diff --git a/.travis.yml b/.travis.yml
index be166146d0c5..123994c1745d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,12 +1,13 @@
-language: go
-
-sudo: false
+language: bash
+services: docker
 
 install:
-  - .travis/get-markdownfmt.sh
+  - docker pull tianon/markdownfmt
+  - docker pull tianon/ymlfmt
 
 script:
   - .travis/check-markdownfmt.sh
+  - .travis/check-ymlfmt.sh
   - .travis/check-short.sh
   - .travis/check-required-files.sh
   - .travis/check-pr-no-readme.sh
diff --git a/.travis/check-markdownfmt.sh b/.travis/check-markdownfmt.sh
index 82f2f11f92b3..142c4afc3918 100755
--- a/.travis/check-markdownfmt.sh
+++ b/.travis/check-markdownfmt.sh
@@ -8,11 +8,11 @@ files="$(
 			-name '*.md' \
 			-not -name 'README.md' \
 		\) -exec test -s '{}' ';' -print0 \
-		| xargs -0 markdownfmt -l)"
+		| xargs -0 ./markdownfmt.sh -l)"
 if [ "$files" ]; then
 	echo >&2 'Need markdownfmt:'
 	echo >&2 "$files"
 	echo >&2
-	echo "$files" | xargs markdownfmt -d >&2
+	echo "$files" | xargs ./markdownfmt.sh -d >&2
 	exit 1
 fi
diff --git a/.travis/check-ymlfmt.sh b/.travis/check-ymlfmt.sh
new file mode 100755
index 000000000000..82cffb1d08f2
--- /dev/null
+++ b/.travis/check-ymlfmt.sh
@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+
+cd "$(dirname "$(readlink -f "$BASH_SOURCE")")/.."
+
+files="$(find -name '*.yml')"
+need=()
+needdiff=
+for f in $files; do
+	fdiff="$(./ymlfmt.sh -d "$f")"
+	if [ -n "$fdiff" ]; then
+		need+=( "$f" )
+		needdiff+="$fdiff"$'\n'
+	fi
+done
+if [ -n "$needdiff" ]; then
+	echo >&2 'Need ymlfmt:'
+	echo >&2 "${need[@]}"
+	echo >&2
+	echo >&2 -n "$needdiff"
+	exit 1
+fi
diff --git a/adminer/stack.yml b/adminer/stack.yml
index 89178f6025f4..56aa33b59f26 100644
--- a/adminer/stack.yml
+++ b/adminer/stack.yml
@@ -4,14 +4,14 @@ version: '3.1'
 
 services:
 
-    adminer:
-        image: adminer
-        restart: always
-        ports:
-            - 8080:8080
+  adminer:
+    image: adminer
+    restart: always
+    ports:
+      - 8080:8080
 
-    db:
-        image: mysql:5.6
-        restart: always
-        environment:
-            MYSQL_ROOT_PASSWORD: example
+  db:
+    image: mysql:5.6
+    restart: always
+    environment:
+      MYSQL_ROOT_PASSWORD: example
diff --git a/bonita/stack.yml b/bonita/stack.yml
index 23960027f88c..6d3279428559 100644
--- a/bonita/stack.yml
+++ b/bonita/stack.yml
@@ -2,43 +2,43 @@
 version: '3'
 
 services:
-    db:
-        image: postgres:9.3
-        environment:
-            POSTGRES_PASSWORD: example
-        restart: always
-        command:
-            - -c
-            - max_prepared_transactions=100
-    bonita:
-        image: bonita
-        ports:
-            - 8080:8080
-        environment:
-            - POSTGRES_ENV_POSTGRES_PASSWORD=example
-            - DB_VENDOR=postgres
-            - DB_HOST=db
-            - TENANT_LOGIN=tech_user
-            - TENANT_PASSWORD=secret
-            - PLATFORM_LOGIN=pfadmin
-            - PLATFORM_PASSWORD=pfsecret
-        restart: always
-        depends_on:
-            - db
-        entrypoint:
-            - bash
-            - -c
-            - |
-              set -e
-              echo 'Waiting for Postgres to be available'
-              export PGPASSWORD="$$POSTGRES_ENV_POSTGRES_PASSWORD"
-              maxTries=10
-              while [ "$$maxTries" -gt 0 ] && ! psql -h "$$DB_HOST" -U 'postgres' -c '\l'; do
-                  sleep 1
-              done
-              echo
-              if [ "$$maxTries" -le 0 ]; then
-                  echo >&2 'error: unable to contact Postgres after 10 tries'
-                  exit 1
-              fi
-              exec /opt/files/startup.sh
+  db:
+    image: postgres:9.3
+    environment:
+      POSTGRES_PASSWORD: example
+    restart: always
+    command:
+      - -c
+      - max_prepared_transactions=100
+  bonita:
+    image: bonita
+    ports:
+      - 8080:8080
+    environment:
+      - POSTGRES_ENV_POSTGRES_PASSWORD=example
+      - DB_VENDOR=postgres
+      - DB_HOST=db
+      - TENANT_LOGIN=tech_user
+      - TENANT_PASSWORD=secret
+      - PLATFORM_LOGIN=pfadmin
+      - PLATFORM_PASSWORD=pfsecret
+    restart: always
+    depends_on:
+      - db
+    entrypoint:
+      - bash
+      - -c
+      - |
+        set -e
+        echo 'Waiting for Postgres to be available'
+        export PGPASSWORD="$$POSTGRES_ENV_POSTGRES_PASSWORD"
+        maxTries=10
+        while [ "$$maxTries" -gt 0 ] && ! psql -h "$$DB_HOST" -U 'postgres' -c '\l'; do
+            sleep 1
+        done
+        echo
+        if [ "$$maxTries" -le 0 ]; then
+            echo >&2 'error: unable to contact Postgres after 10 tries'
+            exit 1
+        fi
+        exec /opt/files/startup.sh
diff --git a/elasticsearch/stack.yml b/elasticsearch/stack.yml
index 1f7a01f820a4..ea77eb1a355c 100644
--- a/elasticsearch/stack.yml
+++ b/elasticsearch/stack.yml
@@ -2,10 +2,10 @@ version: '3.1'
 
 services:
 
-    elasticsearch:
-        image: elasticsearch
+  elasticsearch:
+    image: elasticsearch
 
-    kibana:
-        image: kibana
-        ports:
-            - 5601:5601
+  kibana:
+    image: kibana
+    ports:
+      - 5601:5601
diff --git a/geonetwork/stack.yml b/geonetwork/stack.yml
index c080243e84a0..0be0b317b9f4 100644
--- a/geonetwork/stack.yml
+++ b/geonetwork/stack.yml
@@ -8,15 +8,15 @@
 version: '3.1'
 services:
 
-    geonetwork:
-      image: geonetwork
-      restart: always
-      ports:
-          - 8080:8080
-      environment:
-          DATA_DIR: /var/lib/geonetwork_data
-      volumes:
-         - geonetwork:/var/lib/geonetwork_data
+  geonetwork:
+    image: geonetwork
+    restart: always
+    ports:
+      - 8080:8080
+    environment:
+      DATA_DIR: /var/lib/geonetwork_data
+    volumes:
+      - geonetwork:/var/lib/geonetwork_data
 
 volumes:
-    geonetwork:
+  geonetwork:
diff --git a/joomla/stack.yml b/joomla/stack.yml
index ea3956385882..f1ac990db505 100644
--- a/joomla/stack.yml
+++ b/joomla/stack.yml
@@ -1,19 +1,19 @@
 version: '3.1'
 
 services:
-    joomla:
-        image: joomla
-        restart: always
-        links:
-            - joomladb:mysql
-        ports:
-            - 8080:80
-        environment:
-          JOOMLA_DB_HOST: joomladb
-          JOOMLA_DB_PASSWORD: example
+  joomla:
+    image: joomla
+    restart: always
+    links:
+      - joomladb:mysql
+    ports:
+      - 8080:80
+    environment:
+      JOOMLA_DB_HOST: joomladb
+      JOOMLA_DB_PASSWORD: example
 
-    joomladb:
-        image: mysql:5.6
-        restart: always
-        environment:
-            MYSQL_ROOT_PASSWORD: example
+  joomladb:
+    image: mysql:5.6
+    restart: always
+    environment:
+      MYSQL_ROOT_PASSWORD: example
diff --git a/kibana/stack.yml b/kibana/stack.yml
index 210aba229f9a..a1139cb266e9 100644
--- a/kibana/stack.yml
+++ b/kibana/stack.yml
@@ -2,11 +2,11 @@ version: '3.1'
 
 services:
 
-    kibana:
-        image: kibana
-        ports:
-            - 5601:5601
+  kibana:
+    image: kibana
+    ports:
+      - 5601:5601
 
-    elasticsearch:
-        image: elasticsearch
+  elasticsearch:
+    image: elasticsearch
 
diff --git a/mariadb/stack.yml b/mariadb/stack.yml
index 849dcb700bfd..f03f742cd8b4 100644
--- a/mariadb/stack.yml
+++ b/mariadb/stack.yml
@@ -3,14 +3,14 @@ version: '3.1'
 
 services:
 
-    db:
-        image: mariadb
-        restart: always
-        environment:
-            MYSQL_ROOT_PASSWORD: example
+  db:
+    image: mariadb
+    restart: always
+    environment:
+      MYSQL_ROOT_PASSWORD: example
 
-    adminer:
-        image: adminer
-        restart: always
-        ports:
-            - 8080:8080
+  adminer:
+    image: adminer
+    restart: always
+    ports:
+      - 8080:8080
diff --git a/markdownfmt.sh b/markdownfmt.sh
index c0a99ae0a40b..43eb694c2fb8 100755
--- a/markdownfmt.sh
+++ b/markdownfmt.sh
@@ -1,4 +1,4 @@
 #!/bin/bash
 set -e
 
-exec docker run -i --rm -v "$PWD":/scratch -w /scratch tianon/markdownfmt markdownfmt "$@"
+exec docker run -i --rm -v "$PWD":/scratch -w /scratch -u "$(id -u):$(id -g)" tianon/markdownfmt markdownfmt "$@"
diff --git a/mediawiki/stack.yml b/mediawiki/stack.yml
index 035785ca3191..84e79c4f5472 100644
--- a/mediawiki/stack.yml
+++ b/mediawiki/stack.yml
@@ -22,7 +22,7 @@ services:
     restart: always
     environment:
       # @see https://phabricator.wikimedia.org/source/mediawiki/browse/master/includes/DefaultSettings.php
-      MYSQL_DATABASE: 'my_wiki'
-      MYSQL_USER: 'wikiuser'
-      MYSQL_PASSWORD: 'example'
-      MYSQL_RANDOM_ROOT_PASSWORD: 'yes'
+      MYSQL_DATABASE: my_wiki
+      MYSQL_USER: wikiuser
+      MYSQL_PASSWORD: example
+      MYSQL_RANDOM_ROOT_PASSWORD: yes
diff --git a/mysql/stack.yml b/mysql/stack.yml
index 3f46e8249107..4fb505661b11 100644
--- a/mysql/stack.yml
+++ b/mysql/stack.yml
@@ -3,14 +3,14 @@ version: '3.1'
 
 services:
 
-    db:
-        image: mysql
-        restart: always
-        environment:
-            MYSQL_ROOT_PASSWORD: example
+  db:
+    image: mysql
+    restart: always
+    environment:
+      MYSQL_ROOT_PASSWORD: example
 
-    adminer:
-        image: adminer
-        restart: always
-        ports:
-            - 8080:8080
+  adminer:
+    image: adminer
+    restart: always
+    ports:
+      - 8080:8080
diff --git a/percona/stack.yml b/percona/stack.yml
index ff4fc749e417..9390e2f93a4a 100644
--- a/percona/stack.yml
+++ b/percona/stack.yml
@@ -3,14 +3,14 @@ version: '3.1'
 
 services:
 
-    db:
-        image: percona
-        restart: always
-        environment:
-            MYSQL_ROOT_PASSWORD: example
+  db:
+    image: percona
+    restart: always
+    environment:
+      MYSQL_ROOT_PASSWORD: example
 
-    adminer:
-        image: adminer
-        restart: always
-        ports:
-            - 8080:8080
+  adminer:
+    image: adminer
+    restart: always
+    ports:
+      - 8080:8080
diff --git a/postgres/stack.yml b/postgres/stack.yml
index c58347ed900e..3994b0c470c2 100644
--- a/postgres/stack.yml
+++ b/postgres/stack.yml
@@ -3,14 +3,14 @@ version: '3.1'
 
 services:
 
-    db:
-        image: postgres
-        restart: always
-        environment:
-            POSTGRES_PASSWORD: example
+  db:
+    image: postgres
+    restart: always
+    environment:
+      POSTGRES_PASSWORD: example
 
-    adminer:
-        image: adminer
-        restart: always
-        ports:
-            - 8080:8080
+  adminer:
+    image: adminer
+    restart: always
+    ports:
+      - 8080:8080
diff --git a/storm/stack.yml b/storm/stack.yml
index 14b58a30f795..a1da43b6efa6 100644
--- a/storm/stack.yml
+++ b/storm/stack.yml
@@ -1,31 +1,31 @@
 version: '3.1'
 
 services:
-    zookeeper:
-        image: zookeeper
-        container_name: zookeeper
-        restart: always
+  zookeeper:
+    image: zookeeper
+    container_name: zookeeper
+    restart: always
 
-    nimbus:
-        image: storm
-        container_name: nimbus
-        command: storm nimbus
-        depends_on:
-            - zookeeper
-        links:
-            - zookeeper
-        restart: always
-        ports:
-            - 6627:6627
+  nimbus:
+    image: storm
+    container_name: nimbus
+    command: storm nimbus
+    depends_on:
+      - zookeeper
+    links:
+      - zookeeper
+    restart: always
+    ports:
+      - 6627:6627
 
-    supervisor:
-        image: storm
-        container_name: supervisor
-        command: storm supervisor
-        depends_on:
-            - nimbus
-            - zookeeper
-        links:
-            - nimbus
-            - zookeeper
-        restart: always
+  supervisor:
+    image: storm
+    container_name: supervisor
+    command: storm supervisor
+    depends_on:
+      - nimbus
+      - zookeeper
+    links:
+      - nimbus
+      - zookeeper
+    restart: always
diff --git a/ymlfmt.sh b/ymlfmt.sh
new file mode 100755
index 000000000000..a83bbeb4c2d9
--- /dev/null
+++ b/ymlfmt.sh
@@ -0,0 +1,4 @@
+#!/bin/bash
+set -e
+
+exec docker run -i --rm -v "$PWD":/scratch -w /scratch -u "$(id -u):$(id -g)" tianon/ymlfmt ymlfmt "$@"
diff --git a/zookeeper/stack.yml b/zookeeper/stack.yml
index 66771ced379e..9a34e7d38f7c 100644
--- a/zookeeper/stack.yml
+++ b/zookeeper/stack.yml
@@ -1,32 +1,32 @@
 version: '3.1'
 
 services:
-    zoo1:
-        image: zookeeper
-        restart: always
-        hostname: zoo1
-        ports:
-            - 2181:2181
-        environment:
-            ZOO_MY_ID: 1
-            ZOO_SERVERS: server.1=zoo1:2888:3888 server.2=zoo2:2888:3888 server.3=zoo3:2888:3888
+  zoo1:
+    image: zookeeper
+    restart: always
+    hostname: zoo1
+    ports:
+      - 2181:2181
+    environment:
+      ZOO_MY_ID: 1
+      ZOO_SERVERS: server.1=zoo1:2888:3888 server.2=zoo2:2888:3888 server.3=zoo3:2888:3888
 
-    zoo2:
-        image: zookeeper
-        restart: always
-        hostname: zoo2
-        ports:
-            - 2182:2181
-        environment:
-            ZOO_MY_ID: 2
-            ZOO_SERVERS: server.1=zoo1:2888:3888 server.2=zoo2:2888:3888 server.3=zoo3:2888:3888
+  zoo2:
+    image: zookeeper
+    restart: always
+    hostname: zoo2
+    ports:
+      - 2182:2181
+    environment:
+      ZOO_MY_ID: 2
+      ZOO_SERVERS: server.1=zoo1:2888:3888 server.2=zoo2:2888:3888 server.3=zoo3:2888:3888
 
-    zoo3:
-        image: zookeeper
-        restart: always
-        hostname: zoo3
-        ports:
-            - 2183:2181
-        environment:
-            ZOO_MY_ID: 3
-            ZOO_SERVERS: server.1=zoo1:2888:3888 server.2=zoo2:2888:3888 server.3=zoo3:2888:3888
+  zoo3:
+    image: zookeeper
+    restart: always
+    hostname: zoo3
+    ports:
+      - 2183:2181
+    environment:
+      ZOO_MY_ID: 3
+      ZOO_SERVERS: server.1=zoo1:2888:3888 server.2=zoo2:2888:3888 server.3=zoo3:2888:3888