Gorm + Docker error while connection - postgresql

Question

I trying connection to my postgresql database with Docker:
package main
import (
"fmt"
"log"
"github.com/jinzhu/gorm"
_ "github.com/jinzhu/gorm/dialects/postgres"
)
type Product struct {
gorm.Model
Code string
Price uint
}
var db *gorm.DB
func init() {
connection := fmt.Sprintf("host=db sslmode=disable user=dnz-dev password=dnz-dev")
db, err := gorm.Open("postgres", connection)
if err != nil {
log.Fatalln(err)
}
defer db.Close()
}
func main() {
// Migrate the schema
db.AutoMigrate(&Product{})
}
and docker-compose
version: "3.3"
services:
db:
build: ./dnz-db
container_name: dnz-database
ports:
- "6000:5432"
volumes:
- ./dnz-db/data:/var/lib/postgresql/data
environment:
- POSTGRES_USER=dnz-dev
- POSTGRES_PASSWORD=dnz-dev
api:
build: ./dnz-api
container_name: dnz-api
volumes:
- ./dnz-api:/go/src/app
ports:
- "5000:3000"
depends_on:
- db
I run docker-compose up --build and I get this error:
Attaching to dnz-database, dnz-api dnz-api | 2017/11/05 10:23:46 dial
tcp 172.21.0.2:5432: getsockopt: connection refused dnz-api | exit
status 1 dnz-api exited with code 1
What I doing wrong?

Answer 1

You are unable to connect to your psql container because you haven't linked it. Take a look at Docker-Compose documentation on links.
Also, I'm assuming you aren't scheduling your container startup order. Psql container must start before golang's one. Take a look at Docker Compose documentation on startup order. You can use wait-for-it to achieve such objective ast stated in the docs. Just wget it and save it in your project.
I don't know the contents of your Dockerfile but I'll assume it's something like:
FROM golang:1.9
RUN mkdir -p /go/src/github.com/pavel/gorm-psql
WORKDIR /go/src/github.com/pavel/gorm-psql
ADD . /go/src/github.com/pavel/gorm-psql
RUN go get -v
So, your docker-compose.yml should be edited to first run wait-for-it.sh and link psql container to your app with something like:
version: '3.3'
services:
db:
image: postgres
environment:
POSTGRES_DB: dnz-dev
POSTGRES_USER: dnz-dev
POSTGRES_PASSWORD: dnz-dev
ports:
- 6000:5432
api:
build: .
command: ["./wait-for-it.sh", "db:6000", "--", "go", "run", "main.go"]
volumes:
- .:/go/src/github.com/pavel/gorm-psql
ports:
- "5000:3080"
depends_on:
- db
links:
- db
If your main has another name just change it. Edit your volumes to point whatever path you need. I've set a standard one with /go/src/github.com/pavel/gorm-psql. I'm assuming you created a db named dnz-dev, if the name is different just edit it.
$ go env:
. . .
GOPATH="/home/pavel/go"
GOROOT="/usr/lib/go"
. . .
Just run docker-compose up and it should work just fine. I'm relying on postgresql and golang latest images.