buildkite: bump Go version to 1.16

We're currently on 1.13, which can cause build issues with code targeting later
versions.

PiperOrigin-RevId: 385029528

.buildkite/hooks/pre-command

@@ -8,9 +8,16 @@ function install_pkgs() {
   done
 }
 install_pkgs make "linux-headers-$(uname -r)" linux-libc-dev \
-  graphviz jq curl binutils gnupg gnupg-agent golang-go \
+  graphviz jq curl binutils gnupg gnupg-agent gcc \
   apt-transport-https ca-certificates software-properties-common
 
+# Install Go 1.16, as only 1.13 is available via apt.
+declare -r go_archive=go1.16.6.linux-amd64.tar.gz
+wget "https://golang.org/dl/${go_archive}"
+sudo tar -xzf "${go_archive}" -C /usr/local
+sudo ln -s /usr/local/go/bin/go /usr/bin/go
+rm "${go_archive}"
+
 # Setup for parallelization with PARTITION and TOTAL_PARTITIONS.
 export PARTITION=${BUILDKITE_PARALLEL_JOB:-0}
 PARTITION=$((${PARTITION}+1)) # 1-indexed, but PARALLEL_JOB is 0-indexed.

tools/installers/containerd.sh

@@ -36,9 +36,10 @@ install_helper() {
   mkdir -p "${GOPATH}"/src/$(dirname "${PACKAGE}") && \
      git clone https://"${PACKAGE}" "${GOPATH}"/src/"${PACKAGE}"
 
-  # Checkout and build the repository.
+  # Checkout and build the repository. We use a pre-GO111MODULE containerd.
   (cd "${GOPATH}"/src/"${PACKAGE}" && \
       git checkout "${TAG}" && \
+      export GO111MODULE=off && \
       make && \
       make install)
 }