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dcos-go/dcos-log - HTTP server for journal events

REST API

Endpoints:

  • /range/ get a range of logs matching the request query.
  • /range/framework/{framework_id}/executor/{executor_id}/container/{container_id} get a range of application logs.
  • /stream/ tail logs keeping the connection opened, implements Server Sent Events.
  • /stream/framework/{framework_id}/executor/{executor_id}/container/{container_id} tail application logs.
  • /fields/<field> returns all possible unique values for a specific <field>.

Request Header Accept

  • text/plain, text/html, */* request logs in text format, ending with \n.
  • application/json request logs in JSON format.
  • text/event-stream request logs in Server-Sent-Events format.

Request Header Last-Event-ID

If Last-Event-ID is set dcos-log will use it as a cursor position. Last-Event-ID header works with /stream/ endpoints only.

NOTE: Accept header text/event-stream cannot be used with /fields/<field> endpoint.

Response Header X-Journal-Skip-Prev

X-Journal-Skip-Prev indicates how many entries we actually skipped backwards from the current position.

Example:

request: `?cursor=<cursor string>&skip_prev=1000`
response includes the headers: `X-Journal-Skip-Prev: 100`, `X-Journal-Skip-Next: 0`

This means that there are only 100 entries before the given cursor position and we reached the top of the journal.

Response Header X-Journal-Skip-Next

Header X-Journal-Skip-Next indicates how many entries we actually skipped forward from the current position.

see X-Journal-Skip-Prev example above.

GET parameters:

  • ?filter=FIELD:value add match.
  • ?limit=N limit number of entries.
  • ?skip_next=N skip forward number of entries from the current cursor position.
  • ?skip_prev=N skip backwards number of entries from the current cursor position.
  • ?cursor=CURSOR set cursor position. (Special characters must be escaped).
  • ?read_reverse=true read the journal in opposite direction (bottom to top).

where

  • FIELD, value and CURSOR are strings.
  • N is uint64.

NOTE:

  • It is possbile to move to the tail of the journal. If the ?cursor parameter is not used then we consider the cursor is pointing to a head of the journal. ?skip_prev=1 can be used to move to the tail of the journal (very last entry). If you need to read last 10 entries you should use ?skip_prev=10.
  • Parameter ?limit cannot be used with /stream/ endpoint.

Response codes:

  • 200 OK.
  • 204 Content not found, returned if no entries matching requesting filters.
  • 400 Bad request, returned if request is incorrect.
  • 500 Internal server error.

CLI flags

Usage of dcos-log:
  -config string
       	Use config file.
  -config-json-schema string
       	Use a custom json schema.
  -port int
       	Set TCP port. (default 8080)
  -verbose
       	Print out verbose output.

Examples:

GET parameters

  • /stream/?skip_prev=10 get the last 10 entires from the journal and follow new events.
  • /range/?skip_next=100&limit=10 skip 100 entries from the beggining of the journal and return 10 following entries.
  • /stream/?cursor=s%3Dcea8150abb0543deaab113ed2f39b014%3Bi%3D1%3Bb%3D2c357020b6e54863a5ac9dee71d5872c%3Bm%3D33ae8a1%3Bt%3D53e52ec99a798%3Bx%3Db3fe26128f768a49 get all logs after the specific cursor and follow new events.
  • /range/?cursor=s%3Dcea8150abb0543deaab113ed2f39b014%3Bi%3D1%3Bb%3D2c357020b6e54863a5ac9dee71d5872c%3Bm%3D33ae8a1%3Bt%3D53e52ec99a798%3Bx%3Db3fe26128f768a49&skip_prev=2&limit=2 get 2 entries. The first one is the one before the cursor position and the second one is the entry with given cursor position.

Accept: text/plain

curl -H 'Accept: text/plain' '127.0.0.1:8080/range/?skip_prev=200&limit=1'
Wed Oct 12 06:28:20 2016 a60c1d059aea systemd [1] Starting Daily Cleanup of Temporary Directories.

Accept: application/json

curl -H 'Accept: application/json' '127.0.0.1:8080/range/?skip_prev=200&limit=1' | jq '.'
{
  "fields": {
    "CODE_FILE": "../src/core/unit.c",
    "CODE_FUNCTION": "unit_status_log_starting_stopping_reloading",
    "CODE_LINE": "1272",
    "MESSAGE": "Starting Daily Cleanup of Temporary Directories.",
    "MESSAGE_ID": "7d4958e842da4a758f6c1cdc7b36dcc5",
    "PRIORITY": "6",
    "SYSLOG_FACILITY": "3",
    "SYSLOG_IDENTIFIER": "systemd",
    "UNIT": "systemd-tmpfiles-clean.timer",
    "_BOOT_ID": "637573ba91ae4008b58eaa9505a11f86",
    "_CAP_EFFECTIVE": "3fffffffff",
    "_CMDLINE": "/sbin/init",
    "_COMM": "systemd",
    "_EXE": "/lib/systemd/systemd",
    "_GID": "0",
    "_HOSTNAME": "a60c1d059aea",
    "_MACHINE_ID": "48230110dd084e91b7b6885728b98295",
    "_PID": "1",
    "_SOURCE_REALTIME_TIMESTAMP": "1476253700204523",
    "_SYSTEMD_CGROUP": "e",
    "_TRANSPORT": "journal",
    "_UID": "0"
  },
  "cursor": "s=f78aeb5184144e2a94963a42b0cac49e;i=262;b=637573ba91ae4008b58eaa9505a11f86;m=6fbb8f76b;t=53ea51966297e;x=69cba0539a7e4576",
  "monotonic_timestamp": 29993006955,
  "realtime_timestamp": 1476253700204926
}

Accept: text/event-stream

curl -H 'Accept: text/event-stream' '127.0.0.1:8080/range/?skip_prev=200&limit=1'
id: s=f78aeb5184144e2a94963a42b0cac49e;i=262;b=637573ba91ae4008b58eaa9505a11f86;m=6fbb8f76b;t=53ea51966297e
data: {"fields":{"CODE_FILE":"../src/core/unit.c","CODE_FUNCTION":"unit_status_log_starting_stopping_reloading","CODE_LINE":"1272","MESSAGE":"Starting Daily Cleanup of Temporary Directories.","MESSAGE_ID":"7d4958e842da4a758f6c1cdc7b36dcc5","PRIORITY":"6","SYSLOG_FACILITY":"3","SYSLOG_IDENTIFIER":"systemd","UNIT":"systemd-tmpfiles-clean.timer","_BOOT_ID":"637573ba91ae4008b58eaa9505a11f86","_CAP_EFFECTIVE":"3fffffffff","_CMDLINE":"/sbin/init","_COMM":"systemd","_EXE":"/lib/systemd/systemd","_GID":"0","_HOSTNAME":"a60c1d059aea","_MACHINE_ID":"48230110dd084e91b7b6885728b98295","_PID":"1","_SOURCE_REALTIME_TIMESTAMP":"1476253700204523","_SYSTEMD_CGROUP":"e","_TRANSPORT":"journal","_UID":"0"},"cursor":"s=f78aeb5184144e2a94963a42b0cac49e;i=262;b=637573ba91ae4008b58eaa9505a11f86;m=6fbb8f76b;t=53ea51966297e;x=69cba0539a7e4576","monotonic_timestamp":29993006955,"realtime_timestamp":1476253700204926}