ARC support for OIDC

Support level

Currently the support for OIDC tokens in ARC is at a technology preview level. Only tokens conforming to the WLCG profile have been tested. The current validation is not strict: the token is parsed and the signature is checked if present, but no additional requirements are imposed. Tokens are only accepted for client authentication during job submission through the EMI-ES interface.

Obtaining and using tokens

The suggested way for obtaining a token is through the oidc-agent utility - Install it following the instructions for your Linux distribution.

Point your browser to and create an account.

Start the oidc-agent. It will print few lines of shell commands. Copy them to the command line and execute. This will set up environment variables for other oidc-* commands.

Start oidc-gen. It will guide you through the steps to register the OIDC client and create a profile for the oidc-agent. When asked to select the issuer, select When asked about the scope, write openid profile wlcg. You only need to run the oidc-gen once. Next time when you use the oidc-agent, you can load an already created profile with the ‘oidc-add NAME_YOU_CHOOSE’ command.

When the oidc-gen command tells you “”To continue and approve the registered client visit the following URL in a Browser of your choice:” point your browser (which must be running on the same machine as the oidc tools do) to the adress given.

Obtain the token and store it in the ARC_OTOKEN variable:

export ARC_OTOKEN=`oidc-token NAME_YOU_CHOOSE`

If the oidc tools were installed on a different machine than your ARC client, then first obtain the token on the oidc tool machine:


Then copy the token string and on your ARC client machine do:

export ARC_OTOKEN=<token-string>

Now submit the job to an ARC CE with arcsub through the EMI-ES interface. For that, use the option ‘-S org.ogf.glue.emies.activitycreation’ (or if you are using ARC client >= 6.5.0 ‘-T emies’). The token stored in the ARC_TOKEN variable will be used instead of the X.509 certificate for authenticating the user to the ARC CE server. Data staging currently will still use the X.509 proxy credentials.

Note: You can use any other method for obtaining a WLCG compliant OIDC token. Just store it in the ARC_OTOKEN variable before calling arcsub.

Configuring authorization on server

Token processing is enabled by the presence of the [authtokens] configuration block.

The user can be authorized on the server by adding a dedicated command to the authgroup block:

authtokens=subject issuer audience scope group

The specified parameters must match those in the provided token. Parameters can be ‘*’ to match any value, for example

authtokens=e83eec5a-e2e3-43c6-bb67-df8f5ec3e8d0 * * *

matches a user with subject e83eec5a-e2e3-43c6-bb67-df8f5ec3e8d0 in token issued by .


Until handling of authtokens is integrated with arcproxy you will have to find the subject of the token using a tool like e.g. . Alternatively you can install flaat (

User mapping to a local account is implemented using a simulated X.509 user subject. The subject provided by an OIDC token is unique only in scope of the identity provider. To generate a globally unique user-identifier, the issuer and the subject are cocatenated as “issuer/subject” to provide an identifier suitable for user mapping. For example, a user with subject e83eec5a-e2e3-43c6-bb67-df8f5ec3e8d0 in the token issued by is represented by a simulated identifier