R/docker.R

In stix-global/eutradeflows: Download bilateral trade flow data from Eurostat Comext

#' Open a RMySQL database connection inside a docker container
#' 
#' Facilitate connection to a docker container reunning a mysql database
#' between inside the docker container
#' Connection parameters are passed as environment variables to 
#' the docker container. Use these to create a RMySQL connection object.
#' Note on password files 
#' Such files are only available containers started in swarm mode (docker stack deploy)
#' Use the environment variable envpassword = "HARVESTER_DB_PASSWORD_FILE" to pass a file
#' otherwise use HARVESTER_DB_PASSWORD to pass the password directly.
#' @param envhost name of the environment variable that contains the db host name
#' @param envuser name of the environment variable that contains the user name
#' @param envpassword name of the environment variable that contains the password
#' @return a RMySQL connection object.
#' HARVESTER_DB_HOST: tradeflowsdb:3306
#' HARVESTER_DB_USER: R
#' HARVESTER_DB_PASSWORD_FILE: /run/secrets/db_password
#' @export
dbconnectdocker <- function(dbname = "tradeflows",
                            envuser = "HARVESTER_DB_USER",
                            envpassword = "HARVESTER_DB_PASSWORD",
                            envhost = "HARVESTER_DB_HOST", 
                            envport = "HARVESTER_DB_PORT"){
   # If the password is contained in a secret file, read that file
   if(envpassword == "HARVESTER_DB_PASSWORD_FILE"){
       password <- readLines(Sys.getenv("HARVESTER_DB_PASSWORD_FILE"))
   } else {
       password <- Sys.getenv(envpassword)
   }
    con <- RMariaDB::dbConnect(RMariaDB::MariaDB(), 
                             dbname = dbname,
                             username = Sys.getenv(envuser),
                             password = password,
                             host = Sys.getenv(envhost),
                             port = as.integer(Sys.getenv(envport)))
    return(con)
}