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LogCLI, Grafana Loki’s command-line interface

LogCLI is the command-line interface to Grafana Loki. It facilitates running LogQL queries against a Loki instance.

Installation

Download the logcli binary from the Loki releases page.

Build LogCLI from source

Clone the Loki repository and build logcli from source:

bash 
git clone https://github.com/grafana/loki.git
cd loki
make logcli

Optionally, move the binary into a directory that is part of your $PATH.

bash 
cp cmd/logcli/logcli /usr/local/bin/logcli

LogCLI usage

Grafana Cloud example

If you are running on Grafana Cloud, use:

bash 
export LOKI_ADDR=https://logs-us-west1.grafana.net
export LOKI_USERNAME=<username>
export LOKI_PASSWORD=<password>

Otherwise you can point LogCLI to a local instance directly without needing a username and password:

bash 
export LOKI_ADDR=http://localhost:3100

Note: If you are running Loki behind a proxy server and you have authentication configured, you will also have to pass in LOKI_USERNAME and LOKI_PASSWORD, LOKI_BEARER_TOKEN or LOKI_BEARER_TOKEN_FILE accordingly.

bash 
$ logcli labels job
https://logs-dev-ops-tools1.grafana.net/api/prom/label/job/values
loki-ops/consul
loki-ops/loki-gw
...

$ logcli query '{job="loki-ops/consul"}'
https://logs-dev-ops-tools1.grafana.net/api/prom/query?query=%7Bjob%3D%22loki-ops%2Fconsul%22%7D&limit=30&start=1529928228&end=1529931828&direction=backward&regexp=
Common labels: {job="loki-ops/consul", namespace="loki-ops"}
2018-06-25T12:52:09Z {instance="consul-8576459955-pl75w"} 2018/06/25 12:52:09 [INFO] raft: Snapshot to 475409 complete
2018-06-25T12:52:09Z {instance="consul-8576459955-pl75w"} 2018/06/25 12:52:09 [INFO] raft: Compacting logs from 456973 to 465169
...

$ logcli series -q --match='{namespace="loki",container_name="loki"}'
{app="loki", container_name="loki", controller_revision_hash="loki-57c9df47f4", filename="/var/log/pods/loki_loki-0_8ed03ded-bacb-4b13-a6fe-53a445a15887/loki/0.log", instance="loki-0", job="loki/loki", name="loki", namespace="loki", release="loki", statefulset_kubernetes_io_pod_name="loki-0", stream="stderr"}

Batched queries

LogCLI sends queries to Loki such that query results arrive in batches.

The --limit option for a logcli query command caps the quantity of log lines for a single query. When not set, --limit defaults to 30. The limit protects the user from overwhelming the system for cases in which the specified query would have returned a large quantity of log lines. The limit also protects the user from unexpectedly large responses.

The quantity of log line results that arrive in each batch is set by the --batch option in a logcli query command. When not set, --batch defaults to 1000.

Setting a --limit value larger than the --batch value causes the requests from LogCLI to Loki to be batched. Loki has a server-side limit that defaults to 5000 for the maximum quantity of lines returned for a single query. The batching of requests allows you to query for a results set that is larger than the server-side limit, as long as the --batch value is less than the server limit.

Query metadata is output to stderr for each batch. Set the --quiet option on the logcli query command line to suppress the output of the query metadata.

Configuration

Configuration values are considered in the following order (lowest to highest):

  • Environment variables
  • Command-line options

LogCLI command reference

The output of logcli help:

nohighlight 
usage: logcli [<flags>] <command> [<args> ...]

A command-line for loki.

Flags:
      --help             Show context-sensitive help (also try --help-long and
                         --help-man).
      --version          Show application version.
  -q, --quiet            Suppress query metadata
      --stats            Show query statistics
  -o, --output=default   Specify output mode [default, raw, jsonl]. raw
                         suppresses log labels and timestamp.
  -z, --timezone=Local   Specify the timezone to use when formatting output
                         timestamps [Local, UTC]
      --cpuprofile=""    Specify the location for writing a CPU profile.
      --memprofile=""    Specify the location for writing a memory profile.
      --stdin            Take input logs from stdin
      --addr="http://localhost:3100"
                         Server address. Can also be set using LOKI_ADDR env
                         var.
      --username=""      Username for HTTP basic auth. Can also be set using
                         LOKI_USERNAME env var.
      --password=""      Password for HTTP basic auth. Can also be set using
                         LOKI_PASSWORD env var.
      --ca-cert=""       Path to the server Certificate Authority. Can also be
                         set using LOKI_CA_CERT_PATH env var.
      --tls-skip-verify  Server certificate TLS skip verify.
      --cert=""          Path to the client certificate. Can also be set using
                         LOKI_CLIENT_CERT_PATH env var.
      --key=""           Path to the client certificate key. Can also be set
                         using LOKI_CLIENT_KEY_PATH env var.
      --org-id=""        adds X-Scope-OrgID to API requests for representing
                         tenant ID. Useful for requesting tenant data when
                         bypassing an auth gateway.

Commands:
  help [<command>...]
    Show help.

  query [<flags>] <query>
    Run a LogQL query.

    The "query" command is useful for querying for logs. Logs can be returned in
    a few output modes:

      raw: log line
      default: log timestamp + log labels + log line
      jsonl: JSON response from Loki API of log line

    The output of the log can be specified with the "-o" flag, for example, "-o
    raw" for the raw output format.

    The "query" command will output extra information about the query and its
    results, such as the API URL, set of common labels, and set of excluded
    labels. This extra information can be suppressed with the --quiet flag.

    By default we look over the last hour of data; use --since to modify or
    provide specific start and end times with --from and --to respectively.

    Notice that when using --from and --to then ensure to use RFC3339Nano time
    format, but without timezone at the end. The local timezone will be added
    automatically or if using --timezone flag.

    Example:

      logcli query
         --timezone=UTC
         --from="2021-01-19T10:00:00Z"
         --to="2021-01-19T20:00:00Z"
         --output=jsonl
         'my-query'

    The output is limited to 30 entries by default; use --limit to increase.

    While "query" does support metrics queries, its output contains multiple
    data points between the start and end query time. This output is used to
    build graphs, similar to what is seen in the Grafana Explore graph view. If
    you are querying metrics and just want the most recent data point (like what
    is seen in the Grafana Explore table view), then you should use the
    "instant-query" command instead.

  instant-query [<flags>] <query>
    Run an instant LogQL query.

    The "instant-query" command is useful for evaluating a metric query for a
    single point in time. This is equivalent to the Grafana Explore table view;
    if you want a metrics query that is used to build a Grafana graph, you
    should use the "query" command instead.

    This command does not produce useful output when querying for log lines; you
    should always use the "query" command when you are running log queries.

    For more information about log queries and metric queries, refer to the
    LogQL documentation:

    https://grafana.com/docs/loki/latest/logql/

  labels [<flags>] [<label>]
    Find values for a given label.

  series [<flags>] <matcher>
    Run series query.

    The "series" command will take the provided label matcher and return all the
    log streams found in the time window.

    It is possible to send an empty label matcher '{}' to return all streams.

    Use the --analyze-labels flag to get a summary of the labels found in all
    streams. This is helpful to find high cardinality labels.

LogCLI query command reference

The output of logcli help query:

usage: logcli query [<flags>] <query>

Run a LogQL query.

The "query" command is useful for querying for logs. Logs can be returned in a
few output modes:

  raw: log line
  default: log timestamp + log labels + log line
  jsonl: JSON response from Loki API of log line

The output of the log can be specified with the "-o" flag, for example, "-o raw"
for the raw output format.

The "query" command will output extra information about the query and its
results, such as the API URL, set of common labels, and set of excluded labels.
This extra information can be suppressed with the --quiet flag.

By default we look over the last hour of data; use --since to modify or provide
specific start and end times with --from and --to respectively.

Notice that when using --from and --to then ensure to use RFC3339Nano time
format, but without timezone at the end. The local timezone will be added
automatically or if using --timezone flag.

Example:

  logcli query
     --timezone=UTC
     --from="2021-01-19T10:00:00Z"
     --to="2021-01-19T20:00:00Z"
     --output=jsonl
     'my-query'

The output is limited to 30 entries by default; use --limit to increase.

While "query" does support metrics queries, its output contains multiple data
points between the start and end query time. This output is used to build
graphs, similar to what is seen in the Grafana Explore graph view. If you are
querying metrics and just want the most recent data point (like what is seen in
the Grafana Explore table view), then you should use the "instant-query" command
instead.

Flags:
      --help               Show context-sensitive help (also try --help-long and
                           --help-man).
      --version            Show application version.
  -q, --quiet              Suppress query metadata
      --stats              Show query statistics
  -o, --output=default     Specify output mode [default, raw, jsonl]. raw
                           suppresses log labels and timestamp.
  -z, --timezone=Local     Specify the timezone to use when formatting output
                           timestamps [Local, UTC]
      --cpuprofile=""      Specify the location for writing a CPU profile.
      --memprofile=""      Specify the location for writing a memory profile.
      --stdin              Take input logs from stdin
      --addr="http://localhost:3100"
                           Server address. Can also be set using LOKI_ADDR env
                           var.
      --username=""        Username for HTTP basic auth. Can also be set using
                           LOKI_USERNAME env var.
      --password=""        Password for HTTP basic auth. Can also be set using
                           LOKI_PASSWORD env var.
      --ca-cert=""         Path to the server Certificate Authority. Can also be
                           set using LOKI_CA_CERT_PATH env var.
      --tls-skip-verify    Server certificate TLS skip verify.
      --cert=""            Path to the client certificate. Can also be set using
                           LOKI_CLIENT_CERT_PATH env var.
      --key=""             Path to the client certificate key. Can also be set
                           using LOKI_CLIENT_KEY_PATH env var.
      --org-id=""          adds X-Scope-OrgID to API requests for representing
                           tenant ID. Useful for requesting tenant data when
                           bypassing an auth gateway.
      --limit=30           Limit on number of entries to print.
      --since=1h           Lookback window.
      --from=FROM          Start looking for logs at this absolute time
                           (inclusive)
      --to=TO              Stop looking for logs at this absolute time
                           (exclusive)
      --step=STEP          Query resolution step width, for metric queries.
                           Evaluate the query at the specified step over the
                           time range.
      --interval=INTERVAL  Query interval, for log queries. Return entries at
                           the specified interval, ignoring those between.
                           **This parameter is experimental, please see Issue
                           1779**
      --batch=1000         Query batch size to use until 'limit' is reached
      --forward            Scan forwards through logs.
      --no-labels          Do not print any labels
      --exclude-label=EXCLUDE-LABEL ...
                           Exclude labels given the provided key during output.
      --include-label=INCLUDE-LABEL ...
                           Include labels given the provided key during output.
      --labels-length=0    Set a fixed padding to labels
      --store-config=""    Execute the current query using a configured storage
                           from a given Loki configuration file.
      --colored-output     Show output with colored labels
  -t, --tail               Tail the logs
  -f, --follow             Alias for --tail
      --delay-for=0        Delay in tailing by number of seconds to accumulate
                           logs for re-ordering

Args:
  <query>  eg '{foo="bar",baz=~".*blip"} |~ ".*error.*"'

LogCLI labels command reference

The output of logcli help labels:

usage: logcli labels [<flags>] [<label>]

Find values for a given label.

Flags:
      --help             Show context-sensitive help (also try --help-long and
                         --help-man).
      --version          Show application version.
  -q, --quiet            Suppress query metadata
      --stats            Show query statistics
  -o, --output=default   Specify output mode [default, raw, jsonl]. raw
                         suppresses log labels and timestamp.
  -z, --timezone=Local   Specify the timezone to use when formatting output
                         timestamps [Local, UTC]
      --cpuprofile=""    Specify the location for writing a CPU profile.
      --memprofile=""    Specify the location for writing a memory profile.
      --stdin            Take input logs from stdin
      --addr="http://localhost:3100"
                         Server address. Can also be set using LOKI_ADDR env
                         var.
      --username=""      Username for HTTP basic auth. Can also be set using
                         LOKI_USERNAME env var.
      --password=""      Password for HTTP basic auth. Can also be set using
                         LOKI_PASSWORD env var.
      --ca-cert=""       Path to the server Certificate Authority. Can also be
                         set using LOKI_CA_CERT_PATH env var.
      --tls-skip-verify  Server certificate TLS skip verify.
      --cert=""          Path to the client certificate. Can also be set using
                         LOKI_CLIENT_CERT_PATH env var.
      --key=""           Path to the client certificate key. Can also be set
                         using LOKI_CLIENT_KEY_PATH env var.
      --org-id=""        adds X-Scope-OrgID to API requests for representing
                         tenant ID. Useful for requesting tenant data when
                         bypassing an auth gateway.
      --since=1h         Lookback window.
      --from=FROM        Start looking for labels at this absolute time
                         (inclusive)
      --to=TO            Stop looking for labels at this absolute time
                         (exclusive)

Args:
  [<label>]  The name of the label.

LogCLI series command reference

The output of logcli help series:

usage: logcli series [<flags>] <matcher>

Run series query.

The "series" command will take the provided label matcher and return all the log
streams found in the time window.

It is possible to send an empty label matcher '{}' to return all streams.

Use the --analyze-labels flag to get a summary of the labels found in all
streams. This is helpful to find high cardinality labels.

Flags:
      --help             Show context-sensitive help (also try --help-long and
                         --help-man).
      --version          Show application version.
  -q, --quiet            Suppress query metadata
      --stats            Show query statistics
  -o, --output=default   Specify output mode [default, raw, jsonl]. raw
                         suppresses log labels and timestamp.
  -z, --timezone=Local   Specify the timezone to use when formatting output
                         timestamps [Local, UTC]
      --cpuprofile=""    Specify the location for writing a CPU profile.
      --memprofile=""    Specify the location for writing a memory profile.
      --stdin            Take input logs from stdin
      --addr="http://localhost:3100"
                         Server address. Can also be set using LOKI_ADDR env
                         var.
      --username=""      Username for HTTP basic auth. Can also be set using
                         LOKI_USERNAME env var.
      --password=""      Password for HTTP basic auth. Can also be set using
                         LOKI_PASSWORD env var.
      --ca-cert=""       Path to the server Certificate Authority. Can also be
                         set using LOKI_CA_CERT_PATH env var.
      --tls-skip-verify  Server certificate TLS skip verify.
      --cert=""          Path to the client certificate. Can also be set using
                         LOKI_CLIENT_CERT_PATH env var.
      --key=""           Path to the client certificate key. Can also be set
                         using LOKI_CLIENT_KEY_PATH env var.
      --org-id=""        adds X-Scope-OrgID to API requests for representing
                         tenant ID. Useful for requesting tenant data when
                         bypassing an auth gateway.
      --since=1h         Lookback window.
      --from=FROM        Start looking for logs at this absolute time
                         (inclusive)
      --to=TO            Stop looking for logs at this absolute time (exclusive)
      --analyze-labels   Printout a summary of labels including count of label
                         value combinations, useful for debugging high
                         cardinality series

Args:
  <matcher>  eg '{foo="bar",baz=~".*blip"}'

LogCLI --stdin usage

You can consume log lines from your stdin instead of Loki servers.

Say you have log files in your local, and just want to do run some LogQL queries for that, --stdin flag can help.

NOTE: Currently it doesn’t support any type of metric queries

You may have to use stdin flag for several reasons

  1. Quick way to check and validate a LogQL expressions.
  2. Learn basics of LogQL with just Log files and LogCLItool ( without needing set up Loki servers, Grafana etc.)
  3. Easy discussion on public forums. Like Q&A, Share the LogQL expressions.

NOTES on Usage

  1. --limits flag doesn’t have any meaning when using --stdin (use pager like less for that)
  2. Be aware there are no labels when using --stdin
    • So stream selector in the query is optional e.g just |="timeout"|logfmt|level="error" is same as {foo="bar"}|="timeout|logfmt|level="error"

Examples

  1. Line filter - cat mylog.log | logcli --stdin query '|="too many open connections"'
  2. Label matcher - echo 'msg="timeout happened" level="warning"' | logcli --stdin query '|logfmt|level="warning"'
  3. Different parsers (logfmt, json, pattern, regexp) - cat mylog.log | logcli --stdin query '|pattern <ip> - - <_> "<method> <uri> <_>" <status> <size> <_> "<agent>" <_>'
  4. Line formatters - cat mylog.log | logcli --stdin query '|logfmt|line_format "{{.query}} {{.duration}}"'