTP protocol, you can configure proxy settings:
+
+```yaml
+exporters:
+  coralogix:
+    protocol: "http"
+    domain: "coralogix.com"
+    private_key: "xxx"
+    application_name: "MyApp"
+    subsystem_name: "MySubsystem"
+    domain_settings:
+      proxy_url: "http://proxy.example.com:8080"
+      timeout: 30s
+```
+
+**Notes**:
+- Proxy support (`proxy_url`) is only available when using the HTTP protocol. gRPC protocol does not support this setting.
+- Signal-specific settings (logs, traces, metrics) take precedence over `domain_settings`.
+- **The profiles signal is not supported when using HTTP protocol**. Use gRPC protocol (default) if you need to send profiles data.
+```
+
 ### Compression
 
 By default, the Coralogix exporter uses gzip compression. Alternatively, you can use zstd compression, for example:
@@ -70,7 +110,7 @@ exporters:
       compression: "zstd"
 ```
 
-### v0.76.0 Coralogix Domain 
+### v0.76.0 Coralogix Domain
 
 Since v0.76.0 you can specify Coralogix domain in the configuration file instead of specifying different endpoints for traces, metrics and logs. For example, the configuration below, can be replaced with domain field:
 

exporter/coralogixexporter/config.go

@@ -4,12 +4,16 @@
 package coralogixexporter // import "github.com/open-telemetry/opentelemetry-collector-contrib/exporter/coralogixexporter"
 
 import (
+	"context"
 	"errors"
 	"fmt"
+	"net/http"
 	"strings"
 	"time"
 
+	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config/configgrpc"
+	"go.opentelemetry.io/collector/config/confighttp"
 	"go.opentelemetry.io/collector/config/configopaque"
 	"go.opentelemetry.io/collector/config/configretry"
 	"go.opentelemetry.io/collector/exporter/exporterhelper"
@@ -19,33 +23,67 @@ import (
 const (
 	cxAppNameAttrName       = "cx.application.name"
 	cxSubsystemNameAttrName = "cx.subsystem.name"
+	httpProtocol            = "http"
+	grpcProtocol            = "grpc"
 )
 
-// Config defines by Coralogix.
+// TransportConfig extends configgrpc.ClientConfig with additional HTTP-specific settings
+type TransportConfig struct {
+	// Embed the gRPC configuration to ensure backward compatibility
+	configgrpc.ClientConfig `mapstructure:",squash"`
+
+	// The following fields are only used when protocol is "http"
+	ProxyURL string        `mapstructure:"proxy_url,omitempty"` // Used only if protocol is http
+	Timeout  time.Duration `mapstructure:"timeout,omitempty"`   // Used only if protocol is http
+}
+
+func (c *TransportConfig) ToHTTPClient(ctx context.Context, host component.Host, settings component.TelemetrySettings) (*http.Client, error) {
+	headers := c.Headers
+	if headers == nil {
+		headers = make(map[string]configopaque.String)
+	}
+	headers["Content-Type"] = "application/x-protobuf"
+
+	httpClientConfig := confighttp.ClientConfig{
+		ProxyURL:        c.ProxyURL,
+		TLS:             c.TLS,
+		ReadBufferSize:  c.ReadBufferSize,
+		WriteBufferSize: c.WriteBufferSize,
+		Timeout:         c.Timeout,
+		Headers:         headers,
+		Compression:     c.Compression,
+	}
+	return httpClientConfig.ToClient(ctx, host, settings)
+}
+
+// Config defines configuration for Coralogix exporter.
 type Config struct {
 	QueueSettings             exporterhelper.QueueBatchConfig `mapstructure:"sending_queue"`
 	configretry.BackOffConfig `mapstructure:"retry_on_failure"`
 	TimeoutSettings           exporterhelper.TimeoutConfig `mapstructure:",squash"`
 
+	// Protocol to use for communication. Options: "grpc" (default), "http"
+	Protocol string `mapstructure:"protocol"`
+
 	// Coralogix domain
 	Domain string `mapstructure:"domain"`
 
-	// GRPC Settings used with Domain
-	DomainSettings configgrpc.ClientConfig `mapstructure:"domain_settings"`
+	// Transport settings used with Domain (supports both gRPC and HTTP)
+	DomainSettings TransportConfig `mapstructure:"domain_settings"`
 
 	// Use AWS PrivateLink for the domain
 	PrivateLink bool `mapstructure:"private_link"`
 
-	// Coralogix traces ingress endpoint
-	Traces configgrpc.ClientConfig `mapstructure:"traces"`
+	// Coralogix traces ingress endpoint (supports both gRPC and HTTP)
+	Traces TransportConfig `mapstructure:"traces"`
 
-	// The Coralogix metrics ingress endpoint
-	Metrics configgrpc.ClientConfig `mapstructure:"metrics"`
+	// The Coralogix metrics ingress endpoint (supports both gRPC and HTTP)
+	Metrics TransportConfig `mapstructure:"metrics"`
 
-	// The Coralogix logs ingress endpoint
-	Logs configgrpc.ClientConfig `mapstructure:"logs"`
+	// The Coralogix logs ingress endpoint (supports both gRPC and HTTP)
+	Logs TransportConfig `mapstructure:"logs"`
 
-	// The Coralogix profiles ingress endpoint
+	// The Coralogix profiles ingress endpoint (gRPC only)
 	Profiles configgrpc.ClientConfig `mapstructure:"profiles"`
 
 	// Your Coralogix private key (sensitive) for authentication
@@ -78,6 +116,10 @@ func isEmpty(endpoint string) bool {
 }
 
 func (c *Config) Validate() error {
+	if c.Protocol != grpcProtocol && c.Protocol != httpProtocol && c.Protocol != "" {
+		return fmt.Errorf("protocol must be %s or %s", grpcProtocol, httpProtocol)
+	}
+
 	// validate that at least one endpoint is set up correctly
 	if isEmpty(c.Domain) &&
 		isEmpty(c.Traces.Endpoint) &&
@@ -101,6 +143,12 @@ func (c *Config) Validate() error {
 			return errors.New("`rate_limiter.duration` must be greater than 0")
 		}
 	}
+
+	// Validate that HTTP protocol is not used with profiles
+	if c.Protocol == httpProtocol && !isEmpty(c.Profiles.Endpoint) {
+		return errors.New("profiles signal is not supported with HTTP protocol, use gRPC protocol (default) instead")
+	}
+
 	return nil
 }
 
@@ -146,7 +194,7 @@ func (c *Config) getMetadataFromResource(res pcommon.Resource) (appName, subsyst
 }
 
 func (c *Config) getDomainGrpcSettings() *configgrpc.ClientConfig {
-	settings := c.DomainSettings
+	settings := c.DomainSettings.ClientConfig
 	domain := c.Domain
 
 	// If PrivateLink is enabled, use the private link endpoint.
@@ -159,3 +207,60 @@ func (c *Config) getDomainGrpcSettings() *configgrpc.ClientConfig {
 
 	return &settings
 }
+
+// getMergedTransportConfig returns a TransportConfig that merges signal-specific settings with domain settings.
+// Signal-specific settings take precedence over domain settings.
+func (c *Config) getMergedTransportConfig(signalConfig *TransportConfig) *TransportConfig {
+	merged := c.DomainSettings
+
+	if signalConfig.ProxyURL != "" {
+		merged.ProxyURL = signalConfig.ProxyURL
+	}
+	if signalConfig.Timeout != 0 {
+		merged.Timeout = signalConfig.Timeout
+	}
+
+	if signalConfig.Compression != "" {
+		merged.Compression = signalConfig.Compression
+	}
+	if signalConfig.TLS.Insecure || signalConfig.TLS.InsecureSkipVerify || signalConfig.TLS.CAFile != "" {
+		merged.TLS = signalConfig.TLS
+	}
+	if len(signalConfig.Headers) > 0 {
+		// Deep-copy domain headers to avoid mutating the shared map
+		headers := make(map[string]configopaque.String)
+		for k, v := range merged.Headers {
+			headers[k] = v
+		}
+		for k, v := range signalConfig.Headers {
+			headers[k] = v
+		}
+		merged.Headers = headers
+	}
+	if signalConfig.WriteBufferSize > 0 {
+		merged.WriteBufferSize = signalConfig.WriteBufferSize
+	}
+	if signalConfig.ReadBufferSize > 0 {
+		merged.ReadBufferSize = signalConfig.ReadBufferSize
+	}
+	if signalConfig.WaitForReady {
+		merged.WaitForReady = signalConfig.WaitForReady
+	}
+	if signalConfig.BalancerName != "" {
+		merged.BalancerName = signalConfig.BalancerName
+	}
+	if signalConfig.Keepalive.HasValue() {
+		merged.Keepalive = signalConfig.Keepalive
+	}
+	if signalConfig.Auth.HasValue() {
+		merged.Auth = signalConfig.Auth
+	}
+
+	if isEmpty(signalConfig.Endpoint) {
+		merged.Endpoint = c.getDomainGrpcSettings().Endpoint
+	} else {
+		merged.Endpoint = signalConfig.Endpoint
+	}
+
+	return &merged
+}