Build on Multiple CPU Architectures

This is a beta stage of this feature and we are eager to hear back from you, both for Arm-based and IBM-based feedback. The definition keys used in the .travis.yml file may be further adapted on short notice.

IBM Power and IBM Z-based building is available for Open Source repositories (at travis-ci.com). While available to all Open Source repositories, the concurrency available for multiple CPU arch-based jobs is limited during the beta period.

An attempt to run IBM Power and IBM Z-based builds for a private repository will result in

• a build run on standard, AMD-based infrastructure for IBM-Z
• a build run on PPC64LE infrastructure, but under normal system conditions (incl. any charges if applicable) for IBM Power

For any commercial queries with regards to multi-arch builds before they are available, please contact us.

Arm-based building on Arm64 CPU is only available for Open Source repositories (at travis-ci.com). While available to all Open Source repositories, the concurrency available for multiple CPU arch-based jobs is limited during the beta period.

Arm-based building on Arm64 Graviton2 CPU now supports both Open Source and commercial projects. The total concurrency capacity is limited, but may adjusted based on the demand.

Multi CPU availability #

If your code is used on multiple CPU architectures it probably should be tested on multiple CPU architectures. Travis CI can test on

• amd64,
• ppc64le (IBM Power CPUs),
• s390x (IBM Z CPUs),
• arm64 (run on ARMv8 compliant CPUs)
• arm64-graviton2 (new gen of ARMv8 compliant CPUs on AWS, available only on travis-ci.com)

if the operating system is Linux. The table below gives a brief perspective about the CPU and project type combinations:

The two arm64 tags are used right now to distinguish between OSS-support only (arch: arm64) and available both for OSS & commercial (arch: arm64-graviton2).

Default CPU Architecture #

The default CPU architecture used in Travis CI builds is amd64. It is used when no arch key is present.

Identify Build Jobs CPU Architecture #

You can identify for which CPU architecture a build job is run via

• GUI
  • in the build job list, there’s a specific label and architecture name based on arch tag value
  • in the build job view, the same specific label is displayed near the operating system identifier
• A default environmental variable printed out during your build job: $TRAVIS_CPU_ARCH (for a complete list of available default environmental variables please see our Environment Variables - Default Environment Variables documentation.

Test on Multiple CPU Architectures #

To enable testing on multiple CPU architectures, add the arch key to your .travis.yml:

arch:
  - amd64
  - ppc64le
  - s390x
  - arm64  # please note arm64-graviton2 requires explicit virt: [lxd|vm] tag so it's recommended for jobs.include, see below
os: linux  # different CPU architectures are only supported on Linux

If you are already using a build matrix to test multiple versions, the arch key also multiplies the matrix.

• The ppc64le (IBM Power) and s390x (IBM Z) build jobs are run in an LXD compliant Linux OS image.
• The arm64 CPU architecture build job is run in an LXD compliant Linux OS image.
• The arm64-graviton2 architecture builds can be run on both LXD and regular ‘full VM’ environments. You need to explicitly set the target environment by using virt key. A virt: vm routes build jobs to a full virtual machine setup while virt: lxd routes build jobs to an LXD container setup.
• The default LXD image supported by Travis CI is Ubuntu Xenial 16.04 and by using dist you can select different supported LXD images. Also see our CI Environment Overview - Virtualisation Environment vs Operating System documentation. The LXD host, on which LXD-based builds are run, is on Ubuntu 18.04.
• The amd64 CPU architecture build job currently runs as a regular ‘full VM’ and will be transitioned to an LXD compliant Linux OS image usage over time.

Multi Architecture Build Matrix #

Here’s an example of a .travis.yml file using the arch key to compile against amd64, arm64, arm64-graviton2, ppc64le (IBM Power) and s390x (IBM Z) under Linux and using C as the programming language.

language: c

arch:
  - amd64
  - arm64  # please note arm64-graviton2 requires explicit virt: [lxd|vm] tag so it's recommended for jobs.include, see below
  - ppc64le
  - s390x

compiler:
  - gcc
  - clang

install: skip

script:
  - cd src
  - make all

The .travis.yml file above creates a 2x4 build matrix: compilers x each architecture.

There are many options available and using the matrix.include key is essential to include any specific entries. For example, this matrix would route builds to the arm64 and amd64 architecture environments:

Note that group: edge is required for arm64-graviton2 architectures.

jobs:
  include:
   - os: linux
     arch: amd64
   - os: linux
     arch: arm64
   - os: linux
     arch: arm64-graviton2
     virt: lxd
     group: edge

Similarly, this matrix would route builds to the ppc64le (IBM Power) and s390x (IBM Z) architecture environments:

jobs:
  include:
   - os: linux
     arch: ppc64le
   - os: linux
     arch: s390x

Please note, that explicitly included builds inherit the first value in an array:

arch:
  - amd64
  - arm64
  - ppc64le
  - s390x
jobs:
  include:
   - os: linux
     env: LIB_PATH="/usr/bin/shared/x86_64/v1"
   - os: linux
     env: LIB_PATH="/usr/bin/shared/x86_64/v2"

For example, the above .travis.yml, would result in running both jobs with the environmental variable LIB_PATH assigned different values being run only on amd64 architecture.

Use Docker in Multiple CPU Architecture-Based Builds within LXD Containers #

It is possible to use Docker in multiple CPU architecture-based builds within an LXD container. You may need a specific CPU architecture compliant docker image as a base or ensure relevant libraries required by your build are added to your Dockerfile.

An example of building a docker image from a Dockerfile adjusted to arm64:

arch: arm64
language: c
compiler: gcc
services:
  - docker
script: docker build -t my/test -f Dockerfile.arm64 .

An example of running docker image:

arch: arm64
services:
  - docker
script: docker run my/test #assuming docker image my/test is arm64v8 ready

You can try it out also for ppc64le (IBM Power) and s390x (IBM Z) based docker builds, assuming all dependencies and/or a CPU architecture compliant base docker image are used.

You can also have a look at Using Docker in Builds.

LXD related limitations #

For more details see Build Environment Overview.

Partner Queue Solution #

With the introduction of a new billing system in Travis CI, the IBM and part of the ARM64 infrastructures are kept available free of charge for OSS as a part of the Partner Queue Solution. For more details see Billing Overview - Usage based Plans - Credits.