Grafana LDAP Authentication Error — Quick Fix

In this tutorial, you'll learn about Grafana LDAP Authentication Error. We cover key concepts, practical examples, and best practices.

The Problem

Users cannot log into Grafana using LDAP credentials. The login form shows "Invalid username or password" even though the credentials work for other services. LDAP synchronization may also fail for user details and groups.

Error example:

LDAP authentication failed: "Invalid username or password"
Failed to authenticate user via LDAP: dial tcp: connection refused
Failed to search for user: LDAP Result Code 32 "No Such Object"

The Fix

Step 1: Test LDAP connection from Grafana

WRONG — changing LDAP settings without testing the connection:

# Always test LDAP settings before applying them

RIGHT — use Grafana's built-in LDAP test:

# Grafana provides a CLI tool for LDAP testing
grafana-cli admin ldap test

Output:

LDAP server found: ldap.example.com:389
LDAP bind successful
Search filter: (sAMAccountName=%s)
User 'jdoe' found: DistinguishedName: CN=John Doe,CN=Users,DC=example,DC=com

If the test fails, check the LDAP configuration:

grafana-cli admin ldap show-mapping

Step 2: Fix the LDAP configuration

WRONG — using incorrect LDAP attribute mappings:

# Example WRONG config
[[servers]]
host = "ldap.example.com"
bind_dn = "cn=admin,dc=example,dc=com"
search_filter = "(uid=%s)"  # Wrong for Active Directory

RIGHT — use the correct configuration for your LDAP server:

[[servers]]
host = "ldap.example.com"
port = 389
bind_dn = "cn=grafana,cn=Users,dc=example,dc=com"
search_filter = "(sAMAccountName=%s)"
search_base_dns = ["dc=example,dc=com"]

[[servers.attributes]]
name = "givenName"
surname = "sn"
username = "sAMAccountName"
member_of = "memberOf"
email = "mail"

Use DodaTech's LDAP Configuration Validator to test bind credentials, search filters, and attribute mappings without restarting Grafana.

Prevention Tips

• Use a dedicated LDAP service account for Grafana (not an admin)
• Test LDAP configuration with grafana-cli before enabling LDAP login
• Configure TLS (ldaps://) for production LDAP connections
• Set allow_sign_up = true to auto-create Grafana accounts from LDAP
• Use DodaTech's Grafana Auth Manager for centralized LDAP configuration

Common Mistakes with ldap auth

1. Using return to exit a function early instead of wrapping a pure value in the monad
2. Mixing let bindings with <- bindings in do notation, producing type errors
3. Overlapping type class instances that cause GHC to reject the program with ambiguous dispatch errors

These mistakes appear frequently in real-world GRAFANA code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

Related: DodaTech's Grafana Auth Guide covers LDAP, SAML, OAuth, and basic authentication configuration for enterprise Grafana deployments.