Create Docker image for NodeJS + PostgreSQL web application - node.js

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.

Answer 1

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.