DocsEdge Stack1.14Filters and authentication
Filters and authentication
Filters are used to extend the Ambassador Edge Stack to modify or intercept a request before sending to your backend service. The most common use case for Filters is authentication, and Ambassador Edge Stack includes a number of built-in filters for this purpose. Ambassador Edge Stack also supports developing custom filters.
Filters are managed using a FilterPolicy resource. The FilterPolicy resource specifies a particular host or URL to match, along with a set of filters to run when an request matches the host/URL.
Filter types
Ambassador Edge Stack supports the following filter types:
- JWT - validates JSON Web Tokens
- OAuth2 - performs OAuth2 authorization against an identity provider implementing OIDC Discovery.
- Plugin - allows users to write custom Filters in Go that run as part of the Ambassador Edge Stack container
- External - allows users to call out to other services for request processing. This can include both custom services (in any language) or third party services.
Managing Filters
Filters are created with the Filter resource type, which contains global arguments to that filter. Which Filter(s) to use for which HTTP requests is then configured in FilterPolicy resources, which may contain path-specific arguments to the filter.
Filter definition
Filters are created as Filter resources. The body of the resource spec depends on the filter type:
FilterPolicy definition
FilterPolicy resources specify which filters (if any) to apply to which HTTP requests.
Rule configuration values include:
Value | Example | Description |
---|---|---|
host | * , foo.com | The Host that a given rule should match |
path | /foo/url/ | The URL path that a given rule should match to |
filters | name: keycloak | The name of a given filter to be applied |
The wildcard *
is supported for both path
and host
.
The type of the arguments
property is dependent on which Filter type is being referred to; see the "Path-Specific Arguments" documentation for each Filter type.
When multiple Filters are specified in a rule:
- The filters are gone through in order
- Each filter may either:
- return a direct HTTP response, intended to be sent back to the requesting HTTP client (normally denying the request from being forwarded to the upstream service) OR
- return a modification to make to the HTTP request before sending it to other filters or the upstream service (normally allowing the request to be forwarded to the upstream service with modifications).
- If a filter has an
ifRequestHeader
setting, the filter is skipped unless the request (including any modifications made by earlier filters) has the HTTP header fieldname
set to (or not set to ifnegate: true
):- a non-empty string if neither
value
norvalueRegex
are set - the exact string
value
(case-sensitive) (ifvalue
is set) - a string that matches the regular expression
valueRegex
(ifvalueRegex
is set). This uses [RE2][] syntax (always, not obeying [regex_type
][] in the Ambassador module) but does not support the\C
escape sequence.
- a non-empty string if neither
onDeny
identifies what to do when the filter returns an "HTTP response":"break"
: End processing, and return the response directly to the requesting HTTP client. Later filters are not called. The request is not forwarded to the upstream service."continue"
: Continue processing. The request is passed to the next filter listed; or if at the end of the list, it is forwarded"continue"
: Continue processing. The request is passed to the next filter listed; or if at the end of the list, it is forwarded to the upstream service. The HTTP response returned from the filter is discarded.
onAllow
identifies what to do when the filter returns a "modification to the HTTP request":"break"
: Apply the modification to the request, then end filter processing, and forward the modified request to the upstream service. Later filters are not called."continue"
: Continue processing. Apply the request modification, then pass the modified request to the next filter listed; or if at the end of the list, forward it to the upstream service.
- Modifications to the request are cumulative; later filters have access to all headers inserted by earlier filters.
FilterPolicy example
In the example below, the param-filter
Filter Plugin is loaded and configured to run on requests to /httpbin/
.
Multiple domains
In this example, the foo-keycloak
filter is used for requests to foo.bar.com
, while the example-auth0
filter is used for requests to example.com
. This configuration is useful if you are hosting multiple domains in the same cluster.
Installing self-signed certificates
The JWT and OAuth2 filters speak to other services over HTTP or HTTPS. If those services are configured to speak HTTPS using a self-signed certificate, attempting to talk to them will result in an error mentioning ERR x509: certificate signed by unknown authority
. You can fix this by installing that self-signed certificate into the AES container by copying the certificate to /usr/local/share/ca-certificates/
and then running update-ca-certificates
. Note that the aes
image sets USER 1000
but update-ca-certificates
needs to be run as root.
The following Dockerfile will accomplish this procedure for you. When deploying Ambassador Edge Stack, refer to that custom Docker image rather than to docker.io/datawire/aes:1.14.4