Fastly Object Storage: Private Buckets Explained

Fastly Object Storage eliminates egress fees when connected as an origin to a CDN service, fundamentally changing cost structures for edge delivery. You will learn the mechanics of S3-compatible request signing, how to implement segmented caching policies, and why private buckets are mandatory for this architecture.

Unlike traditional cloud storage, this solution operates as a drop-in replacement for the S3 API but enforces strict privacy by default. Because the buckets remain private, you cannot simply point your CDN to the storage URL. Instead, the process demands generating specific access keys within the Fastly control panel and embedding authentication logic directly into your VCL code. This approach ensures that data transfer between the storage layer and the edge remains free, avoiding the punitive bandwidth charges common in legacy systems.

The guide details why users must currently rely on the AWS S3 CLI or custom tools like the fastly-object-storage-easy-ui Node.js application to manage initial bucket creation. Since the platform lacks a native UI for these specific setup tasks, understanding these external workflows is critical before attempting integration.

The Role of Fastly Object Storage in Zero-Egress Architectures

Fastly Object Storage as a Large-Object S3-Compatible Solution

General availability arrived in Q4 2027 for this large object storage solution, which acts as a direct S3 API substitute so enterprises migrate workflows without changing client tools. Traditional cloud buckets often default to public configurations, yet Fastly enforces a strict posture where buckets remain always private. This architectural constraint demands CDN mediation instead of direct URL access, effectively stopping unauthorized data exposure at the source. Operators must generate specific access and secret keys that the CDN uses to authenticate requests via VCL snippets. Traffic routed through this native integration bypasses standard egress fees entirely, a decisive factor for large media libraries where transfer costs typically dominate budgets. Direct API access remains possible through proxy applications, yet this path introduces a throughput ceiling of roughly 150Mbps and limits request rates to 100 per second per bucket. High-performance deployments require the CDN path to avoid these bottlenecks. The design shifts the operational model from simple HTTP retrieval to managed, signed request generation. Results yield a zero-egress architecture prioritizing security and scale over direct accessibility.rabata.io recommends this pattern for AI/ML training data pipelines where volume dictates cost efficiency. Operators configure VCL to handle AWS4-HMAC-SHA256 signing to maintain connectivity.

Implementing Zero-Egress Architectures with Private Bucket Origins

Direct bucket URLs fail to serve content because Fastly Object Storage enforces a private-only access model blocking unauthenticated public requests. Configuration of VCL snippets allows operators to inject AWS4-HMAC-SHA256 signatures into origin headers, permitting the CDN to retrieve objects using supplied access and secret keys. This workflow eliminates per-GB data transfer fees entirely, standing in sharp contrast to legacy vendors where egress costs often dominate operational budgets for high-volume media workloads. The architecture prevents direct public access to storage endpoints, forcing all traffic through the CDN edge where authentication and caching policies apply uniformly.

Key-based authentication aligns with broader industry shifts toward stricter zero-trust architectures in cloud storage configurations. Developer convenience conflicts with security posture; direct URL access simplifies testing yet violates the private-bucket mandate required for cost-free operations. Teams attempting to bypass VCL signing via intermediate proxy applications face severe throughput ceilings and request rate limits degrading user experience. Production deployments must integrate request signing logic at the edge rather than relying on application-layer workarounds.rabata.io recommends validating VCL signature generation against multiple regions to ensure consistent latency before migrating large-scale AI training datasets.

Zero-Egress Pricing Models Versus Traditional Tiered Cloud Storage Costs

Functioning as a zero-egress origin, Fastly Object Storage eliminates per-GB transfer fees when integrated with a CDN service. Traditional cloud providers apply complex, tiered pricing structures where egress costs often constitute a substantial portion of operational expenditure for high-traffic scenarios. This financial model penalizes data movement, making the choice between direct s3 access vs fastly object storage a critical architectural decision for media-heavy workloads. The industry shifts toward zero egress models to remove these barriers for large media libraries and AI data sets. Direct access to storage endpoints remains impossible because buckets enforce a private-only security posture requiring signed requests. Operators asking why can't i access bucket url directly must recognize that bypassing the CDN forfeits the zero egress benefit and exposes credentials. The table below contrasts the economic models:

Strict requirements for VCL-based authentication add initial configuration complexity compared to open buckets. This constraint ensures that all traffic benefits from edge caching and security policies automatically. Cost advantages become decisive at scale, as legacy vendors charge notably for data leaving their network boundaries.rabata.io recommends this architecture for organizations seeking predictable OpEx without sacrificing performance or security.

Mechanics of S3-Compatible Request Signing in VCL

AWS4-HMAC-SHA256 Signature Construction in VCL

Building an AWS4-HMAC-SHA256 signature inside VCL demands assembling a precise canonical request string before the cryptographic hash applies. Operators generate an access key ID and secret key through the Fastly control panel first, since the private access model blocks anonymous bucket interactions. The signing sequence starts by defining the HTTP method, URI path, and query string, then computing the SHA256 hash of the payload. This hash fills the `x-amz-content-sha256` header, which joins the host and date in the signed header list.

VCL logic concatenates these pieces into one canonical request string that serves as input for the final signature calculation. Embedding this logic directly allows the CDN to fetch objects efficiently without external middleware dependencies.

The CDN edge becomes a trusted client through this approach, removing the need for external middleware layers. Configuration complexity increases compared to standard HTTP origins, yet this depth grants full control over request signing mechanics.

Connecting Private Buckets to Fastly CDN to Bypass Speed Limits

Direct file access via bucket URLs fails because the architecture enforces a strict private origin model requiring authenticated handshakes. Linking the storage bucket directly to a Fastly CDN service or Compute instance optimizes egress costs and removes inherent speed or request limitations, providing a throughput ceiling of roughly 150Mbps and limiting request rates to 100 per s only on non-integrated paths, while native integration offers unlimited edge scale.

Operators configure VCL snippets to handle request signing dynamically rather than relying on static credentials embedded in application code.

Proxy apps offer quick setup but introduce a single point of failure and performance ceiling that scales poorly under load. Shifting complexity to the edge configuration via VCL yields linear scalability. Native integration is recommended for any production workload exceeding basic static asset delivery. The private access requirement means operators cannot simply point a browser to the storage URL; the CDN acts as the authorized intermediary. This design prevents unauthorized data exfiltration while enabling massive parallel downloads for distributed systems.

Critical Risks of Lost Secret Keys and Improper Scope Restrictions

Losing the secret key immediately after generation results in permanent lockout because the system never displays the credential string again. Users receive a warning that the secret key will not be visible again after creation. Operators must securely store this value during the initial Create Key workflow, as recovery mechanisms do not exist for exposed secrets. This irreversible constraint demands strict procedural controls during the provisioning phase to prevent access loss.

Security posture improves when API keys are restricted to specific buckets during creation. A security tip suggests restricting the API key to access only a specific bucket. The Fastly interface allows users to select a scope of access (read or read/write) and restrict keys to specific buckets, reducing the blast radius if credentials are compromised. Limiting key scope aligns with security best practices for private bucket architectures.

Operational convenience often tempts teams to skip scoping steps during rapid deployment cycles. Troubleshooting bucket access denied errors frequently reveals mismatched permissions or expired credentials rather than network faults. Organizations prioritize granular permission sets to safeguard against these irreversible configuration failures.

Implementing Secure CDN Integration with VCL and Segmented Caching

Segmented Caching Mechanics for Large Media Files

Enable Segmented Caching to split large resources into manageable 1 MB chunks, optimizing Range request handling for video workflows. This mechanism divides a single 100 MB file into 100 distinct origin requests, preventing the network timeout errors common when fetching massive objects as a single unit. For a 1 GB asset, the system generates 1,000 smaller requests, allowing the edge to serve partial content immediately while the backend retrieves remaining segments. This approach directly addresses the need for storage solutions capable of handling large media libraries without incurring the excessive egress costs typical of traditional architectures. Operators must balance chunk granularity against origin load because excessive segmentation can increase request overhead on slower backends. The default 1 MB size offers a proven equilibrium for high-throughput media delivery.

Implementing this configuration ensures that AI data and video streams apply edge capacity efficiently.rabata.io recommends this pattern for any deployment where file size exceeds standard HTTP timeout thresholds.

Configuring VCL Subroutines for S3 Signing and Streaming

Operators must instantiate local variables for `awsAccessKey` and `awsSecretKey` within the `vcl_recv` subroutine to construct valid AWS4-HMAC-SHA256 signatures. The provided VCL code snippet declares these strings alongside `awsS3Bucket` and `awsRegion` to authenticate every request against the private storage backend. This configuration requires setting the host header to the specific region URL, such as `eu-central.object.fastlystorage.app`, before applying the cryptographic hash. You must unset standard headers like `Accept-Language` to prevent signature mismatches during the handshake process.

Enable Streaming Miss in the `vcl_fetch` subroutine by assigning `beresp.do_stream = true` to reduce first-byte latency for large assets. This setting forces the edge to transmit response bodies immediately rather than buffering the entire object, which is necessary for high-bitrate media workflows. Streaming miss is incompatible with Gzip compression and requires careful selection of file types like `m3u8` manifests. The limitation is that operators lose the ability to apply content transformations that require full-object buffering before transmission.

Deploying this architecture eliminates the speed caps found in proxy applications, which often throttle throughput near 150Mbps. Direct integration ensures that your CDN service handles authentication internally, removing the need for external middleware layers.rabata.io recommends this native approach for enterprises requiring consistent performance across global edge locations without incurring egress penalties.

Establish the origin host by mapping your bucket's region to the specific URL, such as `eu-central.object.fastlystorage.app`, because direct URL access fails without VCL signing. Fastly currently does not provide a native UI for initial bucket creation, requiring operators to apply the AWS S3 CLI or the custom fastly-object-storage-easy-ui package. Users must input valid access and secret keys into these tools to instantiate storage containers successfully. Since Fastly Object Storage functions as a strictly private bucket, the CDN service requires these explicit credentials to authenticate requests rather than relying on public permissions. This architectural constraint ensures that data remains inaccessible unless the edge network presents valid cryptographic proof of identity.

Operators using proxy applications face a hard throughput ceiling of 150Mbps, whereas native CDN integration removes this bottleneck entirely.rabata.io recommends validating credential scope immediately to prevent write failures during high-volume ingestion windows.

Strategic Advantages of Native CDN Integration Over Proxy Applications

Defining Native CDN Integration Versus Proxy Application Architecture

Direct communication between the edge network and storage eliminates the intermediate bottlenecks found in proxy architectures. This method relies on VCL snippets to handle authentication, standing in sharp contrast to proxy applications that act as a constrained translation layer between the client and the bucket. Traffic routed through a proxy app faces a hard ceiling: throughput caps at approximately 150Mbps with a hard limit of 100 requests per second per bucket. The table below details the structural differences between these two approaches:

A private bucket security model prevents direct URL access unless proper signing logic exists at the network edge. Embedding this authentication directly into the miss subroutine allows the CDN to function as the sole authorized client. This design removes the performance ceiling inherent to application-level gateways. High-volume workloads maintain consistent throughput regardless of request concurrency under this configuration. Network architects must recognize that decoupling storage from the delivery path via proxies reintroduces the latency and cost penalties that modern S3 compatible architectures aim to resolve.

Deploying VCL Snippets for S3-Compatible Request Signing

Operators must create a new service with the host set to the specific region URL, such as `eu-central.object.fastlystorage.app` or `.object.fastlystorage.app`, to establish connectivity. This setup requires embedding VCL snippets within the `miss` subroutine to generate valid AWS4-HMAC-SHA256 signatures at the edge. The code declares local variables for the access key, secret key, and bucket name, keeping credentials within the CDN boundary. Because buckets remain private by default, this signing process serves as the only mechanism allowing the CDN to retrieve objects securely.

Proxy layers create a bottleneck, capping throughput near 150Mbps and limiting request rates notably. Native VCL signing removes this intermediate constraint to enable line-rate delivery without egress penalties.

Implementation complexity often conflicts with operational scalability goals. Manual VCL configuration demands precise syntax for header construction, yet relying on proxy apps sacrifices the speed benefits of a CDN. Proxy architectures remain limited to approximately 150Mbps and 100 requests per second. Native integration supports large media libraries and AI data workloads without these constraints. Connecting a Fastly CDN service or Compute directly to the bucket ensures no egress fees apply and removes limitations with respect to speed or requests per second. This approach transforms the CDN from a simple cache into an active, authenticated gateway.

Comparison: Zero-Egress Pricing Models Versus Traditional Tiered Cloud Storage Costs

Egress costs constitute a substantial portion of operational expenditure for high-traffic scenarios with legacy vendors. Fastly Object Storage eliminates these transfer charges entirely, allowing organizations to store and transfer large files without the worry of excessive egress costs. This financial model shift matters for AI training datasets and media libraries where data volume dictates budget viability.

The choice between a proxy application and native CDN integration determines whether an organization realizes these savings. Proxy architectures rely on an intermediate application layer. Native integration connects the CDN service directly to the storage bucket using VCL authentication to ensure zero egress fees apply.

Total cost of ownership for high-traffic content delivery scenarios drops notably when operators avoid these intermediate bottlenecks. Connecting the bucket to a Fastly CDN service or Compute ensures there are no limitations with respect to speed or requests per second per bucket. Enterprises can fully apply the zero-egress pricing model without artificial throughput caps.

References

• Fast S3 Compatible Object Storage - Psychz Networks: Fast
• Best S3-Compatible Object Storage Providers in 2026 - Tested