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logcli: Add retries to unsuccessful log queries #3879

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Jun 24, 2021
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logcli: Add retries to unsuccessful log queries #3879

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02caa5a
Add retries to unsuccessfull log queries.
vyzigold Jun 22, 2021
98a3361
Differentiate between query attempts and retries
vyzigold Jun 24, 2021
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1 change: 1 addition & 0 deletions cmd/logcli/main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -211,6 +211,7 @@ func newQueryClient(app *kingpin.Application) client.Client {
app.Flag("org-id", "adds X-Scope-OrgID to API requests for representing tenant ID. Useful for requesting tenant data when bypassing an auth gateway.").Default("").Envar("LOKI_ORG_ID").StringVar(&client.OrgID)
app.Flag("bearer-token", "adds the Authorization header to API requests for authentication purposes. Can also be set using LOKI_BEARER_TOKEN env var.").Default("").Envar("LOKI_BEARER_TOKEN").StringVar(&client.BearerToken)
app.Flag("bearer-token-file", "adds the Authorization header to API requests for authentication purposes. Can also be set using LOKI_BEARER_TOKEN_FILE env var.").Default("").Envar("LOKI_BEARER_TOKEN_FILE").StringVar(&client.BearerTokenFile)
app.Flag("retries", "How many times to retry each query when getting an error response from Loki. Can also be set using LOKI_CLIENT_RETRIES").Default("1").Envar("LOKI_CLIENT_RETRIES").IntVar(&client.Retries)

return client
}
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37 changes: 28 additions & 9 deletions pkg/logcli/client/client.go
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Expand Up @@ -56,6 +56,7 @@ type DefaultClient struct {
Tripperware Tripperware
BearerToken string
BearerTokenFile string
Retries int
}

// Query uses the /api/v1/query endpoint to execute an instant query
Expand Down Expand Up @@ -216,21 +217,39 @@ func (c *DefaultClient) doRequest(path, query string, quiet bool, out interface{
if c.Tripperware != nil {
client.Transport = c.Tripperware(client.Transport)
}
resp, err := client.Do(req)
if err != nil {
return err

var resp *http.Response
retries := c.Retries
success := false

for retries > 0 {
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If a user sets the retries flag value to 0 by mistake then they would unexpectedly skip making any calls. Also, retried calls should be the ones done after seeing a failure in the initial call, so let us initialise the retries above to c.Retries + 1.
What do you think?

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You are right, but I enhanced your idea a little bit. I renamed the variable to "attempts", which seemed like a better name to me now. I implemented your suggestion, so attempts = c.Retries + 1 and I made the default value for c.Retries = 0. So there still is 1 attempt unless the user sets the retries flag to something other than 0.

retries--

resp, err = client.Do(req)
if err != nil {
log.Println("error sending request", err)
continue
}
if resp.StatusCode/100 != 2 {
buf, _ := ioutil.ReadAll(resp.Body) // nolint
log.Printf("Error response from server: %s (%v) retries remaining: %d", string(buf), err, retries)
if err := resp.Body.Close(); err != nil {
log.Println("error closing body", err)
}
continue
}
success = true
break
}
if !success {
return fmt.Errorf("Run out of retries while querying the server")
}

defer func() {
if err := resp.Body.Close(); err != nil {
log.Println("error closing body", err)
}
}()

if resp.StatusCode/100 != 2 {
buf, _ := ioutil.ReadAll(resp.Body) // nolint
return fmt.Errorf("Error response from server: %s (%v)", string(buf), err)
}

return json.NewDecoder(resp.Body).Decode(out)
}

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