98 lines
5.0 KiB
Markdown
98 lines
5.0 KiB
Markdown
---
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id: session_storage
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title: Session Storage
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---
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Sessions allow a user's authentication to be tracked between multiple HTTP
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requests to a service.
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The OAuth2 Proxy uses a Cookie to track user sessions and will store the session
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data in one of the available session storage backends.
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At present the available backends are (as passed to `--session-store-type`):
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- [cookie](#cookie-storage) (default)
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- [redis](#redis-storage)
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### Cookie Storage
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The Cookie storage backend is the default backend implementation and has
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been used in the OAuth2 Proxy historically.
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With the Cookie storage backend, all session information is stored in client
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side cookies and transferred with each and every request.
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The following should be known when using this implementation:
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- Since all state is stored client side, this storage backend means that the OAuth2 Proxy is completely stateless
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- Cookies are signed server side to prevent modification client-side
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- It is mandatory to set a `cookie-secret` which will ensure data is encrypted within the cookie data.
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- Since multiple requests can be made concurrently to the OAuth2 Proxy, this session implementation
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cannot lock sessions and while updating and refreshing sessions, there can be conflicts which force
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users to re-authenticate
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### Redis Storage
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The Redis Storage backend stores encrypted sessions in redis. Instead of sending all the information
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back the client for storage, as in the [Cookie storage](#cookie-storage), a ticket is sent back
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to the user as the cookie value instead.
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A ticket is composed as the following:
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`{CookieName}-{ticketID}.{secret}`
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Where:
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- The `CookieName` is the OAuth2 cookie name (_oauth2_proxy by default)
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- The `ticketID` is a 128-bit random number, hex-encoded
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- The `secret` is a 128-bit random number, base64url encoded (no padding). The secret is unique for every session.
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- The pair of `{CookieName}-{ticketID}` comprises a ticket handle, and thus, the redis key
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to which the session is stored. The encoded session is encrypted with the secret and stored
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in redis via the `SETEX` command.
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Encrypting every session uniquely protects the refresh/access/id tokens stored in the session from
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disclosure. Additionally, the browser only has to send a short Cookie with every request and not the whole JWT,
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which can get quite big.
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Two settings are used to configure the OAuth2 Proxy cookie lifetime:
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--cookie-refresh duration refresh the cookie after this duration; 0 to disable
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--cookie-expire duration expire timeframe for cookie 168h0m0s
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The "cookie-expire" value should be equal to the lifetime of the Refresh-Token that is issued by the OAuth2 authorization server.
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If it expires earlier and is deleted by the browser, OAuth2 Proxy cannot find the stored Refresh-Tokens in Redis and thus cannot start
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the refresh flow to get new Access-Tokens. If it is longer, it might be that the old Refresh-Token will be found in Redis but has already
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expired.
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The "cookie-refresh" value controls when OAuth2 Proxy tries to refresh an Access-Token. If it is set to "0", the
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Access-Token will never be refreshed, even it is already expired and there would be a valid Refresh-Token in the
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available. If set, OAuth2 Proxy will refresh the Access-Token after this many seconds even if it is still valid.
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Of course, it will also be refreshed after it has expired, as long as a Refresh Token is available.
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Caveat: It can happen that the Access-Token is valid for e.g. "1m" and a request happens after exactly "59s".
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It would pass OAuth2 Proxy and be forwarded to the backend but is just expired when the backend tries to validate
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it. This is especially relevant if the backend uses the JWT to make requests to other backends.
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For this reason, it's advised to set the cookie-refresh a couple of seconds less than the Access-Token lifespan.
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Recommended settings:
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* cookie_refresh := Access-Token lifespan - 1m
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* cookie_expire := Refresh-Token lifespan (i.e. Keycloak client_session_idle)
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#### Usage
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When using the redis store, specify `--session-store-type=redis` as well as the Redis connection URL, via
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`--redis-connection-url=redis://host[:port][/db-number]`.
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You may also configure the store for Redis Sentinel. In this case, you will want to use the
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`--redis-use-sentinel=true` flag, as well as configure the flags `--redis-sentinel-master-name`
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and `--redis-sentinel-connection-urls` appropriately.
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Redis Cluster is available to be the backend store as well. To leverage it, you will need to set the
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`--redis-use-cluster=true` flag, and configure the flags `--redis-cluster-connection-urls` appropriately.
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Note that flags `--redis-use-sentinel=true` and `--redis-use-cluster=true` are mutually exclusive.
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Note, if Redis timeout option is set to non-zero, the `--redis-connection-idle-timeout`
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must be less than [Redis timeout option](https://redis.io/docs/reference/clients/#client-timeouts). For example: if either redis.conf includes
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`timeout 15` or using `CONFIG SET timeout 15` the `--redis-connection-idle-timeout` must be at least `--redis-connection-idle-timeout=14`
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