Support for using travis-ci has been added in order to automate pull-testing. See travis-ci.org for more info
This procedure is different than the pull-tester that came before it in a few ways.
There is nothing to administer. This is a major feature as it means
that builds have no local state. Because there is no ability to login to the
builders to install packages (tools, dependencies, etc), the entire build
procedure must instead be controlled by a declarative script
This script declares each build configuration, creates virtual machines as
necessary, builds, then discards the virtual machines.
A build matrix is constructed to test a wide range of configurations, rather than a single pass/fail. This helps to catch build failures and logic errors that present on platforms other than the ones the author has tested. This matrix is defined in the build script and can be changed at any time.
All builders use the dependency-generator in the depends dir, rather than using apt-get to install build dependencies. This guarantees that the tester is using the same versions as Gitian, so the build results are nearly identical to what would be found in a final release. However, this also means that builds will fail if new dependencies are introduced without being added to the dependency generator.
In order to avoid rebuilding all dependencies for each build, the binaries are cached and re-used when possible. Changes in the dependency-generator will trigger cache-invalidation and rebuilds as necessary.
These caches can be manually removed if necessary. This is one of the very few manual operations that is possible with Travis, and it can be done by the Bitcoin Core committer via the Travis web interface.
In some cases, secure strings may be needed for hiding sensitive info such as private keys or URLs. The travis client may be used to create these strings: http://docs.travis-ci.com/user/encryption-keys/
For the details of the build descriptor, see the official docs: http://docs.travis-ci.com/user/build-configuration/