Cloud Logging

floci-gcp emulates Google Cloud Logging over gRPC and REST using the real google.logging.v2.LoggingServiceV2 protocol. The primary use case is asserting what the app under test logged: write structured entries, then ListLogEntries back with a filter and verify the payload, severity, and resource.

Configuration

Variable	Default	Description
FLOCI_GCP_SERVICES_LOGGING_ENABLED	true	Enable/disable Cloud Logging

Endpoint

Cloud Logging has no *_EMULATOR_HOST convention. Point the client at floci-gcp by overriding the API endpoint / transport channel and disabling credentials:

• gRPC (Java/Python/Go/Node): build the v2 client with a plaintext channel to localhost:4588 and anonymous/no credentials (see Quick Start).
• REST: POST http://localhost:4588/v2/entries:write and :list.

Quick Start

JavaPythonNode.js

LoggingClient client = LoggingClient.create(
    LoggingSettings.newBuilder()
        .setTransportChannelProvider(
            InstantiatingGrpcChannelProvider.newBuilder()
                .setEndpoint("localhost:4588")
                .setChannelConfigurator(b -> b.usePlaintext())
                .build())
        .setCredentialsProvider(NoCredentialsProvider.create())
        .build());

String logName = "projects/floci-local/logs/my-log";
client.writeLogEntries(WriteLogEntriesRequest.newBuilder()
    .addEntries(LogEntry.newBuilder()
        .setLogName(logName)
        .setResource(MonitoredResource.newBuilder().setType("global"))
        .setSeverity(LogSeverity.ERROR)
        .setTextPayload("something failed")
        .build())
    .build());

for (LogEntry entry : client.listLogEntries(ListLogEntriesRequest.newBuilder()
        .addResourceNames("projects/floci-local")
        .setFilter("logName=\"" + logName + "\" AND severity>=WARNING")
        .build()).iterateAll()) {
    System.out.println(entry.getTextPayload());
}

import grpc
from google.cloud import logging_v2
from google.cloud.logging_v2.services.logging_service_v2.transports.grpc import (
    LoggingServiceV2GrpcTransport,
)

transport = LoggingServiceV2GrpcTransport(channel=grpc.insecure_channel("localhost:4588"))
client = logging_v2.services.logging_service_v2.LoggingServiceV2Client(transport=transport)

log_name = "projects/floci-local/logs/my-log"
client.write_log_entries(request={"entries": [{
    "log_name": log_name,
    "resource": {"type": "global"},
    "severity": "ERROR",
    "text_payload": "something failed",
}]})

for entry in client.list_log_entries(request={
    "resource_names": ["projects/floci-local"],
    "filter": f'logName="{log_name}" AND severity>=WARNING',
}):
    print(entry.text_payload)

import { v2 } from "@google-cloud/logging";
import * as grpc from "@grpc/grpc-js";

const client = new v2.LoggingServiceV2Client({
    servicePath: "localhost",
    port: 4588,
    sslCreds: grpc.credentials.createInsecure(),
});

const logName = "projects/floci-local/logs/my-log";
await client.writeLogEntries({ entries: [{
    logName,
    resource: { type: "global" },
    severity: "ERROR",
    textPayload: "something failed",
}]});

const [entries] = await client.listLogEntries({
    resourceNames: ["projects/floci-local"],
    filter: `logName="${logName}" AND severity>=WARNING`,
});
entries.forEach((e) => console.log(e.textPayload));

Filter subset

ListLogEntries supports a practical subset of the Cloud Logging filter language, combined with AND:

Field	Operators	Example
logName	=	logName="projects/p/logs/app"
severity	= > >= < <=	severity>=WARNING
resource.type	=	resource.type="gce_instance"
timestamp	= > >= < <=	timestamp>="2026-01-01T00:00:00Z"
labels.<key>	=	labels.env="prod"

An empty filter matches all entries in the requested resourceNames. OR/NOT, functions, regex, and nested parentheses are not supported; unrecognized clauses are ignored.

Entry semantics

• Request-level logName, resource, and labels are applied to entries that omit them (entry labels win over request defaults).
• Missing insertId and timestamp are filled in; receiveTimestamp is always set to now.
• Entries are returned ordered by timestamp (ascending by default; order_by: "timestamp desc" reverses).
• DeleteLog removes all entries for a log name (NOT_FOUND if the log has no entries).

Supported Operations

• WriteLogEntries
• ListLogEntries
• ListLogs
• DeleteLog

Not Yet Supported

TailLogEntries (streaming), protoPayload/httpRequest/operation/sourceLocation/split fields, monitored-resource-descriptor catalog, log-based metrics (MetricsServiceV2), sinks and buckets (ConfigServiceV2), advanced filter operators, and retention/dedup semantics.