Create Docker image for NodeJS + PostgreSQL web application

Question

I've been reading Docker's documentation, but I can't get around creating an image that will work.

I have a NodeJS application that uses PostgreSQL as database:

var connectionString = process.env.DATABASE_URL || 'postgres://localhost:5432/db';
var pg = require('pg');
var pgp = require('pg-promise')();
var db = pgp(connectionString);
db.func('some_storedProcedure').then(//...)
//...

I first created a Dockerfile according to Node's documentation for it:

FROM node:argon

# Create app directory
RUN mkdir -p /app
WORKDIR /app

# Install app dependencies
COPY package.json /app
RUN npm install

# Bundle app source
COPY . /app

EXPOSE 5000

CMD [ "npm", "start" ]

I then followed this post regarding connecting the database to it with docker-compose. the docker-compose.yml file looks like:

web:


 build: .
  ports:
    - "5000:5000"
  volumes:
    - .:/app
  links:
    - db
  environment:
    DATABASE_URL: postgres://myuser:mypass@db:5432/db
db:
  image: postgres
  environment:
    POSTGRES_USER: myuser
    POSTGRES_PASSWORD: mypass

This is (some) of what is returned when I run docker-compose up with these files, after creating the image.

npm info ok 
 ---> 87dbbae35721
Removing intermediate container c73f826a0b3d
Step 6 : COPY . /app
 ---> ec56bfc11d3c
Removing intermediate container 745ddf82d742
Step 7 : EXPOSE 5000
 ---> Running in b2be5aecd9d6
 ---> a7d126a7ea5e
Removing intermediate container b2be5aecd9d6
Step 8 : CMD npm start
 ---> Running in 0379d512c688
 ---> 266517f47311
Removing intermediate container 0379d512c688
Successfully built 266517f47311
WARNING: Image for service web was built because it did not already exist. To rebuild this image you must use `docker-compose build` or `docker-compose up --build`.
Starting imagename_db_1
Creating imagename_web_1
Attaching to imagename_db_1, imagename_web_1
web_1  | npm info it worked if it ends with ok
web_1  | npm info using npm@2.15.1
web_1  | npm info using node@v4.4.3
web_1  | npm info prestart SharedServer@5.8.0
web_1  | npm info start SharedServer@5.8.0
web_1  | 
web_1  | > SharedServer@5.8.0 start /app
web_1  | > node index.js
web_1  | 
web_1  | Wed, 27 Apr 2016 00:41:19 GMT body-parser deprecated bodyParser: use individual json/urlencoded middlewares at index.js:13:9
web_1  | Wed, 27 Apr 2016 00:41:19 GMT body-parser deprecated undefined extended: provide extended option at node_modules/body-parser/index.js:105:29
web_1  | Node app is running on port 5000
db_1   | LOG:  database system was interrupted; last known up at 2016-04-25 00:17:59 UTC
db_1   | LOG:  database system was not properly shut down; automatic recovery in progress
db_1   | LOG:  invalid record length at 0/17076E8
db_1   | LOG:  redo is not required
db_1   | LOG:  MultiXact member wraparound protections are now enabled
db_1   | LOG:  database system is ready to accept connections
db_1   | LOG:  autovacuum launcher started

When I access http://localhost:5000, I see the web application running, but whenever I fire up something that tries to access the database, I get a HTTP 500 error with the following body

code: "28P01"
file: "auth.c"
length: 98
line: "285"
name: "error"
routine: "auth_failed"
severity: "FATAL"

What am I doing wrong? I'm not sure I understand what I'm doing with Docker, and the only thing I have for documentation are simple recipes to build specific environments (or at least, that's what I've understood)

Thanks.

The error says your authentication details for the database server failed. Can you connect to the server from your app successfully at all? You can check this: http://stackoverflow.com/questions/36120435/verify-database-connection-with-pg-promise-when-starting-an-app. And if no luck, you can try this: http://stackoverflow.com/questions/35807792/how-do-you-connect-to-a-postgres-database-with-no-password-using-pg-promise. Also, you do not need to include `pg` when you already got `pg-promise` ;) — vitaly-t, Apr 27 '16 at 02:08
@vitaly: if I run my application in my host system, I have no problems connecting at all. It's running the app through the image that brings this problem up — Heathcliff, Apr 27 '16 at 02:50
Probably an issue with the docker configuration. You didn't specify the database port, and maybe your username or password are wrong. — vitaly-t, Apr 27 '16 at 03:27
5000 is node.js application port, right? have you built postgres database docker and is it listening on 5432 port ? — Thanh Nguyen Van, Apr 27 '16 at 04:17
@ThanhNguyenVan: No, I thought PostgreSQL was installed in the image already with docker-compose — Heathcliff, Apr 27 '16 at 12:07
Yes, I saw, db container is installed, but didnot see port to expose that container. Did you try to telnet to port 5432 is open or not ? — Thanh Nguyen Van, Apr 28 '16 at 02:00

score 0 · Answer 1 · answered Apr 27 '16 at 08:49

Check your pg_hba.conf in $PGDATA allows connections from node.js.

By default the pg_hba.conf is like so:

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     trust
# IPv4 local connections:
host    all             all             127.0.0.1/32            trust
# IPv6 local connections:
host    all             all             ::1/128                 trust

This is fine for your standard psql connectivity via the OS owner as it allows local connections trusted for localhost IP address 127.0.0.1. However if you have an IP address set on the server, which I'm guessing you do then you need to allow an entry for that because in your node.js configuration you're referring to a host of "DB". So ping "DB" and add that IP address:

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     trust
# IPv4 local connections:
host    all             all             127.0.0.1/32            trust
# IPv6 local connections:
host    all             all             ::1/128                 trust
host    db              myuser          <ip-for-db-host>        md5

Once you've changed that file you will need to perform a pg_ctl reload.

How can I check that in the image? Is the config file in the same path than I can find it when installing PostgreSQL in Ubuntu, for instance? — Heathcliff, Apr 27 '16 at 12:18
yeah pg_hba.conf is always in the data directory once you have created an instance with initdb. By default it will probably be somewhere like /var/lib/pgsql-9.5/data if you're not explicitly telling it where to install. — d1ll1nger, Apr 27 '16 at 13:03

Create Docker image for NodeJS + PostgreSQL web application

1 Answers1