fix(docker): download Terraform and conftest versions maching image a…

…rchitecture (runatlantis#2101)

* Remove Terraform versions from Docker image which don't have all archs

Terraform versions earlier than 0.11.15 does not have binaries available for
both amd64, arm64 and armv7, so are being dropped as we can't install the older
versions in all the architectures the Docker image is built for.

* Download Terraform version depending on the architecture Docker image is for

This avoids us having arm64 binaries for the ARM Docker images, which won't
work.

* Download arm64 conftest binaries for arm64 Docker image

This doesn't fix the armv7 Docker image because conftest doesn't have a binary
available for that, so it for now still downloads the x86_64 binary, which is
likely to not work - but it's the same as it did before.

Dockerfile

@@ -9,34 +9,48 @@ RUN CGO_ENABLED=0 go build -trimpath -ldflags "-s -w" -v -o atlantis .
 # The runatlantis/atlantis-base is created by docker-base/Dockerfile.
 FROM ghcr.io/runatlantis/atlantis-base:2022.03.02 AS base
 
+# Get the architecture the image is being built for
+ARG TARGETPLATFORM
+
 # install terraform binaries
 ENV DEFAULT_TERRAFORM_VERSION=1.1.6
 
 # In the official Atlantis image we only have the latest of each Terraform version.
-RUN AVAILABLE_TERRAFORM_VERSIONS="0.8.8 0.9.11 0.10.8 0.11.15 0.12.31 0.13.7 0.14.11 0.15.5 1.0.11 ${DEFAULT_TERRAFORM_VERSION}" && \
+RUN AVAILABLE_TERRAFORM_VERSIONS="0.11.15 0.12.31 0.13.7 0.14.11 0.15.5 1.0.11 ${DEFAULT_TERRAFORM_VERSION}" && \
+    case ${TARGETPLATFORM} in \
+        "linux/amd64") TERRAFORM_ARCH=amd64 ;; \
+        "linux/arm64") TERRAFORM_ARCH=arm64 ;; \
+        "linux/arm/v7") TERRAFORM_ARCH=arm ;; \
+    esac && \
     for VERSION in ${AVAILABLE_TERRAFORM_VERSIONS}; do \
-        curl -LOs https://releases.hashicorp.com/terraform/${VERSION}/terraform_${VERSION}_linux_amd64.zip && \
+        curl -LOs https://releases.hashicorp.com/terraform/${VERSION}/terraform_${VERSION}_linux_${TERRAFORM_ARCH}.zip && \
         curl -LOs https://releases.hashicorp.com/terraform/${VERSION}/terraform_${VERSION}_SHA256SUMS && \
-        sed -n "/terraform_${VERSION}_linux_amd64.zip/p" terraform_${VERSION}_SHA256SUMS | sha256sum -c && \
+        sed -n "/terraform_${VERSION}_linux_${TERRAFORM_ARCH}.zip/p" terraform_${VERSION}_SHA256SUMS | sha256sum -c && \
         mkdir -p /usr/local/bin/tf/versions/${VERSION} && \
-        unzip terraform_${VERSION}_linux_amd64.zip -d /usr/local/bin/tf/versions/${VERSION} && \
+        unzip terraform_${VERSION}_linux_${TERRAFORM_ARCH}.zip -d /usr/local/bin/tf/versions/${VERSION} && \
         ln -s /usr/local/bin/tf/versions/${VERSION}/terraform /usr/local/bin/terraform${VERSION} && \
-        rm terraform_${VERSION}_linux_amd64.zip && \
+        rm terraform_${VERSION}_linux_${TERRAFORM_ARCH}.zip && \
         rm terraform_${VERSION}_SHA256SUMS; \
     done && \
     ln -s /usr/local/bin/tf/versions/${DEFAULT_TERRAFORM_VERSION}/terraform /usr/local/bin/terraform
 
 ENV DEFAULT_CONFTEST_VERSION=0.30.0
 
 RUN AVAILABLE_CONFTEST_VERSIONS="${DEFAULT_CONFTEST_VERSION}" && \
+    case ${TARGETPLATFORM} in \
+        "linux/amd64") CONFTEST_ARCH=x86_64 ;; \
+        "linux/arm64") CONFTEST_ARCH=arm64 ;; \
+        # There is currently no compiled version of conftest for armv7
+        "linux/arm/v7") CONFTEST_ARCH=x86_64 ;; \
+    esac && \
     for VERSION in ${AVAILABLE_CONFTEST_VERSIONS}; do \
-        curl -LOs https://github.com/open-policy-agent/conftest/releases/download/v${VERSION}/conftest_${VERSION}_Linux_x86_64.tar.gz && \
+        curl -LOs https://github.com/open-policy-agent/conftest/releases/download/v${VERSION}/conftest_${VERSION}_Linux_${CONFTEST_ARCH}.tar.gz && \
         curl -LOs https://github.com/open-policy-agent/conftest/releases/download/v${VERSION}/checksums.txt && \
-        sed -n "/conftest_${VERSION}_Linux_x86_64.tar.gz/p" checksums.txt | sha256sum -c && \
+        sed -n "/conftest_${VERSION}_Linux_${CONFTEST_ARCH}.tar.gz/p" checksums.txt | sha256sum -c && \
         mkdir -p /usr/local/bin/cft/versions/${VERSION} && \
-        tar -C  /usr/local/bin/cft/versions/${VERSION} -xzf conftest_${VERSION}_Linux_x86_64.tar.gz && \
+        tar -C /usr/local/bin/cft/versions/${VERSION} -xzf conftest_${VERSION}_Linux_${CONFTEST_ARCH}.tar.gz && \
         ln -s /usr/local/bin/cft/versions/${VERSION}/conftest /usr/local/bin/conftest${VERSION} && \
-        rm conftest_${VERSION}_Linux_x86_64.tar.gz && \
+        rm conftest_${VERSION}_Linux_${CONFTEST_ARCH}.tar.gz && \
         rm checksums.txt; \
     done