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"""
API and command-line support for human-readable Eliot messages.
"""
import pprint
import argparse
from datetime import datetime
from sys import stdin, stdout
from collections import OrderedDict
from json import dumps
from json import loads
from ._message import (
TIMESTAMP_FIELD,
TASK_UUID_FIELD,
TASK_LEVEL_FIELD,
MESSAGE_TYPE_FIELD,
)
from ._action import ACTION_TYPE_FIELD, ACTION_STATUS_FIELD
# Ensure binary stdin, since we expect specifically UTF-8 encoded
# messages, not platform-encoding messages.
stdin = stdin.buffer
# Fields that all Eliot messages are expected to have:
REQUIRED_FIELDS = {TASK_LEVEL_FIELD, TASK_UUID_FIELD, TIMESTAMP_FIELD}
# Fields that get treated specially when formatting.
_skip_fields = {
TIMESTAMP_FIELD,
TASK_UUID_FIELD,
TASK_LEVEL_FIELD,
MESSAGE_TYPE_FIELD,
ACTION_TYPE_FIELD,
ACTION_STATUS_FIELD,
}
# First fields to render:
_first_fields = [ACTION_TYPE_FIELD, MESSAGE_TYPE_FIELD, ACTION_STATUS_FIELD]
def _render_timestamp(message: dict, local_timezone: bool) -> str:
"""Convert a message's timestamp to a string."""
# If we were returning or storing the datetime we'd want to use an
# explicit timezone instead of a naive datetime, but since we're
# just using it for formatting we needn't bother.
if local_timezone:
dt = datetime.fromtimestamp(message[TIMESTAMP_FIELD])
else:
dt = datetime.utcfromtimestamp(message[TIMESTAMP_FIELD])
result = dt.isoformat(sep="T")
if not local_timezone:
result += "Z"
return result
def pretty_format(message: dict, local_timezone: bool = False) -> str:
"""
Convert a message dictionary into a human-readable string.
@param message: Message to parse, as dictionary.
@return: Unicode string.
"""
def add_field(previous, key, value):
value = (
pprint.pformat(value, width=40).replace("\\n", "\n ").replace("\\t", "\t")
)
# Reindent second line and later to match up with first line's
# indentation:
lines = value.split("\n")
# indent lines are " <key length>| <value>"
indent = "{}| ".format(" " * (2 + len(key)))
value = "\n".join([lines[0]] + [indent + l for l in lines[1:]])
return " %s: %s\n" % (key, value)
remaining = ""
for field in _first_fields:
if field in message:
remaining += add_field(remaining, field, message[field])
for key, value in sorted(message.items()):
if key not in _skip_fields:
remaining += add_field(remaining, key, value)
level = "/" + "/".join(map(str, message[TASK_LEVEL_FIELD]))
return "%s -> %s\n%s\n%s" % (
message[TASK_UUID_FIELD],
level,
_render_timestamp(message, local_timezone),
remaining,
)
def compact_format(message: dict, local_timezone: bool = False) -> str:
"""Format an Eliot message into a single line.
The message is presumed to be JSON-serializable.
"""
ordered_message = OrderedDict()
for field in _first_fields:
if field in message:
ordered_message[field] = message[field]
for key, value in sorted(message.items()):
if key not in _skip_fields:
ordered_message[key] = value
# drop { and } from JSON:
rendered = " ".join(
"{}={}".format(key, dumps(value, separators=(",", ":")))
for (key, value) in ordered_message.items()
)
return "%s%s %s %s" % (
message[TASK_UUID_FIELD],
"/" + "/".join(map(str, message[TASK_LEVEL_FIELD])),
_render_timestamp(message, local_timezone),
rendered,
)
_CLI_HELP = """\
Convert Eliot messages into more readable format.
Reads JSON lines from stdin, write out pretty-printed results on stdout.
"""
def _main():
"""
Command-line program that reads in JSON from stdin and writes out
pretty-printed messages to stdout.
"""
parser = argparse.ArgumentParser(
description=_CLI_HELP, usage="cat messages | %(prog)s [options]"
)
parser.add_argument(
"-c",
"--compact",
action="store_true",
dest="compact",
help="Compact format, one message per line.",
)
parser.add_argument(
"-l",
"--local-timezone",
action="store_true",
dest="local_timezone",
help="Use local timezone instead of UTC.",
)
args = parser.parse_args()
if args.compact:
formatter = compact_format
else:
formatter = pretty_format
for line in stdin:
try:
message = loads(line)
except ValueError:
stdout.write("Not JSON: {}\n\n".format(line.rstrip(b"\n")))
continue
if REQUIRED_FIELDS - set(message.keys()):
stdout.write("Not an Eliot message: {}\n\n".format(line.rstrip(b"\n")))
continue
result = formatter(message, args.local_timezone) + "\n"
stdout.write(result)
__all__ = ["pretty_format", "compact_format"]
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