feat: Add support for Terraform 1.0

feat: Update Terraform 0.15 to 0.15.5
feat: Remove support for Terraform 0.12
chore: Remove tfplantool workaround for <0.13.2

.gitlab-ci.yml

 variables:
-  STABLE_VERSION: "0.15"
+  STABLE_VERSION: "1.0"
   STABLE_IMAGE_NAME: "$CI_REGISTRY_IMAGE/stable:latest"
+  BASE_IMAGE: "alpine:3.13.1"
   BUILD_IMAGE_NAME: "$CI_REGISTRY_IMAGE/branches/$CI_COMMIT_REF_SLUG-$TERRAFORM_VERSION:$CI_COMMIT_SHA"
   RELEASE_IMAGE_NAME: "$CI_REGISTRY_IMAGE/releases/$TERRAFORM_VERSION"
   TF_ADDRESS: "$CI_API_V4_URL/projects/$CI_PROJECT_ID/terraform/state/$CI_PIPELINE_IID-$STATE_NAME"
-  TFPLANTOOL_VERSION: "v0.1.1"
 
 .versions:
   parallel:
     matrix:
-      - BASE_IMAGE: "alpine:3.13.1"
-        TERRAFORM_BINARY_VERSION: "0.15.3"
+      - TERRAFORM_BINARY_VERSION: "1.0.0"
+        TERRAFORM_VERSION: "1.0"
+        STATE_NAME: terraform10
+      - TERRAFORM_BINARY_VERSION: "0.15.5"
         TERRAFORM_VERSION: "0.15"
         STATE_NAME: terraform015
-      - BASE_IMAGE: "alpine:3.13.1"
-        TERRAFORM_BINARY_VERSION: "0.14.11"
+      - TERRAFORM_BINARY_VERSION: "0.14.11"
         TERRAFORM_VERSION: "0.14"
         STATE_NAME: terraform014
-      - BASE_IMAGE: "alpine:3.13.1"
-        TERRAFORM_BINARY_VERSION: "0.13.7"
+      - TERRAFORM_BINARY_VERSION: "0.13.7"
         TERRAFORM_VERSION: "0.13"
         STATE_NAME: terraform013
-      - BASE_IMAGE: "alpine:3.13.1"
-        TERRAFORM_BINARY_VERSION: "0.12.31"
-        TERRAFORM_VERSION: "0.12"
-        STATE_NAME: terraform012
 
 stages:
   - lint
@@ -66,7 +62,7 @@ build:
     - .versions
   stage: build
   script:
-    - docker image build --tag "$BUILD_IMAGE_NAME" --build-arg BASE_IMAGE=$BASE_IMAGE --build-arg TERRAFORM_BINARY_VERSION=$TERRAFORM_BINARY_VERSION --build-arg TFPLANTOOL_VERSION=$TFPLANTOOL_VERSION .
+    - docker image build --tag "$BUILD_IMAGE_NAME" --build-arg BASE_IMAGE=$BASE_IMAGE --build-arg TERRAFORM_BINARY_VERSION=$TERRAFORM_BINARY_VERSION .
     - docker image push "$BUILD_IMAGE_NAME"
 
 .test:
@@ -105,7 +101,6 @@ test-plan:
   script:
     - gitlab-terraform plan
     - if [[ ! -f "plan.cache" ]]; then echo "expected to find a plan.cache file"; exit 1; fi
-    - tfplantool -f plan.cache backend get -k username
     - gitlab-terraform plan-json
     - if [[ ! -f "plan.json" ]]; then echo "expected to find a plan.json file"; exit 1; fi
     - mv plan.cache $TERRAFORM_VERSION-plan.cache

Dockerfile

 ARG BASE_IMAGE
 
-FROM golang:1.16 AS tfplantool
-
-ARG TFPLANTOOL_VERSION
-ARG TERRAFORM_BINARY_VERSION
-
-WORKDIR /tfplantool
-
-RUN git clone --branch $TFPLANTOOL_VERSION --depth 1 https://gitlab.com/mattkasa/tfplantool.git .
-RUN sed -i -e "/github\.com\/hashicorp\/terraform/s/ v.*\$/ v$TERRAFORM_BINARY_VERSION/" go.mod
-RUN go get -d -v ./...
-RUN CGO_ENABLED=0 GOOS=linux go build -tags terraform_${TERRAFORM_BINARY_VERSION} -a -installsuffix cgo -o tfplantool .
-
 FROM $BASE_IMAGE
 
 ARG TERRAFORM_BINARY_VERSION
@@ -28,8 +16,6 @@ RUN ( curl -sLo terraform.zip "https://releases.hashicorp.com/terraform/${TERRAF
 
 WORKDIR /
 
-COPY --from=tfplantool /tfplantool/tfplantool /usr/bin/tfplantool
-
 COPY src/bin/gitlab-terraform.sh /usr/bin/gitlab-terraform
 RUN chmod +x /usr/bin/gitlab-terraform
 

src/bin/gitlab-terraform.sh

@@ -51,9 +51,6 @@ export TF_HTTP_RETRY_WAIT_MIN="${TF_HTTP_RETRY_WAIT_MIN:-5}"
 export TF_IN_AUTOMATION=true
 
 apply() {
-  if ! terraform_is_at_least 0.13.2; then
-    tfplantool -f "${plan_cache}" backend set -k password -v "${TF_PASSWORD}"
-  fi
   terraform "${@}" -input=false "${plan_cache}"
 }