Add Xenial to build matrix. (#156)

.dockerignore

@@ -0,0 +1,4 @@
+**/Dockerfile*
+**/.dockerignore
+**/.git
+**/.travis.yml

.travis.yml

@@ -20,12 +20,17 @@ services: docker
 cache:
   directories:
     - /home/travis/docker/
+
 env:
   global:
     - DOCKER_CACHE_FILE=/home/travis/docker/cache.tar.gz
+  matrix:
+    - UBUNTU_RELEASE=trusty
+    - UBUNTU_RELEASE=xenial
+
 before_install: scripts/load_docker_cache.sh
 
 install: true
 script:
-  - docker build ${TRAVIS_BUILD_DIR} -t cartographer
+  - docker build ${TRAVIS_BUILD_DIR} -t cartographer:${UBUNTU_RELEASE} -f Dockerfile.${UBUNTU_RELEASE}
   - scripts/save_docker_cache.sh

Dockerfile.xenial

@@ -0,0 +1,25 @@
+# Copyright 2016 The Cartographer Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+FROM ubuntu:xenial
+
+# Xenial's base image doesn't ship with sudo.
+RUN apt-get update && apt-get install -y sudo && rm -rf /var/lib/apt/lists/*
+
+COPY scripts/install_debs.sh cartographer/scripts/
+RUN cartographer/scripts/install_debs.sh && rm -rf /var/lib/apt/lists/*
+COPY scripts/install_ceres.sh cartographer/scripts/
+RUN cartographer/scripts/install_ceres.sh && rm -rf ceres-solver
+COPY . cartographer
+RUN cartographer/scripts/install_cartographer.sh && rm -rf cartographer