CI: convert to GitLab

.build.yml

-image: nixos/unstable
-environment:
-  REPO_NAME: standupbot
-triggers:
-  - action: email
-    condition: failure
-    to: alerts@sumnerevans.com
-artifacts:
-  - standupbot/standupbot
-tasks:
-  - setup: |
-      cd $REPO_NAME
-      echo "cd $REPO_NAME" >> ~/.buildenv
-      nix-shell \
-        --arg forCI true \
-        --run "echo SHELL BUILD COMPLETE"
-
-  - build: |
-      nix-shell \
-        --arg forCI true \
-        --run "go build -v"
-
-  - test: |
-      nix-shell \
-        --arg forCI true \
-        --run "go test -v"

.gitlab-ci.yml

+stages:
+  - build
+
+build:
+  image: dock.mau.dev/tulir/gomuks-build-docker:linux-amd64
+  stage: build
+  cache:
+    paths:
+    - .cache
+  before_script:
+  - apk add --no-cache git ca-certificates build-base su-exec olm-dev
+  - mkdir -p .cache
+  - export GOPATH="$CI_PROJECT_DIR/.cache"
+  - export GOCACHE="$CI_PROJECT_DIR/.cache/build"
+  - export GO_LDFLAGS="-s -w -linkmode external -extldflags -static -X main.Tag=$CI_COMMIT_TAG -X main.Commit=$CI_COMMIT_SHA -X 'main.BuildTime=`date '+%b %_d %Y, %H:%M:%S'`'"
+  script:
+  - go build -ldflags "$GO_LDFLAGS" -o standupbot
+  artifacts:
+    paths:
+    - standupbot
+    - config.sample.json