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index.ts
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import { EventEmitter } from "events";
import { createConnection, TcpNetConnectOpts } from "net";
import { NatMap } from "../../cluster/ClusterOptions";
import {
CONNECTION_CLOSED_ERROR_MSG,
packObject,
sample,
Debug,
} from "../../utils";
import { connect as createTLSConnection, ConnectionOptions } from "tls";
import SentinelIterator from "./SentinelIterator";
import { RedisClient, SentinelAddress, Sentinel } from "./types";
import AbstractConnector, { ErrorEmitter } from "../AbstractConnector";
import { NetStream } from "../../types";
import Redis from "../../Redis";
import { RedisOptions } from "../../redis/RedisOptions";
import { FailoverDetector } from "./FailoverDetector";
const debug = Debug("SentinelConnector");
interface AddressFromResponse {
port: string;
ip: string;
flags?: string;
}
type PreferredSlaves =
| ((slaves: AddressFromResponse[]) => AddressFromResponse | null)
| Array<{ port: string; ip: string; prio?: number }>
| { port: string; ip: string; prio?: number };
export { SentinelAddress, SentinelIterator };
export interface SentinelConnectionOptions {
/**
* Master group name of the Sentinel
*/
name?: string;
/**
* @default "master"
*/
role?: "master" | "slave";
tls?: ConnectionOptions;
sentinelUsername?: string;
sentinelPassword?: string;
sentinels?: Array<Partial<SentinelAddress>>;
sentinelRetryStrategy?: (retryAttempts: number) => number | void | null;
sentinelReconnectStrategy?: (retryAttempts: number) => number | void | null;
preferredSlaves?: PreferredSlaves;
connectTimeout?: number;
disconnectTimeout?: number;
sentinelCommandTimeout?: number;
enableTLSForSentinelMode?: boolean;
sentinelTLS?: ConnectionOptions;
natMap?: NatMap;
updateSentinels?: boolean;
/**
* @default 10
*/
sentinelMaxConnections?: number;
failoverDetector?: boolean;
}
export default class SentinelConnector extends AbstractConnector {
emitter: EventEmitter | null = null;
protected sentinelIterator: SentinelIterator;
private retryAttempts: number;
private failoverDetector: FailoverDetector | null = null;
constructor(protected options: SentinelConnectionOptions) {
super(options.disconnectTimeout);
if (!this.options.sentinels.length) {
throw new Error("Requires at least one sentinel to connect to.");
}
if (!this.options.name) {
throw new Error("Requires the name of master.");
}
this.sentinelIterator = new SentinelIterator(this.options.sentinels);
}
check(info: { role?: string }): boolean {
const roleMatches: boolean = !info.role || this.options.role === info.role;
if (!roleMatches) {
debug(
"role invalid, expected %s, but got %s",
this.options.role,
info.role
);
// Start from the next item.
// Note that `reset` will move the cursor to the previous element,
// so we advance two steps here.
this.sentinelIterator.next();
this.sentinelIterator.next();
this.sentinelIterator.reset(true);
}
return roleMatches;
}
disconnect(): void {
super.disconnect();
if (this.failoverDetector) {
this.failoverDetector.cleanup();
}
}
connect(eventEmitter: ErrorEmitter): Promise<NetStream> {
this.connecting = true;
this.retryAttempts = 0;
let lastError;
const connectToNext = async (): Promise<NetStream> => {
const endpoint = this.sentinelIterator.next();
if (endpoint.done) {
this.sentinelIterator.reset(false);
const retryDelay =
typeof this.options.sentinelRetryStrategy === "function"
? this.options.sentinelRetryStrategy(++this.retryAttempts)
: null;
let errorMsg =
typeof retryDelay !== "number"
? "All sentinels are unreachable and retry is disabled."
: `All sentinels are unreachable. Retrying from scratch after ${retryDelay}ms.`;
if (lastError) {
errorMsg += ` Last error: ${lastError.message}`;
}
debug(errorMsg);
const error = new Error(errorMsg);
if (typeof retryDelay === "number") {
eventEmitter("error", error);
await new Promise((resolve) => setTimeout(resolve, retryDelay));
return connectToNext();
} else {
throw error;
}
}
let resolved: TcpNetConnectOpts | null = null;
let err: Error | null = null;
try {
resolved = await this.resolve(endpoint.value);
} catch (error) {
err = error;
}
if (!this.connecting) {
throw new Error(CONNECTION_CLOSED_ERROR_MSG);
}
const endpointAddress = endpoint.value.host + ":" + endpoint.value.port;
if (resolved) {
debug(
"resolved: %s:%s from sentinel %s",
resolved.host,
resolved.port,
endpointAddress
);
if (this.options.enableTLSForSentinelMode && this.options.tls) {
Object.assign(resolved, this.options.tls);
this.stream = createTLSConnection(resolved);
this.stream.once("secureConnect", this.initFailoverDetector.bind(this));
} else {
this.stream = createConnection(resolved);
this.stream.once("connect", this.initFailoverDetector.bind(this));
}
this.stream.once("error", (err) => {
this.firstError = err;
});
return this.stream;
} else {
const errorMsg = err
? "failed to connect to sentinel " +
endpointAddress +
" because " +
err.message
: "connected to sentinel " +
endpointAddress +
" successfully, but got an invalid reply: " +
resolved;
debug(errorMsg);
eventEmitter("sentinelError", new Error(errorMsg));
if (err) {
lastError = err;
}
return connectToNext();
}
};
return connectToNext();
}
private async updateSentinels(client: RedisClient): Promise<void> {
if (!this.options.updateSentinels) {
return;
}
const result = await client.sentinel("sentinels", this.options.name);
if (!Array.isArray(result)) {
return;
}
result
.map<AddressFromResponse>(
packObject as (value: any) => AddressFromResponse
)
.forEach((sentinel) => {
const flags = sentinel.flags ? sentinel.flags.split(",") : [];
if (
flags.indexOf("disconnected") === -1 &&
sentinel.ip &&
sentinel.port
) {
const endpoint = this.sentinelNatResolve(
addressResponseToAddress(sentinel)
);
if (this.sentinelIterator.add(endpoint)) {
debug("adding sentinel %s:%s", endpoint.host, endpoint.port);
}
}
});
debug("Updated internal sentinels: %s", this.sentinelIterator);
}
private async resolveMaster(
client: RedisClient
): Promise<TcpNetConnectOpts | null> {
const result = await client.sentinel(
"get-master-addr-by-name",
this.options.name
);
await this.updateSentinels(client);
return this.sentinelNatResolve(
Array.isArray(result)
? { host: result[0], port: Number(result[1]) }
: null
);
}
private async resolveSlave(
client: RedisClient
): Promise<TcpNetConnectOpts | null> {
const result = await client.sentinel("slaves", this.options.name);
if (!Array.isArray(result)) {
return null;
}
const availableSlaves = result
.map<AddressFromResponse>(
packObject as (value: any) => AddressFromResponse
)
.filter(
(slave) =>
slave.flags && !slave.flags.match(/(disconnected|s_down|o_down)/)
);
return this.sentinelNatResolve(
selectPreferredSentinel(availableSlaves, this.options.preferredSlaves)
);
}
private sentinelNatResolve(item: SentinelAddress | null) {
if (!item || !this.options.natMap) return item;
return this.options.natMap[`${item.host}:${item.port}`] || item;
}
private connectToSentinel(
endpoint: Partial<SentinelAddress>,
options?: Partial<RedisOptions>
): RedisClient {
const redis = new Redis({
port: endpoint.port || 26379,
host: endpoint.host,
username: this.options.sentinelUsername || null,
password: this.options.sentinelPassword || null,
family:
endpoint.family ||
// @ts-expect-error
("path" in this.options && this.options.path
? undefined
: // @ts-expect-error
this.options.family),
tls: this.options.sentinelTLS,
retryStrategy: null,
enableReadyCheck: false,
connectTimeout: this.options.connectTimeout,
commandTimeout: this.options.sentinelCommandTimeout,
...options,
});
// @ts-expect-error
return redis;
}
private async resolve(
endpoint: Partial<SentinelAddress>
): Promise<TcpNetConnectOpts | null> {
const client = this.connectToSentinel(endpoint);
// ignore the errors since resolve* methods will handle them
client.on("error", noop);
try {
if (this.options.role === "slave") {
return await this.resolveSlave(client);
} else {
return await this.resolveMaster(client);
}
} finally {
client.disconnect();
}
}
private async initFailoverDetector(): Promise<void> {
if (!this.options.failoverDetector) {
return;
}
// Move the current sentinel to the first position
this.sentinelIterator.reset(true);
const sentinels: Sentinel[] = [];
// In case of a large amount of sentinels, limit the number of concurrent connections
while (sentinels.length < this.options.sentinelMaxConnections) {
const { done, value } = this.sentinelIterator.next();
if (done) {
break;
}
const client = this.connectToSentinel(value, {
lazyConnect: true,
retryStrategy: this.options.sentinelReconnectStrategy,
});
client.on("reconnecting", () => {
// Tests listen to this event
this.emitter?.emit("sentinelReconnecting");
});
sentinels.push({ address: value, client });
}
this.sentinelIterator.reset(false);
if (this.failoverDetector) {
// Clean up previous detector
this.failoverDetector.cleanup();
}
this.failoverDetector = new FailoverDetector(this, sentinels);
await this.failoverDetector.subscribe();
// Tests listen to this event
this.emitter?.emit("failoverSubscribed");
}
}
function selectPreferredSentinel(
availableSlaves: AddressFromResponse[],
preferredSlaves?: PreferredSlaves
): SentinelAddress | null {
if (availableSlaves.length === 0) {
return null;
}
let selectedSlave: AddressFromResponse;
if (typeof preferredSlaves === "function") {
selectedSlave = preferredSlaves(availableSlaves);
} else if (preferredSlaves !== null && typeof preferredSlaves === "object") {
const preferredSlavesArray = Array.isArray(preferredSlaves)
? preferredSlaves
: [preferredSlaves];
// sort by priority
preferredSlavesArray.sort((a, b) => {
// default the priority to 1
if (!a.prio) {
a.prio = 1;
}
if (!b.prio) {
b.prio = 1;
}
// lowest priority first
if (a.prio < b.prio) {
return -1;
}
if (a.prio > b.prio) {
return 1;
}
return 0;
});
// loop over preferred slaves and return the first match
for (let p = 0; p < preferredSlavesArray.length; p++) {
for (let a = 0; a < availableSlaves.length; a++) {
const slave = availableSlaves[a];
if (slave.ip === preferredSlavesArray[p].ip) {
if (slave.port === preferredSlavesArray[p].port) {
selectedSlave = slave;
break;
}
}
}
if (selectedSlave) {
break;
}
}
}
// if none of the preferred slaves are available, a random available slave is returned
if (!selectedSlave) {
selectedSlave = sample(availableSlaves);
}
return addressResponseToAddress(selectedSlave);
}
function addressResponseToAddress(input: AddressFromResponse): SentinelAddress {
return { host: input.ip, port: Number(input.port) };
}
function noop(): void {}