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Using Bearer Tokens

As part of the GridFTP and GSI migration, the OSG has transitioned authentication away from X.509 certificates to the use of bearer tokens such as SciTokens or WLCG JWT.

Use this document to learn how to request tokens from an OpenID Connect (OIDC) Provider or how to generate a test token for validating your OSG services.

Requesting Tokens From An OIDC Provider

If you are a member of a collaboration with an OIDC provider (such as CILogon or Indigo IAM), you can use the oidc-agent client to request tokens. This client tool is available either as a container or as an RPM installation.

Alternatively, a collaboration may choose to set up a shared htvault-config service that is registered as the OIDC client or clients and enables each user to have a simpler experience to obtain tokens using the htgettoken command while at the same time keeping long-lived refresh tokens stored more securely. Both of those can be installed as RPMs from OSG repos as described at the above links, and they are also integrated with HTCondor. OSG Software recommends those tools as documented at those links for when collaborations are ready to use tokens in production, but the rest of this page gives instructions for oidc-agent which is better for early experimentation with tokens. At the end of the page we also recommend installing the htgettoken package just for its additional htdecodetoken command which is useful for looking inside tokens.

Alternative tokens for testing

If you are not a member of a collaboration with access to an OIDC provider, you can generate test SciTokens using these instructions

Using a Container

Registering an OIDC profile

  1. Start an agent container in the background and name it my-agent to easily run subsequent commands against it:

    docker run -d --name my-agent opensciencegrid/oidc-agent:23-release

  2. Generate a local client profile and follow the prompts:

    docker exec -it my-agent oidc-gen -w device <CLIENT PROFILE>

    1. Specify an OIDC provider such as CILogon or an IAM instance as the client issuer. For example, if you are requesting tokens from the WLCG IAM instance:

      Issuer [https://iam-test.indigo-datacloud.eu/]: https://wlcg.cloud.cnaf.infn.it/

    2. Request scopes for the capabilities that you need based on the type of tokens that your provider issues:

      Capability SciTokens Scope WLCG Scope
      HTCondor READ condor:/READ compute.read
      HTCondor WRITE condor:/WRITE compute.modify compute.cancel compute.create
      XRootD read read:<PATH> storage.read:<PATH>
      XRootD write write:<PATH> storage.modify:<PATH>

      Replacing <PATH> with a path to the storage location that the bearer should be authorized to access. If you are requesting WLCG tokens, you will need to also add the wlcg and offline_access scopes. For example, to request HTCondor READ and WRITE access from an OIDC provider issuing WLCG tokens, specify the following when prompted for a space delimited list of scopes:

      wlcg offline_access compute.read compute.modify compute.cancel compute.create

    3. When prompted, open the verification URL provided a browser, enter the code provided by oidc-gen, and click "Submit".

    4. Follow the instructions in your browser to authorize your new oidc-agent client

    5. Back in your terminal, enter a password to encrypt your local client profile. You'll need to remember this if you want to re-use this profile in subsequent sessions.

Requesting access tokens

Note

You must first register a new profile.

  1. Request a token using the client profile that you used with oidc-gen:

    docker exec -it my-agent oidc-token --aud="<SERVER AUDIENCE>" <CLIENT PROFILE>

    For tokens used against an HTCondor-CE, set <SERVER AUDIENCE> to <CE FQDN>:<CE PORT>.

  2. Copy the output of oidc-token into a file on the host where you need bearer token authentication, e.g. an HTCondor or XRootD client.

Reloading an OIDC profile

Note

Required after restarting the running container. You must have an existing registered profile.

  1. If your existing container is not already running, start it:

    docker start my-agent

  2. Reload profile:

    docker exec -it my-agent oidc-add <CLIENT PROFILE>

  3. Enter the password used to encrypt your <CLIENT PROFILE> created during profile registration.

Using an RPM installation

Registering an OIDC profile

  1. Start the agent and add the appropriate variables to your environment:

    eval `oidc-agent`

  2. Generate a local client profile and follow the prompts:

    oidc-gen -w device <CLIENT PROFILE>

    1. Specify an OIDC provider such as CILogon or an IAM instance as the client issuer. For example, if you are requesting tokens from the WLCG IAM instance:

      Issuer [https://iam-test.indigo-datacloud.eu/]: https://wlcg.cloud.cnaf.infn.it/

    2. Request scopes for the capabilities that you need based on the type of tokens that your provider issues:

      Capability SciTokens Scope WLCG Scope
      HTCondor READ condor:/READ compute.read
      HTCondor WRITE condor:/WRITE compute.modify compute.cancel compute.create
      XRootD read read:<PATH> storage.read:<PATH>
      XRootD write write:<PATH> storage.modify:<PATH>

      Replacing <PATH> with a path to the storage location that the bearer should be authorized to access. If you are requesting WLCG tokens, you will need to also add the wlcg and offline_access scopes. For example, to request HTCondor READ and WRITE access from an OIDC provider issuing WLCG tokens, specify the following when prompted for a space delimited list of scopes:

      wlcg offline_access compute.read compute.modify compute.cancel compute.create

    3. When prompted, open the verification URL provided a browser, enter the code provided by oidc-gen, and click "Submit".

    4. Follow the instructions in your browser to authorize your new oidc-agent client

    5. Back in your terminal, enter a password to encrypt your local client profile. You'll need to remember this if you want to re-use this profile in subsequent sessions.

Requesting access tokens

Note

You must first register a new profile.

  1. Request a token using the client profile that you used with oidc-gen:

    oidc-token --aud="<SERVER AUDIENCE>" <CLIENT PROFILE>

    For tokens used against an HTCondor-CE, set <SERVER AUDIENCE> to
    <CE FQDN>:<CE PORT>.

  2. Copy the output of oidc-token into a file on the host where you need bearer token authentication, e.g. an HTCondor or XRootD client.

Reloading an OIDC profile

Note

Required if you log out of the running machine. You must have an existing registered profile.

  1. If you do not already have a running 'oidc-agent', start one:

    eval 'oidc-agent'

  2. Reload profile:

    oidc-add <CLIENT PROFILE>

  3. Enter the password used to encrypt your <CLIENT PROFILE> created during profile registration.

Generating SciTokens For Testing

If you are not a member of a collaboration with an OIDC Provider and would like to validate token functionality with your HTCondor-CE or XRootD service, you can use the SciTokens demo website:

  1. Open https://demo.scitokens.org in a browser window

  2. Add a subject claim to the generated token by adding the following to the PAYLOAD: DATA window, between the curly braces:

    "sub": "<subject string>",

    Replacing <subject string> with a subject appropriate for the service that you are testing:

    • Any random string for an HTCondor-CE, which should be reflected in your token mapping
    • If you are using xrootd-multiuser, a local Unix username

  3. Add a scopes claim to the generated token by adding the following to the PAYLOAD: DATA window, between the curly braces:

    "scope": "<space separated list of scopes>",

    Replacing <list of scopes> appropriate for the service and authorization that you are interested in testing:

    Capability Scope Note
    HTCondor READ condor:/READ Required for job submission
    HTCondor WRITE condor:/WRITE Required for job submission
    XRootD read read:<PATH>
    XRootD write write:<PATH>

  4. Copy the entire contents of the Encoded window to a file where you will be running your client commands

  5. Add https://demo.scitokens.org (and subject if appropriate) to your service's configuration to authenticate your new test token

    Remove test mappings

    After completing testing, remove any test demo.scitokens.org mappings that you have added as anyone is capable of creating a demo SciToken.

Using Tokens

Client tools such as condor_submit or xrdcp will search for your access token in order of the following locations:

  1. Token contents in the $BEARER_TOKEN environment variable
  2. Path to the token in the $BEARER_TOKEN_FILE environment variable
  3. Path to the token in $XDG_RUNTIME_DIR/bt_u$UID
  4. Token saved to /tmp/bt_u$UID

For more details, see the WLCG Bearer Token Discovery technical note.

Troubleshooting Tokens

Validating tokens

A token must be a one-line string consisting of 3 base64-encoded parts separated by periods (.). You can use the tools in the scitokens-cpp RPM to validate a SciToken or WLCG token.

  • Run scitokens-verify <TOKEN> (where <TOKEN> is the text of the token) to validate the token using the issuer.

  • Run scitokens-list-access <TOKEN> <ISSUER> <AUDIENCE> (where <TOKEN> is the text of the token, <ISSUER> is the issuer to verify the token with, and <AUDIENCE> is the server you are using the token to access).

Examining tokens

  • Online: paste the token into https://jwt.io.

  • Offline:

    1. Install htgettoken:

      # yum install htgettoken

    2. Write the token to a file named tok or store it in one of the default WLCG Bearer Token Discovery locations described above.

    3. Run htdecodetoken -H tok or leave off the tok filename if it is in one of the default locations.

    htdecodetoken is one of the additional commands that come with the htgettoken package.

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