Release automatically when the version changes

.github/workflows/ci.yml

@@ -23,3 +23,59 @@ jobs:
       - run: cargo clippy --all-targets -- -D warnings
 
       - run: cargo test
+
+  # Tags and releases the version in Cargo.toml once a push to the default
+  # branch is green. Nothing happens when that version is already tagged.
+  release:
+    needs: test
+    if: github.event_name == 'push' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    concurrency:
+      group: release
+      cancel-in-progress: false
+    outputs:
+      tag: ${{ steps.release.outputs.tag }}
+      created: ${{ steps.release.outputs.created }}
+    steps:
+      - uses: actions/checkout@v5
+
+      - id: release
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          VERSION="$(sed -nE 's/^version *= *"([^"]+)".*/\1/p' Cargo.toml | head -1)"
+          if [ -z "$VERSION" ]; then
+            echo "::error::No version found in Cargo.toml"
+            exit 1
+          fi
+          TAG="v$VERSION"
+          echo "tag=$TAG" >> "$GITHUB_OUTPUT"
+
+          STATUS=0
+          git ls-remote --exit-code --tags origin "refs/tags/$TAG" > /dev/null || STATUS=$?
+          case "$STATUS" in
+            0)
+              echo "Tag $TAG already exists; nothing to release."
+              echo "created=false" >> "$GITHUB_OUTPUT"
+              ;;
+            2)
+              gh release create "$TAG" --target "$GITHUB_SHA" --title "$TAG" --generate-notes
+              echo "created=true" >> "$GITHUB_OUTPUT"
+              ;;
+            *)
+              echo "::error::Could not check whether tag $TAG exists (git ls-remote exited with $STATUS)"
+              exit "$STATUS"
+              ;;
+          esac
+
+  # A release created with the workflow's own token does not trigger the
+  # publish workflow, so it is called from this run instead.
+  publish:
+    needs: release
+    if: needs.release.outputs.created == 'true'
+    uses: ./.github/workflows/publish.yml
+    with:
+      tag: ${{ needs.release.outputs.tag }}
+    secrets: inherit

.github/workflows/publish.yml

@@ -3,6 +3,12 @@ name: Publish to crates.io
 on:
   release:
     types: [published]
+  workflow_call:
+    inputs:
+      tag:
+        description: Tag of the release to publish, for example v0.1.2
+        required: true
+        type: string
 
 env:
   CARGO_TERM_COLOR: always
@@ -12,6 +18,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v5
+        with:
+          # The tag being published: the input when called from the release job
+          # in ci.yml, the release's own tag when a release is published by hand.
+          ref: refs/tags/${{ inputs.tag || github.event.release.tag_name }}
 
       - uses: dtolnay/rust-toolchain@stable
         with:

README.md

@@ -140,6 +140,10 @@ The main response type is `IpInfo` which includes:
 
 All response structs ignore unknown keys and decode a missing key and an explicit `null` alike: `Option` fields read `None`, every other field reads its default (`""`, `false`, `0`, `0.0` or an empty list), so a `null` anywhere in a response does not fail the lookup.
 
+## Releasing
+
+Releases are cut by CI; nothing is tagged by hand. Bump `version` in `Cargo.toml` in a pull request and merge it: once the tests on the merge commit pass, CI tags it `vX.Y.Z`, creates the GitHub release with generated notes and publishes the crate to [crates.io](https://crates.io/crates/ipdata). A merge whose version is already tagged publishes nothing. A release published by hand on GitHub still runs the same publish workflow.
+
 ## License
 
 MIT