Move documentation build to circleci

.circleci/config.yml

@@ -0,0 +1,37 @@
+apt-run: &apt-install
+  name: Install apt packages
+  command: |
+    sudo apt update
+    sudo apt install -y graphviz
+
+pip-run: &pip-install
+  name: Install Python dependencies
+  command: |
+    python3 -m venv venv
+    . venv/bin/activate
+    pip install -r requirements/docs.txt
+
+version: 2
+jobs:
+  build:
+    environment:
+      - MAIN_CMD: "venv/bin/python setup.py"
+      - SETUP_CMD: "build_docs -w"
+    docker:
+      - image: circleci/python:3.6
+    steps:
+      - checkout
+      - run: *apt-install
+      - run: *pip-install
+      - run: $MAIN_CMD $SETUP_CMD
+
+      - store_artifacts:
+          path: docs/_build/html
+
+      - run:
+          name: "Built documentation is available at:"
+          command: DOCS_URL="${CIRCLE_BUILD_URL}/artifacts/${CIRCLE_NODE_INDEX}/${CIRCLE_WORKING_DIRECTORY/#\~/$HOME}/docs/_build/html/index.html"; echo $DOCS_URL
+
+notify:
+  webhooks:
+    - url: https://giles.cadair.com/circleci

.travis.yml

@@ -82,10 +82,6 @@ matrix:
            env: MAIN_CMD="py.test"
                 SETUP_CMD="--remote-data -k-figure --cov --cov-config sunpy/tests/coveragerc ./docs/"
 
-         - python: 3.6
-           stage: Comprehensive tests
-           env: SETUP_CMD='build_docs -w'
-
          # Python 2.7 (implicit astropy 2)
          - python: 2.7
            stage: Comprehensive tests

requirements/docs.txt

@@ -6,4 +6,4 @@
 
 sphinx
 sunpy-sphinx-theme
-sphinx-gallery
+git+https://github.com/sphinx-gallery/sphinx-gallery