Close http bodies and add linter for it

Not closing the response body presumably claused flakyness in the
registry replacer when it tries to read a response body[0], see[1]
for why this can happen.

As this seems to be a common mistake in our codebase, this change
activates a linter for it.

[0] https://issues.redhat.com/browse/DPTP-1692
[1] golang/go#36700

.golangci.yml

@@ -14,6 +14,7 @@ linters:
     - errcheck
     - ineffassign
     - misspell
+    - bodyclose
   disable-all: true
 
 issues:

pkg/backporter/httpcache.go

@@ -67,6 +67,9 @@ func (t *cachingTransport) RoundTrip(req *http.Request) (*http.Response, error)
 	g := errgroup.Group{}
 	g.Go(func() error {
 		var err error
+		// Disable the bodyclose linter, in this particular case the caller is responsible
+		// for closing the body.
+		// nolint:bodyclose
 		resp, err = t.transport.RoundTrip(req)
 		if err != nil {
 			return err

pkg/github/github.go

@@ -52,6 +52,7 @@ func FileGetterFactory(org, repo, branch string, opts ...Opt) FileGetter {
 		if err != nil {
 			return nil, fmt.Errorf("failed to GET %s: %w", url, err)
 		}
+		defer resp.Body.Close()
 		if resp.StatusCode == http.StatusNotFound {
 			return nil, nil
 		}

pkg/job-runtime-analyzer/job-runtime-analyzer.go

@@ -168,6 +168,7 @@ func fetchFromURL(urlString string) ([]byte, error) {
 	if err != nil {
 		return nil, fmt.Errorf("failed to GET %s: %w", parsedURL.String(), err)
 	}
+	defer result.Body.Close()
 	body, err := ioutil.ReadAll(result.Body)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read response body for request to %s: %w", parsedURL.String(), err)

pkg/load/load.go

@@ -192,6 +192,7 @@ func configFromResolver(info *ResolverInfo) (*api.ReleaseBuildConfiguration, err
 	if err != nil {
 		return nil, fmt.Errorf("failed to make request to configresolver: %w", err)
 	}
+	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {
 		return nil, fmt.Errorf("response from configresolver == %d (%s)", resp.StatusCode, http.StatusText(resp.StatusCode))
 	}
@@ -221,6 +222,7 @@ func literalConfigFromResolver(raw []byte, address string) (*api.ReleaseBuildCon
 	if err != nil {
 		return nil, fmt.Errorf("failed to request resolved config: %w", err)
 	}
+	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {
 		return nil, fmt.Errorf("response from configresolver == %d (%s)", resp.StatusCode, http.StatusText(resp.StatusCode))
 	}

pkg/release/candidate/client.go

@@ -76,6 +76,7 @@ func resolvePullSpec(client release.HTTPClient, endpoint string, relative int) (
 	if resp == nil {
 		return "", errors.New("failed to request latest release: got a nil response")
 	}
+	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {
 		return "", fmt.Errorf("failed to request latest release: server responded with %d: %s", resp.StatusCode, resp.Body)
 	}

pkg/release/official/client.go

@@ -45,6 +45,7 @@ func resolvePullSpec(client release.HTTPClient, endpoint string, release api.Rel
 	if resp == nil {
 		return "", "", errors.New("failed to request latest release: got a nil response")
 	}
+	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {
 		return "", "", fmt.Errorf("failed to request latest release: server responded with %d: %s", resp.StatusCode, resp.Body)
 	}

pkg/release/prerelease/client.go

@@ -45,6 +45,7 @@ func resolvePullSpec(client release.HTTPClient, endpoint string, bounds api.Vers
 	if resp == nil {
 		return "", errors.New("failed to request latest release: got a nil response")
 	}
+	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {
 		return "", fmt.Errorf("failed to request latest release: server responded with %d: %s", resp.StatusCode, resp.Body)
 	}