prometheus-gmail-exporter

Checks gmail labels for unread messages and exposes the counts via prometheus.

This project is implemented in Go. The exporter serves Prometheus metrics, OAuth login, and a Kubernetes readiness endpoint on port 8080 by default.

There is a blog article about why this was created, with an example integration to Grafana. It looks like this;

Example prometheus Metrics

# HELP gmail_INBOX_total INBOX Total
# TYPE gmail_INBOX_total gauge
gmail_INBOX_total 44351.0
# HELP gmail_INBOX_unread INBOX Unread
# TYPE gmail_INBOX_unread gauge
gmail_INBOX_unread 43.0
# HELP gmail_Label_33_total >/0. Triage Total
# TYPE gmail_Label_33_total gauge
gmail_Label_33_total 159.0
# HELP gmail_Label_33_unread >/0. Triage Unread
# TYPE gmail_Label_33_unread gauge
gmail_Label_33_unread 0.0
# HELP gmail_fooquery fooquery
# TYPE gmail_fooquery gauge
gmail_fooquery 201.0

Example configuration file (prometheus-gmail-exporter.yaml)

labels:
  - Label_33

customQueries:
  - name: fooquery
    query: "important in:inbox"

Configuration files are read from, in order:

• ~/.prometheus-gmail-exporter/prometheus-gmail-exporter.cfg
• ~/.prometheus-gmail-exporter/prometheus-gmail-exporter.yaml
• /etc/prometheus-gmail-exporter.cfg
• /etc/prometheus-gmail-exporter.yaml

CLI flags override file settings. Run with --help for the full list.

Setup API access

To allow this app to access your gmail, it needs a client_secret.json file, and a login_cookie.dat. The instructions below explain how to set this up.

Getting client_secret.json

NOTE: Google frequently changes it's API, Web interface, and similar without much notice. These instructions were last tested and validated on 2024-04-14 - if the instructions or screenshots don't match what you're seeing, it would be really helpful if you could raise a GitHub issue on this repository and report it. Thanks!

• Go to the Google Developers API Console: https://console.developers.google.com/apis/credentials
• In the sidebar, select Credentials.
• On the Credentials page, click the Create Credentials button in the toolbar.

• From the Create Credentials dropdown menu, select OAuth Client ID.
  • Application Type: Desktop App (previously labeled Other, do not choose Web application).
  • Name: prometheus-gmail-exporter (or a name that you prefer)
  • Finally, click the blue Create button.
• On the OAuth client created popup window;
  • Take a copy of your Client ID and save it in a "secure text file" somewhere!
  • Click the "Download JSON" link to get your client_secrets file, named something like - client_secret_1234.apps.googleusercontent.com__.json.

Create a OAuth 2 Content screen

• In the sidebar, select OAuth 2 consent screen
• Create a OAuth 2 Consent screen with whatever name and icon you like. The scopes needed are;

• Once the scopes have been selected, you should see a screen that looks like this;

Next steps

• Rename your downloaded client_secret_____.json to just client_secret.json and put it in the directory; ~/.prometheus-gmail-exporter/.

NOTE: To use this on Google Accounts with Advanced Protection, you cannot use an OAuth consent screen that is only in Publishing status = Testing, but must Publish the App and then have it verified.

Getting login_cookie.dat

The ~/.prometheus-gmail-exporter/client_secret.json file which you download from Google only identifies (your own instance of) this app to talk to the GMail API.

The ~/.prometheus-gmail-exporter/login_cookie.dat secret file identifies YOU, and gives access to your Gmail account via Google's API. This file cannot be directly downloaded from the Google Cloud Console, but is created by this tool on its first run, via an OAuth-based flow. Visit http://localhost:8080/ and click Login. If this fails (e.g. due to an "Error 400: redirect_uri_mismatch"), add http://localhost:8080/oauth2callback as an Authorized redirect URI on the OAuth 2.0 Client ID to complete the authentication flow.

To run this tool on a headless server, you may want to first create the login_cookie.dat on a Desktop/Workstation where a web browser is available, and then move it to the headless server, perhaps by mounting this file from some form of secret provider into the container. (See also issue #9 for more background.)

HTTP endpoints

Path	Purpose
/metrics	Prometheus metrics
/	Status page and OAuth login link
/oauth2callback	OAuth redirect handler
/readyz	Kubernetes readiness probe

Troubleshooting: accessNotConfigured

The GMail API is probably not enabled in your account yet. You can enable it by following instructions here; https://developers.google.com/workspace/guides/enable-apis .

Run as a container image

There is a published container in ghcr.io, called ghcr.io/jamesread/prometheus-gmail-exporter:latest.

Using either docker or podman will be fine. I like podman better, so examples are with podman.

podman run -v ~/.prometheus-gmail-exporter/:/root/.prometheus-gmail-exporter/ ghcr.io/jamesread/prometheus-gmail-exporter:latest

Build your own container image

podman build . -t gmail-exporter
podman run -v ~/.prometheus-gmail-exporter/:/root/.prometheus-gmail-exporter/ gmail-exporter --labels Label_33

Running via command line

Option A) Go toolchain

go build -o prometheus-gmail-exporter ./cmd/prometheus-gmail-exporter/
./prometheus-gmail-exporter --labels Label_33 INBOX -d

Option B) Makefile

make
./prometheus-gmail-exporter --labels Label_33 INBOX -d

Options can be found with --help.

Development

make test
make lint

Releases

Pushes to master run tests and go-semantic-release. Use Conventional Commits (feat:, fix:, etc.) so the next version, changelog, GitHub release, container image, and binary are produced automatically when there are releasable changes.