avoid downloading dagger if requested version is already installed

.github/workflows/test.yml

@@ -248,3 +248,66 @@ jobs:
       - name: "Test Install"
         run: |
           dagger core version
+
+  existing-install:
+    runs-on: "ubuntu-latest"
+    steps:
+      - uses: actions/checkout@v4
+      - name: "preinstall dagger"
+        run: |
+          curl -fsS https://dl.dagger.io/dagger/install.sh \
+          | BIN_DIR=/usr/local/bin DAGGER_VERSION="v0.18.17" sh
+      - name: "Install with version"
+        uses: ./
+        with:
+          version: "v0.18.16"
+      - name: "Test Install"
+        run: |
+          if [[ "$(dagger core version)" == "v0.18.16" ]]; then
+            exit 0
+          else
+            echo "Existing install was not overridden"
+            exit 1
+          fi
+
+  commit-install:
+    runs-on: "ubuntu-latest"
+    steps:
+      - uses: actions/checkout@v4
+      - name: "preinstall dagger"
+        run: |
+          curl -fsS https://dl.dagger.io/dagger/install.sh \
+          | BIN_DIR=/usr/local/bin DAGGER_VERSION="v0.18.17" sh
+      - name: "Install with version"
+        uses: ./
+        with:
+          commit: "71f2e104b045ddc3b0cc611b81370707bf21bc27"
+      - name: "Test Install"
+        run: |
+          if [[ "$(dagger version)" == *"v0.18.19-250918123923-71f2e104b045"* ]]; then
+            exit 0
+          else
+            echo "Existing install was not overridden"
+            exit 1
+          fi
+
+  latest-install:
+    runs-on: "ubuntu-latest"
+    steps:
+      - uses: actions/checkout@v4
+      - name: "preinstall dagger"
+        run: |
+          curl -fsS https://dl.dagger.io/dagger/install.sh \
+          | BIN_DIR=/usr/local/bin DAGGER_VERSION="v0.18.17" sh
+      - name: "Install with version"
+        uses: ./
+        with:
+          version: "latest"
+      - name: "Test Install"
+        run: |
+          if [[ "$(dagger version)" != "v0.18.17" ]]; then
+            exit 0
+          else
+            echo "Existing install was not overridden with latest"
+            exit 1
+          fi

README.md

@@ -43,18 +43,18 @@ By setting the version to `latest`, this action will install the latest version
 
 ### All `with:` input parameter options
 
-| Key            | Description                                                 | Required | Default            |
-| -------------- | ----------------------------------------------------------- | -------- | ------------------ |
-| `version`      | Dagger Version                                              | true    | n/a use semver x.y.z or 'latest'
-| `commit`       | Dagger Dev Commit (overrides `version`)                     | false    | ''                 |
-| `dagger-flags` | Dagger CLI Flags                                            | false    | '--progress plain' |
-| `verb`         | CLI verb (call, run, download, up, functions, shell, query) | false    | 'call'             |
-| `workdir`      | The working directory in which to run the Dagger CLI        | false    | '.'                |
-| `cloud-token`  | Dagger Cloud Token                                          | false    | ''                 |
-| `module`       | Dagger module to call. Local or Git                         | false    | ''                 |
-| `args`         | Arguments to pass to CLI                                    | false    | ''                 |
-| `call`         | Arguments to pass to CLI (Alias for args with verb:call)    | false    | ''                 |
-| `shell`        | Arguments to pass to CLI (Alias for args with verb:shell)   | false    | ''                 |
+| Key             | Description                                                       | Required | Default            |
+| --------------- | ----------------------------------------------------------------- | -------- | ------------------ |
+| `version`       | Dagger Version. Use semver vX.Y.Z or 'latest'                     | true     | 'latest'           |
+| `commit`        | Dagger Dev Commit (overrides `version`)                           | false    | ''                 |
+| `dagger-flags`  | Dagger CLI Flags                                                  | false    | '--progress plain' |
+| `verb`          | CLI verb (call, run, download, up, functions, shell, query)       | false    | 'call'             |
+| `workdir`       | The working directory in which to run the Dagger CLI              | false    | '.'                |
+| `cloud-token`   | Dagger Cloud Token                                                | false    | ''                 |
+| `module`        | Dagger module to call. Local or Git                               | false    | ''                 |
+| `args`          | Arguments to pass to CLI                                          | false    | ''                 |
+| `call`          | Arguments to pass to CLI (Alias for args with verb:call)          | false    | ''                 |
+| `shell`         | Arguments to pass to CLI (Alias for args with verb:shell)         | false    | ''                 |
 
 ### All output variables
 

action.yml

@@ -2,8 +2,9 @@ name: "Dagger for GitHub"
 description: "Run dagger commands in Github Actions"
 inputs:
   version:
-    description: "Dagger Version"
-    required: true
+    description: "Dagger Version. Use semver vX.Y.Z or 'latest'"
+    required: false
+    default: "latest"
   commit:
     description: "Dagger Dev Commit"
     required: false
@@ -72,12 +73,25 @@ runs:
         if [[ "$VERSION" == "latest" ]]; then
           VERSION=
         fi
+        latest=$(curl https://dl.dagger.io/dagger/versions/latest)
 
         COMMIT=${{ inputs.commit }}
 
-        # The install.sh script creates path ${prefix_dir}/bin
-        curl -fsS https://dl.dagger.io/dagger/install.sh \
-        | BIN_DIR=${prefix_dir}/bin DAGGER_VERSION="$VERSION" DAGGER_COMMIT="$COMMIT" sh
+        if [[ -x "$(command -v dagger)" ]]; then
+          echo "::group::Checking dagger"
+          version="$(dagger --silent version | cut --fields 2 --delimiter ' ')"
+          echo "Found existing dagger version: $version"
+          if [[ "$version" == "$VERSION" ]] || [[ "$version" == "$latest" ]]; then
+            echo "dagger ${version} is already installed, skipping installation"
+            exit 0
+          fi
+          echo "::endgroup::"
+        fi
+
+        echo "::group::Installing dagger"
+        curl -fsSL https://dl.dagger.io/dagger/install.sh | \
+        BIN_DIR=${prefix_dir}/bin DAGGER_VERSION="$VERSION" DAGGER_COMMIT="$COMMIT" sh
+        echo "::endgroup::"
 
     - id: assemble
       if: inputs.call != '' || inputs.shell != '' || inputs.args != ''