CODEWITHSUNDEEP
mysqlrdocker
Hanjo Odendaal
Hanjo Odendaal

Reputation: 1431

connect to host mysql database from inside rstudio docker

I have set up Rstudio as a container on a server using a Rocker image. My MySQL instance is not in a docker and is running on the host machine. The db is a production database - so to dockerise the db as well isn't an option.

Can I connect to the host MySQL from inside the docker container running RStudio? The RStudio container runs perfectly, its just when I try and connect to the 'outside' MySQL to write data to db that I get a problem.

Currently trying with R just hanging in the end:

library(RMySQL)
library(DBI)
  db_user <- Sys.getenv("server_user")
  db_password <- Sys.getenv("server_pass")
  db_host <- '172.17.0.1' # docker ip
  db_dbname <- "test"

  mydb <-
    dbConnect(
      MySQL(),
      user = db_user,
      password = db_password,
      dbname = db_dbname,
      host = db_host, 
      port = 3306
    )
Error in .local(drv, ...) : 
  Failed to connect to database: Error: Can't connect to MySQL server on '172.17.0.1' (107)

UPDATE, hack solution:

Wanting to keep the container running with all the port mapping I ended up adding a rule to the iptables and connecting to the database as if I was connecting to it from another server:

sudo iptables -I INPUT 5 -p tcp -s 172.17.0.2 --dport 3306 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT -m comment --comment "docker DB access"

I also created a special docker user in MySQL that can access database:

CREATE USER 'docker'@'172.17.0.2' IDENTIFIED BY 'XXX';
GRANT SELECT, INSERT, CREATE ON *.* 'docker'@'172.17.0.2' IDENTIFIED BY 'XXX';

Although its a bit of a hack, I avoid all the problems that come with --net='host'

Upvotes: 2

Views: 907

Answers (1)

Frank AK
Frank AK

Reputation: 1781

Yes. You can run your image as host mode.

docker run --net="host" ...

If you use host mode, mean you can't listen the same port in your container, because that will cause port already bind error.

When you run your container as host mode, you can visit your Host's server. Here is MySQL with 127.0.0.1 instead of 172.17.0.1.

Upvotes: 1

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