8-bit Assembly was Fun Ramblings of a not-so-old Programmer

Building with Travis CI

22 Aug 2015

Travis CI is one of the hosted continuous integration frameworks that offer C++ support (ref). Their instructions looked promising, and they are easy to follow. Unfortunately their default setup does not work for C++11 libraries, and this is where I learn that I needed to setup a C++11 development environment on Ubuntu 12.04 first.

The Configuration File

Travis follows the instructions on a simple .travis.yml file in the top level directory of your project. The instructions in the website are comprehensive enough, but I think it is easier to follow if we describe the contents of our Travis file section by section.

Configure the Language and Compilers

First we tell Travis to use C++ and to compile on Linux.

language: cpp

os:
  - linux

Then we tell it what compilers to use. This is a nice feature, testing C++ with more than one compiler is a good way to avoid portability problems, both to other platforms and to future updates in the compiler. We will initially configure just one compiler, just to make testing easier, but we will want to setup additional compilers later:

compiler:
  - clang

Setting Up the Development environment

We are going to use the the before_install section to install the development environment. The documentation explicitly recommends installing Ubuntu packages there.

The set of apt repositories and packages was described in the previous post, here we simply reproduce those commands in the .travis.yml format:

before_install:
  - sudo apt-get -qq -y install python-software-properties
  - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
  - sudo add-apt-repository -y ppa:dns/gnu
  - sudo add-apt-repository -y ppa:boost-latest/ppa
  - sudo add-apt-repository -y "deb http://llvm.org/apt/precise/ llvm-toolchain-precise main"
  - sudo add-apt-repository -y "deb http://llvm.org/apt/precise/ llvm-toolchain-precise-3.6 main"
  - wget -O - http://llvm.org/apt/llvm-snapshot.gpg.key|sudo apt-key add -
  - sudo apt-get -qq update
  - sudo apt-get -qq -y install clang-3.6
  - sudo apt-get -qq -y install g++-4.9
  - sudo apt-get -qq -y install boost1.55
  - sudo apt-get -qq -y install autoconf automake autoconf-archive make
  - sudo apt-get -qq -y install git

Logging the Configuration

As this program will run automatically, it is always useful to log the critical dependency versions to make debugging easier. We do this just before running the configuration script:

before_script:
  - uname -a
  - g++ --version || echo "no g++ found"
  - clang++ --version || echo "no clang++ found"
  - g++-4.9 --version || echo "no g++-4.9 found"
  - clang++-3.6 --version || echo "no clang++-3.6 found"
  - make --version || echo "no make found"
  - automake --version || echo "no automake found"
  - autoconf --version || echo "no autoconf found"
  - dpkg -s autoconf-archive || echo "no autoconf-archive found"
  - dpkg -s libboost-test1.55-dev || echo "no libboost-test1.55-dev found"
  - echo $CXX
  - echo $CC
  - CC=clang-3.6
  - export CC
  - CXX=clang++-3.6
  - export CXX

Compiling the Code

With all these preambles behind us, we can now compile the code:

script:
  - ./bootstrap
  - echo CC=${CC?} CXX=${CXX?}
  - buildir=$(basename ${CC?})
  - mkdir ${buildir?} && cd ${buildir?}
  - ../configure --with-boost-libdir=/usr/lib/x86_64-linux-gnu
  - make
  - make check

At the end of this process you should have a file that looks like this one. Notice that this link points to an specific version, I am planning to update the file, but not these instructions.

Sign-in To Travis

I have been using travis-ci.org (notice the TLD) for these builds. You may be using the version with commercial support at travis-ci.com. I used github to create a travis-ci.org account. And then enabled builds for the github.com/coryan/Skye project.

Travis scanned my github account and discovered by repositories. From there, I selected the settings for the Skye project, and enabled “Build only if .travis.yml is present”, and “Build pushes”, leaving all other options to their defaults (disabled). With apologies to any visually impaired readers, this screenshot may help image.

What is Next

So far we successfully built with clang, but we want to build with g++ too. That comes in the next installment of this series.

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