openid_connect.server_conf

    # Advanced configuration START
    set $internal_error_message "NGINX / OpenID Connect login failure\n";
    set $pkce_id "";
    set $idp_sid "";
    resolver 8.8.8.8; # For DNS lookup of IdP endpoints;
    subrequest_output_buffer_size 32k; # To fit a complete tokenset response
    gunzip on; # Decompress IdP responses if necessary
    # Advanced configuration END

    location = /_jwks_uri {
        internal;
        proxy_cache jwk;                              # Cache the JWK Set received from IdP
        proxy_cache_valid 200 12h;                    # How long to consider keys "fresh"
        proxy_cache_use_stale error timeout updating; # Use old JWK Set if cannot reach IdP
        proxy_ssl_server_name on;                     # For SNI to the IdP
        proxy_method GET;                             # In case client request was non-GET
        proxy_set_header Content-Length "";           # ''
        proxy_pass $oidc_jwt_keyfile;                 # Expecting to find a URI here
        proxy_ignore_headers Cache-Control Expires Set-Cookie; # Does not influence caching
    }

    location @do_oidc_flow {
        status_zone "OIDC start";
        js_content oidc.auth;
        default_type text/plain; # In case we throw an error
    }

    set $redir_location "/_codexch";
    location = /_codexch {
        # This location is called by the IdP after successful authentication
        status_zone "OIDC code exchange";
        js_content oidc.codeExchange;
        error_page 500 502 504 @oidc_error;
    }

    location = /_token {
        # This location is called by oidcCodeExchange(). We use the proxy_ directives
        # to construct the OpenID Connect token request, as per:
        #  http://openid.net/specs/openid-connect-core-1_0.html#TokenRequest
        internal;

        # Exclude client headers to avoid CORS errors with certain IdPs (e.g., Microsoft Entra ID)
        proxy_pass_request_headers off;

        proxy_ssl_server_name on; # For SNI to the IdP
        proxy_set_header      Content-Type "application/x-www-form-urlencoded";
        proxy_set_header      Authorization $arg_secret_basic;
        proxy_pass            $oidc_token_endpoint;
    }

    location = /_refresh {
        # This location is called by oidcAuth() when performing a token refresh. We
        # use the proxy_ directives to construct the OpenID Connect token request, as per:
        #  https://openid.net/specs/openid-connect-core-1_0.html#RefreshingAccessToken
        internal;

        # Exclude client headers to avoid CORS errors with certain IdPs (e.g., Microsoft Entra ID)
        proxy_pass_request_headers off;

        proxy_ssl_server_name on; # For SNI to the IdP
        proxy_set_header      Content-Type "application/x-www-form-urlencoded";
        proxy_set_header      Authorization $arg_secret_basic;
        proxy_pass            $oidc_token_endpoint;
    }

    location = /_token_validation {
        # Internal location to verify any JWT (e.g., id_token, logout_token)
        # using the auth_jwt module. Extracts the claims and returns them as JSON.
        internal;
        auth_jwt "" token=$arg_token;
        js_content oidc.extractTokenClaims;
        error_page 500 502 504 @oidc_error;
    }

    location = /logout {
        status_zone "OIDC logout";
        add_header Set-Cookie "auth_token=; $oidc_cookie_flags";
        add_header Set-Cookie "auth_nonce=; $oidc_cookie_flags";
        add_header Set-Cookie "auth_redir=; $oidc_cookie_flags";
        js_content oidc.logout;
    }

    location = /front_channel_logout {
        status_zone "OIDC logout";
        add_header Cache-Control "no-store";
        default_type text/plain;
        js_content oidc.handleFrontChannelLogout;
    }

    location = /_logout {
        # This location is the default value of $oidc_logout_redirect (in case it wasn't configured)
        default_type text/plain;
        return 200 "Logged out\n";
    }

    location @oidc_error {
        # This location is called when oidcAuth() or oidcCodeExchange() returns an error
        status_zone "OIDC error";
        default_type text/plain;
        return 500 $internal_error_message;
    }

    location /api/ {
        api write=on;
        allow 127.0.0.1; # Only the NGINX host may call the NGINX Plus API
        deny all;
        access_log off;
    }

# vim: syntax=nginx