mirror of https://github.com/grafana/grafana
Loki: backend: use custom http code (#44643)
* Loki: backend: use custom http code * simplfied comment Co-authored-by: Ivana Huckova <30407135+ivanahuckova@users.noreply.github.com> Co-authored-by: Ivana Huckova <30407135+ivanahuckova@users.noreply.github.com>pull/45608/head
Gábor Farkas
4 years ago
committed by
GitHub
parent
380e07ba29
commit
5d704fd46e
@ -0,0 +1,134 @@ |
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package loki |
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import ( |
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"bytes" |
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"context" |
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"encoding/json" |
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"fmt" |
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"io" |
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"net/http" |
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"net/url" |
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"strconv" |
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"github.com/grafana/grafana/pkg/infra/log" |
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"github.com/grafana/loki/pkg/loghttp" |
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jsoniter "github.com/json-iterator/go" |
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) |
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type LokiAPI struct { |
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client *http.Client |
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url string |
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log log.Logger |
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} |
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func newLokiAPI(client *http.Client, url string, log log.Logger) *LokiAPI { |
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return &LokiAPI{client: client, url: url, log: log} |
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} |
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func makeRequest(ctx context.Context, lokiDsUrl string, query lokiQuery) (*http.Request, error) { |
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qs := url.Values{} |
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qs.Set("query", query.Expr) |
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qs.Set("step", query.Step.String()) |
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qs.Set("start", strconv.FormatInt(query.Start.UnixNano(), 10)) |
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qs.Set("end", strconv.FormatInt(query.End.UnixNano(), 10)) |
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lokiUrl, err := url.Parse(lokiDsUrl) |
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if err != nil { |
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return nil, err |
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} |
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lokiUrl.Path = "/loki/api/v1/query_range" |
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lokiUrl.RawQuery = qs.Encode() |
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req, err := http.NewRequestWithContext(ctx, "GET", lokiUrl.String(), nil) |
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if err != nil { |
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return nil, err |
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} |
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// NOTE:
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// 1. we are missing "dynamic" http params, like OAuth data.
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// this never worked before (and it is not needed for alerting scenarios),
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// so it is not a regression.
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// twe need to have that when we migrate to backend-queries.
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//
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// 2. we will have to send a custom http header based on the VolumeQuery prop
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// (again, not needed for the alerting scenario)
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// if query.VolumeQuery {
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// req.Header.Set("X-Query-Tags", "Source=logvolhist")
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// }
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return req, nil |
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} |
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type lokiError struct { |
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Message string |
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} |
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// we know there is an error,
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// based on the http-response-body
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// we have to make an informative error-object
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func makeLokiError(body io.ReadCloser) error { |
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var buf bytes.Buffer |
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_, err := buf.ReadFrom(body) |
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if err != nil { |
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return err |
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} |
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bytes := buf.Bytes() |
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// the error-message is probably a JSON structure,
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// with a string-field named "message". we want the
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// value of that field.
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// but, the response might be just a simple string,
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// this was used in older Loki versions.
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// so our approach is this:
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// - we try to convert the bytes to JSON
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// - we take the value of the field "message"
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// - if any of these steps fail, or if "message" is empty, we return the whole text
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var data lokiError |
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err = json.Unmarshal(bytes, &data) |
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if err != nil { |
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// we were unable to convert the bytes to JSON, we return the whole text
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return fmt.Errorf("%v", string(bytes)) |
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} |
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errorMessage := data.Message |
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if errorMessage == "" { |
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// we got no usable error message, we return the whole text
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return fmt.Errorf("%v", string(bytes)) |
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} |
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return fmt.Errorf("%v", errorMessage) |
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} |
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func (api *LokiAPI) QueryRange(ctx context.Context, query lokiQuery) (*loghttp.QueryResponse, error) { |
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req, err := makeRequest(ctx, api.url, query) |
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if err != nil { |
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return nil, err |
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} |
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resp, err := api.client.Do(req) |
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if err != nil { |
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return nil, err |
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} |
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defer func() { |
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if err := resp.Body.Close(); err != nil { |
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api.log.Warn("Failed to close response body", "err", err) |
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} |
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}() |
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if resp.StatusCode/100 != 2 { |
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return nil, makeLokiError(resp.Body) |
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} |
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var response loghttp.QueryResponse |
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err = jsoniter.NewDecoder(resp.Body).Decode(&response) |
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if err != nil { |
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return nil, err |
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} |
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return &response, nil |
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} |
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