Support guides
Getting started
These articles provide basic instructions for getting started with Fastly services.
Basics
These articles provide basic information and instructions for configuring Fastly services after getting started.
- About the web interface controls
- Always-on DDoS mitigation
- Browser recommendations when using the Fastly web interface
- Content and its delivery
- Fastly POP locations
- Getting started with Fastly
- How caching and CDNs work
- How Fastly's CDN Service works
- HTTP status codes cached by default
- Self-provisioned Fastly services
- Shielding
- Sign up and create your first service
- Working with services
Domains & Origins
These articles describe configuration settings and changes you can make to your domains and origins when setting up Fastly services.
- Adding CNAME records
- Testing setup before changing domains
- Working with domains
- Working with health checks
Configuration
These articles provide basic instructions for configuring Fastly services after getting started.
Caching
These articles describe configuration settings and changes you can make to your cache settings when setting up Fastly services.
- Caching configuration best practices
- Configuring caching
- Controlling caching
- Enabling API caching
- Implementing API cache control
- Overriding caching defaults based on a backend response
- Segmented Caching
Conditions
These articles describe conditions and how to use them in VCL and the Fastly web interface.
Custom VCL
These articles describe how to create your own VCL files with specialized configurations.
- Accept-Language header VCL features
- Authenticating before returning a request
- Basic authentication
- Creating location-based tagging
- Custom responses that don't hit origin servers
- Delivering different content to different devices
- Enabling URL token validation
- Guide to VCL
- Isolating header values without regular expressions
- Manipulating the cache key
- IP geolocation variables: Migrating to the new dataset
- Overriding which IP address the geolocation features use
- Response Cookie handling
- Support for the Edge-Control header
- Understanding the different PASS action behaviors
- Using edge side includes (ESI)
- VCL regular expression cheat sheet
Dictionaries
These articles describe how to move rapid key/value pair decision logic to the edge using dictionaries.
- About Edge Dictionaries
- Private Edge Dictionaries
- Working with Edge Dictionaries using the API
- Working with Edge Dictionaries using the web interface
- Working with Edge Dictionary items using the API
Domains & Origins
These articles describe configuration settings and changes you can make to your domains and origins when setting up Fastly services.
- Changing origins based on user location
- Connecting to origins
- Failover configuration
- IPv6 support
- Maintaining separate HTTP and HTTPS requests to origin servers
- Routing assets to different origins
- Setting up redundant origin servers
- Specifying an override host
- Using Fastly with apex domains
- Using Fastly's global POP network
Headers
These articles describe configuration settings and changes you can make to your headers when setting up Fastly services.
- Adding or modifying headers on HTTP requests and responses
- Enabling cross-origin resource sharing (CORS)
- Removing headers from backend response
- Setting Content Type based on file extension
- Understanding cache HIT and MISS headers with shielded services
- Understanding the X-Timer header
Image optimization
These articles provide basic instructions for and examples of setting up and beginning to use the Fastly Image Optimizer.
- About Fastly Image Optimizer
- Automating optimization
- Controlling image quality
- Cropping images
- Fastly Image Optimizer API
- Image optimization VCL boilerplate
- Purging optimized images
- Reorienting images
- Resizing images
- Serving images
- Serving responsive images
- Setting up image optimization
- Trimming images
Load balancing
These articles provide information about distributing requests across multiple servers to optimize resource use and avoid overloading any single resource.
- About Dynamic Servers
- Creating and using pools with Dynamic Servers
- Creating and using server entries with Dynamic Servers
- Load-balancing configuration
Performance
These articles describe how to adjust the performance of Fastly's services beyond standard configuration methods.
- Enabling automatic gzipping
- Failure modes with large files
- HTTP/2 server push
- Making query strings agnostic
- Request collapsing
- Serving stale content
- Streaming Miss
Purging
These articles describe how to purge cache.
- Authenticating URL purge requests via API
- Getting started with surrogate keys
- Logging purge requests
- Purging API cache with surrogate keys
- Setting Surrogate-Key headers based on a URL
- Setting Surrogate-Key headers for Amazon S3 origins
- Single purges
- Soft purges
- Wildcard purges
Requests
These articles describe configuration settings and changes you can make to requests when working with Fastly services.
- Checking multiple backends for a single request
- Conditionally changing a URL
- How request settings are applied
- Manipulating the X-Forwarded-For header
Responses
These articles describe configuration settings and changes you can make to your response settings when setting up Fastly services.
- Creating and customizing a robots.txt file
- Creating error pages with custom responses
- Generating HTTP redirects at the edge
- Responses tutorial
Video
These articles describe setup and configuration guidelines for setting up live stream delivery or video on-demand.
- Adaptive bitrate playback URL guidelines
- Collecting OTFP metrics
- Configuration guidelines for live streaming
Security
These articles provide information about the administrative, physical, and technical safeguards that protect the Fastly CDN service, as well as describe how to secure communications between Fastly and your origin servers and customers.
Access Control Lists
These articles describe how to restrict access to resources by allowing or blocking IP addresses with access control lists (ACLs).
- About ACLs
- Manually creating access control lists
- Using the IP block list
- Working with ACLs using the API
- Working with ACLs using the web interface
Securing communications
These articles describe how to secure communications between Fastly, your origin servers, and your customers.
Security measures
These articles provide information about the administrative, physical, and technical safeguards that protect the Fastly CDN service.
- Penetration testing your service behind Fastly
- Security measures
- Security program
- Technology compliance
TLS
These articles describe how to set up TLS certificates with Fastly services.
- Domain validation for TLS certificates
- Enabling HSTS through Fastly
- Forcing a TLS redirect
- Managing domains on TLS certificates
- Serving HTTPS traffic using certificates you manage
- Serving HTTPS traffic using Fastly-managed certificates
- Setting up free TLS
- TLS key and certificate replacement
- TLS termination
Web Application Firewall
These articles provide information about the Fastly Web Application Firewall (WAF) security product.
- About the Fastly WAF dashboard
- Creating a custom WAF error page
- Fastly WAF logging
- Fastly WAF rule set updates and maintenance
- Managing the Fastly WAF
- Web Application Firewall (WAF)
Integrations
These articles describe how non-Fastly services interoperate with Fastly.
Logging endpoints
These articles describe Fastly's support for protocols that allow you to stream logs to a variety of locations, including third-party services, for storage and analysis.
- Log streaming: Amazon S3
- Log streaming: Microsoft Azure Blob Storage
- Log streaming: Cloud Files
- Log streaming: Datadog via syslog
- Log streaming: Datadog
- Log streaming: DigitalOcean Spaces
- Log streaming: Elasticsearch
- Log streaming: FTP
- Log streaming: Google BigQuery
- Log streaming: Google Cloud Pub/Sub
- Log streaming: Google Cloud Storage
- Log streaming: Honeycomb
- Log streaming: HTTPS
- Log streaming: Kafka
- Log streaming: Log Shuttle
- Log streaming: LogDNA
- Log streaming: Logentries
- Log streaming: Loggly
- Log streaming: Heroku's Logplex
- Log streaming: New Relic Logs
- Log streaming: OpenStack
- Log streaming: Papertrail
- Log streaming: Scalyr
- Log streaming: SFTP
- Log streaming: Splunk
- Log streaming: Sumo Logic
- Log streaming: Syslog
Non-Fastly services
These articles describe how non-Fastly services interoperate with Fastly.
- Amazon S3
- DigitalOcean Spaces
- Discounted egress from Google
- Google Cloud Storage
- Google Compute Engine
- Microsoft Azure Blob Storage
- Outbound data transfer from Azure
- PerimeterX Bot Defender
- Wasabi
Diagnostics
These articles describe how to log data, troubleshoot problems, and tune performance.
Common errors
These articles describe common errors you may encounter when setting up and configuring Fastly services.
- Common 503 errors on Fastly
- Common service and domain errors
- Error 1000 with CloudFlare DNS
- Fixing cross-domain errors
- Loop detection
- TLS certificate errors
- TLS origin configuration messages
Debugging techniques
Because Fastly doesn't store customer logs, we provide information about debugging techniques that help you gain insights into your service configurations.
- Changing connection timeouts to your origin
- Checking cache
- Debugging with mtr
- Debugging with WebPageTest
- Fastly's network status
- Google Pagespeed module errors
- Googlebot crawl stats
- Temporarily disabling caching
- Using GET instead of HEAD for command line caching tests
Streaming logs
These articles describe how we support real-time log streaming of data that passes through Fastly.
- About Fastly's Real-Time Log Streaming features
- Changing log line formats
- Changing where log files are written
- Custom log formats
- Encrypting logs
- Setting up remote log streaming
- Useful conditions for logging
- Useful log formats
- Useful variables to log
Account info
These articles describe how to manage account access, billing, and security.
Account management
These articles describe how to manage account access.
- Account lockouts
- Changing your account's company name
- Enabling an IP allowlist for account logins through the web interface
- Enabling and disabling two-factor authentication
- Finding and managing your account info
- Monitoring account activity with the audit log
- Reviewing service activity with the event log
- Using API tokens
Billing
These articles describe Fastly's billing and payment plans and how to make adjustments to your billing information.
User access and control
These articles describe how to manage users with permission to access to your account.
- Adding and deleting user accounts
- Configuring user roles and permissions
- Email and password changes
- Setting up single sign-on (SSO)
- Transferring services to other accounts
Reference
These articles provide reference information about common Fastly terms and configuration settings.
Products
Products and services
These articles provide summary definitions and plain English descriptions about Fastly's products and features and their paths through Fastly's product lifecycle. They also describe service level agreements offered by Fastly that provide information to customers based on the nature of their agreement with Fastly and the Fastly products they have purchased.
- Application Programming Interface (API)
- Assurance Services
- Cloud Optimizer
- DDoS Protection and Mitigation Service and SLA
- Dedicated IP addresses
- Designated Technical Specialist
- Fastly product lifecycle
- Fastly’s Full-Site Delivery
- Fastly's Media Shield
- Fastly's On-the-Fly Packaging service
- Fastly’s Streaming Delivery
- HIPAA-Compliant Caching and Delivery
- Live Event Monitoring Service
- Logging Insights Package
- Origin Connect
- PCI-Compliant Caching and Delivery
- Performance Optimization Package
- Platform TLS Certificate Management Product
- Professional Services
- Related offerings
- Service availability SLA
- Subscriber Provided Prefix
- Summary product definitions
- Support description and SLA
- TLS オプション
- TLS service options
- WAF Quick Start Package
- WAF Support and SLA
- WAF Tuning Package
- WAF Tuning Plus Package
Legacy offerings
These articles provide information about Fastly's legacy offerings.
- Fastly's Legacy Full-site Delivery services
- Fastly's Legacy Media Shield
- Legacy Customer-Provided TLS Certificate Hosting Service
- Legacy Platinum Support and SLA
- Legacy Premium Support and SLA
Third-party information
These articles provide information about third-party technology and services incorporated into the Fastly CDN service.
VCL
Content negotiation
Functions
- accept.charset_lookup()
- accept.encoding_lookup()
- accept.language_filter_basic()
- accept.language_lookup()
- accept.media_lookup()
Cryptographic
Functions
- digest.awsv4_hmac()
- digest.base64_decode()
- digest.base64()
- digest.base64url_decode()
- digest.base64url_nopad_decode()
- digest.base64url_nopad()
- digest.base64url()
- digest.hash_crc32()
- digest.hash_crc32b()
- digest.hash_md5()
- digest.hash_sha1()
- digest.hash_sha224()
- digest.hash_sha256()
- digest.hash_sha384()
- digest.hash_sha512()
- digest.hmac_md5_base64()
- digest.hmac_md5()
- digest.hmac_sha1_base64()
- digest.hmac_sha1()
- digest.hmac_sha256_base64()
- digest.hmac_sha256()
- digest.hmac_sha512_base64()
- digest.hmac_sha512()
- digest.rsa_verify()
- digest.secure_is_equal()
- digest.time_hmac_md5()
- digest.time_hmac_sha1()
- digest.time_hmac_sha256()
- digest.time_hmac_sha512()
Date and time
Functions
- parse_time_delta()
- std.integer2time()
- std.time()
- strftime()
- time.add()
- time.hex_to_time()
- time.is_after()
- time.sub()
Variables
- now.sec
- now
- time.elapsed.msec_frac
- time.elapsed.msec
- time.elapsed.sec
- time.elapsed.usec_frac
- time.elapsed.usec
- time.elapsed
- time.end.msec_frac
- time.end.msec
- time.end.sec
- time.end.usec_frac
- time.end.usec
- time.end
- time.start.msec_frac
- time.start.msec
- time.start.sec
- time.start.usec_frac
- time.start.usec
- time.start
- time.to_first_byte
Edge Side Includes (ESI)
Variables
Floating point classifications
Functions
Geolocation
Variables
- client.as.name
- client.as.number
- client.geo.area_code
- client.geo.city.ascii
- client.geo.city.latin1
- client.geo.city.utf8
- client.geo.city
- client.geo.conn_speed
- client.geo.conn_type
- client.geo.continent_code
- client.geo.country_code
- client.geo.country_code3
- client.geo.country_name.ascii
- client.geo.country_name.latin1
- client.geo.country_name.utf8
- client.geo.country_name
- client.geo.gmt_offset
- client.geo.ip_override
- client.geo.latitude
- client.geo.longitude
- client.geo.metro_code
- client.geo.postal_code
- client.geo.proxy_description
- client.geo.proxy_type
- client.geo.region.ascii
- client.geo.region.latin1
- client.geo.region.utf8
- client.geo.region
- client.geo.utc_offset
Math constants and limits
Variables
- math.1_PI
- math.2_PI
- math.2_SQRTPI
- math.2PI
- math.E
- math.FLOAT_DIG
- math.FLOAT_EPSILON
- math.FLOAT_MANT_DIG
- math.FLOAT_MAX_10_EXP
- math.FLOAT_MAX_EXP
- math.FLOAT_MAX
- math.FLOAT_MIN_10_EXP
- math.FLOAT_MIN_EXP
- math.FLOAT_MIN
- math.INTEGER_BIT
- math.INTEGER_MAX
- math.INTEGER_MIN
- math.LN10
- math.LN2
- math.LOG10E
- math.LOG2E
- math.NAN
- math.NEG_HUGE_VAL
- math.NEG_INFINITY
- math.PHI
- math.PI_2
- math.PI_4
- math.PI
- math.POS_HUGE_VAL
- math.POS_INFINITY
- math.SQRT1_2
- math.SQRT2
- math.TAU
Math rounding
Functions
- math.ceil()
- math.floor()
- math.round()
- math.roundeven()
- math.roundhalfdown()
- math.roundhalfup()
- math.trunc()
Math trigonometric
Functions
- math.acos()
- math.acosh()
- math.asin()
- math.asinh()
- math.atan()
- math.atan2()
- math.atanh()
- math.cos()
- math.cosh()
- math.sin()
- math.sinh()
- math.sqrt()
- math.tan()
- math.tanh()
Miscellaneous
Functions
- addr.extract_bits()
- addr.is_ipv4()
- addr.is_ipv6()
- http_status_matches()
- if()
- setcookie.get_value_by_name()
- std.collect()
- subfield()
Variables
- backend.socket.congestion_algorithm
- backend.socket.cwnd
- bereq.url.basename
- bereq.url.dirname
- bereq.url.qs
- bereq.url
- beresp.backend.ip
- beresp.backend.name
- beresp.backend.port
- beresp.grace
- beresp.hipaa
- beresp.pci
- client.ip
- client.port
- client.requests
- client.socket.pace
- fastly.error
- fastly.ff.visits_this_pop_this_service
- fastly.ff.visits_this_service
- req.backend.healthy
- req.backend.is_cluster
- req.backend.is_origin
- req.backend.is_shield
- req.backend
- req.body.base64
- req.body
- req.grace
- req.http.host
- req.is_ipv6
- req.restarts
- req.url.basename
- req.url.dirname
- req.url.ext
- req.url.path
- req.url.qs
- req.url
- stale.exists
Query string manipulation
Functions
- boltsort.sort()
- querystring.add()
- querystring.clean()
- querystring.filter_except()
- querystring.filter()
- querystring.filtersep()
- querystring.globfilter_except()
- querystring.globfilter()
- querystring.regfilter_except()
- querystring.regfilter()
- querystring.remove()
- querystring.set()
- querystring.sort()
Randomness
Functions
Segmented Caching
Variables
- segmented_caching.autopurged
- segmented_caching.block_number
- segmented_caching.cancelled
- segmented_caching.client_req.is_open_ended
- segmented_caching.client_req.is_range
- segmented_caching.client_req.range_high
- segmented_caching.client_req.range_low
- segmented_caching.completed
- segmented_caching.error
- segmented_caching.failed
- segmented_caching.is_inner_req
- segmented_caching.is_outer_req
- segmented_caching.obj.complete_length
- segmented_caching.rounded_req.range_high
- segmented_caching.rounded_req.range_low
- segmented_caching.total_blocks
Server
Variables
Size
Variables
- bereq.body_bytes_written
- bereq.header_bytes_written
- req.body_bytes_read
- req.bytes_read
- req.header_bytes_read
- resp.body_bytes_written
- resp.bytes_written
- resp.completed
- resp.header_bytes_written
String manipulation
Functions
- cstr_escape()
- json.escape()
- regsub()
- regsuball()
- std.anystr2ip()
- std.atof()
- std.atoi()
- std.ip()
- std.ip2str()
- std.prefixof()
- std.replace_prefix()
- std.replace_suffix()
- std.replace()
- std.replaceall()
- std.str2ip()
- std.strlen()
- std.strpad()
- std.strrep()
- std.strrev()
- std.strstr()
- std.strtof()
- std.strtol()
- std.suffixof()
- std.tolower()
- std.toupper()
- substr()
- urldecode()
- urlencode()
- utf8.codepoint_count()
- utf8.is_valid()
- utf8.strpad()
- utf8.substr()
Table
Functions
TCP info
Variables
- backend.socket.tcpi_advmss
- backend.socket.tcpi_bytes_acked
- backend.socket.tcpi_bytes_received
- backend.socket.tcpi_data_segs_in
- backend.socket.tcpi_data_segs_out
- backend.socket.tcpi_delivery_rate
- backend.socket.tcpi_delta_retrans
- backend.socket.tcpi_last_data_sent
- backend.socket.tcpi_max_pacing_rate
- backend.socket.tcpi_min_rtt
- backend.socket.tcpi_notsent_bytes
- backend.socket.tcpi_pacing_rate
- backend.socket.tcpi_pmtu
- backend.socket.tcpi_rcv_mss
- backend.socket.tcpi_rcv_rtt
- backend.socket.tcpi_rcv_space
- backend.socket.tcpi_rcv_ssthresh
- backend.socket.tcpi_reordering
- backend.socket.tcpi_rtt
- backend.socket.tcpi_rttvar
- backend.socket.tcpi_segs_in
- backend.socket.tcpi_segs_out
- backend.socket.tcpi_snd_cwnd
- backend.socket.tcpi_snd_mss
- backend.socket.tcpi_snd_ssthresh
- backend.socket.tcpi_total_retrans
- client.socket.tcpi_advmss
- client.socket.tcpi_bytes_acked
- client.socket.tcpi_bytes_received
- client.socket.tcpi_data_segs_in
- client.socket.tcpi_data_segs_out
- client.socket.tcpi_delivery_rate
- client.socket.tcpi_delta_retrans
- client.socket.tcpi_last_data_sent
- client.socket.tcpi_max_pacing_rate
- client.socket.tcpi_min_rtt
- client.socket.tcpi_notsent_bytes
- client.socket.tcpi_pacing_rate
- client.socket.tcpi_pmtu
- client.socket.tcpi_rcv_mss
- client.socket.tcpi_rcv_rtt
- client.socket.tcpi_rcv_space
- client.socket.tcpi_rcv_ssthresh
- client.socket.tcpi_reordering
- client.socket.tcpi_rtt
- client.socket.tcpi_rttvar
- client.socket.tcpi_segs_in
- client.socket.tcpi_segs_out
- client.socket.tcpi_snd_mss
- client.socket.tcpi_snd_ssthresh
- client.socket.tcpi_snd_total_retrans
TLS and HTTP
Functions
Variables
- fastly_info.h2.is_push
- fastly_info.h2.stream_id
- fastly_info.is_h2
- tls.client.cipher
- tls.client.ciphers_list_sha
- tls.client.ciphers_list_txt
- tls.client.ciphers_list
- tls.client.ciphers_sha
- tls.client.protocol
- tls.client.servername
- tls.client.tlsexts_list_sha
- tls.client.tlsexts_list_txt
- tls.client.tlsexts_list
- tls.client.tlsexts_sha
UUID
Functions
- uuid.dns()
- uuid.is_valid()
- uuid.is_version3()
- uuid.is_version4()
- uuid.is_version5()
- uuid.oid()
- uuid.url()
- uuid.version3()
- uuid.version4()
- uuid.version5()
- uuid.x500()
Custom VCL
VCL Snippets
API
- Authentication
- Clients
- Account
- Configuration
- Purging
- Historical stats
- Real-time analytics
- Remote logging
- Utilities
- Image optimization
- Web Application Firewall Configuration Set
- Dynamic Servers
- Transport Layer Security
- Fastly-managed TLS subscriptions
- Platform TLS