Move from Travis to Semaphore CI

We need somewhere that will let us run `kvm`; that excludes GitHub
actions and CircleCI (unless we set up our own machines as runners)

.semaphore/semaphore.yml

@@ -0,0 +1,35 @@
+version: v1.0
+name: CI Build
+
+agent:
+ machine:
+ type: e1-standard-2
+ os_image: ubuntu1804
+
+blocks:
+ - name: Run tests
+ task:
+ env_vars:
+ - name: GIMME_GO_VERSION
+ value: "1.14.2"
+ jobs:
+ - name: Tests
+ commands:
+ - eval "$(curl -sL https://raw.githubusercontent.com/travis-ci/gimme/master/gimme | bash)" # install specific go version
+ - |
+ # https://ignite.readthedocs.io/en/latest/installation.html
+ sudo apt-get install -y cpu-checker
+ sudo apt-get install -y --no-install-recommends dmsetup openssh-client git binutils
+ # Install containerd if it's not present -- prevents breaking docker-ce installations
+ sudo which containerd || sudo apt-get install -y --no-install-recommends containerd
+ - kvm-ok
+ - |
+ export CNI_VERSION=v0.8.7
+ export ARCH=$([ $(uname -m) = "x86_64" ] && echo amd64 || echo arm64)
+ sudo mkdir -p /opt/cni/bin
+ curl -sSL https://github.com/containernetworking/plugins/releases/download/${CNI_VERSION}/cni-plugins-linux-${ARCH}-${CNI_VERSION}.tgz | sudo tar -xz -C /opt/cni/bin
+ - checkout
+ - make ignite ignite-spawn ignited bin/amd64/Dockerfile GO_MAKE_TARGET=local
+ - make test
+ - make root-test
+ - make e2e-nobuild # this depends on Semaphore CI's support for nested virtualization