How vLLM authentication and SSO fit in front of an API key that covers only some endpoints
A team running a self-hosted vLLM server that wants staff to sign in with corporate identity cannot rely on vLLM's built-in --api-key option as its access model. The vLLM security documentation states that the option protects endpoints under /v1, /v2, /inference and /cohere, but not /invocations, /pause, /resume, /abort_requests, /metrics or /health. A single shared key therefore leaves some endpoints open, cannot tell one caller from another, and says nothing about which team or application used which model. The first decision is to treat the key as one layer of defense and put an authenticating layer in front of the server.
The usual control is an authenticating gateway or reverse proxy that performs OIDC or SAML sign-in against the identity provider already in use, validates the resulting token, and forwards only an allowlist of inference paths such as /v1/chat/completions and /v1/embeddings to vLLM. Every other path, including the control endpoints, is denied at the proxy. The allowlist should be written as an explicit list of paths to permit, reviewed against each vLLM release, and tested from outside the cluster. The vLLM security documentation recommends this pattern, so the work is choosing a proxy, configuring the identity integration, and verifying that the denied paths cannot be reached through any route, including direct access to the server port.
The harder parts appear once the proxy is in place. Identity mapping must decide whether a corporate group, an application client or a single user becomes the unit of access, and whether that mapping lives in the gateway or in the identity provider. Token lifetimes determine how long a revoked employee can still call the model, so the team should confirm the access-token and refresh settings with its identity platform owners. Service accounts for batch jobs and backend applications need their own credentials, not a borrowed user session. Log attribution requires the gateway to record the authenticated identity on each request and pass it to the access logs, because vLLM itself does not record which caller made a request. Finally, control endpoints such as /pause and /abort_requests must stay unreachable from user networks, which usually means restricting them to an operations network or removing them from the proxy entirely.
vLLM is licensed under Apache-2.0 and has no paid edition, so the cost of this work is not a license fee. It is integration and operations effort: designing the identity mapping, building and testing the proxy configuration, wiring logs into existing monitoring, and maintaining the allowlist as vLLM releases change. The identity platform already in use is also part of the cost, because it may need new clients, groups or token policies. When requesting a quote, ask the provider to separate proxy and gateway configuration, identity integration, attribution and log pipeline work, and the ongoing review of the allowlist after each upgrade. Confirm whether the gateway product chosen carries its own license terms, since that is a separate cost from vLLM.
Components involved in vLLM access control
Controlling access to a self-hosted vLLM server takes more than its built-in API key. Several components work together: the server itself, the key option, an enforcing gateway, an identity provider, credential storage and the logs that record who called what.
vLLM API server and OpenAI-compatible endpoints
The server started with vllm serve exposes the OpenAI-compatible endpoints that applications call, including /v1/completions, /v1/chat/completions, /v1/responses, /v1/embeddings and the audio transcription and translation routes. These are the surfaces users should reach. Confirm which of them your applications actually use, because every endpoint left open is an access decision you must document and test.
The --api-key option and protected prefixes
The --api-key option protects endpoints under /v1, /v2, /inference and /cohere, but it does not cover /invocations, /pause, /resume, /abort_requests, /metrics or /health. The vLLM security documentation warns against relying on this key alone. Treat it as one control layer, and confirm for your vLLM version exactly which paths the key guards before you define the gateway rules.
Unprotected control and metrics paths
The control paths /invocations, /pause, /resume and /abort_requests change server state, and /metrics and /health expose operational detail. None of them is covered by the API key, so a reachable deployment exposes them directly. Block them at the gateway for all external callers, and allow health checks and Prometheus scraping only from the internal monitoring network.
Reverse proxy or API gateway
The reverse proxy or API gateway is the enforcement point. It validates the identity or key on each request, applies an endpoint allowlist that exposes only the paths meant for users, and forwards identity to vLLM. Confirm how your chosen gateway maps identity claims to upstream headers, and test that vLLM receives only the headers and paths you intended.
Identity provider speaking OIDC or SAML
The identity provider authenticates people and services through OIDC or SAML, so access follows existing corporate accounts, groups and offboarding. SAML is typically used for browser-based sign-in and OIDC for token-based API access. Confirm which protocol your gateway supports for API calls, and which group or role claims it can map to team-level permissions.
Token or key store for per-team credentials
Per-team API keys or tokens let you rotate, revoke and attribute usage without changing the identity provider. This store holds credential issuance, expiry and revocation records. Decide who can create keys, how long they live, where secrets are kept, and how a leaked key is revoked before the next request reaches the server.
Logs and metrics pipeline for attribution
The gateway access logs and the vLLM Prometheus metrics record which team or identity made each call, along with throughput and latency. Attribution depends on the gateway writing the caller identity into each log line. Confirm that logs retain the caller, endpoint and status, that they are stored under your retention policy, and that metrics scraping does not expose them publicly.
Which access pattern to choose and what each one costs to run
This table compares five ways to control access to a self-hosted vLLM server, from the built-in API key to an identity-aware proxy from the organization's platform. Read each row by asking when the pattern fits, what ongoing work it creates for the team, and what the team is left owning after the engagement. The main takeaway is that the built-in key is a starting point, and most regulated deployments need a gateway or proxy that handles identity and allowlists.
| Access pattern | When it fits | Operational burden | What the team keeps |
|---|---|---|---|
| vLLM --api-key alone | A trusted internal lab with a small group of users and no regulated data. The vLLM docs warn against relying on it alone. | Low setup effort, but the key covers only some endpoints. /invocations, /pause, /resume, /abort_requests, /metrics and /health stay outside it, so exposure must be managed elsewhere. | One shared secret to rotate by hand. No per-user identity, no usage attribution per person or team, and no route allowlist. |
| Reverse proxy with OIDC login and route allowlist | Web or internal applications where users sign in with the organization's OpenID Connect provider and only inference routes should be reachable. | Ongoing work for client registration secrets, redirect URIs, claim mapping to team roles, session lifetime settings and proxy upgrades. Allowlist rules need review when vLLM adds endpoints. | Proxy configuration with the allowlist as code, claim mapping rules, and a runbook for registering new applications. Confirm the proxy choice against the organization's standards. |
| Reverse proxy with SAML bridged through an identity provider | Organizations whose identity provider exposes SAML only, or whose applications already use SAML. The proxy usually receives OIDC from a bridge the identity provider runs. | Adds certificate and signing key rotation, metadata refresh when the identity provider changes, attribute mapping and an extra hop to troubleshoot during login failures. | Documented metadata and certificate rotation steps, attribute mapping tables and a test plan for login failures. Confirm the bridge is an approved component. |
| Existing enterprise API gateway with OAuth2 or JWT validation | Organizations that already run a central API gateway for other services and want vLLM routes governed the same way, including rate limits and quotas. | Work is mostly route definitions, JWT issuer and audience settings, key set refresh and claim-based authorization. Gateway upgrades and policy changes follow the enterprise change process. | Gateway route and policy definitions, JWT validation settings and per-team quota rules. Usage data appears in the enterprise gateway, which may need its own retention review. |
| Identity-aware proxy from the organization's platform | Teams that already use a platform-provided identity-aware proxy for internal tools, and want vLLM access granted through the same device and user checks. | Burden sits mostly with the platform team: policy definitions, device posture rules and access reviews. vLLM still needs its own allowlist of inference endpoints behind the proxy. | Access policies written against the platform's model, plus a vLLM allowlist and documentation. Confirm which platform components are in scope and who owns their upgrades. |
How an OIDC or SAML login reaches vLLM
vLLM does not log users in. The login decision happens in front of it, and the request path is the control. A user or application first authenticates at the identity provider, which issues an OIDC token or, for SAML, an assertion that is usually exchanged for a session at the gateway. The gateway then validates that token or assertion (signature, issuer, audience and expiry for OIDC), reads the caller's group or claim, and checks it against an endpoint allowlist. Only if that check passes does the gateway forward the request to vLLM on a private address that the public network cannot reach. Every step must be tested in the order it runs, because a gateway that forwards first and checks later gives no protection. The gateway is also responsible for what crosses the boundary in each direction. In most designs it should strip the caller's own Authorization header before forwarding, so that an identity token issued for the gateway is never passed to the inference server. If you do want vLLM's --api-key option as a second layer, the gateway should set that key itself from a secret it holds, and the key should be treated as an upstream credential, not the caller's. The gateway should also remove or overwrite any identity headers a client sends, such as user or team headers, and then set its own trusted values from the validated token. Otherwise a caller can claim to be another team in the usage records. SAML is usually handled differently from OIDC. vLLM itself has no SSO login, so SAML is normally terminated at the gateway or at an identity broker that converts the assertion into a token or session the gateway understands. Decide early which component owns the SAML metadata exchange, certificate rotation and signature validation, because that component becomes part of your authentication path. Confirm with your identity provider which attributes carry group membership and whether they are sent on every login or only at session start. Service-to-service callers, such as backend jobs and batch pipelines, typically should not use interactive login at all. They are better served by OAuth 2.0 client credentials issued to the calling service or by a per-team API key that the gateway maps to a team identity and allowlisted endpoints. Keys should be stored in a secrets manager, rotated on a schedule you set, and revocable without touching other teams. The exact claim names, group formats and header behavior depend on the gateway you choose, and they will not match examples from documentation or other deployments. Before go-live, run test identities through each path: an allowed user, a user outside the allowed group, an expired token, a forged header, and a call to an endpoint that is not allowlisted. Confirm in testing that vLLM receives only the headers you intend and that /metrics, /health and the control endpoints stay unreachable through the gateway.
Build sequence for gateway-based vLLM access
This sequence moves vLLM from an open serving endpoint to one that only an authenticating gateway can reach, with SSO-backed identity, per-team credentials, an endpoint allowlist and usage attribution. Each step closes with a check, so the team can confirm the controls work before any user gets access.
Bind vLLM to a private interface
Start vLLM so its API server listens only on a private address that the gateway can reach, not on a public or shared network interface. The platform or network engineer makes this change in the service definition or launch command and confirms the listening address on the host. The step is done when a connection to the vLLM port from any address other than the gateway fails, and a connection from the gateway succeeds. Keep the same isolation in mind for multi-node runs, because the vLLM security docs describe inter-node traffic as unauthenticated and unencrypted by default.
Inventory and classify every vLLM route
List every HTTP route the running server exposes, including the OpenAI-compatible inference routes and the control and observability routes such as /metrics, /health, /pause, /resume, /abort_requests and /invocations. Confirm the list against the version you pinned, because routes can differ between releases. Classify each route as user-facing or control, and record the owner of each control route. The output is a reviewed table signed off by the platform and security leads. The step is done when every route has exactly one classification and no route is unclassified.
Write the endpoint allowlist
Configure the gateway or reverse proxy so that only the user-facing OpenAI-compatible routes are forwarded, such as chat completions, completions, responses and embeddings, if your models use them. Deny everything else by default, including the control routes and metrics. The security engineer reviews the rule set and the proxy configuration is version controlled. The check is a request through the gateway to a control route with a valid user token, which must return a denial, and a request to a permitted inference route, which must succeed.
Register the gateway with the identity provider
Register the gateway as an OIDC or SAML client in your identity provider and define the redirect URIs, scopes and token lifetimes that your security policy requires. Map identity provider groups to platform teams so that membership in a group determines which team and which models a user can call. The identity administrator and the platform lead own this mapping. The check is a test login from one user in each mapped group, with the resulting token showing the expected team claim and nothing beyond it.
Validate tokens at the gateway
Configure the gateway to verify token signatures against the identity provider keys, check the issuer and audience, and reject tokens that are expired, malformed or issued by an unknown issuer. Test rejection paths as carefully as acceptance paths. The check is three requests: a valid token that succeeds, an expired token that is refused, and a token signed by an unknown key that is refused, each returning the expected status code and a log entry at the gateway.
Decide on the vLLM API key and store its value
Decide whether to keep vLLM's --api-key option as an internal second layer between the gateway and the server. The vLLM security docs say it protects only some endpoints and should not be relied on alone, so it is a defense in depth choice rather than the access control. If you keep it, generate the value, store it in your secrets manager, and inject it into the gateway and the vLLM process at startup without writing it to images or configuration files. The check is a direct request to vLLM without the key being refused on a protected route, and the secret being absent from the repository and container image.
Create per-team credentials and service accounts
Create a credential for each team and a service account for each automated workload, and bind each one to the team mapping from the identity provider. Set a rotation and revocation procedure, and document who can issue or revoke a credential. The check is that a credential issued to one team is accepted for that team's models, refused for another team's models, and that revoking it blocks the next request within the gateway's configured token lifetime.
Add request logging for attribution
Configure the gateway to write one log record per request containing the team, the authenticated subject, the requested model and the endpoint, along with the timestamp and response status. Send these records to the central log store your security team uses, and keep prompt content out of the record unless your data policy allows it. Monitoring of vLLM's /metrics route belongs with the metrics work, not this log. The check is a sample request from two teams that produces two records, each carrying the correct team, subject, model and endpoint.
Run the verification suite before opening access
Run the full test suite from the verification section against the staging deployment, covering the route allowlist, the denial of control routes with user tokens, token rejection, team scoping, revocation and log attribution. Record the results and the vLLM version under test. Open access to users only after every test passes and the platform and security leads have signed off. The check is a clean run with the results stored alongside the change record, and any failure treated as a blocker until fixed and retested.
Issuing per-team keys and attributing usage to teams
A single shared vLLM key answers whether a caller is allowed in, but not who made the call. Every application, notebook and engineer presents the same bearer token, so the logs show traffic without an owner. The --api-key option checks that a key is present on the /v1 endpoints, and it does not record which caller sent it. The fix belongs at the gateway or reverse proxy in front of vLLM. Issue a separate credential per team or per application, bind each one to a named identity or group in your identity provider, and make the gateway write the credential's owner into every request log line. The gateway then holds the mapping that the vLLM server cannot provide: which credential may call which model and which endpoint.
Separate two kinds of credential. Interactive users should receive short-lived tokens through the SSO flow, so access ends when their session or group membership ends. Services and batch jobs need long-lived credentials, which should be scoped to one application, kept in a secrets manager and assigned a named owner. For service credentials, plan rotation so that a second key can be issued and tested before the first is retired. Ask the gateway team to confirm that overlapping keys are supported, because that decides whether applications can switch without downtime. Revocation must be demonstrated, not assumed. Check that a revoked key stops working on every gateway replica and that cached sessions expire within the window your security team sets. Record each issuance, rotation and revocation with the requester and the approver.
Define the usage record before you write the gateway configuration. A useful entry includes the team, the credential identifier, the subject (user or service account), the model name, the endpoint path, a timestamp, the status code and a request identifier. Add prompt and completion token counts only if the gateway can read them from response bodies for the endpoints you expose. Confirm separately how streaming responses report usage, since the figures may arrive differently or not at all. The vLLM metrics endpoint at /metrics reports request counts and token throughput, but these figures are aggregate across the server and do not identify callers. Per-team reports therefore come from gateway logs joined to identity records, and that join should be tested with a known test credential before anyone relies on the numbers.
Confirm log retention and personal data handling with your privacy team before go-live. Request logs tied to named users can be personal data in many jurisdictions, and they may contain identifiers or metadata about prompts. Agree retention periods, who may read the logs, the lawful basis for attributing usage to individuals, and whether prompt content is logged at all. Check that log storage sits inside the boundary you have approved and that deletion requests can be carried out in practice. Also ask the logging stack owner to confirm that attribution fields survive shipping and parsing. A field dropped in transit produces a wrong team report without raising any error, so test the full path end to end.
What drives the effort and cost of vLLM SSO integration
This table lists the factors that change the effort and cost of putting SSO and per-team credentials in front of vLLM, with ways to keep each one down. Read it before requesting a quote, because each row is a question a written scope must answer. vLLM itself has no license fee, so most of the spend follows from these drivers.
| Driver | Why it changes effort or cost | How to keep it down |
|---|---|---|
| Number of identity providers and SAML need | Each identity provider needs its own trust configuration, claim mapping and test cases. SAML usually adds certificate handling and metadata work compared with OIDC. | Confirm whether your organization can use OIDC through one provider. Limit SAML to systems that truly require it and standardize on one federation point. |
| Teams and applications needing separate credentials | Each team or application that needs its own key adds issuance, rotation, revocation and usage attribution work. | Group consumers by team rather than by application where risk allows. Issue one key per team and document who owns each. |
| Number of vLLM routes and models behind the gateway | Each model or route adds allowlist entries, test cases and per-route policy. Multi-model setups multiply verification effort. | Allowlist only user-facing routes such as chat and completions. Keep internal endpoints such as metrics, health and control routes closed to consumers. |
| Existing gateway standards and an approved gateway | If an approved gateway or reverse proxy already exists, the work is mostly configuration. If not, selection, hardening and operations become part of the scope. | Reuse the approved gateway where it supports the required authentication flow. Ask whether the gateway already handles token validation and logging. |
| Environments and separate identity configurations | Development, test and production usually need separate identity clients, redirect addresses and keys. Each environment is tested on its own. | Use the same configuration template in every environment with only the values changed. Confirm which environments need full SSO and which can use a lighter setup. |
| Compliance evidence such as access reviews and log retention | Assessors may ask for periodic access reviews, evidence of who used which key and retention periods for gateway logs. Producing this evidence adds reporting and storage work. | Agree the evidence list before design. Use group-based membership so reviews run against identity provider groups instead of per-key lists. |
| Client application base to migrate to new credentials | Existing applications that call vLLM directly will need new keys, updated configuration and coordinated cutover. The more applications, the more testing and communication. | Inventory consumers first and migrate in groups. Ask whether a transition period with both old and new credentials is needed. |
| Group-based mapping versus per-user rules | Per-user rules must be maintained as people join, move and leave. Each change is a configuration task and a review item. | Map identity provider groups to vLLM access roles. Keep per-user exceptions to a short, reviewed list. |
| Licensing and operating cost | vLLM has no license fee. Cost comes from the people who design and operate the gateway and identity integration, plus the gateway and its operation. Ask for these as separate line items in the quote. | Not applicable |
Access control, secrets and exposure controls for this topic
vLLM's built-in API key does not cover every route, so access control depends on what sits in front of the server and how credentials are issued, stored and retired. The cards below cover network placement, gateway route denial, secrets handling, token lifetime, group mapping and log protection. Confirm each control against your own threat model before treating it as settled.
Keep the server off public networks
Bind vLLM to a private interface and place it in a subnet that only the authenticating gateway can reach, so the gateway is the only path to the server. Without this, a client that reaches the port directly can skip every check made at the gateway. Confirm the network policy, security group or firewall rules in your own environment, and test from outside the trusted segment to verify that the port does not answer.
Deny control and metrics routes at the gateway
The --api-key option does not protect /invocations, /pause, /resume, /abort_requests, /metrics or /health, so the gateway should deny these routes for all external callers unless a specific need exists. Pause, resume and abort affect every request on the server, and metrics expose operational detail. Allowlist only the /v1 endpoints your applications call, and confirm the route list against the vLLM version you run.
Store API keys in a secrets manager
Keep the vLLM --api-key value and each team's gateway credentials in a dedicated secrets manager, not in configuration files, container images or shell history. Define who can read each secret, log access, and set a rotation schedule that the team can actually execute. Confirm how the secret reaches the server process, since environment variables and command arguments can appear in process listings and crash dumps.
Set short token lifetimes and revoke on offboarding
Issue short-lived access tokens from the identity provider and keep refresh behavior under the gateway's control, so a leaked token expires quickly. Remove a user's group membership or revoke their sessions as part of offboarding, and confirm that cached tokens stop working at the gateway within a window your security team accepts. Test revocation end to end, because gateways often cache validation results.
Map groups to least-privilege model access
Map identity provider groups to gateway roles that grant access to specific models and endpoints, not to the whole server. A team building a chat feature rarely needs embeddings, audio or administrative routes. Review the mapping whenever a model is added, and confirm which claim the gateway reads for group membership, since a misconfigured claim can grant broader access than intended.
Protect logs that contain identifiers
Gateway and server logs can hold user identifiers, team names, API key fragments and request metadata, which may fall under your data protection obligations. Decide which fields are logged, mask or hash identifiers where possible, restrict log access by role, and set retention periods. Confirm with your privacy and compliance leads which logged values count as personal data in your jurisdiction.
How to test that vLLM access fails safely
The point of this section is that access control is only proven when a scripted test suite tries to get through it and fails. Reading the gateway configuration is not enough. For a vLLM deployment behind an authenticating gateway, the suite should cover both the paths that must work and the paths that must be refused, and it should produce a record that an auditor or security reviewer can read later. Start with the positive cases. A valid user token, issued through the OIDC or SAML flow your gateway is configured for, should reach each allowlisted OpenAI-compatible endpoint, such as /v1/chat/completions and /v1/embeddings, if your allowlist includes them. Run a request against each one and confirm a normal response. Then test the negative cases that matter most: an expired token, a token with a bad signature (forged), and a token whose audience claim names a different service. Each must be refused at the gateway with no request reaching vLLM. Add a user from a team that is not in the model's group and confirm refusal on that model, since per-team scoping is the control most likely to drift silently.
Next, test the bypass. A direct request to the vLLM server from outside the gateway, using the network path a client would not normally have, must fail. This check matters because the vLLM security documentation says the --api-key option does not cover /invocations, /pause, /resume, /abort_requests, /metrics or /health, and recommends a reverse proxy that allowlists only user-facing endpoints. For each of those six paths, send a request carrying a valid user token and confirm it is denied. Also confirm that the --api-key layer, if you kept it, rejects requests without the key. Treat a pass on the gateway alone as insufficient if the server port is reachable from the wrong network. The gateway log is part of the test, not an afterthought. Every accepted and refused request should record the team and the subject identifier, so you can show which identity made which call. Check this by reading the log entries produced by your test run. For revocation, revoke a test key and confirm access stops within the token lifetime you configured. Ask your identity provider team to confirm how revocation propagates, because a gateway that caches token validation can extend that window.
Script every check so the suite can run in a pipeline. Rerun it after each gateway change, each vLLM upgrade that adds routes (the project ships new minor releases about every two weeks, so route changes are frequent), and each edit to the endpoint allowlist. Record each failure with its date, the change that triggered the run, and the remediation. Keep passing and failing runs together. Those records are the acceptance evidence for this control set, and they show that a refused request was refused for the stated reason. Before you start, decide three things with your security and platform leads: which token lifetime is acceptable, which team groups map to which models, and whether the --api-key layer stays as a second barrier. The third decision changes the test list, so settle it first. Ask your implementation partner or internal team to confirm the exact route list for the vLLM version you run, because the suite is only as complete as the list of paths it tests.
What to monitor, rotate, back up and document after go-live
This table lists the recurring tasks, their owners in practice, and the records to keep for a vLLM access layer after launch. Read each row as a standing duty with a trigger, such as a release, an expiry date, a team change or a review cycle. The main takeaway is that vLLM's own metrics do not show who is calling, so attribution and the allowlist record depend on gateway logs and maintained documentation.
| Area | What to do | Evidence to keep |
|---|---|---|
| Gateway authentication and denied routes | Track authentication failures and denied-route counts at the gateway, and review spikes against the allowlist. Confirm which metrics your gateway exports, since vLLM's Prometheus metrics do not identify callers. | Dashboards, alert history and a log of reviewed spikes with the outcome of each review |
| SAML certificate and metadata expiry | Record the expiry date of the identity provider signing certificate and the SAML metadata. Schedule renewal and test the new metadata in a non-production gateway before the old certificate expires. | Expiry calendar entry, change record and the metadata version deployed to the gateway |
| OIDC key and client secret rotation | Confirm how the identity provider rotates signing keys and how the gateway picks up new keys. Rotate the gateway client secret on a fixed schedule and verify token validation after each change. | Rotation log, test results after each rotation and the identity provider settings export |
| Per-team key rotation and offboarding | Rotate team API keys on the schedule your policy sets. When a person or team leaves, disable their keys at the gateway and confirm that the identity provider session is also closed. | Key inventory with owner and last rotation date, plus offboarding tickets |
| Allowlist review after each vLLM release | vLLM ships minor releases about every two weeks, for example v0.31.0 on October 5, 2026. Read each release note for new or changed routes, and update the allowlist before the new version reaches production. | Release note review record, allowlist diff and approval by the allowlist owner |
| Gateway and identity configuration backups | Back up gateway routing rules, authentication settings, claim mapping and the identity provider client configuration. Test a restore in a separate environment at a set interval. | Backup schedule, storage location, restore test results and the date of the last successful test |
| Access reviews | Review which teams, service accounts and users hold access to each vLLM route. Remove access that is no longer needed and confirm the group membership that drives claim mapping. | Signed review records, removal tickets and the group membership snapshot used for each review |
| Runbook for revoking a team | Define the steps to revoke a team's keys, remove its group mapping at the identity provider, block its routes at the gateway and confirm that in-flight requests stop. Name the people who can execute each step. | Tested runbook with named roles, and a record from each drill or real revocation |
Questions teams ask before building vLLM SSO
Is the built-in vLLM API key enough for multiple teams?
No. The --api-key option protects only some routes, under /v1, /v2, /inference and /cohere. It does not cover /invocations, /pause, /resume, /abort_requests, /metrics or /health. The vLLM security documentation warns against relying on the key alone and recommends a reverse proxy that allowlists only the endpoints meant for users. A single shared key also cannot identify which team made a request, revoke one team's access, or attribute usage. Confirm the route list against the vLLM version you plan to pin, because endpoints change between releases.
Does vLLM have native SSO with OIDC or SAML?
The materials used to prepare this page do not establish that vLLM provides native SSO, so confirm it against the current vLLM documentation and the release you intend to deploy before relying on it. Until that is confirmed, plan on an authenticating gateway or reverse proxy in front of the vLLM server. The gateway handles OIDC or SAML sign-in with your identity provider, maps groups to teams, and forwards only allowlisted routes to vLLM. This design works regardless of the answer, and it keeps identity logic outside the inference server, where upgrades are frequent.
What drives the cost of building vLLM SSO?
vLLM itself has no license fee, so the cost is the work to put identity and access control around it, plus internal time. The main drivers are the complexity of your identity provider, the number of teams and groups, whether an API gateway already exists, the compliance evidence you need, the number of environments, and how precisely the scope is written. One-time work includes design, gateway configuration, identity integration, the endpoint allowlist, testing and documentation. Recurring work includes reviewing the allowlist at each vLLM upgrade, managing group changes, rotating keys and certificates, and retaining logs. Ask any quote to itemize these two groups separately.
How long does a vLLM SSO implementation take?
The duration depends mostly on how ready your identity provider and gateway are. DeployOpen does not publish fixed durations. Most engagements are fixed-scope, so the timeline is agreed in writing before work starts. The factors that move it most are whether identity provider admin access and a group structure already exist, whether a gateway is already in place, whether network paths between the gateway, vLLM hosts and identity provider are open, and how many environments need the same design. As an illustrative case, a team with existing OIDC application registrations and a working gateway usually has less to set up than one starting from zero. Ask for milestones and the dependencies each one needs.
What do we need to provide before SSO work starts?
Five things are needed before the work begins:
- Identity provider admin access, or a named administrator who can make the changes during the engagement.
- A group structure that maps teams and roles to identity provider groups.
- Network access between the gateway, the vLLM hosts and the identity provider.
- A log destination that your security team owns and can query for attribution and audit.
- Named owners who approve each endpoint on the allowlist and who sign off on changes.
Missing any of these usually delays the schedule, so confirm them in the written scope rather than assuming they will be ready.
Can our internal platform team build vLLM SSO without a partner?
Yes, if the team already has gateway and identity skills. The work is well defined: place an authenticating proxy in front of vLLM, integrate it with OIDC or SAML, map groups to per-team credentials, allowlist the routes users need, and log usage by team. The verification checklist makes the result testable, so the team can show that it works. The harder ongoing part is keeping the allowlist correct through upgrades and changes to group membership. If your team lacks that capacity, DeployOpen can plan, implement and document the setup as a fixed-scope engagement, or provide ongoing support through a retainer.
How do we verify that a vLLM SSO setup works?
Test from outside the trust boundary, using identities from each group. Confirm that unauthenticated requests fail on every /v1 route, and that /metrics, /health, /pause, /resume, /abort_requests and /invocations are unreachable through the proxy. Check that each team's credentials reach only its permitted routes, that removing a user from a group revokes access within your agreed window, and that token expiry is enforced. Confirm that each request appears in the logs with the team or user identity. For multi-node deployments, verify network isolation, because the vLLM security documentation states that inter-node traffic is insecure by default. Keep these results as evidence for your reviewers.
How DeployOpen scopes, builds and hands over vLLM access control
DeployOpen plans, implements, documents and supports vLLM access control inside your own infrastructure, so the gateway, identity provider and keys sit where your security team already works. The written scope fixes what gets protected, how users sign in and what evidence you receive before work begins.
How we scope
- Inventory every vLLM endpoint in use and mark which ones users may call, since the --api-key option does not cover every route.
- Agree the identity provider, OIDC or SAML settings, group-to-team mapping and key lifecycle rules in the written scope.
- Confirm the target platform, network path and which internal systems will receive usage attribution data before quoting.
How we build
- Place an authenticating reverse proxy or gateway in front of vLLM that allowlists only the user-facing endpoints.
- Issue per-team API keys and keep vLLM's own control, health and metrics routes off the user network path.
- Test sign-in, key rejection, blocked endpoints and attribution records against the agreed scope before handover.
How we hand over
- Deliver configuration, gateway rules, identity mapping and runbooks written for your engineers to operate and change.
- Provide test evidence and a record of each control, organized so your auditors can trace it to the scope.
- Walk through key rotation, user offboarding and endpoint allowlist changes with the team that will own them.
How we support
- Offer ongoing support as a retainer covering gateway updates, vLLM version changes and access rule reviews.
- Retest the allowlist and authentication path after each vLLM minor release, which ships about every two weeks.
- Keep documentation current with changes to identity provider settings, team keys and endpoint exposure.
