Travis CI

For many use cases, the Travis caching section of the user guide will be sufficient.

This page documents how to use Stack on Travis CI. We assume you have basic familiarity with Travis.

Note: both Travis and Stack infrastructures are actively developed. We try to document best practices at the moment.

Container infrastructure

For Stack on Travis to be practical, we must use caching. Otherwise build times will take an incredibly long time, about 30 minutes versus 3-5. Caching is currently available only for container-based Travis infrastructure. Shortly we have to add

sudo: false

# Caching so the next build will be fast too.
cache:
  directories:
  - $HOME/.stack

To the .travis.yml. This however restricts how we can install GHC and Stack on the Travis machines.

Installing Stack

Currently there is only one reasonable way to install Stack: fetch precompiled binary from the Github.

before_install:
# Download and unpack the stack executable
- mkdir -p ~/.local/bin
- export PATH=$HOME/.local/bin:$PATH
- travis_retry curl -L https://www.stackage.org/stack/linux-x86_64 | tar xz --wildcards --strip-components=1 -C ~/.local/bin '*/stack'

Once Travis whitelists the stack .deb files, we'll be able to simply include stack in the addons section, and automatically use the newest version of stack, avoiding that complicated before_install section This is being tracked in the apt-source-whitelist and apt-package-whitelist issue trackers.

Installing GHC

There are two ways to install GHC:

  • Let Stack download GHC
  • Install GHC using apt plugin

See the Travis caching section of the user guide for an example of the first option (letting Stack download GHC). Here, we will explain the second option. With single GHC the situation is simple:

before_install:
  - export PATH=/opt/ghc/7.10.2/bin:$PATH

addons:
  apt:
    sources:
    - hvr-ghc
    packages:
    - ghc-7.10.2

Multiple GHC - parametrised builds

Travis apt plugin doesn't yet support installing apt packages dynamically (https://github.com/travis-ci/travis-ci/issues/4291). That for we need to write a bit repetitive .travis.yml.

Also for different GHC versions, you probably want to use different stack.yaml files.

# N.B. No top-level env: declaration!

matrix:
  include:
  - env: GHCVER=7.8.4 STACK_YAML=stack.yaml
    addons:
      apt:
        sources:
        - hvr-ghc
        packages:
        - ghc-7.8.4
  - env: GHCVER=7.10.1 STACK_YAML=stack-7.10.yaml
    addons:
      apt:
        sources:
        - hvr-ghc
        packages:
        - ghc-7.10.1
  - env: GHCVER=head STACK_YAML=stack-head.yaml
    addons:
      apt:
        sources:
        - hvr-ghc
        packages:
        - ghc-head
  allow_failures:
    - env: GHCVER=head STACK_YAML=stack-head.yaml

before_install:
  # ghc
  - export PATH=/opt/ghc/$GHCVER/bin:$PATH

Especially to use ghc HEAD you need to pass --skip-ghc-check option to Stack.

Running tests

After the environment setup, actual test running is simple:

script:
  - stack --no-terminal --skip-ghc-check test

Other details

Some Stack commands will run for long time (when cache is cold) without producing any output. For Travis not to timeout, one can wrap commands in a simple script.

install:
  - ./travis_long stack --no-terminal --skip-ghc-check setup
  - ./travis_long stack --no-terminal --skip-ghc-check test --only-snapshot

Examples