Docker: A Dockerfile to Fix the “Call to undefined function pg_connect()” Error when Using PHP with Postgres

When integrating a PHP application connecting to a PostgreSQL database, both services running as Docker containers using the official PHP and Postgre images, you might encounter (as I have) an error that looks something like this:

    Uncaught Error: Call to undefined function pg_connect() in ...

It’s actually a simple error, which means that there’s something wrong with the connection between the app and the PostgreSQL database, but when I first stumbled on it I had a hard time finding out what I needed to do to fix it. There was definitely something missing from the Docker setup, but I did not know what it was until I sought help from a teammate.

Apparently the official PHP docker image does not contain the PDO and PGSQL drivers necessary for the successful connection. Silly me for assuming it does.

The fix is simple. We have to create a Dockerfile that updates our PHP image with the required drivers, which contains the following code:

FROM php:7.1-fpm

RUN apt-get update

# Install PDO and PGSQL Drivers
RUN apt-get install -y libpq-dev \
  && docker-php-ext-configure pgsql -with-pgsql=/usr/local/pgsql \
  && docker-php-ext-install pdo pdo_pgsql pgsql

Easy peasy. And to run this Dockerfile from a docker-compose.yml file, we’ll need the build, context, and dockerfile commands, replacing the single image command that does not use a Dockerfile:

version: '3'
services:
  php:
    build:
      context: ./directory/of/Dockerfile
      dockerfile: ./Dockerfile
    # All your other settings follow ...

And that should be all that you need to do! 🙂

Using a Git Pre-Commit Hook for Automatic Linting, Unit Testing, and Code Standards Checking of Application Code

Problem: I want to automatically run unit tests, lint the application code, and check it’s state against team standards every time I try to commit my changes to a project. It would be nice if the commit aborts if any of the existing tests fails or if I did not follow a particular standard that the team agrees to uphold. The commit pushes through if there are no errors. If possible, I don’t have to change anything in my software development workflow.

Solution: Use a Git pre-commit hook. Under the .git/hooks hidden folder in the project directory, create a new file called pre-commit (without any file extension) containing something like the following bash script (for testing PHP code):

#!/bin/sh

stagedFiles=$(git diff-index --cached HEAD | grep ".php" | grep "^:" | sed 's:.*[DAM][ \\''t]*\([^ \\''t]*\):\1:g');
errorMessage="Please correct the errors above. Commit aborted."

printf "Linting and checking code standards ..."
for file in $stagedFiles
do
  php -l $file
  LINTVAL=$?
  if [[ $LINTVAL != 0 ]]
  then
    printf $errorMessage
    exit 1
  fi
  php core/phpcs.phar --colors --standard=phpcs.xml $file
  STANDVAL=$?
  if [[ $STANDVAL != 0 ]]
  then
    printf $errorMessage
    exit 1
  fi
done

printf "Running unit tests ..."
core/vendor/bin/phpunit --colors="always" [TESTS_DIRECTORY]
TESTSVAL=$?
if [[ $TESTSVAL != 0 ]]
then
  printf $errorMessage
  exit 1
fi

where

  • linting and code standard checks only runs for the files you want to commit changes to
  • code standard checks are based on a certain phpcs.xml file
  • unit tests inside a particular TESTS_DIRECTORY will run
  • the commit will abort whenever any of the lints, code standard checks, or unit tests fails

Basic API Testing with PHP’s HTTP Client Guzzle

I like writing test code in Ruby. It’s a preference; I feel I write easy-to-read and easy-to-maintain code in them than with using Java, the programming language I started with in learning to write automated checks. We use PHP in building apps though. So even if I can switch programming languages to work with, sometimes I think about how to replicate my existing test code with PHP, because maybe sometime in the future they’ll have an interest in doing what I do for themselves. If I know how to re-write my test code in a programming language they are familiar with then I can help them with that.

In today’s post, I’m sharing some notes about what I found working when building simple API tests with PHP’s HTTP client Guzzle.

To start with, we have to install necessary dependencies. One such way for PHP projects is through Composer, which we’ll have a composer.json file in the root directory. I have mine set up with the following:

{
     "require-dev": {
          "behat/behat": "2.5.5",
          "guzzlehttp/guzzle": "~6.0",
          "phpunit/phpunit": "^5.7"
     }
}

Using Guzzle in code, often in combination with Behat we’ll have something like this:

use Behat\Behat\Tester\Exception\PendingException;
use Behat\Behat\Context\Context;
use Behat\Behat\Context\SnippetAcceptingContext;
use Behat\Gherkin\Node\PyStringNode;
use Behat\Gherkin\Node\TableNode;
use GuzzleHttp\Client;

     class FeatureContext extends PHPUnit_Framework_TestCase implements Context, SnippetAcceptingContext
     {
         // test code here
     }

where test steps will become functions inside the FeatureContext class. Our API tests will live inside such functions.

Here’s an example of a GET request, where we can check if some content is displayed on a page:

/**
* @Given a sample GET API test
*/
public function aSampleGET()
{
     $client = new Client();
     $response = $client -> request('GET', 'page_URL');
     $contents = (string) $response -> getBody();
     $this -> assertContains($contents, 'content_to_check');
}

For making requests to a secure site, we’ll have to update the sample request method to:

request('GET', 'page_URL', ['verify' => 'cacert.pem']);

where cacert.pem is a certificate file in the project’s root directory. We can of course change the file location if we please.

Now here’s an example of a POST request, where we are submitting an information to a page and verifying the application’s behavior afterwards:

/**
* @Given a sample POST API test
*/
public function aSamplePOST()
{
     $client = new Client(['cookies' => true]);
     $response = $client -> request('POST', 'page_URL', ['form_params' => [
          'param_1' => 'value_1',
          'param_2' => 'value_2'
     ]]);
     $contents = (string) $response -> getBody();
     $this -> assertContains($contents, 'content_to_check');
}

This is a basic POST request. You may notice that I added a cookies parameter when initializing the Guzzle client this time. That’s because I wanted the same cookies in the initial request to be used in succeeding requests. We can remove that if we want to.

There’s a more tricky kind of POST request, something where we need to upload a certain file (often an image or a document) as a parameter to the request. We can do that by:

/**
* @Given a sample POST Multipart API test
*/
public function aSampleMultipartPOST()
{
     $client = new Client(['cookies' => true]);
     $response = $client -> request('POST', 'page_URL', ['multipart' => [
          [
               'name' => 'param_1',
               'contents' => 'value_1'
          ],
          [
               'name' => 'param_2_file',
               'contents' => fopen('file_location', 'r')
          ]
     ]]);
     $contents = (string) $response -> getBody();
     $this -> assertContains($contents, 'content_to_check');
}

and use whatever document/image we have in our machine. We just need to specify the correct location of the file we want to upload.