Add bind-tools to base image to address alpine dns issues

[chrisbennight]

Any chance of including bind-tools as one of the apks in the dockerfile? ref: https://github.com/nodejs/docker-node/issues/339

It only adds ~1MB and addresses alpine DNS resolution issues

Specifically when I have multiple networks I can't get container names to resolve in the docker-db-backup image. exec'ing in and running apk update && apk add bind-tools fixes it.

Happy to submit a PR, just wanted to see if there was a willingness first.

[tiredofit]

Interesting that you are having DNS issues within the container. I run this image on a variety of Linux hosts and the majority of my images are alpine based and haven't run into it. Whats your host OS?

I typically also use a multi network configuration within the docker stack using the bridge driver.

[chrisbennight]

Ubuntu 22.04.5, though on kernel 6.8

Example below - 172.30.0.2 is the right answer, the first nslookup is for some reason skipping docker resolution (192.168.0.20 was returned because I have a wildcard in dnsmasq on my dns server).

[tiredofit/db-backup:4.1.4 23:38:34 /] $ nslookup obslivesync
Server:         127.0.0.11
Address:        127.0.0.11:53

** server can't find obslivesync.tailb(...).ts.net: NXDOMAIN

** server can't find obslivesync.tailb(...).ts.net: NXDOMAIN

Non-authoritative answer:

Non-authoritative answer:
Name:   obslivesync.domain.tld
Address: 192.168.0.20

[tiredofit/db-backup:4.1.4 23:38:49 /] $ apk update && apk add bind-tools
fetch https://dl-cdn.alpinelinux.org/alpine/v3.20/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/v3.20/community/x86_64/APKINDEX.tar.gz
v3.20.3-171-ge0d8a949f52 [https://dl-cdn.alpinelinux.org/alpine/v3.20/main]
v3.20.3-170-gb7926213bd4 [https://dl-cdn.alpinelinux.org/alpine/v3.20/community]
OK: 24186 distinct packages available
(1/6) Installing fstrm (0.6.1-r4)
(2/6) Installing json-c (0.17-r0)
(3/6) Installing protobuf-c (1.5.0-r0)
(4/6) Installing libuv (1.48.0-r0)
(5/6) Installing bind-libs (9.18.27-r0)
(6/6) Installing bind-tools (9.18.27-r0)
Executing busybox-1.36.1-r29.trigger
OK: 725 MiB in 188 packages
[tiredofit/db-backup:4.1.4 23:39:34 /] $ nslookup obslivesync
Server:         127.0.0.11
Address:        127.0.0.11#53

Non-authoritative answer:
Name:   obslivesync
Address: 172.30.0.2

[tiredofit/db-backup:4.1.4 23:39:38 /] $ 

that said, my solution doesn't completely fix things; nslookup and ping now resolve fine, but curl still has issues:

[tiredofit/db-backup:4.1.4 23:39:38 /] $ curl obslivesync:5984
curl: (7) Failed to connect to obslivesync port 5984 after 5 ms: Could not connect to server
[tiredofit/db-backup:4.1.4 23:43:37 /] $ ping obslivesync
PING obslivesync (172.30.0.2) 56(84) bytes of data.
64 bytes from obslivesync.obsidian-livesync_obsidian (172.30.0.2): icmp_seq=1 ttl=64 time=0.117 ms
64 bytes from obslivesync.obsidian-livesync_obsidian (172.30.0.2): icmp_seq=2 ttl=64 time=0.064 ms
64 bytes from obslivesync.obsidian-livesync_obsidian (172.30.0.2): icmp_seq=3 ttl=64 time=0.060 ms
64 bytes from obslivesync.obsidian-livesync_obsidian (172.30.0.2): icmp_seq=4 ttl=64 time=0.063 ms
64 bytes from obslivesync.obsidian-livesync_obsidian (172.30.0.2): icmp_seq=5 ttl=64 time=0.049 ms
^C
--- obslivesync ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4107ms
rtt min/avg/max/mdev = 0.049/0.070/0.117/0.023 ms
[tiredofit/db-backup:4.1.4 23:43:55 /] $ curl obslivesync:5984
curl: (7) Failed to connect to obslivesync port 5984 after 4 ms: Could not connect to server
[tiredofit/db-backup:4.1.4 23:44:04 /] $ curl 172.30.0.2:5984
{"error":"unauthorized","reason":"Authentication required."}
[tiredofit/db-backup:4.1.4 23:44:21 /] 

nothing fancy in the docker compose

services:
  obslivesync:
    image: couchdb:latest
    container_name: obslivesync
    user: 1000:1000
    networks:
      - t3_proxy
      - obsidian
    environment:
      - COUCHDB_USER=...
      - COUCHDB_PASSWORD=...
    volumes:
      - "cdb-data:/opt/couchdb/data"
      - "cdb-config:/opt/couchdb/etc/local.d"
    restart: unless-stopped
    labels:
      - "com.centurylinklabs.watchtower.enable=true"
      - "traefik.enable=true"
      - "traefik.http.routers.obsidian-rtr.entrypoints=websecure"
      - "traefik.http.routers.obsidian-rtr.rule=Host(`obsync.domain.tld`)" 
      - "traefik.http.routers.obsidian-rtr.middlewares=secured@file"
      - "traefik.http.routers.obsidian-rtr.service=obsidian-svc"
      - "traefik.http.services.obsidian-svc.loadbalancer.server.port=5984"

  obs_db_backup:
    container_name: obs_db_backup
    image: tiredofit/db-backup
    networks:
      - obsidian
    depends_on:
      - obslivesync
    volumes:
      - obs-db-backup:/backup
    environment:
      - DB01_TYPE=couch
      - DB01_HOST=obslivesync
      - DB01_NAME=obsync
      - DB01_USER=...
      - DB01_PORT=5984
      - DB01_PASS=...
      - DB01_DUMP_FREQ=720          
      - DB01_CLEANUP_TIME=72000     
      - DEFAULT_CHECKSUM=SHA1
      - DEFAULT_COMPRESSION=GZ
      - DB01_SPLIT_DB=true
      - CONTAINER_ENABLE_MONITORING=FALSE
    restart: unless-stopped
    labels:
      - "com.centurylinklabs.watchtower.enable=true"

networks:
  t3_proxy:
    external: true
  obsidian:

volumes:
(...)

feels like #muslc/alpine things to me, not docker-db-backup issues. just manually setting private ip's for now

[chrisbennight]

aha, yep, alpine things - https://github.com/gliderlabs/docker-alpine/issues/574#issuecomment-1879741479

adding a . at the end also results in correct resolution without adding bindtools - obslivesync.

[tiredofit]

Musl has some interesting issues that creep up under certain environments for sure.

You can try adding CONTAINER_POST_INIT_COMMAND="apk update ; apk add bind-tools" which might help you? I built a couple weird things into the base image to execute commands after init for precisely this purpose without having to muck about with forking/running your own version of image or putting too many more utils in the base image.

There is another one that allows you to execute a script, although that will require you to export a volume with said script. The command above should work, if not try without the quotes..

Reference: https://github.com/tiredofit/docker-alpine?tab=readme-ov-file#container-options

Maybe related - Also, I saw a ts.net in the above output. I wonder if that is overriding things as it's known to have its own resolver I think at 100.100.100.53 if I recall correctly. Has been a while since I have run ts. Newer unreleased images of my base have TS baked right in..