From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/11954 Path: news.gmane.org!.POSTED!not-for-mail From: Srinivasa Raghavan Newsgroups: gmane.linux.lib.musl.general Subject: DNS resolution happenning only after timeout Date: Thu, 28 Sep 2017 15:45:28 +0530 Message-ID: Reply-To: musl@lists.openwall.com NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="001a11407ab80effa1055a3d30c4" X-Trace: blaine.gmane.org 1506593746 22026 195.159.176.226 (28 Sep 2017 10:15:46 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 28 Sep 2017 10:15:46 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-11967-gllmg-musl=m.gmane.org@lists.openwall.com Thu Sep 28 12:15:41 2017 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by blaine.gmane.org with smtp (Exim 4.84_2) (envelope-from ) id 1dxVr2-0005KD-8k for gllmg-musl@m.gmane.org; Thu, 28 Sep 2017 12:15:40 +0200 Original-Received: (qmail 3191 invoked by uid 550); 28 Sep 2017 10:15:42 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 3149 invoked from network); 28 Sep 2017 10:15:41 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=N0dlkRIMz1WMGBTtu2ThtcldASAaNRailQMh18Tt7yA=; b=BTs73UVvG7f8dvtkDTGyW99H6UnIOOuYEzxJYNSums4oAgEldm6hXtEyaVzOtBKD7b oRZ8LADpLtPLK2LJDs2bxI4A+bugNj2RXStjuznujgnEwI2bZCPNRanhJ6iQ2Bd7Wuqc UUtExqLvXy+aHwztTMAVTYGXQZj8WV7xg5J5/fJNYsRGWL99BNt0G5z8RK5S61/x8FS1 +kwrBnYSgVZfmmEXB/LjunzIYo6Wzhcl0czUKm1ygykYTD920ZTH67cm1RzriC52Ejv6 8Z3kiRoM6GAHQ4f5LkVxLznI4GTG8tWtyvbZ33kOHaSl6bXbCO0luY/lGpuH11vAjexS xjsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=N0dlkRIMz1WMGBTtu2ThtcldASAaNRailQMh18Tt7yA=; b=KHpXB8V6sYpsWV2+Fd7p5ELPJCPl9kgnFXNgSiI0vjVyQr7PfuWZ+jQ8rPsfQNNpUN QK1sozq19b/wkFYltxkBN6+Y890egpIGGrOzhn0xqGR910mJeRExpuXZ7fVwQirY1FTy z6DiYFOtDNUwQEyQ4GWjDjgKHur3l90SdGGvxpYZd0lKhPWAj+gYGzQjRz6OVUV4mj7f doHlfuWfJwlWaiTI8FSq3iu9Z5DZ/3KHQGj6wPiLH+OXHU5a5EsIwq2BCSnqjxjmC5yA Gx/t8m3Yk+8mwODygyWTUWOvW4G1uF4TPw/4Znm/aXhdrn7+G/d6/spXYxVpjZqd+QUM SzGA== X-Gm-Message-State: AHPjjUgQs1fyGCbgAcLillvLEg7GNOgHEKgxdL1FD9al/jRBqJY08WXO pqiET4HaO/DACO3DORMtaCdDzLa5ncaoHZNZB4Q= X-Google-Smtp-Source: AOwi7QCdhcZjTK2U8HumwL8xKzCQ5wlmDWXrZ96LGDWSI44XFRk7UkBp4edRjRTTRgAXchxERCWwa5QEpKpkHvtsAR0= X-Received: by 10.129.48.198 with SMTP id w189mr2977469yww.116.1506593729336; Thu, 28 Sep 2017 03:15:29 -0700 (PDT) Xref: news.gmane.org gmane.linux.lib.musl.general:11954 Archived-At: --001a11407ab80effa1055a3d30c4 Content-Type: multipart/alternative; boundary="001a11407ab80eff9c055a3d30c2" --001a11407ab80eff9c055a3d30c2 Content-Type: text/plain; charset="UTF-8" Hi, When using "Alpine" docker image which uses musl-libc, we are facing delay when we do operations like below in our production environment, 1. ping 2. nslookup 3. traceroute 4. http request from node.js There is a 5 second delay in name resolution, and then the above command returns the response. The same problem does not occur in "debian" docker image (which uses GNU libc). In our case, there is a combination of SERVFAIL, "canonical name" along with "Non authoritative answer". Some learnings after doing some trial and error: 1. If I install "bind-tools" package in alpine, the "nslookup" happens without delay. 2. If I set "options timout:1" in /etc/resolv.conf , then the name is resolved after 1 second (instead of 5 seconds). 3. Whatever I change in /etc/resolv.conf (Like setting "domain", "search"), there was no benefit. 4. output of "host"/"nslookup" command shows "SERVFAIL" 5. The problem does not occur if run from the host machine (Not from alpine container). 6. The problem does not occur if run from another container which uses Gnu libc, like "Debian" image. Sample command outputs attached for reference. Request you to kindly help in debugging / resolution of this. Kind Regards, R. Srinivasa Raghavan. --001a11407ab80eff9c055a3d30c2 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi,

When using "Alpine" docker imag= e which uses musl-libc, we are facing delay when we do operations like belo= w in our production environment,=C2=A0
1. ping <name>
2. nslookup <name>
3. traceroute <name>
4. http request from node.js

There is a 5 se= cond delay in name resolution, and then the above command returns the respo= nse. The same problem does not occur in "debian" docker image (wh= ich uses GNU libc).

In our case, there is a = combination of SERVFAIL, "canonical name" along with "Non au= thoritative answer".

Some learnings after doi= ng some trial and error:
1. If I install "bind-tools" p= ackage in alpine, the "nslookup" happens without delay.
2. If I set "options timout:1" in /etc/resolv.conf , then the na= me is resolved after 1 second (instead of 5 seconds).
3. Whatever= I change in /etc/resolv.conf (Like setting "domain", "searc= h"), there was no benefit.
4. output of "host"/&qu= ot;nslookup" command shows "SERVFAIL"
5. The probl= em does not occur if run from the host machine (Not from alpine container).=
6. The problem does not occur if run from another container whic= h uses Gnu libc, like "Debian" image.

Sa= mple command outputs attached for reference.

Reque= st you to kindly help in debugging / resolution of this.=C2=A0
Kind Regards,
R. Srinivasa Raghavan.
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