An example of calling the Analytics API using machine creds and the V4 API from Ruby

analytics.rb

require 'google/apis/analyticsreporting_v4'
require 'googleauth'

include Google::Apis::AnalyticsreportingV4
include Google::Auth

VIEW_ID = "12345678" #your profile ID from your Analytics Profile
SCOPE = 'https://www.googleapis.com/auth/analytics.readonly'

@client = AnalyticsReportingService.new

#Using the "Server to Server auth mechanism as documented at
#https://developers.google.com/api-client-library/ruby/auth/service-accounts
@creds = ServiceAccountCredentials.make_creds({:json_key_io => File.open('client_secrets.json'),
                                                    :scope => SCOPE})
@client.authorization = @creds

grr = GetReportsRequest.new
rr = ReportRequest.new

rr.view_id = VIEW_ID

#put a filter which only returns results for the root page
rr.filters_expression="ga:pagePath==/"

#We want the number of sessions
metric = Metric.new
metric.expression = "ga:sessions"
rr.metrics = [metric]

#We want this for the last 7 days
range = DateRange.new
range.start_date = "7daysAgo"
range.end_date = "today"
rr.date_ranges = [range]

grr.report_requests = [rr]

response = @client.batch_get_reports(grr)
puts response.inspect
puts response.reports.inspect

thanks @CoryFoy !
@aldrienht when you create the service account at https://console.developers.google.com/iam-admin/serviceaccounts you should be given the option to download the JSON file & it should be in the file. In the file, the type should be service_account, the project_id should be whatever project name you provided it like abc123, and the client_email should be like [email protected]
To satisfy the forbidden error, you need to add that service account email to an account or property or view (at https://analytics.google.com/analytics, -> Admin page/gear icon -> User Management -> plus sign + -> Add new users. Needs at least Read & Analyze permissions).

Quick question. Do you add this file into config folder? Or in the helper or controller folder?

Also, is the Profile ID, as mentioned in the comment section is considered the View ID in view settings?

Thank you so much for this gist. This should be an example in the official docs, rather than the other confusing mess...