X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=src%2Fgrpc.cc;h=8b76954d6748090a795d2eaf09fcfe7a8110f7c0;hb=3d74a63ae43c1786eb9b966e2209c24c5643dae8;hp=2f79f42d2b75ae4f3f119eac275b9d098fc65d5e;hpb=b43eedf73eab4848a94c42cc8b9cff3349f37171;p=collectd.git

diff --git a/src/grpc.cc b/src/grpc.cc
index 2f79f42d..8b76954d 100644
--- a/src/grpc.cc
+++ b/src/grpc.cc
@@ -1,6 +1,6 @@
 /**
  * collectd - src/grpc.cc
- * Copyright (C) 2015 Sebastian Harl
+ * Copyright (C) 2015-2016 Sebastian Harl
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -27,79 +27,191 @@
 #include <grpc++/grpc++.h>
 #include <google/protobuf/util/time_util.h>
 
+#include <fstream>
+#include <iostream>
+#include <queue>
+#include <vector>
+
 #include "collectd.grpc.pb.h"
 
 extern "C" {
+#include <fnmatch.h>
 #include <stdbool.h>
-#include <pthread.h>
 
 #include "collectd.h"
 #include "common.h"
-#include "configfile.h"
 #include "plugin.h"
 
 #include "daemon/utils_cache.h"
-
-	typedef struct {
-		char *addr;
-		char *port;
-	} listener_t;
-
-	static listener_t *listeners;
-	static size_t listeners_num;
 }
 
 using collectd::Collectd;
 
 using collectd::DispatchValuesRequest;
-using collectd::DispatchValuesReply;
-using collectd::ListValuesRequest;
-using collectd::ListValuesReply;
+using collectd::DispatchValuesResponse;
+using collectd::QueryValuesRequest;
+using collectd::QueryValuesResponse;
 
 using google::protobuf::util::TimeUtil;
 
 /*
- * proto conversion
+ * private types
  */
 
-static grpc::Status unmarshal_value_list(const collectd::types::ValueList &msg, value_list_t *vl)
+struct Listener {
+	grpc::string addr;
+	grpc::string port;
+
+	grpc::SslServerCredentialsOptions *ssl;
+};
+static std::vector<Listener> listeners;
+static grpc::string default_addr("0.0.0.0:50051");
+
+/*
+ * helper functions
+ */
+
+static bool ident_matches(const value_list_t *vl, const value_list_t *matcher)
 {
-	vl->time = NS_TO_CDTIME_T(TimeUtil::TimestampToNanoseconds(msg.time()));
-	vl->interval = NS_TO_CDTIME_T(TimeUtil::DurationToNanoseconds(msg.interval()));
+	if (fnmatch(matcher->host, vl->host, 0))
+		return false;
 
+	if (fnmatch(matcher->plugin, vl->plugin, 0))
+		return false;
+	if (fnmatch(matcher->plugin_instance, vl->plugin_instance, 0))
+		return false;
+
+	if (fnmatch(matcher->type, vl->type, 0))
+		return false;
+	if (fnmatch(matcher->type_instance, vl->type_instance, 0))
+		return false;
+
+	return true;
+} /* ident_matches */
+
+static grpc::string read_file(const char *filename)
+{
+	std::ifstream f;
+	grpc::string s, content;
+
+	f.open(filename);
+	if (!f.is_open()) {
+		ERROR("grpc: Failed to open '%s'", filename);
+		return "";
+	}
+
+	while (std::getline(f, s)) {
+		content += s;
+		content.push_back('\n');
+	}
+	f.close();
+	return content;
+} /* read_file */
+
+/*
+ * proto conversion
+ */
+
+static void marshal_ident(const value_list_t *vl, collectd::types::Identifier *msg)
+{
+	msg->set_host(vl->host);
+	msg->set_plugin(vl->plugin);
+	if (vl->plugin_instance[0] != '\0')
+		msg->set_plugin_instance(vl->plugin_instance);
+	msg->set_type(vl->type);
+	if (vl->type_instance[0] != '\0')
+		msg->set_type_instance(vl->type_instance);
+} /* marshal_ident */
+
+static grpc::Status unmarshal_ident(const collectd::types::Identifier &msg, value_list_t *vl,
+		bool require_fields)
+{
 	std::string s;
 
 	s = msg.host();
-	if (!s.length())
+	if (!s.length() && require_fields)
 		return grpc::Status(grpc::StatusCode::INVALID_ARGUMENT,
 				grpc::string("missing host name"));
 	sstrncpy(vl->host, s.c_str(), sizeof(vl->host));
 
 	s = msg.plugin();
-	if (!s.length())
+	if (!s.length() && require_fields)
 		return grpc::Status(grpc::StatusCode::INVALID_ARGUMENT,
 				grpc::string("missing plugin name"));
 	sstrncpy(vl->plugin, s.c_str(), sizeof(vl->plugin));
 
 	s = msg.type();
-	if (!s.length())
+	if (!s.length() && require_fields)
 		return grpc::Status(grpc::StatusCode::INVALID_ARGUMENT,
 				grpc::string("missing type name"));
 	sstrncpy(vl->type, s.c_str(), sizeof(vl->type));
 
 	s = msg.plugin_instance();
-	if (s.length())
-		sstrncpy(vl->plugin_instance, s.c_str(), sizeof(vl->plugin_instance));
+	sstrncpy(vl->plugin_instance, s.c_str(), sizeof(vl->plugin_instance));
 
 	s = msg.type_instance();
-	if (s.length())
-		sstrncpy(vl->type_instance, s.c_str(), sizeof(vl->type_instance));
+	sstrncpy(vl->type_instance, s.c_str(), sizeof(vl->type_instance));
+
+	return grpc::Status::OK;
+} /* unmarshal_ident() */
+
+static grpc::Status marshal_value_list(const value_list_t *vl, collectd::types::ValueList *msg)
+{
+	auto id = msg->mutable_identifier();
+	marshal_ident(vl, id);
+
+	auto ds = plugin_get_ds(vl->type);
+	if ((ds == NULL) || (ds->ds_num != vl->values_len)) {
+		return grpc::Status(grpc::StatusCode::INTERNAL,
+				grpc::string("failed to retrieve data-set for values"));
+	}
+
+	auto t = TimeUtil::NanosecondsToTimestamp(CDTIME_T_TO_NS(vl->time));
+	auto d = TimeUtil::NanosecondsToDuration(CDTIME_T_TO_NS(vl->interval));
+	msg->set_allocated_time(new google::protobuf::Timestamp(t));
+	msg->set_allocated_interval(new google::protobuf::Duration(d));
+
+	for (size_t i = 0; i < vl->values_len; ++i) {
+		auto v = msg->add_values();
+		switch (ds->ds[i].type) {
+			case DS_TYPE_COUNTER:
+				v->set_counter(vl->values[i].counter);
+				break;
+			case DS_TYPE_GAUGE:
+				v->set_gauge(vl->values[i].gauge);
+				break;
+			case DS_TYPE_DERIVE:
+				v->set_derive(vl->values[i].derive);
+				break;
+			case DS_TYPE_ABSOLUTE:
+				v->set_absolute(vl->values[i].absolute);
+				break;
+			default:
+				return grpc::Status(grpc::StatusCode::INTERNAL,
+						grpc::string("unknown value type"));
+		}
+
+		auto name = msg->add_ds_names();
+		name->assign(ds->ds[i].name);
+	}
+
+	return grpc::Status::OK;
+} /* marshal_value_list */
+
+static grpc::Status unmarshal_value_list(const collectd::types::ValueList &msg, value_list_t *vl)
+{
+	vl->time = NS_TO_CDTIME_T(TimeUtil::TimestampToNanoseconds(msg.time()));
+	vl->interval = NS_TO_CDTIME_T(TimeUtil::DurationToNanoseconds(msg.interval()));
+
+	auto status = unmarshal_ident(msg.identifier(), vl, true);
+	if (!status.ok())
+		return status;
 
 	value_t *values = NULL;
 	size_t values_len = 0;
-	auto status = grpc::Status::OK;
 
-	for (auto v : msg.value()) {
+	status = grpc::Status::OK;
+	for (auto v : msg.values()) {
 		value_t *val = (value_t *)realloc(values, (values_len + 1) * sizeof(*values));
 		if (!val) {
 			status = grpc::Status(grpc::StatusCode::RESOURCE_EXHAUSTED,
@@ -126,7 +238,7 @@ static grpc::Status unmarshal_value_list(const collectd::types::ValueList &msg,
 			break;
 		default:
 			status = grpc::Status(grpc::StatusCode::INVALID_ARGUMENT,
-					grpc::string("unkown value type"));
+					grpc::string("unknown value type"));
 			break;
 		}
 
@@ -145,225 +257,225 @@ static grpc::Status unmarshal_value_list(const collectd::types::ValueList &msg,
 } /* unmarshal_value_list() */
 
 /*
- * request call-backs and call objects
+ * Collectd service
  */
+class CollectdImpl : public collectd::Collectd::Service {
+public:
+	grpc::Status QueryValues(grpc::ServerContext *ctx, QueryValuesRequest const *req, grpc::ServerWriter<QueryValuesResponse> *writer) override {
+		value_list_t match;
+		auto status = unmarshal_ident(req->identifier(), &match, false);
+		if (!status.ok()) {
+			return status;
+		}
 
-static grpc::Status Process(grpc::ServerContext *ctx,
-		DispatchValuesRequest request, DispatchValuesReply *reply)
-{
-	value_list_t vl = VALUE_LIST_INIT;
-	auto status = unmarshal_value_list(request.values(), &vl);
-	if (!status.ok())
-		return status;
-
-	if (plugin_dispatch_values(&vl))
-		status = grpc::Status(grpc::StatusCode::INTERNAL,
-				grpc::string("failed to enqueue values for writing"));
-	return status;
-} /* Process(): DispatchValues */
+		std::queue<value_list_t> value_lists;
+		status = this->queryValuesRead(&match, &value_lists);
+		if (status.ok()) {
+			status = this->queryValuesWrite(ctx, writer, &value_lists);
+		}
 
-static grpc::Status Process(grpc::ServerContext *ctx,
-		ListValuesRequest request, ListValuesReply *reply)
-{
-	char **names = NULL;
-	cdtime_t *times = NULL;
-	size_t i, n = 0;
+		while (!value_lists.empty()) {
+			auto vl = value_lists.front();
+			value_lists.pop();
+			sfree(vl.values);
+		}
 
-	if (uc_get_names(&names, &times, &n))
-		return grpc::Status(grpc::StatusCode::INTERNAL,
-				grpc::string("failed to retrieve values"));
-
-	for (i = 0; i < n; i++) {
-		auto v = reply->add_value();
-		auto t = TimeUtil::NanosecondsToTimestamp(CDTIME_T_TO_NS(times[i]));
-		v->set_name(names[i]);
-		v->set_allocated_time(new google::protobuf::Timestamp(t));
-		sfree(names[i]);
+		return status;
 	}
-	sfree(names);
-	sfree(times);
 
-	return grpc::Status::OK;
-} /* Process(): ListValues */
+	grpc::Status DispatchValues(grpc::ServerContext *ctx,
+								grpc::ServerReader<DispatchValuesRequest> *reader,
+								DispatchValuesResponse *res) override {
+		DispatchValuesRequest req;
 
-class Call
-{
-public:
-	Call(Collectd::AsyncService *service, grpc::ServerCompletionQueue *cq)
-		: service_(service), cq_(cq), status_(CREATE)
-	{ }
+		while (reader->Read(&req)) {
+			value_list_t vl = VALUE_LIST_INIT;
+			auto status = unmarshal_value_list(req.value_list(), &vl);
+			if (!status.ok())
+				return status;
 
-	virtual ~Call()
-	{ }
-
-	void Handle()
-	{
-		if (status_ == CREATE) {
-			Create();
-			status_ = PROCESS;
-		}
-		else if (status_ == PROCESS) {
-			Process();
-			status_ = FINISH;
+			if (plugin_dispatch_values(&vl))
+				return grpc::Status(grpc::StatusCode::INTERNAL,
+									grpc::string("failed to enqueue values for writing"));
 		}
-		else {
-			GPR_ASSERT(status_ == FINISH);
-			Finish();
-		}
-	} /* Handle() */
-
-protected:
-	virtual void Create() = 0;
-	virtual void Process() = 0;
-	virtual void Finish() = 0;
 
-	Collectd::AsyncService *service_;
-	grpc::ServerCompletionQueue *cq_;
-	grpc::ServerContext ctx_;
+		res->Clear();
+		return grpc::Status::OK;
+	}
 
 private:
-	enum CallStatus { CREATE, PROCESS, FINISH };
-	CallStatus status_;
-}; /* class Call */
+	grpc::Status queryValuesRead(value_list_t const *match, std::queue<value_list_t> *value_lists) {
+		uc_iter_t *iter;
+		if ((iter = uc_get_iterator()) == NULL) {
+			return grpc::Status(grpc::StatusCode::INTERNAL,
+								grpc::string("failed to query values: cannot create iterator"));
+		}
 
-template<typename RequestT, typename ReplyT>
-class RpcCall final : public Call
-{
-	typedef void (Collectd::AsyncService::*CreatorT)(grpc::ServerContext *,
-			RequestT *, grpc::ServerAsyncResponseWriter<ReplyT> *,
-			grpc::CompletionQueue *, grpc::ServerCompletionQueue *, void *);
+		grpc::Status status = grpc::Status::OK;
+		char *name = NULL;
+		while (uc_iterator_next(iter, &name) == 0) {
+			value_list_t vl;
+			if (parse_identifier_vl(name, &vl) != 0) {
+				status = grpc::Status(grpc::StatusCode::INTERNAL,
+									  grpc::string("failed to parse identifier"));
+				break;
+			}
 
-public:
-	RpcCall(Collectd::AsyncService *service,
-			CreatorT creator, grpc::ServerCompletionQueue *cq)
-		: Call(service, cq), creator_(creator), responder_(&ctx_)
-	{
-		Handle();
-	} /* RpcCall() */
+			if (!ident_matches(&vl, match))
+				continue;
 
-	virtual ~RpcCall()
-	{ }
+			if (uc_iterator_get_time(iter, &vl.time) < 0) {
+				status = grpc::Status(grpc::StatusCode::INTERNAL,
+									  grpc::string("failed to retrieve value timestamp"));
+				break;
+			}
+			if (uc_iterator_get_interval(iter, &vl.interval) < 0) {
+				status = grpc::Status(grpc::StatusCode::INTERNAL,
+									  grpc::string("failed to retrieve value interval"));
+				break;
+			}
+			if (uc_iterator_get_values(iter, &vl.values, &vl.values_len) < 0) {
+				status = grpc::Status(grpc::StatusCode::INTERNAL,
+									  grpc::string("failed to retrieve values"));
+				break;
+			}
 
-private:
-	void Create()
-	{
-		(service_->*creator_)(&ctx_, &request_, &responder_, cq_, cq_, this);
-	} /* Create() */
+			value_lists->push(vl);
+		} // while (uc_iterator_next(iter, &name) == 0)
 
-	void Process()
-	{
-		// Add a new request object to the queue.
-		new RpcCall<RequestT, ReplyT>(service_, creator_, cq_);
-		grpc::Status status = ::Process(&ctx_, request_, &reply_);
-		responder_.Finish(reply_, status, this);
-	} /* Process() */
+		uc_iterator_destroy(iter);
+		return status;
+	}
 
-	void Finish()
-	{
-		delete this;
-	} /* Finish() */
+	grpc::Status queryValuesWrite(grpc::ServerContext *ctx,
+					   grpc::ServerWriter<QueryValuesResponse> *writer,
+					   std::queue<value_list_t> *value_lists) {
+		while (!value_lists->empty()) {
+			auto vl = value_lists->front();
+			QueryValuesResponse res;
+			res.Clear();
+
+			auto status = marshal_value_list(&vl, res.mutable_value_list());
+			if (!status.ok()) {
+				return status;
+			}
 
-	CreatorT creator_;
+			if (!writer->Write(res)) {
+				return grpc::Status::CANCELLED;
+			}
 
-	RequestT request_;
-	ReplyT reply_;
+			value_lists->pop();
+			sfree(vl.values);
+		}
 
-	grpc::ServerAsyncResponseWriter<ReplyT> responder_;
-}; /* class RpcCall */
+		return grpc::Status::OK;
+	}
+};
 
 /*
  * gRPC server implementation
  */
-
 class CollectdServer final
 {
 public:
 	void Start()
 	{
-		// TODO: make configurable
 		auto auth = grpc::InsecureServerCredentials();
 
 		grpc::ServerBuilder builder;
 
-		if (!listeners_num) {
-			std::string default_addr("0.0.0.0:50051");
+		if (listeners.empty()) {
 			builder.AddListeningPort(default_addr, auth);
 			INFO("grpc: Listening on %s", default_addr.c_str());
 		}
 		else {
-			size_t i;
-			for (i = 0; i < listeners_num; i++) {
-				auto l = listeners[i];
-				std::string addr(l.addr);
-				addr += std::string(":") + std::string(l.port);
-				builder.AddListeningPort(addr, auth);
-				INFO("grpc: Listening on %s", addr.c_str());
+			for (auto l : listeners) {
+				grpc::string addr = l.addr + ":" + l.port;
+
+				auto use_ssl = grpc::string("");
+				auto a = auth;
+				if (l.ssl != nullptr) {
+					use_ssl = grpc::string(" (SSL enabled)");
+					a = grpc::SslServerCredentials(*l.ssl);
+				}
+
+				builder.AddListeningPort(addr, a);
+				INFO("grpc: Listening on %s%s", addr.c_str(), use_ssl.c_str());
 			}
 		}
 
-		builder.RegisterAsyncService(&service_);
-		cq_ = builder.AddCompletionQueue();
+		builder.RegisterService(&collectd_service_);
+
 		server_ = builder.BuildAndStart();
 	} /* Start() */
 
 	void Shutdown()
 	{
 		server_->Shutdown();
-		cq_->Shutdown();
 	} /* Shutdown() */
 
-	void Mainloop()
-	{
-		// Register request types.
-		new RpcCall<DispatchValuesRequest, DispatchValuesReply>(&service_,
-				&Collectd::AsyncService::RequestDispatchValues, cq_.get());
-		new RpcCall<ListValuesRequest, ListValuesReply>(&service_,
-				&Collectd::AsyncService::RequestListValues, cq_.get());
-
-		while (true) {
-			void *req = NULL;
-			bool ok = false;
-
-			if (!cq_->Next(&req, &ok))
-				break; // Queue shut down.
-			if (!ok) {
-				ERROR("grpc: Failed to read from queue");
-				break;
-			}
-
-			static_cast<Call *>(req)->Handle();
-		}
-	} /* Mainloop() */
-
 private:
-	Collectd::AsyncService service_;
+	CollectdImpl collectd_service_;
 
 	std::unique_ptr<grpc::Server> server_;
-	std::unique_ptr<grpc::ServerCompletionQueue> cq_;
 }; /* class CollectdServer */
 
+class CollectdClient final
+{
+public:
+	CollectdClient(std::shared_ptr<grpc::ChannelInterface> channel) : stub_(Collectd::NewStub(channel)) {
+	}
+
+	int DispatchValues(value_list_t const *vl) {
+		grpc::ClientContext ctx;
+
+		DispatchValuesRequest req;
+		auto status = marshal_value_list(vl, req.mutable_value_list());
+		if (!status.ok()) {
+			ERROR("grpc: Marshalling value_list_t failed.");
+			return -1;
+		}
+
+		DispatchValuesResponse res;
+		auto stream = stub_->DispatchValues(&ctx, &res);
+		if (!stream->Write(req)) {
+			NOTICE("grpc: Broken stream.");
+			/* intentionally not returning. */
+		}
+
+		stream->WritesDone();
+		status = stream->Finish();
+		if (!status.ok()) {
+			ERROR ("grpc: Error while closing stream.");
+			return -1;
+		}
+
+		return 0;
+	} /* int DispatchValues */
+
+private:
+	std::unique_ptr<Collectd::Stub> stub_;
+};
+
 static CollectdServer *server = nullptr;
 
 /*
  * collectd plugin interface
  */
-
 extern "C" {
-	static pthread_t *workers;
-	static size_t workers_num = 5;
+	static void c_grpc_destroy_write_callback (void *ptr) {
+		delete (CollectdClient *) ptr;
+	}
 
-	static void *worker_thread(void *arg)
-	{
-		CollectdServer *s = (CollectdServer *)arg;
-		s->Mainloop();
-		return NULL;
-	} /* worker_thread() */
+	static int c_grpc_write(__attribute__((unused)) data_set_t const *ds,
+			value_list_t const *vl,
+			user_data_t *ud) {
+		CollectdClient *c = (CollectdClient *) ud->data;
+		return c->DispatchValues(vl);
+	}
 
 	static int c_grpc_config_listen(oconfig_item_t *ci)
 	{
-		listener_t *listener;
-		int i;
-
 		if ((ci->values_num != 2)
 				|| (ci->values[0].type != OCONFIG_TYPE_STRING)
 				|| (ci->values[1].type != OCONFIG_TYPE_STRING)) {
@@ -372,27 +484,139 @@ extern "C" {
 			return -1;
 		}
 
-		listener = (listener_t *)realloc(listeners,
-				(listeners_num + 1) * sizeof(*listeners));
-		if (!listener) {
-			ERROR("grpc: Failed to allocate listeners");
+		auto listener = Listener();
+		listener.addr = grpc::string(ci->values[0].value.string);
+		listener.port = grpc::string(ci->values[1].value.string);
+		listener.ssl = nullptr;
+
+		auto ssl_opts = new(grpc::SslServerCredentialsOptions);
+		grpc::SslServerCredentialsOptions::PemKeyCertPair pkcp = {};
+		bool use_ssl = false;
+
+		for (int i = 0; i < ci->children_num; i++) {
+			oconfig_item_t *child = ci->children + i;
+
+			if (!strcasecmp("EnableSSL", child->key)) {
+				if (cf_util_get_boolean(child, &use_ssl)) {
+					ERROR("grpc: Option `%s` expects a boolean value",
+							child->key);
+					return -1;
+				}
+			}
+			else if (!strcasecmp("SSLCACertificateFile", child->key)) {
+				char *certs = NULL;
+				if (cf_util_get_string(child, &certs)) {
+					ERROR("grpc: Option `%s` expects a string value",
+							child->key);
+					return -1;
+				}
+				ssl_opts->pem_root_certs = read_file(certs);
+			}
+			else if (!strcasecmp("SSLCertificateKeyFile", child->key)) {
+				char *key = NULL;
+				if (cf_util_get_string(child, &key)) {
+					ERROR("grpc: Option `%s` expects a string value",
+							child->key);
+					return -1;
+				}
+				pkcp.private_key = read_file(key);
+			}
+			else if (!strcasecmp("SSLCertificateFile", child->key)) {
+				char *cert = NULL;
+				if (cf_util_get_string(child, &cert)) {
+					ERROR("grpc: Option `%s` expects a string value",
+							child->key);
+					return -1;
+				}
+				pkcp.cert_chain = read_file(cert);
+			}
+			else {
+				WARNING("grpc: Option `%s` not allowed in <%s> block.",
+						child->key, ci->key);
+			}
+		}
+
+		ssl_opts->pem_key_cert_pairs.push_back(pkcp);
+		if (use_ssl)
+			listener.ssl = ssl_opts;
+		else
+			delete(ssl_opts);
+
+		listeners.push_back(listener);
+		return 0;
+	} /* c_grpc_config_listen() */
+
+	static int c_grpc_config_server(oconfig_item_t *ci)
+	{
+		if ((ci->values_num != 2)
+				|| (ci->values[0].type != OCONFIG_TYPE_STRING)
+				|| (ci->values[1].type != OCONFIG_TYPE_STRING)) {
+			ERROR("grpc: The `%s` config option needs exactly "
+					"two string argument (address and port).", ci->key);
 			return -1;
 		}
-		listeners = listener;
-		listener = listeners + listeners_num;
-		listeners_num++;
 
-		listener->addr = strdup(ci->values[0].value.string);
-		listener->port = strdup(ci->values[1].value.string);
+		grpc::SslCredentialsOptions ssl_opts;
+		bool use_ssl = false;
 
-		for (i = 0; i < ci->children_num; i++) {
+		for (int i = 0; i < ci->children_num; i++) {
 			oconfig_item_t *child = ci->children + i;
-			WARNING("grpc: Option `%s` not allowed in <%s> block.",
-					child->key, ci->key);
+
+			if (!strcasecmp("EnableSSL", child->key)) {
+				if (cf_util_get_boolean(child, &use_ssl)) {
+					return -1;
+				}
+			}
+			else if (!strcasecmp("SSLCACertificateFile", child->key)) {
+				char *certs = NULL;
+				if (cf_util_get_string(child, &certs)) {
+					return -1;
+				}
+				ssl_opts.pem_root_certs = read_file(certs);
+			}
+			else if (!strcasecmp("SSLCertificateKeyFile", child->key)) {
+				char *key = NULL;
+				if (cf_util_get_string(child, &key)) {
+					return -1;
+				}
+				ssl_opts.pem_private_key = read_file(key);
+			}
+			else if (!strcasecmp("SSLCertificateFile", child->key)) {
+				char *cert = NULL;
+				if (cf_util_get_string(child, &cert)) {
+					return -1;
+				}
+				ssl_opts.pem_cert_chain = read_file(cert);
+			}
+			else {
+				WARNING("grpc: Option `%s` not allowed in <%s> block.",
+						child->key, ci->key);
+			}
 		}
 
+		auto node    = grpc::string(ci->values[0].value.string);
+		auto service = grpc::string(ci->values[1].value.string);
+		auto addr    = node + ":" + service;
+
+		CollectdClient *client;
+		if (use_ssl) {
+			auto channel_creds = grpc::SslCredentials(ssl_opts);
+			auto channel = grpc::CreateChannel(addr, channel_creds);
+			client = new CollectdClient(channel);
+		} else {
+			auto channel = grpc::CreateChannel(addr, grpc::InsecureChannelCredentials());
+			client = new CollectdClient(channel);
+		}
+
+		auto callback_name = grpc::string("grpc/") + addr;
+		user_data_t ud = {
+			.data = client,
+			.free_func = c_grpc_destroy_write_callback,
+		};
+
+		plugin_register_write (callback_name.c_str(), c_grpc_write, &ud);
 		return 0;
-	} /* c_grpc_config_listen() */
+	} /* c_grpc_config_server() */
 
 	static int c_grpc_config(oconfig_item_t *ci)
 	{
@@ -405,12 +629,11 @@ extern "C" {
 				if (c_grpc_config_listen(child))
 					return -1;
 			}
-			else if (!strcasecmp("WorkerThreads", child->key)) {
-				int n;
-				if (cf_util_get_int(child, &n))
+			else if (!strcasecmp("Server", child->key)) {
+				if (c_grpc_config_server(child))
 					return -1;
-				workers_num = (size_t)n;
 			}
+
 			else {
 				WARNING("grpc: Option `%s` not allowed here.", child->key);
 			}
@@ -422,47 +645,22 @@ extern "C" {
 	static int c_grpc_init(void)
 	{
 		server = new CollectdServer();
-		size_t i;
-
-		if (! server) {
+		if (!server) {
 			ERROR("grpc: Failed to create server");
 			return -1;
 		}
 
-		workers = (pthread_t *)calloc(workers_num, sizeof(*workers));
-		if (! workers) {
-			delete server;
-			server = nullptr;
-
-			ERROR("grpc: Failed to allocate worker threads");
-			return -1;
-		}
-
 		server->Start();
-		for (i = 0; i < workers_num; i++) {
-			pthread_create(&workers[i], /* attr = */ NULL,
-					worker_thread, server);
-		}
-		INFO("grpc: Started %zu workers", workers_num);
 		return 0;
 	} /* c_grpc_init() */
 
 	static int c_grpc_shutdown(void)
 	{
-		size_t i;
-
 		if (!server)
-			return -1;
+			return 0;
 
 		server->Shutdown();
 
-		INFO("grpc: Waiting for %zu workers to terminate", workers_num);
-		for (i = 0; i < workers_num; i++)
-			pthread_join(workers[i], NULL);
-		free(workers);
-		workers = NULL;
-		workers_num = 0;
-
 		delete server;
 		server = nullptr;