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Service for batching and relaying metric traffic to Wavefront
package com.wavefront.agent.channel;
import com.fasterxml.jackson.databind.JsonNode;
import com.github.benmanes.caffeine.cache.Caffeine;
import com.github.benmanes.caffeine.cache.LoadingCache;
import com.google.common.base.Throwables;
import com.wavefront.agent.SharedMetricsRegistry;
import com.wavefront.common.TaggedMetricName;
import com.yammer.metrics.Metrics;
import com.yammer.metrics.core.Counter;
import com.yammer.metrics.core.MetricName;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpHeaderValues;
import io.netty.handler.codec.http.HttpMessage;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpUtil;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.util.CharsetUtil;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
/**
* A collection of helper methods around Netty channels.
*
* @author [email protected]
*/
public abstract class ChannelUtils {
private static final Map> RESPONSE_STATUS_CACHES =
new ConcurrentHashMap<>();
/**
* Create a detailed error message from an exception, including current handle (port).
*
* @param message the error message
* @param e the exception (optional) that caused the error
* @param ctx ChannelHandlerContext (optional) to extract remote client ip
* @return formatted error message
*/
public static String formatErrorMessage(
final String message,
@Nullable final Throwable e,
@Nullable final ChannelHandlerContext ctx) {
StringBuilder errMsg = new StringBuilder(message);
if (ctx != null) {
errMsg.append("; remote: ");
errMsg.append(getRemoteName(ctx));
}
if (e != null) {
errMsg.append("; ");
errMsg.append(errorMessageWithRootCause(e));
}
return errMsg.toString();
}
/**
* Writes HTTP response back to client.
*
* @param ctx Channel handler context
* @param status HTTP status to return with the response
* @param contents Response body payload (JsonNode or CharSequence)
* @param request Incoming request (used to get keep-alive header)
*/
public static void writeHttpResponse(
final ChannelHandlerContext ctx,
final HttpResponseStatus status,
final Object /* JsonNode | CharSequence */ contents,
final HttpMessage request) {
writeHttpResponse(ctx, status, contents, HttpUtil.isKeepAlive(request));
}
/**
* Writes HTTP response back to client.
*
* @param ctx Channel handler context
* @param status HTTP status to return with the response
* @param contents Response body payload (JsonNode or CharSequence)
* @param keepAlive Keep-alive requested
*/
public static void writeHttpResponse(
final ChannelHandlerContext ctx,
final HttpResponseStatus status,
final Object /* JsonNode | CharSequence */ contents,
boolean keepAlive) {
writeHttpResponse(ctx, makeResponse(status, contents), keepAlive);
}
/**
* Writes HTTP response back to client.
*
* @param ctx Channel handler context.
* @param response HTTP response object.
* @param request HTTP request object (to extract keep-alive flag).
*/
public static void writeHttpResponse(
final ChannelHandlerContext ctx, final HttpResponse response, final HttpMessage request) {
writeHttpResponse(ctx, response, HttpUtil.isKeepAlive(request));
}
/**
* Writes HTTP response back to client.
*
* @param ctx Channel handler context.
* @param response HTTP response object.
* @param keepAlive Keep-alive requested.
*/
public static void writeHttpResponse(
final ChannelHandlerContext ctx, final HttpResponse response, boolean keepAlive) {
getHttpStatusCounter(ctx, response.status().code()).inc();
// Decide whether to close the connection or not.
if (keepAlive) {
// Add keep alive header as per:
// - http://www.w3.org/Protocols/HTTP/1.1/draft-ietf-http-v11-spec-01.html#Connection
response.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
ctx.write(response);
} else {
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
}
}
/**
* Create {@link FullHttpResponse} based on provided status and body contents.
*
* @param status response status.
* @param contents response body.
* @return http response object
*/
public static HttpResponse makeResponse(
final HttpResponseStatus status, final Object /* JsonNode | CharSequence */ contents) {
final FullHttpResponse response;
if (contents instanceof JsonNode) {
response =
new DefaultFullHttpResponse(
HttpVersion.HTTP_1_1,
status,
Unpooled.copiedBuffer(contents.toString(), CharsetUtil.UTF_8));
response.headers().set(HttpHeaderNames.CONTENT_TYPE, HttpHeaderValues.APPLICATION_JSON);
} else if (contents instanceof CharSequence) {
response =
new DefaultFullHttpResponse(
HttpVersion.HTTP_1_1,
status,
Unpooled.copiedBuffer((CharSequence) contents, CharsetUtil.UTF_8));
response.headers().set(HttpHeaderNames.CONTENT_TYPE, HttpHeaderValues.TEXT_PLAIN);
} else {
throw new IllegalArgumentException(
"Unexpected response content type, JsonNode or "
+ "CharSequence expected: "
+ contents.getClass().getName());
}
response.headers().set(HttpHeaderNames.CONTENT_LENGTH, response.content().readableBytes());
return response;
}
/**
* Write detailed exception text.
*
* @param e Exceptions thrown
* @return error message
*/
public static String errorMessageWithRootCause(@Nonnull final Throwable e) {
StringBuilder msg = new StringBuilder();
final Throwable rootCause = Throwables.getRootCause(e);
msg.append("reason: \"");
msg.append(e.getMessage());
msg.append("\"");
if (rootCause != null && rootCause != e && rootCause.getMessage() != null) {
msg.append(", root cause: \"");
msg.append(rootCause.getMessage());
msg.append("\"");
}
return msg.toString();
}
/**
* Get remote client's address as string (without rDNS lookup) and local port
*
* @param ctx Channel handler context
* @return remote client's address in a string form
*/
@Nonnull
public static String getRemoteName(@Nullable final ChannelHandlerContext ctx) {
if (ctx != null) {
InetAddress remoteAddress = getRemoteAddress(ctx);
InetSocketAddress localAddress = (InetSocketAddress) ctx.channel().localAddress();
if (remoteAddress != null && localAddress != null) {
return remoteAddress.getHostAddress() + " [" + localAddress.getPort() + "]";
}
}
return "";
}
/**
* Get {@link InetAddress} for the current channel.
*
* @param ctx Channel handler's context.
* @return remote address
*/
public static InetAddress getRemoteAddress(@Nonnull ChannelHandlerContext ctx) {
InetSocketAddress remoteAddress = (InetSocketAddress) ctx.channel().remoteAddress();
return remoteAddress == null ? null : remoteAddress.getAddress();
}
/**
* Get a counter for ~proxy.listeners.http-requests.status.###.count metric for a specific status
* code, with port= point tag for added context.
*
* @param ctx channel handler context where a response is being sent.
* @param status response status code.
*/
public static Counter getHttpStatusCounter(ChannelHandlerContext ctx, int status) {
if (ctx != null && ctx.channel() != null) {
InetSocketAddress localAddress = (InetSocketAddress) ctx.channel().localAddress();
if (localAddress != null) {
return RESPONSE_STATUS_CACHES
.computeIfAbsent(
localAddress.getPort(),
port ->
Caffeine.newBuilder()
.build(
statusCode ->
Metrics.newCounter(
new TaggedMetricName(
"listeners",
"http-requests.status." + statusCode + ".count",
"port",
String.valueOf(port)))))
.get(status);
}
}
// return a non-reportable counter otherwise
return SharedMetricsRegistry.getInstance().newCounter(new MetricName("", "", "dummy"));
}
}
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