Logging API Examples

PREVIEW

This topic provides common usage examples for the Logging API.

Prerequisites:

  • Bash

  • Curl

  • jq

  • DC/OS

  • DC/OS CLI must be installed, configured, and logged in.

  • Extract DCOS_URL and DCOS_AUTH_TOKEN from the DC/OS CLI:

    DCOS_URL="$(dcos config show core.dcos_url)"
    DCOS_URL="${DCOS_URL%/}" # strip trailing slash, if present
    DCOS_AUTH_TOKEN="$(dcos config show core.dcos_acs_token)"
    

Node Logs

Get the last 100 journal entries from a single node:

curl -k -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/logs/v1/range/?skip_prev=100"

Component Logs

Get the last 100 journal entries from a single component service:

Leading Mesos Master:

curl -k -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/leader/mesos/logs/v1/range/?skip_prev=100&filter=_SYSTEMD_UNIT:dcos-mesos-master.service"

Leading Marathon:

curl -k -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/leader/marathon/logs/v1/range/?skip_prev=100&filter=_SYSTEMD_UNIT:dcos-mesos-master.service"

Agent DNS Forwarder (Spartan):

# select an agent ID
AGENT_ID="$(dcos node --json | jq -r '.[0].id)')"
curl -k -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/agent/${AGENT_ID}/logs/v1/range/?skip_prev=1&filter=_SYSTEMD_UNIT:dcos-spartan.service"

Container Logs

Get the last 100 journal entries from a single service container:

FRAMEWORK_NAME="marathon"
APP_ID="nginx"

# get the mesos task state json
MESOS_STATE="$(curl -k -H "Authorization: token=${DCOS_AUTH_TOKEN}" ${DCOS_URL}/mesos/state)"
TASK_STATE="$(echo "${MESOS_STATE}" | jq ".frameworks[] | select(.name == \"${FRAMEWORK_NAME}\") | .tasks[] | select(.name == \"${APP_ID}\")")"

# extract values from the task json
AGENT_ID="$(echo "${TASK_STATE}" | jq -r '.slave_id')"
TASK_ID="$(echo "${TASK_STATE}" | jq -r '.id')"
FRAMEWORK_ID="$(echo "${TASK_STATE}" | jq -r '.framework_id')"
EXECUTOR_ID="$(echo "${TASK_STATE}" | jq -r '.executor_id')"
CONTAINER_ID="$(echo "${TASK_STATE}" | jq -r '.statuses[0].container_status.container_id.value')"

# default to container ID when executor ID is empty
EXECUTOR_ID="${EXECUTOR_ID:-${TASK_ID}}"

# Using Mesos API, agent/files endpoint
curl -k -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/agent/${AGENT_ID}/files/read?path=/var/lib/mesos/slave/slaves/${AGENT_ID}/frameworks/${FRAMEWORK_ID}/executors/${EXECUTOR_ID}/runs/${CONTAINER_ID}/stdout&offset=0&length=50000"

Important: Journald task logging is disabled in DC/OS 1.9.0. For more information, see Logging API: Compatibility.

Tail

Get the last 10 journal entries and follow new events:

curl -k -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/logs/v1/stream/?skip_prev=10"

Range

Skip 100 entries from the beginning of the journal and return the next 10 entries:

curl -k -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/logs/v1/range/?skip_next=100&limit=10"

Plain Text

Skip 200 entries from the beginning of the journal and return the next entry in plain text:

curl -k -H "Accept: text/plain" -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/logs/v1/range/?skip_next=200&limit=1"

JSON

Skip 200 entries from the beginning of the journal and return the next entry in JSON:

curl -k -H "Accept: application/json" -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/logs/v1/range/?skip_next=200&limit=1"

Event Stream

Skip 200 entries from the beginning of the journal and return the next entry as an event stream:

curl -k -H "Accept: text/event-stream" -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/logs/v1/range/?skip_next=200&limit=1"

Event Stream Cursor

Get all journal entries after a specific cursor and stream new entries:

# Get the 10th line in json and parse its cursor
CURSOR="$(curl -k -H "Accept: application/json" -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/logs/v1/range/?skip_next=9&limit=1" | jq -r ".cursor")"

# Follow the stream in plain text starting at the 11th line using the cursor
curl -k -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/logs/v1/stream/" --get --data-urlencode "cursor=${CURSOR}"

The cursor must be URL encoded.

Range Cursor

Get 1,000 journal entries, 100 at a time:

TIMES=10 # number of times to call the endpoint
LINES=100 # number of log lines to retrieve per call
CURSOR="" # first call uses an empty cursor to start from the beginning
for i in $(seq 1 ${TIMES}); do
  BUFFER="$(curl -k -H "Accept: application/json" -H "Authorization: token=${DCOS_AUTH_TOKEN}" "${DCOS_URL}/system/v1/logs/v1/range/?limit=${LINES}" --get --data-urlencode "cursor=${CURSOR}")"
  echo "${BUFFER}"
  CURSOR="$(echo "${BUFFER}" | jq -r ".cursor" | tail -1)"
done

Each call uses the cursor of the last entry from the previous call. The cursor must be URL encoded.