Remove travis support and unused buildmode

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

.travis.yml

@@ -1,31 +0,0 @@
-sudo: required
-language: minimal
-
-env:
-  global:
-    - DOCKER_CHANNEL="stable"
-    - DOCKER_CLI_EXPERIMENTAL="enabled"
-    - PLATFORMS="linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64,linux/s390x,linux/ppc64le"
-    - CROSS_PLATFORMS="${PLATFORMS},darwin/amd64,windows/amd64"
-    - PREFER_BUILDCTL="1"
-
-before_install:
-  # update docker
-  - curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
-  - sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) $DOCKER_CHANNEL"
-  - sudo apt-get update
-  - sudo apt-get -y -o Dpkg::Options::="--force-confnew" install docker-ce docker-ce-cli
-  # check
-  - sudo systemctl restart docker
-  - docker info
-
-install:
-  - docker buildx create --name builder --driver docker-container --driver-opt image=$REPO_SLUG_ORIGIN --use
-  - docker run --rm --privileged tonistiigi/binfmt:latest --install all
-  - docker run --name buildkit --rm -d --privileged -p 1234:1234 $REPO_SLUG_ORIGIN --addr tcp://0.0.0.0:1234
-  - sudo docker cp buildkit:/usr/bin/buildctl /usr/bin/
-  - export BUILDKIT_HOST=tcp://0.0.0.0:1234
-
-script:
-  - make binaries validate-all
-  - TARGETPLATFORM="${CROSS_PLATFORMS}" ./hack/cross

hack/util

@@ -8,28 +8,19 @@
 : ${CACHEDIR_FROM=}
 : ${CACHEDIR_TO=}
 
-newerEqualThan() { # $1=minimum wanted version $2=actual-version
-  [ "$1" = "$(printf "$1\n$2" | sort -V | head -n 1)" ]
-}
+if [ "$PREFER_BUILDCTL" = "1" ]; then
+  echo >&2 "WARNING: PREFER_BUILDCTL is no longer supported. Ignoring."
+fi
+
+if [ "$PREFER_LEGACY" = "1" ]; then
+  echo >&2 "WARNING: PREFER_LEGACY is no longer supported. Ignoring."
+fi
 
 progressFlag=""
 if [ "$CI" = "true" ]; then
   progressFlag="--progress=plain"
 fi
 
-buildmode="legacy"
-if [ "$PREFER_BUILDCTL" = "1" ]; then
-  buildmode="buildkit";
-else
-  serverVersion=$(docker info --format '{{.ServerVersion}}')
-  experimental=$(docker info --format '{{.ExperimentalBuild}}')
-  if [ "$PREFER_LEGACY" != "1" ] && ( newerEqualThan "18.09" $serverVersion || \
-    ( newerEqualThan "18.06" $serverVersion && [ "true" = "$experimental" ] ) || \
-    [ "$DOCKER_BUILDKIT" = "1" ]); then
-    buildmode="docker-buildkit";
-  fi
-fi
-
 buildxCmd() {
   if docker buildx version >/dev/null 2>&1; then
     set -x