port cache workflow to woodpecker

.forgejo/workflows/cache.yaml

@@ -1,25 +0,0 @@
-name: cache-build
-
-on:
-  workflow_dispatch: # allows manual triggering
-  push:
-    branches:
-      # - main
-
-jobs:
-  deploy:
-    runs-on: native
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@v4
-
-      - name: Cache
-        run: |
-          nix-shell --run "attic login fediversity https://attic.fediversity.net '${{ secrets.ATTIC_PUSH_KEY }}' && attic use demo"
-          env
-          mkdir -p ~/.ssh
-          echo "${{ secrets.CD_SSH_KEY }}" > ~/.ssh/id_ed25519
-          chmod 600 ~/.ssh/id_ed25519
-          cat ~/.config/attic/config.toml
-          cat ~/.config/nix/nix.conf
-          nix-shell --run "attic push demo $(nix-build)"

.woodpecker/cache.yaml

@@ -0,0 +1,25 @@
+$schema: https://raw.githubusercontent.com/woodpecker-ci/woodpecker/refs/heads/main/pipeline/frontend/yaml/linter/schema/schema.json
+
+when:
+  - event: manual
+  - event: push
+    branch: main
+
+steps:
+  - name: cache-build
+    image: nixos/nix
+    commands:
+      - |
+        nix-shell --run "attic login fediversity https://attic.fediversity.net '$ATTIC_PUSH_KEY' && attic use demo"
+        env
+        mkdir -p ~/.ssh
+        echo "$CD_SSH_KEY" > ~/.ssh/id_ed25519
+        chmod 600 ~/.ssh/id_ed25519
+        cat ~/.config/attic/config.toml
+        cat ~/.config/nix/nix.conf
+        nix-shell --run "attic push demo $(nix-build)"
+    environment:
+      ATTIC_PUSH_KEY:
+        from_secret: attic_push_key
+      CD_SSH_KEY:
+        from_secret: cd_ssh_key