feat: validate action

validate/Dockerfile

@@ -0,0 +1,5 @@
+FROM tufin/oasdiff:v1.15.3
+RUN apk add --no-cache jq
+ENV PLATFORM github-action
+COPY entrypoint.sh /entrypoint.sh
+ENTRYPOINT ["/entrypoint.sh"]

validate/action.yml

@@ -0,0 +1,24 @@
+name: 'Validate an OpenAPI spec'
+description: 'Validate an OpenAPI spec against the spec, with per-finding PR annotations'
+inputs:
+  spec:
+    description: 'Path of the OpenAPI spec in YAML or JSON format'
+    required: true
+  fail-on-finding:
+    description: 'Fail with exit code 1 if any finding is reported (default: true)'
+    required: false
+    default: 'true'
+  allow-external-refs:
+    description: 'Allow external $refs in the spec; disable to prevent SSRF when validating untrusted specs'
+    required: false
+    default: 'true'
+outputs:
+  findings:
+    description: 'Number of findings reported by validate (0 if the spec is well-formed)'
+runs:
+  using: 'docker'
+  image: 'Dockerfile'
+  args:
+    - ${{ inputs.spec }}
+    - ${{ inputs.fail-on-finding }}
+    - ${{ inputs.allow-external-refs }}

validate/entrypoint.sh

@@ -0,0 +1,70 @@
+#!/bin/sh
+set -e
+
+if [ -n "$GITHUB_WORKSPACE" ]; then
+  git config --global --get-all safe.directory | grep -q "$GITHUB_WORKSPACE" || \
+  git config --global --add safe.directory "$GITHUB_WORKSPACE"
+fi
+
+readonly spec="$1"
+readonly fail_on_finding="$2"
+readonly allow_external_refs="$3"
+
+echo "running oasdiff validate... spec: $spec, fail_on_finding: $fail_on_finding, allow_external_refs: $allow_external_refs"
+
+# Build flags. --allow-external-refs defaults to true in oasdiff so we
+# only pass --allow-external-refs=false when the input explicitly opts
+# out; otherwise rely on the binary's default.
+flags=""
+if [ "$allow_external_refs" = "false" ]; then
+    flags="$flags --allow-external-refs=false"
+fi
+echo "flags: $flags"
+
+# Run 1: capture the text-format findings count for GITHUB_OUTPUT and
+# the user-facing step log. Tolerate non-zero exit — oasdiff returns 1
+# when any finding is reported, but we render annotations and the
+# fail-on-finding decision below regardless.
+validate_exit=0
+findings_text=$(oasdiff validate $flags "$spec") || validate_exit=$?
+
+# Run 2: render annotations to stdout via --format githubactions so
+# GitHub parses them onto the PR's "Files changed" tab. Tolerate
+# non-zero exit (same reason as Run 1).
+oasdiff validate $flags --format githubactions "$spec" || true
+
+# *** GitHub Action step output ***
+
+# Extract the finding count from the first line of the text output:
+# "N findings: N error, N warning, N info"
+findings_count=0
+if [ -n "$findings_text" ]; then
+    header=$(printf '%s' "$findings_text" | head -n 1)
+    findings_count=$(printf '%s' "$header" | awk '{print $1}')
+    if ! printf '%s' "$findings_count" | grep -qE '^[0-9]+$'; then
+        findings_count=0
+    fi
+fi
+echo "findings=$findings_count" >>"$GITHUB_OUTPUT"
+
+# Emit upgrade notice with a clickable summary link pointing at the
+# free review surface. Same pattern as the breaking action: notice
+# annotation + GITHUB_STEP_SUMMARY markdown link.
+if [ "$findings_count" -gt 0 ]; then
+    notice_url="https://www.oasdiff.com/review?owner=$(printf '%s' "${GITHUB_REPOSITORY%%/*}" | jq -sRr @uri)&repo=$(printf '%s' "${GITHUB_REPOSITORY#*/}" | jq -sRr @uri)"
+    echo "::notice::🔎 ${findings_count} OpenAPI validation finding(s) — see annotations above. oasdiff.com → ${notice_url}"
+    {
+        echo "### 🔎 oasdiff validate found ${findings_count} OpenAPI spec issue(s)"
+        echo ""
+        echo "See annotations on the Files Changed tab for the precise line and column of each finding."
+        echo ""
+        echo "[Learn more about oasdiff →](${notice_url})"
+    } >> "$GITHUB_STEP_SUMMARY"
+fi
+
+# Honour fail-on-finding (default true). When false, we report findings
+# but the step still passes — useful for non-blocking visibility runs.
+if [ "$fail_on_finding" = "false" ]; then
+    exit 0
+fi
+exit "$validate_exit"