Can't connect to Mongo Cloud mongodb Database in Golang on Ubuntu

Question

I have this Go Code to connect to my Mongo Cloud Database:

func connectToDataBase() {
    ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
    defer cancel()
    client, err := mongo.Connect(ctx, options.Client().ApplyURI(dbURL))
    if err != nil {
        log.Fatal("Error connecting to Database: ", err.Error())
    }
    DB = client.Database("storyfactory")
}

I already ran this code on a Windows machine, and it worked. Now I tried to run it on ubuntu, and I get following error:

2019/04/13 00:20:37 Error connecting to Database: error parsing uri (mongodb+srv://User:[email protected]/test?retryWrites=true): lookup cluster0-gpxjk.gcp.mongodb.net on 127.0.0.53:53: cannot unmarshal DNS message
exit status 1

I don't know, why it worked on windows, and now it doesn't on ubuntu.
Thanks for your help!

Answer 1

cannot unmarshal DNS message

This is not quite related to MongoDB Go driver.

There is a patch in Go version 1.11.x #10622 net: target domain names in SRV records should not be compressed that tighten the way SRV records are read to follow RFC-2782.

If an authoritative DNS server (non-compliantly) sends an SRV records using domain name compression, the net.lookupSRV() will throw an error with cannot unmarshal DNS message (net/lookup_unix.go#L130). For example, the embedded Docker DNS maybe doing the server name compression.

The workarounds for Go v1.11 are:

• Use the non-SRV MongoDB URI
• Update the content of /etc/resolv.conf by replacing the nameserver to use a compliant and/or public DNS server i.e. 1.1.1.1 or 8.8.8.8

See also GODRIVER-829