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Version: v1.4


This file keeps track of questions and discussions from Gitter and general help with various issues.

Please be aware that some things noted here might be highly outdated. If you find an outdated section, please create a PR which removes or updates it!

How can I control SQL connection limits?

You can configure SQL connection limits by appending parameters max_conns, max_idle_conns, or max_conn_lifetime to the DSN: postgres://foo:bar@host:port/database?max_conns=12.

Why is the Resource Owner Password Credentials grant not supported?

The following is a copy of the original comment on GitHub:

I took a long time for this issue, primarily because I felt very uncomfortable implementing it. The ROCP grant is something from the "dark ages" of OAuth2 and there are suitable replacements for mobile clients, such as public oauth2 clients, which are supported by Hydra:

The OAuth2 Thread Model explicitly states that the ROPC grant is commonly used in legacy/migration scenarios, and

This grant type has higher risk because it maintains the UID/password anti-pattern. Additionally, because the user does not have control over the authorization process, clients using this grant type are not limited by scope but instead have potentially the same capabilities as the user themselves. As there is no authorization step, the ability to offer token revocation is bypassed.

Because passwords are often used for more than 1 service, this anti-pattern may also put at risk whatever else is accessible with the supplied credential. Additionally, any easily derived equivalent (e.g., and might easily allow someone to guess that the same password can be used elsewhere.

Impact: The resource server can only differentiate scope based on the access token being associated with a particular client. The client could also acquire long-lived tokens and pass them up to an attacker's web service for further abuse. The client, eavesdroppers, or endpoints could eavesdrop the user id and password.

o Except for migration reasons, minimize use of this grant type.

Thus, I decided to not implement the ROPC grant in Hydra. Over time, I will add documentation how to deal with mobile scenarios and similar.

Should I use OAuth2 tokens for authentication?

OAuth2 tokens are like money. It allows you to buy stuff, but the cashier does not really care if the money is yours or if you stole it, as long as it's valid money. Depending on what you understand as authentication, this is a yes and no answer:

  • Yes: You can use access tokens to find out which user ("subject") is performing an action in a resource provider (blog article service, shopping basket, ...). Coming back to the money example: You, the subject, receives a cappuccino from the vendor (resource provider) in exchange for money (access token).
  • No: Never use access tokens for logging people in, for example Coming back to the money example: The police officer ("authentication server") will not accept money ("access token") as a proof of identity ("it's really you"). Unless he is corrupt ("vulnerable"), of course.

In the second example ("authentication server"), you must use OpenID Connect ID Tokens.

How to deal with mobile apps?

Read this article.

How should I run migrations?

Since ORY Hydra 0.8.0, migrations are no longer run automatically on boot. This is required in production environments, because:

  1. Although SQL migrations are tested, migrating schemas can cause data loss and should only be done consciously with prior back ups.
  2. Running a production system with a user that has right such as ALTER TABLE is a security anti-pattern.

Thus, to initialize the database schemas, it is required to run hydra migrate sql driver://user:password@host:port/db before running hydra host.

What does the installation process look like?

  1. Run hydra migrate sql ... on a host close to the database (e.g. a virtual machine with access to the SQL instance).

What does a migration process look like?

  1. Make sure a database update is required by checking the release notes.
  2. Make a back up of the database.
  3. Run the migration script on a host close to the database (e.g. a virtual machine with access to the SQL instance). Schemas are usually backwards compatible, so instances running previous versions of ORY Hydra should keep working fine. If backwards compatibility is not given, this will be addressed in the patch notes.
  4. Upgrade all ORY Hydra instances.

How can I do this in docker?

Many deployments of ORY Hydra use Docker. Although several options are available, we advise to extend the ORY Hydra Docker image


FROM oryd/hydra:<tag>

ENTRYPOINT hydra migrate sql --yes $DATABASE_URL

and run it in your infrastructure once.

Additionally, but not recommended, it is possible to override the entry point of the ORY Hydra Docker image using CLI flag --entrypoint "hydra migrate sql --yes $DATABASE_URL; hydra host" or with entrypoint: hydra migrate sql $DATABASE_URL; hydra host set in your docker compose config.

Can I set the log level to warn, error, debug, ...?

Yes, you can do so by setting the environment variable LOG_LEVEL=<level>. There are various levels supported:

  • debug
  • info
  • warn
  • error
  • fatal
  • panic

How can I import TLS certificates?

You can import TLS certificates when running hydra host. This can be done by setting the following environment variables:

Read from file

  • HTTPS_TLS_CERT_PATH: The path to the TLS certificate (pem encoded).
  • HTTPS_TLS_KEY_PATH: The path to the TLS private key (pem encoded).


  • HTTPS_TLS_CERT: A pem encoded TLS certificate passed as string. Can be used instead of TLS_CERT_PATH.
  • HTTPS_TLS_KEY: A pem encoded TLS key passed as string. Can be used instead of TLS_KEY_PATH.

Or by specifying the following flags:

--https-tls-cert-path string   Path to the certificate file for HTTP/2 over TLS (https). You can set HTTPS_TLS_KEY_PATH or HTTPS_TLS_KEY instead.
--https-tls-key-path string Path to the key file for HTTP/2 over TLS (https). You can set HTTPS_TLS_KEY_PATH or HTTPS_TLS_KEY instead.

Is there an HTTP API Documentation?


How can I disable HTTPS for testing?

You can do so by running hydra host --dangerous-force-http.

MySQL gives unsupported Scan, storing driver.Value type []uint8 into type *time.Time

did a quick test to get mysql running, but run into migrate sql issue - seems mysql related An error occurred while running the migrations: Could not apply ladon SQL migrations: Could not migrate sql schema, applied 0 migrations: sql: Scan error on column index 0: unsupported Scan, storing driver.Value type []uint8 into type *time.Time is this a known bug ? or any specific mysql version which is required (running 5.7) ?

$ hydra help host
- MySQL: If DATABASE_URL is a DSN starting with mysql:// MySQL will be used as storage backend.
Example: DATABASE_URL=mysql://user:password@tcp(host:123)/database?parseTime=true

Be aware that the ?parseTime=true parameter is mandatory, or timestamps will not work.

The docker image exits immediately

Check the logs using docker logs <container-id>.

Insufficient Entropy

Hey there , I am getting this error when I try request an access token "The request used a security parameter (e.g., anti-replay, anti-csrf) with insufficient entropy (minimum of 8 characters)"

Kareem Diaa @kimooz Jun 07 16:41
Hey there , I am getting this error when I try request an access token "The request used a security parameter (e.g., anti-replay, anti-csrf) with insufficient entropy (minimum of 8 characters)"

Aeneas @arekkas Jun 07 16:41
@kimooz make sure state and nonce are set in your auth code url (http://hydra/oauth2/auth?client_id=...&nonce=THIS_NEEDS_TO_BE_SET&state=THIS_ALSO_NEEDS_TO_BE_SET

I get compile errors!

I would try deleting the vendor dir and glide’s files and try glide init again or clear Glide’s global cache.

follow the steps in the readme

Refreshing tokens

Kareem Diaa @kimooz 15:48
One last question if you don't mind from your experience do you think that saving the user access token in a session and validating it from the client on ever refresh does that make sense or not? using the introspect endpoint

Aeneas @arekkas 15:51
nah, simply write your http calls in a way that if a 401 or 403 occurs, the token is refreshed that's the easiest and cleanest

Hydra won't remember my login

Hydra only keeps track of the session if you set the remember_me parameter in the accept login request. Otherwise the login challenge will always instruct you to show the login UI.

Where can I get documentation on running multiple instances of Hydra?

@killa#7335 20190103 01:06
My company is thinking about adopting Hydra. There is a performance benchmark including data at and some information on how to scale hydra. Where can I get documentation on running multiple instances of Hydra?
Source: Discord/ory/general

Hydra scales according to 12 factor principles. Just add another instance with the same config.
Please check the documentation section for 12 factor principles for more information: There is also some information on collecting statistics in the section on prometheus in the five minute tutorial: