unable to connect to mysql running on my mac - mysql

Question

I am using golang app , wrapped up in a docker container to connect to mysql db running on my localhost(not container). Her eis what I tried:
Docker File
FROM artifactory.cloud.com//golang:1.10-alpine3.7
RUN mkdir -p /go/src/github.kdc.mafsafdfsacys.com/perfGo/
WORKDIR /go/src/github.kdc.mafsafdfsacys.com/perfGo
COPY ./ $WORKDIR
RUN apk update && apk upgrade
RUN go build
RUN chmod +x ./entrypoint.sh
RUN ls
RUN chmod +x ./perfGo
ENTRYPOINT ["./entrypoint.sh"]
perfGo.go
package main
import (
"database/sql"
_ "github.com/go-sql-driver/mysql"
)
func main() {
db, err := sql.Open("mysql", "root:#tcp(localhost:3306)/testdb")
checkErr(err)
_,dbErr := db.Exec("USE testdb")
if err != nil {
panic(dbErr)
}
// insert
_, inErr := db.Query("INSERT INTO books VALUES('rewyrewryewwrewyt','dsfdsfs','fdsfasaf','55')")
defer db.Close()
// if there is an error inserting, handle it
if inErr != nil {
panic(inErr.Error())
}
}
func checkErr(err error) {
if err != nil {
panic(err)
}
}
entrypoint.sh
!/usr/bin/env bash
./perfGo
Command am using to build is
docker build .
command used to run the container:
docker run -p 3306:3306 -ti
The error that I see is
panic: dial tcp 127.0.0.1:3306: connect: connection refused
goroutine 1 [running]:
main.main()
/go/src/github.kdc.capitalone.com/midnight-tokens/perfGo/perf.go:22 +0x1d4
If I run the binary without the container, it runs totally fine on my mac, but when I try to run it as part of docker container, it fails to connect

Answer 1

If the application is running in a container, and the database is on the host, then the address of the database from the container is obviously not localhost (That is the loopback device of the container).
If you are using Docker For Mac, then you can use:
"docker.for.mac.localhost:3306" in place of "localhost:3306"