# Parsing GitLab logs with `jq`

We recommend using log aggregation and search tools like Kibana and Splunk whenever possible,
but if they are not available you can still quickly parse
[GitLab logs](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/26311) in JSON format
(the default since GitLab 12.0) using [`jq`](https://stedolan.github.io/jq/).

## What is JQ?

As noted in its [manual](https://stedolan.github.io/jq/manual/), jq is a command-line JSON processor. The following examples
include use cases targeted for parsing GitLab log files.

## Parsing Logs

### General Commands

#### Pipe colorized `jq` output into `less`

```shell
jq . <FILE> -C | less -R
```

#### Search for a term and pretty-print all matching lines

```shell
grep <TERM> <FILE> | jq .
```

#### Skip invalid lines of JSON

```shell
jq -cR 'fromjson?' file.json | jq <COMMAND>
```

By default `jq` will error out when it encounters a line that is not valid JSON.
This skips over all invalid lines and parses the rest.

### Parsing `production_json.log` and `api_json.log`

#### Find all requests with a 5XX status code

```shell
jq 'select(status >= 500)' <FILE>
```

#### Top 10 slowest requests

```shell
jq -s 'sort_by(-.duration) | limit(10; .[])' <FILE>
```

#### Find and pretty print all requests related to a project

```shell
grep <PROJECT_NAME> <FILE> | jq .
```

#### Find all requests with a total duration > 5 seconds

```shell
jq 'select(.duration > 5000)' <FILE>
```

#### Find all project requests with more than 5 rugged calls

```shell
grep <PROJECT_NAME> <FILE> | jq 'select(.rugged_calls > 5)'
```

#### Find all requests with a Gitaly duration > 10 seconds

```shell
jq 'select(.gitaly_duration > 10000)' <FILE>
```

#### Find all requests with a queue duration > 10 seconds

```shell
jq 'select(.queue_duration > 10000)' <FILE>
```

#### Top 10 requests by # of Gitaly calls

```shell
jq -s 'map(select(.gitaly_calls != null)) | sort_by(-.gitaly_calls) | limit(10; .[])' <FILE>
```

### Parsing `production_json.log`

#### Print the top three controller methods by request volume and their three longest durations

```shell
jq -s -r 'group_by(.controller+.action) | sort_by(-length) | limit(3; .[]) | sort_by(-.duration) | "CT: \(length)\tMETHOD: \(.[0].controller)#\(.[0].action)\tDURS: \(.[0].duration),  \(.[1].duration),  \(.[2].duration)"' production_json.log
```

**Example output**

```plaintext
CT: 2721   METHOD: SessionsController#new  DURS: 844.06,  713.81,  704.66
CT: 2435   METHOD: MetricsController#index DURS: 299.29,  284.01,  158.57
CT: 1328   METHOD: Projects::NotesController#index DURS: 403.99,  386.29,  384.39
```

### Parsing `api_json.log`

#### Print top three routes with request count and their three longest durations

```shell
jq -s -r 'group_by(.route) | sort_by(-length) | limit(3; .[]) | sort_by(-.duration) | "CT: \(length)\tROUTE: \(.[0].route)\tDURS: \(.[0].duration),  \(.[1].duration),  \(.[2].duration)"' api_json.log
```

**Example output**

```plaintext
CT: 2472 ROUTE: /api/:version/internal/allowed   DURS: 56402.65,  38411.43,  19500.41
CT: 297  ROUTE: /api/:version/projects/:id/repository/tags       DURS: 731.39,  685.57,  480.86
CT: 190  ROUTE: /api/:version/projects/:id/repository/commits    DURS: 1079.02,  979.68,  958.21
```

### Parsing `gitaly/current`

#### Find all Gitaly requests sent from web UI

```shell
jq 'select(."grpc.meta.client_name" == "gitlab-web")' current
```

#### Find all failed Gitaly requests

```shell
jq 'select(."grpc.code" != null and ."grpc.code" != "OK")' current
```

#### Find all requests that took longer than 30 seconds

```shell
jq 'select(."grpc.time_ms" > 30000)' current
```

#### Print top three projects by request volume and their three longest durations

```shell
jq -s -r 'map(select(."grpc.request.glProjectPath" != null and ."grpc.request.glProjectPath" != "" and ."grpc.time_ms" != null)) | group_by(."grpc.request.glProjectPath") | sort_by(-length) | limit(3; .[]) | sort_by(-."grpc.time_ms") | "CT: \(length)\tPROJECT: \(.[0]."grpc.request.glProjectPath")\tDURS: \(.[0]."grpc.time_ms"),  \(.[1]."grpc.time_ms"),  \(.[2]."grpc.time_ms")"' current
```

**Example output**

```plaintext
CT: 635 PROJECT: groupA/project1     DURS: 4292.269,  4228.853,  2885.548
CT: 462 PROJECT: groupB/project5     DURS: 4368.981,  3623.553,  361.399
CT: 455 PROJECT: groupC/project7     DURS: 387.295,  381.874,  373.988
```
