Synology NAS DS218 docker issue causes 'DNS not available'

It seems that after DSM 7.2 update for DS218, docker containers cannot access the internet and hence pihole+unbound container startup fails with DNS not available.

I modified the following files to directly use host networking instead, which fixes this problem. Just make sure nothing is running natively on ports 8000 and 5443. Also, don't forget to add exception to these ports in Control Panel->Security->Firewall. Don't handle DHCP here.

My docker-compose.yaml was:

version: '3'

services:
  pihole:
    container_name: pihole
    image: cbcrowe/pihole-unbound:latest
    hostname: ${HOSTNAME}
    domainname: ${DOMAIN_NAME}
    network_mode: host
    dns:
      - "127.0.0.1"
    environment:
      - FTLCONF_LOCAL_IPV4=${FTLCONF_LOCAL_IPV4}
      - TZ=${TZ:-UTC}
      - WEBPASSWORD="${WEBPASSWORD}"
      - WEBTHEME=${WEBTHEME:-default-light}
      - REV_SERVER=${REV_SERVER:-false}
      - REV_SERVER_TARGET=${REV_SERVER_TARGET}
      - REV_SERVER_DOMAIN=${REV_SERVER_DOMAIN}
      - REV_SERVER_CIDR=${REV_SERVER_CIDR}
      - PIHOLE_DNS_=127.0.0.1#5335
      - DNSSEC="true"
      - DNSMASQ_LISTENING=single
    volumes:
      - ./etc-pihole:/etc/pihole:rw
      - ./etc-dnsmasq.d:/etc/dnsmasq.d:rw
      - ./lighttpd.conf:/etc/lighttpd/lighttpd.conf:rw
    restart: unless-stopped

Create a lighttpd.conf file (only change made is server.port = 8000 which should match PIHOLE_WEBPORT in your .env file) in the same path:

server.modules = (
        "mod_indexfile",
        "mod_access",
        "mod_alias",
        "mod_redirect",
)

server.document-root        = "/var/www/html"
server.upload-dirs          = ( "/var/cache/lighttpd/uploads" )
server.errorlog             = "/var/log/lighttpd/error.log"
server.pid-file             = "/run/lighttpd.pid"
server.username             = "www-data"
server.groupname            = "www-data"
server.port                 = 8000

# features
#https://redmine.lighttpd.net/projects/lighttpd/wiki/Server_feature-flagsDetails
server.feature-flags       += ("server.h2proto" => "enable")
server.feature-flags       += ("server.h2c"     => "enable")
server.feature-flags       += ("server.graceful-shutdown-timeout" => 5)
#server.feature-flags       += ("server.graceful-restart-bg" => "enable")

# strict parsing and normalization of URL for consistency and security
# https://redmine.lighttpd.net/projects/lighttpd/wiki/Server_http-parseoptsDetails
# (might need to explicitly set "url-path-2f-decode" = "disable"
#  if a specific application is encoding URLs inside url-path)
server.http-parseopts = (
  "header-strict"           => "enable",# default
  "host-strict"             => "enable",# default
  "host-normalize"          => "enable",# default
  "url-normalize-unreserved"=> "enable",# recommended highly
  "url-normalize-required"  => "enable",# recommended
  "url-ctrls-reject"        => "enable",# recommended
  "url-path-2f-decode"      => "enable",# recommended highly (unless breaks app)
 #"url-path-2f-reject"      => "enable",
  "url-path-dotseg-remove"  => "enable",# recommended highly (unless breaks app)
 #"url-path-dotseg-reject"  => "enable",
 #"url-query-20-plus"       => "enable",# consistency in query string
)

index-file.names            = ( "index.php", "index.html" )
url.access-deny             = ( "~", ".inc" )
static-file.exclude-extensions = ( ".php", ".pl", ".fcgi" )

# default listening port for IPv6 falls back to the IPv4 port
include_shell "/usr/share/lighttpd/use-ipv6.pl " + server.port
include_shell "/usr/share/lighttpd/create-mime.conf.pl"
include "/etc/lighttpd/conf-enabled/*.conf"

#server.compat-module-load   = "disable"
server.modules += (
        "mod_dirlisting",
        "mod_staticfile",
)

Web interface's (at port 8000) password needs to be set with pihole -a -p even though WEBPASSWORD is set. Not sure why.

chriscrowe / docker-pihole-unbound

Synology NAS DS218 docker issue causes 'DNS not available' #237