Environment Variables

All Thunder configuration can be set via environment variables prefixed with EDGE_RUNTIME_. Environment variables take the lowest precedence — CLI flags override them, and manifest-level settings override both where applicable.

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Admin listener

Variable	CLI flag	Default	Description
EDGE_RUNTIME_ADMIN_HOST	--admin-host	127.0.0.1	Bind address for the admin API listener.
EDGE_RUNTIME_ADMIN_PORT	--admin-port	9001	Port for the admin API listener.
EDGE_RUNTIME_API_KEY	--api-key	None	Shared secret for admin API authentication. Sent as Authorization: Bearer <key>.
EDGE_RUNTIME_ADMIN_TLS_CERT	--admin-tls-cert	None	Path to TLS certificate file for the admin listener.
EDGE_RUNTIME_ADMIN_TLS_KEY	--admin-tls-key	None	Path to TLS private key file for the admin listener.

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Ingress listener

Variable	CLI flag	Default	Description
EDGE_RUNTIME_HOST	--host	0.0.0.0	Bind address for the ingress (user-facing) listener.
EDGE_RUNTIME_PORT	--port	9000	Port for the ingress listener.
EDGE_RUNTIME_UNIX_SOCKET	--unix-socket	None	Path to a Unix domain socket. When set, the ingress listener binds to this socket instead of TCP.
EDGE_RUNTIME_TLS_CERT	--tls-cert	None	Path to TLS certificate file for the ingress listener.
EDGE_RUNTIME_TLS_KEY	--tls-key	None	Path to TLS private key file for the ingress listener.

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Isolate resource limits

Variable	CLI flag	Default	Description
EDGE_RUNTIME_MAX_HEAP_MIB	--max-heap-mib	128	Maximum V8 heap size per isolate in MiB.
EDGE_RUNTIME_CPU_TIME_LIMIT_MS	--cpu-time-limit-ms	50000	Maximum CPU time per isolate in milliseconds.
EDGE_RUNTIME_WALL_CLOCK_TIMEOUT_MS	--wall-clock-timeout-ms	60000	Maximum wall-clock time per request in milliseconds.
EDGE_RUNTIME_VFS_TOTAL_QUOTA_BYTES	--vfs-total-quota-bytes	10485760	Total writable bytes in /tmp per isolate.
EDGE_RUNTIME_VFS_MAX_FILE_BYTES	--vfs-max-file-bytes	5242880	Maximum size of a single file in /tmp.

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Security

Variable	CLI flag	Default	Description
EDGE_RUNTIME_DISABLE_SSRF_PROTECTION	--disable-ssrf-protection	false	Set to true to allow outbound requests to private/internal IP ranges. Not recommended for production.
EDGE_RUNTIME_ALLOW_PRIVATE_NET	--allow-private-net	None	Comma-separated list of CIDR ranges to allow even when SSRF protection is enabled. Example: 10.0.0.0/8,172.16.0.0/12.
EDGE_RUNTIME_REQUIRE_BUNDLE_SIGNATURE	--require-bundle-signature	false	Require that deployed bundles are signed.
EDGE_RUNTIME_BUNDLE_PUBLIC_KEY_PATH	--bundle-public-key-path	None	Path to the public key file used to verify bundle signatures.

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Body size limits

Variable	CLI flag	Default	Description
EDGE_RUNTIME_MAX_REQUEST_BODY_SIZE	--max-request-body-size	5242880	Maximum request body size in bytes (5 MiB).
EDGE_RUNTIME_MAX_RESPONSE_BODY_SIZE	--max-response-body-size	10485760	Maximum response body size in bytes (10 MiB).

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Connection limits

Variable	CLI flag	Default	Description
EDGE_RUNTIME_MAX_CONNECTIONS	--max-connections	10000	Maximum concurrent TCP connections on the ingress listener.
EDGE_RUNTIME_RATE_LIMIT	--rate-limit	0 (unlimited)	Maximum requests per second. 0 disables rate limiting.

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Outbound proxy

Variable	CLI flag	Default	Description
EDGE_RUNTIME_HTTP_OUTGOING_PROXY	--http-outgoing-proxy	None	HTTP proxy URL for outbound HTTP requests. Example: http://proxy:3128.
EDGE_RUNTIME_HTTPS_OUTGOING_PROXY	--https-outgoing-proxy	None	HTTP proxy URL for outbound HTTPS requests (CONNECT tunneling).
EDGE_RUNTIME_TCP_OUTGOING_PROXY	--tcp-outgoing-proxy	None	SOCKS5 or HTTP CONNECT proxy for outbound TCP connections.
EDGE_RUNTIME_HTTP_NO_PROXY	--http-no-proxy	None	Comma-separated list of hosts/domains to bypass the HTTP proxy.
EDGE_RUNTIME_HTTPS_NO_PROXY	--https-no-proxy	None	Comma-separated list of hosts/domains to bypass the HTTPS proxy.
EDGE_RUNTIME_TCP_NO_PROXY	--tcp-no-proxy	None	Comma-separated list of hosts/domains to bypass the TCP proxy.

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Isolate pool

Variable	CLI flag	Default	Description
EDGE_RUNTIME_POOL_ENABLED	--pool-enabled	true	Enable the isolate pool. When disabled, a fresh isolate is created per request.
EDGE_RUNTIME_POOL_GLOBAL_MAX_ISOLATES	--pool-global-max-isolates	256	Maximum number of live isolates across all functions.
EDGE_RUNTIME_POOL_MIN_FREE_MEMORY_MIB	--pool-min-free-memory-mib	None	Minimum free system memory in MiB. The pool evicts idle isolates to maintain this threshold.

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Context pool

Variable	CLI flag	Default	Description
EDGE_RUNTIME_CONTEXT_POOL_ENABLED	--context-pool-enabled	false	Enable context pooling within isolates for request-level isolation.
EDGE_RUNTIME_MAX_CONTEXTS_PER_ISOLATE	--max-contexts-per-isolate	10	Maximum V8 contexts per isolate when context pooling is enabled.
EDGE_RUNTIME_MAX_ACTIVE_REQUESTS_PER_CONTEXT	--max-active-requests-per-context	1	Maximum concurrent requests per context.

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OpenTelemetry

Variable	CLI flag	Default	Description
EDGE_RUNTIME_OTEL_ENABLED	--otel-enabled	false	Enable OpenTelemetry export.
EDGE_RUNTIME_OTEL_ENDPOINT	--otel-endpoint	http://localhost:4317	OTEL collector endpoint URL.
EDGE_RUNTIME_OTEL_SERVICE_NAME	--otel-service-name	thunder	Service name reported in OTEL telemetry.
EDGE_RUNTIME_OTEL_PROTOCOL	--otel-protocol	grpc	Export protocol: grpc or http.
EDGE_RUNTIME_OTEL_TRACES_ENABLED	--otel-traces-enabled	true	Enable trace export (when OTEL is enabled).
EDGE_RUNTIME_OTEL_METRICS_ENABLED	--otel-metrics-enabled	true	Enable metrics export (when OTEL is enabled).
EDGE_RUNTIME_OTEL_LOGS_ENABLED	--otel-logs-enabled	true	Enable log export (when OTEL is enabled).
EDGE_RUNTIME_OTEL_TRACES_SAMPLE_RATE	--otel-traces-sample-rate	1.0	Trace sampling rate between 0.0 and 1.0.

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Other

Variable	CLI flag	Default	Description
EDGE_RUNTIME_LOG_FORMAT	--log-format	json	Log output format: json or text.
EDGE_RUNTIME_PRINT_ISOLATE_LOGS	--print-isolate-logs	false	Print console.* output from isolates to the server log. Useful for development.
EDGE_RUNTIME_SOURCE_MAP	--source-map	false	Enable source map support for stack traces.
EDGE_RUNTIME_DNS_DOH_ENDPOINT	--dns-doh-endpoint	https://cloudflare-dns.com/dns-query	DNS-over-HTTPS endpoint for node:dns resolution.
EDGE_RUNTIME_GRACEFUL_SHUTDOWN_TIMEOUT_MS	--graceful-shutdown-timeout-ms	30000	Time to wait for in-flight requests to complete during shutdown.

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Precedence

Configuration values are resolved in this order (highest to lowest precedence):

1. CLI flags — --max-heap-mib 256
2. Environment variables — EDGE_RUNTIME_MAX_HEAP_MIB=256
3. Built-in defaults

Function-level overrides in the deployment manifest can further override server-level defaults for per-isolate settings (heap, CPU, timeout, VFS quotas).