chore: support multiple Go versions

.github/workflows/build.yml

@@ -20,16 +20,23 @@ jobs:
     steps:
       - name: Get Go versions
         id: versions
+        env:
+          GO_VERSION: ${{ vars.GO_VERSION }}
         run: |
-          VERSIONS=$(
-            curl -s 'https://go.dev/dl/?mode=json' \
-              | jq -r '
-                [.[] | select(.stable) | .version]
-                | group_by(split(".")[0:2] | join("."))
-                | map(max_by(ltrimstr("go") | split(".") | map(tonumber)))[]
-              ' | sed 's/go//'
-          )
-          VERSIONS_ARRAY=$(echo "$VERSIONS" | jq -R -s -c 'split("\n") | map(select(length > 0))')
+          if [ -n "$GO_VERSION" ]; then
+            # Repository variable overrides the API — build only that version
+            VERSIONS_ARRAY=$(jq -cn --arg v "$GO_VERSION" '[$v]')
+          else
+            VERSIONS=$(
+              curl -s 'https://go.dev/dl/?mode=json' \
+                | jq -r '
+                  [.[] | select(.stable) | .version]
+                  | group_by(split(".")[0:2] | join("."))
+                  | map(max_by(ltrimstr("go") | split(".") | map(tonumber)))[]
+                ' | sed 's/go//'
+            )
+            VERSIONS_ARRAY=$(echo "$VERSIONS" | jq -R -s -c 'split("\n") | map(select(length > 0))')
+          fi
           echo "matrix={\"go-version\":$VERSIONS_ARRAY}" >> $GITHUB_OUTPUT
 
       - name: Get latest version

Dockerfile

@@ -29,6 +29,8 @@ WORKDIR /go
 
 FROM ubuntu:24.04@sha256:d1e2e92c075e5ca139d51a140fff46f84315c0fdce203eab2807c7e495eff4f9
 
+ARG GO_VERSION
+LABEL org.opencontainers.image.version="${GO_VERSION}"
 
 RUN set -eux && \
     apt-get update && \
@@ -43,6 +45,7 @@ RUN set -eux && \
 ENV GOPATH=/go
 ENV PATH=$GOPATH/bin:/usr/local/go/bin:$PATH
 ENV CGO_ENABLED=0
+ENV GO_VERSION=${GO_VERSION}
 
 COPY --from=base /usr/local/go /usr/local/go