Access host database from a docker container

Question

If I have a mysql database running on some host machine  and that host is also running a docker container  How would I access the mysql database from within the docker container that is running on the host    For instance  is there a way to publish a hosts port to the container  the inverse of what docker run -p does

User · Answer

From Docker 17 06 onwards  a special Mac-only DNS name is available in docker containers that resolves to the IP address of the host  It is   docker for mac localhost  The documentation is here  https   docs docker com docker-for-mac networking  httphttps-proxy-support

User · Answer

Use host docker internal from Docker 18 03 onwards

User · Answer

From the 18 03 docs   I want to connect from a container to a service on the host The host has a changing IP address  or none if you have no network access   From 18 03 onwards our recommendation is to connect to the special DNS name host docker internal  which resolves to the internal IP address used by the host  The gateway is also reachable as gateway docker internal   EXAMPLE  Here s what I use for my MySQL connection string inside my container to access the MySQL instance on my host  mysql   host docker internal 3306 my awesome database

User · Answer

Other answers did not work well for me  My container could not resolve host ip using host docker internal  There are two ways   Sharing host network --net host   docker run -it --net host  myimage  Using docker s ip address  which is usually 172 17 0 1   You can check it by calling ifconfig command and grabbing inet addr of docker interface  user ubuntu    ifconfig docker0   Link encap Ethernet  HWaddr 02 42 a4 a2 b2 f1     inet addr 172 17 0 1  Bcast 0 0 0 0  Mask 255 255 0 0   inet6 addr  fe80  42 a4ff fea2 b2f1 64 Scope Link    Once you have this ip address  you can pass it as an argument to docker run and then to application or as I do it  map the location of jdbc properties via volume to the directory on host machine  so you can manage the file externally     docker run -it -v  host dir docker jdbc config   jetty base  var config myimage   NOTE  Your database might not allow external connections  In case of postgresql  you need to edit 2 files  as described here and here    Edit postgresql conf to listen on all addresses  By default it will point to localhost   listen addresses        Edit pg hba conf to allow connections from all addresses  Add on the last line   host     all             all             0 0 0 0 0               md5    IMPORTANT  Last step updating database access is not recommended for production use unless you are really sure what you are doing

User · Answer

If you want access to a Docker container where there is a DB  you have to add a bash  docker exec -it postgresql bash  postgresql is the container name  Once inside  from the bash  access to DB e g   psql -U postgres

User · Answer

There are several long standing discussions about how to do this in a consistent  well understood and portable way  No complete resolution but I ll link you to the discussions below   In any event you many want to try using the --add-host option to docker run to add the ip address of the host into the container s  etc host file  From there it s trivial to connect to the host on any required port      Adding entries to a container hosts file      You can add other hosts into a container s  etc hosts file by using   one or more --add-host flags  This example adds a static address for a   host named docker      docker run --add-host docker 10 180 0 1 --rm -it debian        ping docker     PING docker  10 180 0 1   48 data bytes     56 bytes from 10 180 0 1  icmp seq 0 ttl 254 time 7 600 ms     56 bytes from 10 180 0 1  icmp seq 1 ttl 254 time 30 705 ms      C--- docker ping statistics ---     2 packets transmitted  2 packets received  0  packet loss     round-trip min avg max stddev   7 600 19 152 30 705 11 553 ms       Note  Sometimes you need to connect to the Docker host  which means   getting the IP address of the host  You can use the following shell   commands to simplify this process      alias hostip  ip route show 0 0 0 0 0   grep -Eo  via  S     awk    print  2        docker run  --add-host docker   hostip  --rm -it debian    Documentation   https   docs docker com engine reference commandline run   Discussions on accessing host from container   https   github com docker docker issues 1143  https   github com docker docker issues 10023

[docker] Access host database from a docker container

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