Jedis should not require localhost to be resolved so it can run clean in serverless env

[xoraes]

Expected behavior

Jedis should not require localhost to be resolved so it can run clean in serverless env - aws lambda.

Actual behavior

When running jedis on aws lambda, it tries to resolve localhost which is not available in serverless env resulting in a "SEVERE" log output.

Write here what happens instead ...

15:02:45 SEVERE: cant resolve localhost address
15:02:45 java.net.UnknownHostException: ip-10-29-121-116: ip-10-29-121-116: unknown error
15:02:45 at java.net.InetAddress.getLocalHost(InetAddress.java:1505)
15:02:45 at redis.clients.jedis.HostAndPort.getLocalHostQuietly(HostAndPort.java:105)

Steps to reproduce:

Use jedis client in aws lambda to connect to aws redis service endpoint
public class RedisClientDao {

private static JedisPool pool = null;

static {
    String endpoint = Preconditions.checkNotNull((String)Config.get("CACHE_ENDPOINT"));
    JedisPoolConfig poolConfig = new JedisPoolConfig();
    poolConfig.setJmxEnabled(false);
    pool = new JedisPool(poolConfig, endpoint);

}

public static Jedis getRedisClient() {
    return pool.getResource();
}
}

Redis / Jedis Configuration

jedis 2.9.0 running on java 1.8 running on aws lambda connecting to redis 3.2.4

Jedis version:

2.9

Redis version:

3.2.4

Java version:

1.8

[smagellan]

I suppose it is related with #1367, #1099, #1076 and was merged as part of #1342. My proposal is to:

• Introduce HostAndPortBuilder. It should resolve localhost if configured to do so.

or

• Introduce more conditional logic into HostAndPort.parseString, e.g.:

    boolean doLocalhostAliasing = System.getProperty("redis.clients.jedis.doLocalhostAliasing") != null;
    return new HostAndPort( doLocalhostAliasing ? convertHost(host) : host, port);

@marcosnils, @xetorthio, @allanwax any ideas?

[allanwax]

The original intent of the fix I submitted was to resolve the problem of specifying localhost in a cluster. The fix changed localhost to the ip of the localhost so that node information passed around would succeed. Putting a conditional on this is fine with me but may affect testing.

What will the default value of this flag be?

[xoraes]

is there a prior release/version I can use which may not have this issue? This issue is a blocker for me.

[marcosnils]

@xoraes can you try 2.8.x? That release shouldn't have this logic. I'm on vacation atm, I'll check this issue next week

@HeartSaVioR can u take a look if u have some time plz??

[jkrahul]

@marcosnils encountered the same issue. working fine with 2.8.1

[marcosnils]

@jkrahul thx. I'll close this if confirmed it works with 2.8.1

[marcosnils]

Whoops, we need to fix this somehow so it works in future versions. Anyone willing to craft a PR?. I don't have too much time in my hands lately.

[jkrahul]

This error is occurring not just in serverless env (AWS Lambda), but in AWS ec2 instances also.

[marcosnils]

@jkrahul thx for reporting. Any chances you'd like to craft a patch for this?

[allanwax]

@marcosnils I have looked at the way AWS uses REDIS and the few examples that I saw do not use an IP address to set up the connection but instead use an ENDPOINT address. I'd also like to say that I'm not an AWS user.

The examples I saw treat REDIS as a single instance and setting up the Jedis instance looks something like

try (Jedis jedis = new Jedis(Global.CLUSTER_ENDPOINT, 6379, 10000);) {              
    jedis.hset(f.dayOfFile, "content", f.xmlFile);
}

HostAndPort would not seem to be used at all in creating a Jedis instance. Again, this is based upon the limited amount of example code I could find. So using HostAndPort in an AWS context may be meaningless. However that is not to say that it couldn't be.

So along that line of reasoning I've come up with a proposed change to HostAndPort that may make the problem better but not necessarily make the problem go away.

public static String convertHost(String host) {
	try {
		/*
		 * Validate the host name as an IPV4/IPV6 address.
		 * If this is an AWS ENDPOINT it will not parse.
		 * In that case accept host as is.
		 * 
		 * Costs: If this is an IPV4/6 encoding, e.g. 127.0.0.1 then no DNS lookup
		 * is done.  If it is a name then a DNS lookup is done but it is normally cached.
		 * Secondarily, this class is typically used to create a connection once
		 * at the beginning of processing and then not used again.  So even if the DNS
		 * lookup needs to be done then the cost is miniscule.
		 */
		InetAddress inetAddress = InetAddress.getByName(host);

		// isLoopbackAddress() handles both IPV4 and IPV6
		if (inetAddress.isLoopbackAddress() || host.equals("0.0.0.0") || host.startsWith("169.254"))
			return LOCALHOST_STR;
		else
			return host;
	}
	catch (Exception e) {
		// Not a valid IP address
		log.logp(Level.WARNING, HostAndPort.class.getName(), "convertHost", "'" + host + "' is not a valid IP address", e);
		return host;
	}
}

This basically 'punts' on ENDPOINT addresses and handles IP addresses in the normal way. It does not change the value of LOCALHOST_STR but perhaps a method should be added: setLocalhost(String localhost)

[jkrahul]

@marcosnils @allanwax Along with this, Lazy resolution of static variable LOCALHOST_STR should be done to avoid the exception in the first place.

[allanwax]

Something like this maybe

...
protected static String localhost = null;
...
// isLoopbackAddress() handles both IPV4 and IPV6
		if (inetAddress.isLoopbackAddress() || host.equals("0.0.0.0") || host.startsWith("169.254"))
			return getLocalhost();
		else
			return host;
...
public static void setLocalhost(String localhost) {
    this.localhost = localhost;
}

public static String getLocalhost() {
    if (localhost != null) {
        return localhost;
    }
    else {
        return localhost = getLocalHostQuietly();
    }
}
...

[marcosnils]

@allanwax @jkrahul thx the feedback. I don't have time to craft a PR currently. I hope @jkrahul has some time to do it soon.